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The Ant Mosaic - Tropical Tree Crops and the Limiting of Pests and Diseases
... and Cecropia spp. in the Neotropics and Barteria fistulosa in Africa, can be found in rainforests where they are able to reach the canopy (Fonseca and Benson 2003;Davidson 2005a;Dejean et al. 2007a). Wilson (1958) first noted that the arboreal ant fauna in tropical rainforests had a patchy distribution, but the notion of an "ant mosaic" appeared later in a series of studies conducted in African cocoa tree plantations (Room 1971;Majer 1972;Leston 1973;Majer 1976aMajer , 1976bTaylor 1977;Jackson 1984b). Cocoa plantations provide an easily attainable "canopy" that allows for the rapid and efficient identification of the ant species occupying each individual tree. ...
... These studies have shown that the canopies of tropical forests and tree crop plantations are occupied by "territorially-dominant" species, or those ant species that defend space per se (i.e., absolute spatial territories), usually from both intra-and some interspecific enemies (Davidson 1998). They are characterized by: (1) extremely populous colonies (several hundred thousand to several million individuals), (2) the ability to build large and/or polydomous nests (carton builders, carpenter ants and weaver ants; Fig. 3), and particularly (3) a highly developed intra-as well as interspecific territoriality that causes their territories to be distributed in a mosaic pattern in the forest canopies (Leston 1973). Hölldobler and Lumsden (1980) showed, for instance, that territorially-dominant species such as Oecophylla gain a considerable advantage by excluding conspecific aliens and other dominant ant species from their "absolute territory" rather than only from their nests and food resources. ...
... An intermediary status, known as "sub-dominant", corresponds to species that generally act as non-dominants but which are able, under certain conditions, to defend territories in the same way as do dominants (Majer 1972(Majer , 1993Leston 1973;Hölldobler andWilson 1977, 1978;Hölldobler 1979Hölldobler , 1983Majer et al. 1994). A colony of a non-dominant species reaches the status of sub-dominant when it is able to occupy an entire tree crown and exclude neighboring dominant species from its trees (plantations: Majer 1976aMajer , 1976bmangrove: Dejean et al. 2003). ...
After first being ground-nesters and predators or scavengers, ants became arboreal with the rise of angiosperms and provided plants a biotic defense by foraging for prey on their foliage. Plants induce ants to patrol on their leaves through food rewards (e.g., extra-floral nectar and food bodies), while ants attend hemipterans for their honeydew. Most arboreal-nesting ants build their own nests, but myrmecophytes, plants that offer hollow structures that serve as nesting places to specialized "plant-ants", illustrate the tight evolutionary bonds between ants and plants. In tree-crop plantations and in some rainforest canopies territorially-dominant arboreal ants have large colonies with large and/or polydomous nests. Their territories are defended both intra-and interspecifically, and are distributed in a mosaic pattern, creating what has become known as "arboreal ant mosaics". They tolerate non-dominant species with smaller colonies on their territories. Arboreal ant mosaics are dynamic because ant nesting preferences differ depending on the species and the size and age of supporting trees. Because the canopy is discontinuous, arboreal-foraging ants can be found in ant mosaics; invasive ants can affect also the structure of the mosaic. We discuss here the methods that permit us to study these mosaics. Territorially-dominant arboreal ants are good predators that use group ambushing to catch flying insects on their host tree foliage. When producing winged sexuals they also forage for prey on the ground and plunder the colonies of non-dominant species sharing their host tree. When expanding their territories, the workers of the victorious colony raid the defeated colony. Because territorially-dominant arboreal ants prey on herbivores and strongly affect their general activity, ants are frequently used as biological control agents.
... Parmi les fourmis arboricoles, les espèces « territorialement dominantes » sont abondantes numériquement et leurs colonies très populeuses défendent les territoires étendus (plusieurs arbres voisins) (Leston, 1973 ;Dejean et al., 2007), et sont distribuées en modèle de mosaïque, créant ce qui est devenu notoire en tant que « mosaïque de fourmis » (Leston, 1973 ;Hölldobler et Wilson, 1990). En conséquence, chaque espèce simple de fourmi monopolise généralement un arbre (soit nidifiant au sol, soit arboricole) dont le territoire se prolonge à d'autres arbres (Dejean et al., 2008b). ...
... Parmi les fourmis arboricoles, les espèces « territorialement dominantes » sont abondantes numériquement et leurs colonies très populeuses défendent les territoires étendus (plusieurs arbres voisins) (Leston, 1973 ;Dejean et al., 2007), et sont distribuées en modèle de mosaïque, créant ce qui est devenu notoire en tant que « mosaïque de fourmis » (Leston, 1973 ;Hölldobler et Wilson, 1990). En conséquence, chaque espèce simple de fourmi monopolise généralement un arbre (soit nidifiant au sol, soit arboricole) dont le territoire se prolonge à d'autres arbres (Dejean et al., 2008b). ...
... Hémiptères pour obtenir du miellat, et leur compétence à capturer les proies (Leston, 1973 ;Dejean et al., 2007). Les ouvrières de fourmis arboricoles d"Afrique « territorialement dominantes » patrouillent fréquemment la base du tronc de l"arbre hôte et chassent même des arthropodes qui s"y trouvent (Dejean et Corbara, 2003). ...
Cette recherche est un travail sur l'inventaire de la faune sur les plantes C. peltata rencontrées sur les rives gauche et droite de la Dibamba. Elle a été réalisée en 2012.
Lien pour accéder à l'ouvrage:
https://www.morebooks.de/store/gb/book/la-myrm%C3%A9cofaune-de-la-plante-cecropia-peltata-l-en-afrique-centrale/isbn/978-620-2-28003-7
... Ants are extremely efficient foragers, with large numbers of workers constantly monitoring large areas and rapidly mass-recruiting nest mates to exploit discovered food items. They are among the leading invertebrate predators in most terrestrial habitats, and in the tropics dead insects are scavenged within minutes (Carroll and Janzen 1973;Leston 1973;Hölldobler and Wilson 1990 and references therein). Ant predation protects plants from their herbivores: a colony of Formica rufa Linnaeus fed upon 21 700 caterpillars (Lepidoptera and Symphyta) in a day, and one of F. polyctena Förster took about six million prey items per year from a 0.33 ha plot (Hölldobler and Wilson 1990 and references therein). ...
... In New York State, United States of America, they disperse 37-48% of aboveground herbaceous biomass, half of all stems (Handel et al. 1981). Major insect pollinators (bees, some Diptera) may have flourished in this role at least in part through resistance to predation by ants (Leston 1973), and flowers may have evolved characters to exclude them (Faegri and van der Pijl 1979). In these ways, ants strongly influence differential floral and invertebrate patchiness, taxon compositions and diversities across the landscape, and so are a major factor controlling overall biotic composition, diversity, and distributions (Leston 1978;Gilbert 1980;Majer 1983). ...
... While molecular analyses indicate that many higher-level ant taxa were established in the Cretaceous, only a few are confirmed by fossils Moreau et al. 2006;LaPolla et al. 2013). Most recent hypotheses on the diversification of ants use "diversification" to mean divergence of their higher-level sub-taxa, although a few concern increase of richness at lower levels, which we mean here (e.g., see differing meanings by Leston 1973;Wilson and Hölldobler 2005;Moreau et al. 2006;Dunn et al. 2007;Dlussky and Wedmann 2012;Lucky et al. 2013;Ward 2014). The Cretaceous fossil record suggests a low community presence and impact of small numbers of individuals and species (Zherikhin 2002;Barden and Grimaldi 2016). ...
Most major modern families of Hymenoptera were established in the Mesozoic, but the diversifications within ecologically key trophic guilds and lineages that significantly influence the character of modern terrestrial ecosystems – bees (Apiformes), ants (Formicidae), social Vespidae, parasitoids (Ichneumonidae), and phytophagous Tenthredinoidea – were previously known to occur mostly in the middle to late Eocene. We find these changes earlier, seen here in the early Eocene Okanagan Highlands fossil deposits of western North America. Some of these may have occurred even earlier, but have been obscured by taphonomic processes. We provide an overview of the Okanagan Highlands Hymenoptera to family level and in some cases below that, with a minimum of 25 named families and at least 30 when those tentatively assigned or distinct at family level, but not named are included. Some are poorly known as fossils (Trigonalidae, Siricidae, Peradeniidae, Monomachidae), and some represent the oldest confirmed occurrences (Trigonalidae, Pompilidae, Sphecidae sensu stricto , Peradeniidae, Monomachidae, and possibly Halictidae). Some taxa previously thought to be relictual or extinct by the end of the Cretaceous (Angarosphecidae, Archaeoscoliinae, some Diapriidae) are present and sometimes abundant in the early Eocene. Living relatives of some taxa are now present in different climate regimes or on different continents.
... Generalist predators, such as the weaver ant, Oecophylla longinoda (Latreille) (Hymenoptera: Formicidae: Formicinae), play an important role in orchard, forest and savanna ecosystems in sub-Saharan Africa (Leston 1973 ). Weaver ants are highly effective and effi cient in controlling arthropod pests in perennial crops due to their tireless predatory activities (Dejean 1991 ). ...
... Various authors have revealed the importance of different patterns of vegetation on O. longinoda distribution (Leston 1973 ;Room 1971 ;Majer 1972 ;Way 1963 ). Many types of vegetation can support O. longinoda , and vegetation manipulation can induce changes in the ant-mosaic. ...
... There are reports of O. longinoda signifi cantly reducing damage in cocoa due to Distantiella theobroma (Distant) (Room 1971 ;Majer 1972 ), and in coconut due to Pseudotheraptus wayi Brown (Simmonds 1924 ;Way 1951Way , 1953Vanderplank 1960 ). Studies in Ghana have also shown that the presence of O. longinoda reduces the incidence of two serious diseases of cocoa that are transmitted by a mirid bug and they suggest that this was because O. longinoda workers were effi cient in capturing phytophagous insects, especially the cacao mirid bugs (Leston 1973 ). ...
Generalist predators such as the weaver ant, Oecophylla longinoda (Latreille), play an important role as biological control agents in West African orchards and, by extension, also in forest and savanna ecosystems within sub-Saharan Africa. These weaver ants are one of the most effective and efficient predators of arthropods in perennial tropical tree crops; their presence also acts as a deterrent to insect herbivores, particularly tephritid female fruit flies, due to the semiochemicals they produce. Emerging African markets for organic and sustainably-managed fruits and nuts have encouraged an interest in the use of weaver ants. Protection of tropical forests and savannas is ecologically and environmentally crucial and also essential for the protection of O. longinoda.
... According to ant mosaic theory, dominant ant species (i.e. both numeric and behavioral dominance) are mutually exclusive in their territories (Leston 1973). Dominant ant species often exploit very important amounts of resources (e.g. ...
... Dominant ant species often exploit very important amounts of resources (e.g. nectar rewards) and only coexist with submissive and/or opportunistic ant species (Room 1971, Leston 1973, 1978, Savolainen and Vepsalainen 1988, Arnan et al. 2011. Therefore, dominant ant species are thought to play a key role in structuring local ant communities and species composition by aggressively displacing competitors (Andersen 1992, Arnan et al. 2011, Camarota et al. 2020, Mottl et al. 2021. ...
Ants often interact aggressively for resources (e.g. nest sites and food) with members of their own or another species. In these competitive interactions, dominant ant species exert a strong influence on ant species coexistence and plant-associated arthropod community structure. However, few studies have experimentally manipulated the relative abundance of dominant ant species on plants, preventing a mechanistic understanding of the effects of ant competitive interactions on ant community structure as well as on their interactions with other insects, particularly mutualistic hemipterans. In this study, we performed a field experiment in a tropical dry forest in Brazil to investigate the effects of two dominant ant species (Camponotus crassus and Cephalotes pusillus) on the structure ant communities and the abundance of the ant-tended hemipteran Enchenopa brasiliensis in Solanum lycocarpum plants. For this, we identified and quantified all ant species foraging on plants and estimated the number of egg masses, nymphs and adults of the mutualistic hemipteran before and after experimentally removing nests of both two dominant ant species. Our results showed that removal of C. pusil-lus nests significantly changed ant community structure, whereas removal of C. crassus nests did not. We also found that nest removal of both dominant ant species had significant effects on hemipteran abundance. In particular, plants generally hosted more hemipteran eggs, nymphs and adults after (vs before) nest removal of both dominant ant species. Overall, this study demonstrates that dominant ant species can play a pivotal role in structuring ant communities and the interactions between ants and honeydew-producing hemipteran insects.
... The citrus growers in China were pioneers in biological control using ants centuries ago [7]. Over time, these organisms have been used to control pests around the world, such as Spodoptera exempta (Walk.) in Kenya [8], forest pests in Canada [9], cocoa pests in Ghana [10], crop pests in Nigeria [11] and many other pests in different countries [12,13]. Despite the gradual evolution over time in the use of ants against pests, a major challenge still is to identify positive and negative ant-crop matches, using management to boost positive effects (services) and decrease negative effects (disservices) [14]. ...
... Overall, these studies provided 857 cases (gathered through effect size estimates) for our analyses. Despite the existence of pioneering studies (see [9][10][11][12][13]), studies prior to 1987 that were located did not meet the inclusion criteria. Therefore, our review included studies carried out in the last 35 years. ...
Environmental impacts of conventional agriculture have generated interest in sustainable agriculture. Biological pest control is a fundamental tool, and ants are key players providing ecological services, as well as some disservices. We have used a meta-analytical approach to investigate the contribution of ants to biological control, considering their effects on pest and natural enemy abundance, plant damage and crop yield. We also evaluated whether the effects of ants are modulated by traits of ants, pests and other natural enemies, as well as by field size, crop system and experiment duration. Overall (considering all meta-analyses), from 52 studies on 17 different crops, we found that ants decrease the abundance of non-honey-dew-producing pests, decrease plant damage and increase crop yield (services). In addition, ants decrease the abundance of natural enemies, mainly the generalist ones, and increase honeydew-producing pest abundance (disservices). We show that the pest control and plant protection provided by ants are boosted in shaded crops compared to monocultures. Furthermore, ants increase crop yield in shaded crops, and this effect increases with time. Finally, we bring new insights such as the importance of shaded crops to ant services, providing a good tool for farmers and stakeholders considering sustainable farming practices.
... Arboreal ant communities are structured by interactions among ant species, food availability, and physical structures within the environment. Competition among a small number of dominant arboreal ant species can result in the formation of arboreal ant mosaics (Leston 1973). Ant mosaics are best visualized as a patchwork formation in which dominant species maintain distinct territories. ...
... Ant mosaics are best visualized as a patchwork formation in which dominant species maintain distinct territories. Most of the early work on ant mosaics was conducted in relatively simple, plantation ecosystems (e.g., Room 1971, Majer 1972, Leston 1973 and their existence in natural systems is a subject of debate (Floren and Linsenmair 2000, Ribas and Schoereder 2002, Blüthgen and Stork 2007. Competition among dominant ants may play a major role in structuring ant communities (Parr and Gibb 2010), but other factors are also integral to explaining their composition. ...
Arboreal ant communities are primarily structured by interactions among ant species, food availability, and physical structures within the environment. Epiphytes are a common feature of tropical forests that can provide ants with both food and nesting space. To date, little work has examined what role epiphytic ant-plants play in structuring arboreal ant communities. We surveyed ant species inhabiting the Australian epiphytic ant-plant Myrmecodia beccarii Hook.f. (Gentianales: Rubiaceae) and how arboreal ant communities are structured in relation to M. beccarii presence on trees. Myrmecodia beccarii was inhabited by the ant Philidris cordata Smith, F. (Hymenoptera: Formicidae) on the majority of Melaleuca viridiflora Sol. Ex Gaertn. (Myrtales: Myrtaceae) trees with ant-occupied ant-plants at our two sites. Dominant arboreal ant species at both study sites exhibited discrete, nonoverlapping distributions, and C-score analysis detected an ant mosaic at one site. The distribution of P. cordata was limited by the distribution of ant-plants for both sites. Philidris cordata dominance on trees was also determined by the presence of M. beccarii occupied by P. cordata at both sites. We suggest that by providing P. cordata with nesting space M. beccarii plays a role in structuring these arboreal ant communities.
... Earlier work in West African cocoa plantations has indicated that certain ants are numerically and behaviorally dominant and tend to be distributed in mutually exclusive territories, resulting in the formation of a densely packed ant mosaic (Majer 1972;Leston 1973). Some of these dominants, notably Oecophylla longinoda Latreille and to a lesser extent Tetramorium aculeatum (Mayr) (Macromischoides aculeatus in earlier articles), have the beneficial effect of reducing pest occurrence or abundance, while others such as Crematogaster spp. ...
... Thirdly, the microhabitat differed between the two plantations as the result of different age of the plantation and the type of the soil (red rich volcanic soil in Howe's coffee plantation versus sandy soil in Skybury coffee plantation), so this may also have been a factor. Other studies suggest that species-specific microhabitat requirements may play an important role in shaping ant distribution (Leston 1973;Majer 1976;Way and Bolton 1997), which supports the latter possible reason. ...
Native ants are the oldest example of biological control agents used in tropical tree crops. Unfortunately, intensification of agricultural practices has led to a simplification of habitat and subsequent loss of native ant biodiversity. This article describes research that evaluated the native and introduced ants present in the canopies of two Australian sun coffee plantations, their distribution pattern and their potential to limit pests. The presence in coffee plantations of a range of beneficial insects and parasites, plus the effect of ants, most notably Iridomyrmex suchieri Forel, may maintain potential pests at low levels in coffee plantations. These effects may be important for future biological control programs of coffee pests in Australia, although the sun coffee grown here does not harbor a large variety of canopy ant species.
... The interest in using ants for biological control has been especially intense in tropical parts of Africa, with foundation studies having been undertaken across the western part of the continent from Guinea (Van Mele et al. 2009), Ivory Coast (Kone et al. 2012, Ghana (Leston 1973), Benin (Van Mele et al. 2007), Nigeria (Taylor & Adedoyin 1978) and Cameroon (Dejean et al. 2008) and also in east Africa, most notably Tanzania (Zanzibar) (Way 1953). Some related studies have also been undertaken in Uganda (Schulz & Wagner 2002). ...
... Only five ant species were found in the canopy of this plantation of Rwandan coffee and all were predominantly ground-nesting species. In stark contrast to the aforementioned studies in the other plantations throughout tropical Africa, there was a complete absence of dominant arboreal ants such as Oecophylla longinoda Latreille, Tetramorium aculeatum (Mayr) and the various Crematogaster spp. that commonly dominate canopy (Leston 1973;Taylor & Adedoyin 1978). The diversity of ants was also much lower than all of the studies mentioned earlier, including the 13 ant species found in a Nigerian coffee plantation (Taylor 1977). ...
Native ants are the oldest example of biological control agents used in tropical tree crops. Unfortunately, intensification of agricultural practices has led to a simplification of habitat and subsequent loss of native ant biodiversity. This paper describes an evaluation of the ants present in a Rwandan coffee plantation. The plantation was unshaded, intensively managed and regularly treated with pesticides. No herbicides or fertilisers were used, although the area had been mulched. Only five ant species were found in the plantation (Pheidole megacephala, Lepisiota depressa, Nesomyrmex angulatus and Camponotus (Myrmosericus) spp. (2 spp.). Pheidole megacephala dominated the plantation and occurred on 94 % of trees, while L. depressa, C. (Myrmosericus) spp. and N. angulatus each occurred on 13 % or less of trees. Pheidole megacephala and L. depressa were negatively associated, whereas C. (Myrmosericus) spp. were positively associated with L. depressa. Association between the coffee pests and ant species was not significant. We conclude that intensification of coffee production in this plantation and domination by P. megacephala has contributed to the low diversity of ants present and that those species that do occur there are not particularly efficient at reducing pest densities.
... For example, recent measurements suggest that ants and termites compose one third of the entire animal biomass of the Amazonian upland rainforest (Wilson, 1987). In Guianan cacao plantations, ants constitute 89% of the total insect numbers (Leston, 1973) and up to 70% of the arthropod biomass (Majer, 1976). In Ibarra-N6iiez's study (1990), ants represented 12.2% of the total arthropods. ...
... data). These swarming ants usually are mutually exclusive, forming a mosaic of dominant ants with associated nondominant species in the canopy of shade trees (Leston, 1973;Majer, 1972Majer, , 1976. Recent studies in Mexico suggest that these swarming ants nest primarily in the shade trees and their foraging area includes several adjacent coffee bushes (Philpott, unpubl. ...
... Consequently, these territories are distributed in a mosaic pattern when they are numerous enough to be contiguous, creating what has become to be known as "arboreal ant mosaics" (Room, 1971;Leston, 1973;Taylor, 1977;Majer, 1993;Blüthgen & Stork, 2007). Because TDAs protect their host trees through their predatory behavior and/or by deterring defoliating insects (Room, 1973;Taylor, 1977;Way & Khoo, 1992;Majer, 1993;Dejean et al., 1997) or because they displace ground-nesting, arboreal-foraging ant species (Taylor & Griffin, 1981;Kenne et al., 2003), certain of them are recognized as potential biological control agents. ...
... Among the TDAs rather associated with A. vogelii trees of different heights (maps 16-21; Fig. 1E), it is well known that O. longinoda, Cr. Striatula, and T. aculeatum are frequent in tree crop plantations, forest edges, and in secondary forests (Leston, 1973;Majer, 1993;Dejean et al., 1997;Kenne et al., 2003;Taylor, 2013). The other TDAs are rather associated with L. alata. ...
Ants, the most abundant taxa among canopy-dwelling animals in tropical rainforests, are mostly represented by territorially-dominant arboreal ants (TDAs) whose territories are distributed in a mosaic pattern (arboreal ant mosaics). Large TDA colonies regulate insect herbivores, with implications for forestry and agronomy. What generates these mosaics in vegetal formations, which are dynamic, still needs to be better understood. So, from empirical research based on three Cameroonian tree species (Lophira alata, Ochnaceae; Anthocleista vogelii, Gentianaceae; and Barteria fistulosa, Passifloraceae), we used the Self-Organizing Map (SOM, neural network) to illustrate the succession of TDAs as their host trees grow and age. The SOM separated the trees by species and by size for L. alata, which can reach 60 m in height and live several centuries. An ontogenic succession of TDAs from sapling to mature trees is shown, and some ecological traits are highlighted for certain TDAs. Also, because the SOM permits the analysis of data with many zeroes with no effect of outliers on the overall scatterplot distributions, we obtained ecological information on rare species. Finally, the SOM permitted us to show that functional groups cannot be selected at the genus level as congeneric species can have very different ecological niches, something particularly true for Crematogaster spp. which include a species specifically associated with B. fistulosa, non-dominant species and TDAs. Therefore, the SOM permitted the complex relationships between TDAs and their growing host trees to be analyzed, while also providing new information on the ecological traits of the ant species involved. This article is protected by copyright. All rights reserved.
This article is protected by copyright. All rights reserved.
... Se considera que el primer caso conocido de control biológico fue realizado en el siglo IV antes de Cristo por los chinos empleando hormigas (Vandermeer 1999). También se han usado mosaicos de hormigas para el manejo de plagas y enfermedades fitosanitarias en Ghana (Majer 1972;Leston 1973;Majer 1976), Asia con Dolichoderus thoracicus (Smith, 1860) (Way y Khoo 1992; Perfecto y Castiñeiras 1998) y Brasil (Delabie 1990;Medeiro et al. 1995). Way y Khoo (1992) discutieron las características valiosas que tienen las hormigas como grupo benéfico para el control de plagas y consideraron que algunas mezclas de cultivos pueden estimular las especies benéficas de control biológico en cultivos de palmas, coco y cacao. ...
... Se considera que el primer caso conocido de control biológico fue realizado en el siglo IV antes de Cristo por los chinos empleando hormigas (Vandermeer 1999). También se han usado mosaicos de hormigas para el manejo de plagas y enfermedades fitosanitarias en Ghana (Majer 1972;Leston 1973;Majer 1976), Asia con Dolichoderus thoracicus (Smith, 1860) (Way y Khoo 1992; Perfecto y Castiñeiras 1998) y Brasil (Delabie 1990;Medeiro et al. 1995). Way y Khoo (1992) discutieron las características valiosas que tienen las hormigas como grupo benéfico para el control de plagas y consideraron que algunas mezclas de cultivos pueden estimular las especies benéficas de control biológico en cultivos de palmas, coco y cacao. ...
Los árboles aislados en agroecosistemas favorecen la biodiversidad asociada y pueden promover funciones como la depredación. Se examinó si la presencia de los árboles afecta la presencia y actividad de depredación de las hormigas en potreros y cafetales en dos regiones del suroccidente Andino colombiano. Además, se exploró si durante la estación seca las hormigas arbóreas descienden de los árboles hacia el sistema productivo para depredar. Durante las épocas seca y lluviosa del año 2006 se realizaron muestreos intensivos de hormigas forrajeras de suelo en 16 lotes de Pescador y Dagua. En cada lote se instalaron 10 trampas de caída por 96 h. Por otra parte, se ofrecieron adultos de Drosophila melanogaster como presa, adheridas en papel o Cinta de enmascarar, colocadas a 1m y 5m de distancia de un árbol y, sobre éste, a 1.5 m de altura. Se encontraron diferencias significativas en la riqueza e identidad de hormigas en cada localidad, indicando como mayor factor la barrera geográfica de la cordillera Occidental. Generalmente las presas fueron consumidas en 24 h; sin embargo, el consumo estuvo influenciado por la presencia de árboles, pues la depredación fue mayor a 1 m que a 5 m del árbol. Las hormigas concentraron su actividad sobre el suelo en la época seca. Linepithema neotropicum, reclutadora masiva, depredó activamente en ambas localidades. Los resultados apuntan a que los árboles pueden favorecer la fauna de hormigas y la depredación.
... In tree-crop plantations, particularly in mango-citrus plantations in West Africa, territorially dominant arboreal Oecophylla ants have large colonies with large and/or polydomous nests. As biocontrol agents they are closely adapted to many species of fruit-trees where several ant species Territories marked by workers with their deposits or landmarks are distributed in a mosaic pattern creating what has become known as "arboreal ant mosaics" (Dejean et al., 1997;Hölldobler & Wilson, 1990;Leston, 1973;Majer, 1972;Room, 1971). They are effective predators that have developed strategies allowing them to attack other arthropods on their host trees as to feed on some of their associated hemipteran also called trophobionts (Vanderplank, 1960). ...
The African weaver ant Oecophylla longinoda builds woven leaf nests inside tree canopies and is a major conservation biocontrol agent in sub‐Saharan Africa. Weaver ant colonies provide well‐protected and resource‐rich environments for many associated trophobionts, thereby boosting their establishment on host plants.
There is very little published literature on O. longinoda , their hosts plants and their associated trophobionts in West Africa. These tri‐trophic interactions were studied over a period of four consecutive years (2010–2013) from south to north Benin.
Our fieldwork revealed that all O. longinoda colonies were consistently associated with trophobionts . Oecophylla longinoda nests were recorded on 82 plant species belonging to 30 families, with 35 associated trophobiont species representing 11 families.
Among cultivated plants, Mangifera indica was the most common species hosting O. longinoda , while Sarcocephalus latifolius the most frequent native one. Among trophobionts, Parasaissetia nigra , Udinia catori , Udinia farquharsoni (Coccidae) and Stictococcus sjostedti (Stictococcidae) were the most common hemipterans associated with O. longinoda .
We identified a wide range of host plants that could be preserved (or planted) to promote the establishment of weaver ants to control different insect pests in fruit plantations in sub‐Saharan Africa. When planted around fruit plantations with their nests and tended hemipterans, these host plants could facilitate biocontrol of mango fruit flies (Tephritidae) and cashew bugs (Coreidae, Miridae), by O. longinoda in the fruit plantations.
... In ant mosaics, three hierarchical dominance status are commonly cited in the literature: dominant, sub-dominant and non-dominant. This classification rests on their behavioral and numerical dominance [1,2]. Behavioral dominance is defined as dominance in the inter-specific encounter competition, due to superior fighting and/or recruitment abilities; and numerical dominance as predominance of particular species in numbers, biomass and/or frequency of occurrence in ant communities [3]. ...
... In the Solomon Islands, O'Connor (1950) recommended the use of a cover crop in coconut groves to improve the biological control of coreid pests by the ant Oecophylla smaragdina subnitida. In Ghana, coconut gave light shade to cocoa and, without apparent crop loss, supported high populations of Oecophylla longinoda, keeping the cocoa crop free from cocoa capsids (Leston 1973). ...
This book contains 14 chapters discussing the field of habitat manipulation and how ecological engineering approaches to pest management can be developed and applied. Chapters explore the frontiers of ecological engineering methods including molecular approaches, high-tech marking and remote sensing. They also review the theoretical aspects of this field and how ecological engineering may interact with genetic engineering. The wide array of habitat manipulations currently include agroforestry, biological control, crop rotations, crop diversity, flower strips, natural enemy refuges, trap crops and other technologies. Each of these technologies and combinations of these pest suppression technologies, offers opportunities to reduce crop losses to pests while at the same time reducing the use of pesticides and providing potentially valuable habitat for wildlife conservation.
... The tendency for species to exclude one another is interpreted as an indication of the presence of a mosaic. Chisquare independence tests were firstly used (Leston, 1973;Majer et al., 1994;Blüthgen & Stork, 2007), but, subsequently, the use of null models became widespread. Null models compare observed species co-occurrence on trees with randomised matrices of species co-occurrences used as benchmarks to determine if the observed pattern of exclusion is more or less frequent than observed by chance (Gotelli & Graves, 1996). ...
• Ants are omnipresent in tropical forests, especially territorially dominant arboreal ants whose territories are spatially segregated forming ‘ant mosaics’. These ecologically important species are rarely used in conservation monitoring because of the difficulty in collecting them. We developed a standardised baitline protocol to study the distribution of dominant ants on canopy trees and also a procedure to objectively define species dominance, even in unknown ant assemblages.
• Besides eliminating the need to climb trees, this protocol allows live arboreal ant specimens to be sampled at different heights. Behavioural aggressiveness assays between the collected workers provide data on the three‐dimensional distribution of colonies and on interactions between species. We compared the results of the behavioural tests to those from null models.
• In the New Guinean lowland forest studied, we show that the canopy was either shared by multiple territorial species or inhabited by a single species with a large territory. The baitline protocol collected up to half of the arboreal ant species found in a felling census. However, the proportion of species collected at baits decreased with the increasing spatial dominance of single territorial species.
• Behavioural observations used in the protocol allowed a more efficient detection of ant mosaics than null models. Territorially dominant ants were active on both understorey and canopy trees.
• The protocol is fast and easy to replicate. It is a potential tool for understanding and monitoring the spatiotemporal dynamics of arboreal ant assemblages and can detect populous colonies, including those of invasive species.
... For instance, TDAAs may monopolise valuable resources over time and space (Majer, 1993;Dejean et al., 2007;Ribeiro et al., 2013;Adams, 2016), leading to a partitioning of the resource in zones of the canopy (Ribeiro et al., 2013;Yusah et al., 2018). The spatial and temporal segregation of dominant arboreal ants whose territories do not overlap has been characterised as an 'ant mosaic' in some tropical systems (Majer, 1972;Leston, 1973). In this context, there is consistent evidence showing increased competition among ant species or colonies for control of those areas in tree crowns where resources are concentrated (Blüthgen et al., 2000(Blüthgen et al., , 2004Ribeiro et al., 2013). ...
• Tropical trees accommodate a high co‐occurrence of ant species, mainly due to the high diversity of microhabitats available. However, a few ant species are highly abundant, dominating resources and defending territories in tree canopies. Although arboreal ants have been studied extensively, little is known about the structural drivers of ant spatial dominance in tropical rainforest canopies.
• This study investigated whether canopy tree microhabitats and micro‐environmental factors (given by branch characteristics and spatial position of sampling points within tree crowns) are determinants of ant presence and species composition in a Mexican tropical rainforest. It also analysed whether whole tree characteristics, that is, the tree canopy, given by tree size and epiphyte/climbing plant richness and abundance, could determine ant spatial dominance of food resources.
• This study found a higher probability of ant presence on baits lower in the canopy, probably a result of ants foraging in the zones between the treetops and the ground layer. No microhabitat or micro‐environmental variables were related to ant species composition. It also observed less dissimilarity of species composition between baits and between trees than between plots, revealing that each plot presents a unique set of species.
• Moreover, increased tree height and epiphyte/climbing plant abundance (i.e., structural heterogeneity and greater foraging area) and lower epiphyte/climbing plant richness led to decreasing ant dominance.
• This study's findings reveal that, while micro‐environmental factors have almost no influence on the foraging of dominant ant species within canopy trees, the size and heterogeneity of trees shape ants' spatial dominance.
... The seasonal changes in circadian activity patterns probably explained by some authors have reported O. smaragdina to be primarily diurnal (Greenslade, 1971(Greenslade, , 1972Holldobler, 1979;Holldobler and Wilson, 1978), while others have observed substantial nocturnal foraging (Leston, 1973;Weber, 1949). The effects of varying climates and levels of inter-specific competition may also influence patterns of activity. ...
... The present study results are in accordance with Leston (1973) who stated that colonies of weaver ants in cocoa plantations in Ghana can cover over 20 trees, and it is also asserted by Taylor and Adedoy (1978) whom inferred that colonies in Nigeria may occupy over 100 cocoa trees. These differences in colony sizes could be caused by vegetation influences, such as tree density, tree condition, levels of canopy interconnection, amount of under storey growth, and the proximity of native forest vegetation. ...
... The hymenopterans were dominated by ant species which formed the bulk of the insect biomass. Studies by various workers (Leston, 1973;Room, 1971Room, , 1975 point to the fact that in general, ants tend to dominate the abundance and species richness of the arthropod fauna of many tropical ecosystems. Badejo (1982) highlighted that the high level • NIGERIAN JOURNAL OF ENTOMOLOGY -Volume 33. ...
... In Tanzania, Way (1951) and Vanderplank (1960) also highlighted the efficiency of O. longinoda against Pseudotheraptus wayi Brown in coconut palms. Some studies undertaken in Ghana showed that the presence of O. longinoda reduced the incidence of two major cacao diseases transmitted by mirid bugs captured by weaver ants (Leston, 1973). ...
Description. In West Africa, fruit trees are a crucial but often neglected component of people's lives and more than 50% of fruit crops are thought to be lost to insect pests every year. The relatively low adoption rate of old-IPM practices underpins the need to take up challenges and propose new pioneering control methods, such as using weaver ants in cashew plantations. Literature. The genus Oecophylla is represented by two tropical species, Oecophylla longinoda (Latreille) and Oecophylla smaragdina (Fabricius), occurring in sub-Saharan Africa and Australasia, respectively. In southern China, but also in Vietnam, weaver ant husbandry is a centuries-old tradition. Positive ant-managing experiences from Asia have generated some recent interest in Africa. In sub-Saharan Africa, cashew production is severely constrained by infestations of several insect pests. Sap-sucking bugs, leaf miners and trunk-branch borers are pests that adversely affect yields (total losses of up to 80%) and the quality of harvestable nuts. Recent studies have highlighted the positive role of weaver ants against these insect pests in cashew plantations of Benin, Ghana and Tanzania. Finally, O. longinoda provided four comparative advantages for cashew production i) better yields, ii) larger nuts, iii) higher proportions of marketable kernel mass and iv) a potential fertilization effect. Conclusions. The "weaver ant technology" could be more widely used in sub-Saharan Africa because it is i) effective, ii) low-cost, iii) labour-saving, iv) self-regenerating. It is thus particularly suitable for low-resource smallholder farmers in sub-Saharan cashew plantations and also for mango, citrus, guava plantations. Les planteurs africains ont des alliées étonnants dans leurs plantations d'anacardiers Description. En Afrique de l'Ouest, les fruitiers constituent une composante cruciale pour le développement des populations rurales mais une composante souvent sous-valorisée avec plus de 50 % de pertes dues aux insectes. Le taux d'adoption relativement faible des anciennes méthodes de lutte intégrée pourrait être un argument supplémentaire pour faire face aux défis et proposer de nouvelles méthodes de lutte novatrices comme la gestion des fourmis oecophylles dans les plantations d'anacardiers. Littérature. Le genre Oecophylla est représenté par deux espèces tropicales Oecophylla longinoda (Latreille) et Oecophylla smaragdina (Fabricius), d'Afrique sub-Saharienne and d'Australasie, respectivement. Dans le sud de la Chine mais aussi au Vietnam l'élevage des oecophylles est une très vieille tradition (pluri-centenaire). Les expériences asiatiques positives d'utilisation des oecophylles ont éveillé l'intérêt du secteur rural Africain. En Afrique sub-Saharienne, la production d'anacarde est sévèrement pénalisée par les infestations de plusieurs types de ravageurs dont les punaises piqueuses des fruits, les mineuses des feuilles, les foreurs de troncs et branches, ravageurs qui affectent négativement les rendements (pertes globales jusqu'à 80 %) et la qualité des noix. Des études récentes ont mis en évidence qu'O. longinoda était un agent de contrôle biologique efficace contre ces ravageurs au Bénin, au Ghana et en Tanzanie. Au final, O. longinoda fournit quatre avantages comparatifs aux producteurs d'anacardes à savoir i) l'augmentation des rendements, ii) une taille plus importante des noix, iii) une proportion plus importante des amandes commercialisables, et iv) une amélioration potentielle de la fertilisation.
... In Tanzania, Way (1951) and Vanderplank (1960) also highlighted the efficiency of O. longinoda against Pseudotheraptus wayi Brown in coconut palms. Some studies undertaken in Ghana showed that the presence of O. longinoda reduced the incidence of two major cacao diseases transmitted by mirid bugs captured by weaver ants (Leston, 1973). ...
Description. In West Africa, fruit trees are a crucial but often neglected component of people's lives and more than 50% of fruit crops are thought to be lost to insect pests every year. The relatively low adoption rate of old-IPM practices underpins the need to take up challenges and propose new pioneering control methods, such as using weaver ants in cashew plantations. Literature. The genus Oecophylla is represented by two tropical species, Oecophylla longinoda (Latreille) and Oecophylla smaragdina (Fabricius), occurring in sub-Saharan Africa and Australasia, respectively. In southern China, but also in Vietnam, weaver ant husbandry is a centuries-old tradition. Positive ant-managing experiences from Asia have generated some recent interest in Africa. In sub-Saharan Africa, cashew production is severely constrained by infestations of several insect pests. Sap-sucking bugs, leaf miners and trunk-branch borers are pests that adversely affect yields (total losses of up to 80%) and the quality of harvestable nuts. Recent studies have highlighted the positive role of weaver ants against these insect pests in cashew plantations of Benin, Ghana and Tanzania. Finally, O. longinoda provided four comparative advantages for cashew production i) better yields, ii) larger nuts, iii) higher proportions of marketable kernel mass and iv) a potential fertilization effect. Conclusions. The "weaver ant technology" could be more widely used in sub-Saharan Africa because it is i) effective, ii) low-cost, iii) labour-saving, iv) self-regenerating. It is thus particularly suitable for low-resource smallholder farmers in sub-Saharan cashew plantations and also for mango, citrus, guava plantations. Les planteurs africains ont des alliées étonnants dans leurs plantations d'anacardiers Description. En Afrique de l'Ouest, les fruitiers constituent une composante cruciale pour le développement des populations rurales mais une composante souvent sous-valorisée avec plus de 50 % de pertes dues aux insectes. Le taux d'adoption relativement faible des anciennes méthodes de lutte intégrée pourrait être un argument supplémentaire pour faire face aux défis et proposer de nouvelles méthodes de lutte novatrices comme la gestion des fourmis oecophylles dans les plantations d'anacardiers. Littérature. Le genre Oecophylla est représenté par deux espèces tropicales Oecophylla longinoda (Latreille) et Oecophylla smaragdina (Fabricius), d'Afrique sub-Saharienne and d'Australasie, respectivement. Dans le sud de la Chine mais aussi au Vietnam l'élevage des oecophylles est une très vieille tradition (pluri-centenaire). Les expériences asiatiques positives d'utilisation des oecophylles ont éveillé l'intérêt du secteur rural Africain. En Afrique sub-Saharienne, la production d'anacarde est sévèrement pénalisée par les infestations de plusieurs types de ravageurs dont les punaises piqueuses des fruits, les mineuses des feuilles, les foreurs de troncs et branches, ravageurs qui affectent négativement les rendements (pertes globales jusqu'à 80 %) et la qualité des noix. Des études récentes ont mis en évidence qu'O. longinoda était un agent de contrôle biologique efficace contre ces ravageurs au Bénin, au Ghana et en Tanzanie. Au final, O. longinoda fournit quatre avantages comparatifs aux producteurs d'anacardes à savoir i) l'augmentation des rendements, ii) une taille plus importante des noix, iii) une proportion plus importante des amandes commercialisables, et iv) une amélioration potentielle de la fertilisation.
... In Tanzania, Way (1951) and Vanderplank (1960) also highlighted the efficiency of O. longinoda against Pseudotheraptus wayi Brown in coconut palms. Some studies undertaken in Ghana showed that the presence of O. longinoda reduced the incidence of two major cacao diseases transmitted by mirid bugs captured by weaver ants (Leston, 1973). ...
Description. In West Africa, fruit trees are a crucial but often neglected component of people's lives and more than 50% of fruit crops are thought to be lost to insect pests every year. The relatively low adoption rate of old-IPM practices underpins the need to take up challenges and propose new pioneering control methods, such as using weaver ants in cashew plantations. Literature. The genus Oecophylla is represented by two tropical species, Oecophylla longinoda (Latreille) and Oecophylla smaragdina (Fabricius), occurring in sub-Saharan Africa and Australasia, respectively. In southern China, but also in Vietnam, weaver ant husbandry is a centuries-old tradition. Positive ant-managing experiences from Asia have generated some recent interest in Africa. In sub-Saharan Africa, cashew production is severely constrained by infestations of several insect pests. Sap-sucking bugs, leaf miners and trunk-branch borers are pests that adversely affect yields (total losses of up to 80%) and the quality of harvestable nuts. Recent studies have highlighted the positive role of weaver ants against these insect pests in cashew plantations of Benin, Ghana and Tanzania. Finally, O. longinoda provided four comparative advantages for cashew production i) better yields, ii) larger nuts, iii) higher proportions of marketable kernel mass and iv) a potential fertilization effect. Conclusions. The "weaver ant technology" could be more widely used in sub-Saharan Africa because it is i) effective, ii) low-cost, iii) labour-saving, iv) self-regenerating. It is thus particularly suitable for low-resource smallholder farmers in sub-Saharan cashew plantations and also for mango, citrus, guava plantations. Les planteurs africains ont des alliées étonnants dans leurs plantations d'anacardiers Description. En Afrique de l'Ouest, les fruitiers constituent une composante cruciale pour le développement des populations rurales mais une composante souvent sous-valorisée avec plus de 50 % de pertes dues aux insectes. Le taux d'adoption relativement faible des anciennes méthodes de lutte intégrée pourrait être un argument supplémentaire pour faire face aux défis et proposer de nouvelles méthodes de lutte novatrices comme la gestion des fourmis oecophylles dans les plantations d'anacardiers. Littérature. Le genre Oecophylla est représenté par deux espèces tropicales Oecophylla longinoda (Latreille) et Oecophylla smaragdina (Fabricius), d'Afrique sub-Saharienne and d'Australasie, respectivement. Dans le sud de la Chine mais aussi au Vietnam l'élevage des oecophylles est une très vieille tradition (pluri-centenaire). Les expériences asiatiques positives d'utilisation des oecophylles ont éveillé l'intérêt du secteur rural Africain. En Afrique sub-Saharienne, la production d'anacarde est sévèrement pénalisée par les infestations de plusieurs types de ravageurs dont les punaises piqueuses des fruits, les mineuses des feuilles, les foreurs de troncs et branches, ravageurs qui affectent négativement les rendements (pertes globales jusqu'à 80 %) et la qualité des noix. Des études récentes ont mis en évidence qu'O. longinoda était un agent de contrôle biologique efficace contre ces ravageurs au Bénin, au Ghana et en Tanzanie. Au final, O. longinoda fournit quatre avantages comparatifs aux producteurs d'anacardes à savoir i) l'augmentation des rendements, ii) une taille plus importante des noix, iii) une proportion plus importante des amandes commercialisables, et iv) une amélioration potentielle de la fertilisation.
... The increase of O. smaragdina workers did not reduce the species diversity of ants on trees. As a reason, native ants that act as subdominant species could defend overlapping territories in the same way as dominant species (Leston, 1973). The species segregation among dominant species and the interactions of O. smaragdina with other ants appear to lead to high diversity of arboreal ants in site A. It indicates that native ants acting as dominant species facilitate arboreal ant communities with high species diversity. ...
Human activities influence ant community structure. In tropical areas, the habitat characteristics of crop plantations frequently shape the structure of arboreal ant communities. The present study investigated the spatial distribution of arboreal ants dwelling in durian Durio zibethinus and citrus Citrus amblycarpa plantations in the Tarakan Island, North Kalimantan. Specifically, it was investigated whether ant communities are dominated by native or invasive species; and if ant arboreal mosaics occur. This study included two sites (A and C) comprising durian and citrus plantations and one site B with only citrus plantations. Ant workers dwelling on crop trees were collected by branch beating, and subsequently identified and counted. Across all sites, a total of 64,360 workers, from 22 ant species, were collected from 59 durian and 63 citrus trees. In site A, the invasive species Tapinoma melanocephalum and the native species Oecophylla smaragdina were numerically dominant. A null model analysis of species co-occurrence revealed that species segregation existed in this site. Conversely, in sites B and C the invasive species T. melanocephalum and Technomyrmex albipes were dominant, and native arboreal ants almost co-occurred with the two species. Moreover, the number of T. melanocephalum and T. albipes workers was negatively correlated with the species diversity index of arboreal ants. However, the number of O. smaragdina workers showed no significant correlation. The results suggest that the invasion and domination of non-native species dissasemble spatial structures and reduce the species diversity in arboreal ant communities. The community structures of arboreal ants in fruit plantations were varied, depending on the fruit species and the properties of dominant ants.
... Thanks to their predatory and territorial behaviours, dominant arboreal ants may efficiently protect their host plants from herbivorous insects (Dejean et al., 2000;Majer, 1976Majer, , 1994. The use of ants as biological control agents in plant protection may involve either the periodic introduction of predatory species or the manipulation of the ant mosaic in order to favour the expansion of beneficial species (Majer, 1986;Way & Khoo, 1992 (Tadu, Djieto-Lordon, Yede, Messop Youbi, Aléne, et al., 2014; cited as potential biological control agents against pest in cocoa farms across Africa (Leston, 1973). The colonies of these two species and those of various species of Crematogaster genus exhibit high resistance to insecticide treatment in the cocoa farm (Tadu et al., 2013). ...
We investigated the ant community structure in cocoa farms in the Centre Region of Cameroon. Ants were collected on the cocoa trees during the years 2006 and 2007 using chemical knock‐down. We tested the hypothesis of the existence of deterministic factor in the structuration of ant mosaic using C‐Score; we assessed the relationship between the numerical dominant and subdominant ant species using Spearman correlation test and discussed on the influence of vegetation structure and farm management on the ant community structure. A total of 53 ant species belonging to 20 genera and five subfamilies were identified from a set of 51,525 workers collected. C‐score analysis supported the hypothesis that ant community were structured by competition. Negative relationships were found between dominant ant species. Farming practices which were mainly pruning, chemical treatment and habitat structure appeared to influence the ecological status and distribution of dominant ant species.
... That the arboreal ant fauna in tropical rainforests has a patchy distribution was first noted by Wilson (1958). The notion of 'ant mosaic' was later presented in studies conducted in African cocoa tree plantations whose canopy is easily attainable, permitting the rapid and efficient identification of the ant species occupying each individual tree (Room, 1971;Majer, 1972Majer, , 1993Leston, 1973). Ant mosaics have been noted in the upper canopies of tropical African, Asian, Bornean, New Guinean and Neotropical rainforests (Adams, 1994;Dejean et al., 1994Dejean et al., , 2000Dejean et al., , 2007Dejean et al., , 2010Dejean et al., , 2015Dejean et al., , 2018Armbrecht et al., 2001;Blüthgen & Stork, 2007;Davidson et al., 2007;Ribeiro et al., 2013;Klimes, 2017;Yusah et al., 2018;Leponce et al., 2019). ...
... O controle biológico natural de pragas utilizando formigas em sistemas agroflorestais (SAFs), tais como em cacauais ou cafezais, tem chamado a atenção no último meio século em função da ubiquidade e abundância desses predadores nas plantações (Majer, 1972;Leston, 1973;Majer, 1976a;Kenne et al., 1999;Perfecto, 1991;Way & Khoo, 1992). O mais antigo caso de controle biológico reportado na literatura mundial foi de formigas predadoras quando, no século III de nossa era, os chineses recomendavam seu uso contra pragas de citrus (Pavan & Ceballos, 1979;Perfecto & Castiñeiras, 1998;Gallo et al., 2002). ...
... Leston [17] . Fruits potting bug, Amblypelta theobromae Room and Smith [35] . ...
The present study was undertaken a survey of host plants of red weaver ant in two different habitats such as rural and urban areas of Madurai (9.93°N, 78.12°E), Tamil Nadu during May, 2015-December, 2015. All out search method was used to list the occurrence of red weaver ant on plants and also counted the number of their nests on the host plants. The red weaver ants built their nests on 23 plant species in both rural and urban habitats, among these, thirteen plant species (range of nos. of nests 2-10) in urban and twenty two species (range of nos. of nests 5-15) in rural areas. The more number of nesting was noticed on Mangifera indica, whereas, less number of nesting was found to be in the host plants of Nerium odorum, Cocos nucifera L., Tamarindus indica etc. The highest relative abundance of nesting's of red weaver ants were recorded during October, November and December 2015, whereas lowest during June, July and August 2015. The red weaver ants weaving the nest on some selected plants in both urban and rural habitats by establishing their colonies. The occurrence of nesting may due to the influence of environmental factors that would limit the growth and distribution of ants on its host plants. The present study indicates the existence of mutualistic interactions between plants and red weaver ants.
... important ecological roles (Clausen, 1940;Leston, 1973;Offenberg, 2015), and management practices can strongly influence ant behavior and their potential for providing biological pest control services (Abdulla, Rwegasira, Jensen, Mwatawala, & Offenberg, 2016;Armbrecht & Gallego, 2007;Teodoro, Sousa-Souto, Klein, & Tscharntke, 2010). Indeed, one of the oldest known records of the use of ants for pest control dates to 304 A.D in citrus plantations in China. ...
In natural and managed systems, connections between trees are important structural resources for arboreal ant communities with ecosystem‐level effects. However, ongoing agricultural intensification in agroforestry systems, which reduces shade trees and connectivity between trees and crop plants, may hinder ant recruitment rates to resources and pest control services provided by ants. We examined whether increasing connectivity between coffee plants and shade trees in coffee plantations increases ant activity and enhances biological control of the coffee berry borer, the most devastating insect pest of coffee. Further, we examined whether artificial connections buffer against the loss of vegetation connectivity in coffee plants located at larger distances from the nesting tree. We used string to connect Inga micheliana shade trees containing Azteca sericeasur ant nests to coffee plants to compare ant activity before and after placement of the strings, and measured borer removal by ants on coffee plants with and without strings. Ant activity significantly increased after the addition of strings on connected plants, but not on control plants. Borer removal by ants was also three times higher on connected plants after string placement. Greater distance from the nesting tree negatively influenced ant activity on control coffee plants, but not on connected plants, suggesting that connections between coffee plants and nest trees could potentially compensate for the negative effects that larger distances pose on ant activity. Our study shows that favoring connectivity at the local scale, by artificially adding connections, promotes ant activity and may increase pest removal in agroecosystems.
Abstract in Spanish is available with online material.
... Dominant, aggressive canopy ants often form 'ant mosaics' defined as a patchy distributions of ant species with non-overlapping foraging ranges resulting from territory defense and aggressive behavior (Adams 1994). Ant mosaic formation is often attributed to competition for patchily distributed canopy resources, including hemipterans and extrafloral nectar (Leston 1973, Majer et al. 1994, Blüthgen and Stork 2007, Dejean et al. 2007), but reasons for existence of these patchy distributions of dominant ants are contentious (e.g., Schoereder 2002, Camarota et al. 2016). Canopy ants may be affected by habitat filters both on the trees in which they live and in the surrounding habitat. ...
Ant community assembly is driven by many factors including species interactions (e.g., competition, predation, parasitism), habitat filtering (e.g., vegetation differences, microclimate, food and nesting resources), and dispersal. Canopy ant communities, including dominant and twig-nesting ants, are structured by all these different factors, but we know less about the impacts of species interactions and habitat filters acting at the colonization or recruitment stage. We examined occupation of artificial twig nests placed in shade trees in coffee agroecosystems. We asked whether species interactions-aggression from the dominant canopy ant, Azteca sericeasur Longino (Hymenoptera: Formicidae)-or habitat filtering-species of tree where nests were placed or surrounding vegetation-influence colonization, species richness, and community composition of twig-nesting ants. We found 20 species of ants occupying artificial nests. Nest occupation was lower on trees with A. sericeasur, but did not differ depending on tree species or surrounding vegetation. Yet, there were species-specific differences in occupation depending on A. sericeasur presence and tree species. Ant species richness did not vary with A. sericeasur presence or tree species. Community composition varied with A. sericeasur presence and surrounding vegetation. Our results suggest that species interactions with dominant ants are important determinants of colonization and community composition of twig-nesting ants. Habitat filtering at the level of tree species did not have strong effects on twig-nesting ants, but changes in coffee management may contribute to differences in community composition with important implications for ant conservation in agricultural landscapes, as well as biological control of coffee pests.
... These chemical substances are secreted from endocrine glands located either in the insect's head, legs, or abdomen [94]. [95,96], while O. longinoda is restricted to sub-Saharan Africa [97,98] (Table 1). Both species are arboreal, building nests by weaving leaves in the canopy and displaying territorial dominance over other ant species [73,99]. ...
Ants are a very diverse taxonomic group. They display remarkable social organization that has enabled them to be ubiquitous throughout the world. They make up approximately 10% of the world’s animal biomass. Ants provide ecosystem services in agrosystems by playing a major role in plant pollination, soil bioturbation, bioindication, and the regulation of crop-damaging insects. Over recent decades, there have been numerous studies in ant ecology and the focus on tree cropping systems has given added importance to ant ecology knowledge. The only missing point in this knowledge is the reasons underlying difference between the positive and negative effects of ants in tree cropping systems. This review article provides an overview of knowledge of the roles played by ants in orchards as functional elements, and on the potential of Oecophylla weaver ants as biological control agents. It also shows the potential and relevance of using ants as an agro-ecological diagnosis tool in orchards. Lastly, it demonstrates the potential elements which may determine the divergent negative and positive of their effects on cropping systems.
... The hymenoptera was dominated by ant species which formed the bulk of the insect biomass. Studies by various workers (Leston, 1973;Room, 1971Room, , 1975Majer et al., 1994) point to the fact that in general, ants tend to dominate the abundance and species richness of the arthropod fauna of many tropical ecosystems, including cocoa plantations. The non-effect of distance observed in the study may in part be the result of adaptability of ants to diverse ecological conditions. ...
Objective: An insect survey was carried out on the hypothesis that cocoa farm ecosystems closer to intact forest will have higher insect assemblage than farms distant away. Methodology and results: About 2,721 individual insects belonging to 36 species and 7 orders were recorded. Insect species of four of the orders viz: hymenoptera, diptera, orthoptera, and coleoptera were common to all the ten farm plots. The results showed strong negative effect of distance of the farm plots to the Bobiri forest on spatial distribution of insect assemblage both in species richness and abundance (F = 221.92, p < 0.001). The number of insect taxa decreased linearly with distance to the forest (y = 0524– 0013x), however, the effect of distance to the forest on the species richness was relatively consistent among years. Insect species richness and abundance depended significantly on the proximity of farms to the Bobiri forest (p < 0.012). More species of insects were sampled in farm plots which were closer to the forest. The effect of distance to the forest on insect distribution was also highly significant (p < 0.001). Closeness to the forest significantly predicted insect composition and structure (p < 0.05). Among all the insect species the ceratopogonids or midges (Order: Diptera) and the ants (Order: Hymenoptera) were found in all the ten farms. Conclusions and application of findings: The study showed that agro-ecosystems that maintain similar microclimate to that of the natural forest can provide abundance and diversity of food, nesting-sites, and hiding places for resident insects. The study shows that different insect taxa resident in the cocoa ecosystem contribute both directly and indirectly to the productivity of cocoa and as such proper attention should be paid to cocoa agro-ecosystems.
... Direct tests of this predicted pattern of competitiondriven spatial structuring have dominated the literature on community assembly in arboreal ant communities for many years (Blüthgen & Stork 2007;Jackson, 1984;Room, 1971). The central part of this hypothesis is that the whole habitat would be divided up into large mutually exclusive territories (Leston, 1973). We did not observe this pattern in our study. ...
A major goal of community ecology is to identify the patterns of species associations and the processes that shape them. Arboreal ants are extremely diverse and abundant, making them an interesting and valuable group for tackling this issue. Numerous studies have used observational data of species co-occurrence patterns to infer underlying assembly processes, but the complexity of these communities has resulted in few solid conclusions. This study takes advantage of an observational dataset that is unusually well-structured with respect to habitat attributes (tree species, tree sizes, and vegetation structure), to disentangle different factors influencing community organization. In particular, this study assesses the potential role of interspecific competition and habitat selection on the distribution patterns of an arboreal ant community by incorporating habitat attributes into the co-occurrence analyses. These findings are then contrasted against species traits, to explore functional explanations for the identified community patterns. We ran a suite of null models, first accounting only for the species incidence in the community and later incorporating habitat attributes in the null models. We performed analyses with all the species in the community and then with only the most common species using both a matrix-level approach and a pairwise-level approach. The co-occurrence patterns did not differ from randomness in the matrix-level approach accounting for all ant species in the community. However, a segregated pattern was detected for the most common ant species. Moreover, with the pairwise approach, we found a significant number of negative and positive pairs of species associations. Most of the segregated associations appear to be explained by competitive interactions between species, not habitat affiliations. This was supported by comparisons of species traits for significantly associated pairs. These results suggest that competition is the most important influence on the distribution patterns of arboreal ants within the focal community. Habitat attributes, in contrast, showed no significant influence on the matrix-wide results and affected only a few associations. In addition, the segregated pairs shared more biological characteristic in common than the aggregated and random ones.
... Many ants (Hymenoptera, Formicidae) are generalist predators and have the potential to control herbivore abundance, reducing the plant damage while increasing plant growth, Corresponding author Email: rksdias@kln.ac.lk reproduction and yield (Majer 1972, Leston 1973, Schmitz et al. 2000, Symondson et al. 2002, Van Mele 2008 in agro-ecosystems (Way & Khoo 1992, Peng & Christian 2004, 2005, Peng et al. 1995, 1997, 1999, 2014. Cashew, Anacardium occidentale L., a tree crop native to coastal Brazil, grown in many other countries including Sri Lanka (Cashew Corporation of Sri Lanka 2010) has high economic value as a fruit, nut and oil globally (Blomhoff et al. 2006, FAO 2013. ...
Ant assemblages on cashew trees in the wet zone of Sri Lanka were recorded throughout three phenological phases from March to June in 2015. Baited trapping and hand collection recorded fourteen ant species in five subfamilies and species richness observed on each occasion ranged from 7 to 11. Absence of serious cashew pests was noticeable in the current phenological cycle. Oecophylla smaragdina (Fabricius) was the only species recorded on all trees. Number of O. smaragdina nests observed on the same cashew trees in the two plots was recorded from April to June in 2015 and nests of the species were observed only on large and medium-sized trees. The materials carried by O. smaragdina workers on cashew tree branches were also collected, preserved in 70% ethanol and identified as far as possible using a Low Power Stereo-microscope and various plant and animal materials carried by workers confirmed that the species is an omnivore and a generalist predator. In the current study absence of serious damages caused by the cashew insect pests even without any insecticide application might be due to the presence of ant assemblages on cashew trees.
... Some ants were found to be important in pollination, soil improvement and nutrient cycling (Gotwald, 1986). In West Africa, Oecophylla longinoda was found to be beneficial predator against Distantiella theobroma (Leston, 1973 and Markin et al., 1973). Crematogaster sp. ...
Experiments were carried out to study the management of entomofauna of cocoa through survey, monitoring, identification of insect pests using morphological and molecular tools, biology of sucking pests, predatory potential of natural enemies and to develop integrated pest management module against sucking pest complex of cocoa.
During survey, 23 species of insect pests and 13 species of natural enemies were documented. Among the insect pests, 14, 2 and 7 species were sucking pests, borers and defoliators, respectively. Among the natural enemies, 7 species of predators and 6 species of parasitoids were documented on different insect pests of cocoa.
The highest number of aphids (178 per top three leaves per tree) was recorded during tenth standard week and the lowest (99.2) during forty-fifth standard week. Population of mealybugs was recorded to be the maximum (361 per three pods per tree) during ninth standard week and minimum (135.40) during forty-fourth standard week. The highest number of tea mosquito bugs (12 per three pods per tree) was recorded during forty-fourth standard week and the lowest (0.8) during fifth standard week. The highest number of aphids (15.21 per week) was trapped on yellow sticky light traps followed by blue sticky light traps (12.71) as against the lowest in red sticky light traps (5.52).
Abundance of aphids and mealybugs was positively correlated with maximum temperature and negatively correlated with minimum temperature. Population of tea mosquito bugs was positively correlated with relative humidity.
As per morphological identification report, tea mosquito bugs documented were identified as, Helopeltis bradyi, H.antonii, mealybugs as Planococcus citri, Paracoccus marginatus, Pseudococcus longispinus, Dysmicoccus brevipes and Rastrococcus iceryoides, aphids as Toxoptera aurantii and Aphis gossypii, planthoppers as Pochazia sp., Eurybrachis tomentosa and Proutista moesta, scale insect as Icerya aegyptiaca, cowbug as Telingana sp., pod borer as Dichocrocis punctiferalis, bark eating caterpillar as Inderbala sp., hairy caterpillars as Dasychira moerens, Euproctis fraterna, Olene mendosa and tortricid (unidentified), ash weevil as Myllocerus sp., bagworms as psychid (unidentified) and grasshopper as Diabolocatantops sp. Predators in cocoa ecosystem were morphologically identified as Cheilomenus sexmaculata, Cryptolaemus montrouzieri, Spalgis epeus, Chrysoperla zastrowi sillemi, Humbertiella sp., syrphids (unidentified), Argiope anasuja and parasitoids as Promusidea unfasciativentris, Leptomastix tsukumiensis, Aenasius sp., encyrtid parasitoid (unidentified), Acerophagus papayae and eurytomid parasitoid (unidentified).
Molecular identification of sucking pests of cocoa revealed that specimens 1, 2, 3 and 4 were identified as Helopeltis bradyi, H.antonii (Miridae), Paracoccus marginatus (Pseudococcidae) and Icerya purchasi (Monophlebidae).
Biology of sucking pests of cocoa revealed that the duration of first, second, third and fourth instar nymphs of T. aurantii was 1.45±0.43, 2.15±0.47, 2.35±0.51 and 2.05±0.37 days, respectively with a reproductive capacity of 52.17±4.19 nymphs in 4.40±0.40 days and adult longevity was 12.10±1.29 days. Regarding P. citri, the egg period, duration of first, second and third instar nymphs was 3.50±0.50, 5.17±0.29, 6.17±0.58 and 7.33±0.29 days, respectively with pupal period of 4.83±0.76 days. Total life cycle of male was 29.50±1.50 days and 41.50±1.80 days for females. The egg period, duration of first, second and third instar nymphs of P. marginatus was 6.50±0.87, 3.67±0.58, 3.92±0.39 and 4.58±0.40 days, respectively with the pupal period of 3.25±0.43 days. Total life cycle was found to be 23.58±1.87 days for males and 39.17±1.04 days for females. Regarding H. bradyi, the egg period, duration of first, second, third, fourth and fifth instar nymphs was 7.54±0.46, 1.60±0.42, 1.10±0.22, 1.24±0.18, 1.88±0.40 and 2.52±0.36 days, respectively. Total life cycle was 38.08±1.59 days for males and 41.88±1.11 days for females. The oviposition period of adult female was 21.80±0.84 days with the fecundity of 137.60±1.82 eggs.
Predatory potential of natural enemies revealed that third and fourth instar grubs of Cryptolaemus montrouzieri were voracious and consumed 278.60±5.81, 88.00±2.74, 48.80±2.59 and 389.20±4.97, 124.20±2.59 and 56.40±4.83 first, second and third instar nymphs of P. citri and 2.60±0.55, 38.20±2.86, 20.80±0.84 and 3.40±0.44, 62.60±5.77 and 25.80±1.30 ovisacs, nymphs and adults of P. marginatus, respectively. Second and third instar larvae of Chrysoperla zastrowi sillemi were voracious and consumed 224.40±4.14, 69.20±3.27, 41.00±3.16 and 326.60±2.96, 116.20 ±6.45 and 97.40±2.05 first, second and third instar nymphs of P. citri, respectively and 2.20±0.45, 128.80±2.77, 19.40±2.88 and 3.60±0.55, 213.80±8.84 and 27.40±3.13 ovisacs, nymphs and adults of P. marginatus, respectively.
IPM module was significantly superior over farmer’s practice and untreated control in checking the population of aphids, mealybugs and tea mosquito bug with the mean per cent reduction of 91.1, 94.0 and 84.4 over untreated control, respectively. Untreated control was significantly superior in conserving the population of natural enemies followed by IPM module.
Maximum number of harvestable pods, pod length, pod girth and pod weight was recorded in IPM plot followed by farmer’s practice. Maximum number of beans per pod, wet and dry bean weight, dry bean yield per tree per season were recorded in IPM plot followed by farmer’s practice. IPM module was found to be statistically superior over farmer’s practice and untreated control in terms of protection and pod and bean yield parameters.
... Solenopsis species, for example, although unpopular, often thrive in ploughed crop fields and are known to control a variety of important pests (Summerlin et al. 1977;Morrill 1978;Sterling 1978;Risch & Carroll 1982). Perhaps, most importantly, patterns of ant foraging behaviour can be manipulated, through the provision of resources such as EFN, in order to maximize the rate at which they encounter pests (Leston 1973). ...
Extrafloral nectar ( EFN ) provides plants with indirect defence against herbivores by attracting predatory insects, predominantly ants. Decades of research have supported the role of EFN as an effective plant defence, dating back to Thomas Belt's description of ants on acacia in 1874.
Despite this extensive body of literature, knowledge of the ecological role of EFN has rarely been applied in the field of pest management. We review the existing literature on the use of EFN in agriculture and consider the obstacles that have hindered this transition.
Chief among these obstacles is the influence of ecological context on the outcome of EFN ‐mediated interactions. As such, we consider the options for various agricultural systems in the light of the growth habit of EFN ‐producing species, focusing first on orchard species and then on herbaceous crops. In each case, we highlight the benefits and difficulties of utilizing EFN as a pest management tool and of measuring its efficacy.
Synthesis and applications . We argue that it is time for a shift in extrafloral nectar ( EFN ) research towards applied settings and seek to address the question: How can a context‐dependent and often inducible plant trait be utilized as a reliable tool in agricultural pest management? Breeding crops for increased EFN production, and intercropping with EFN ‐producing plants, can enhance assemblages of beneficial insects in many agricultural settings. Orchard systems, in particular, provide an ecological context in which the attraction of ants can contribute to cost‐effective and sustainable pest management programmes over a broad geographic range.
... A second option could involve actions to facilitate the movement of predators among bunches within a tree and among trees. This could be done by connecting bunches of coconut fruits and coconut trees, for example with nets or sticks, reminiscent of a practice already used millenia ago by chinese farmers in citrus orchards (Leston 1973), by intercropping with climbing plants, or perhaps by reducing the planting distance among coconut trees so that their leaves will touch. ...
Predators face the challenge of accessing prey that live in sheltered habitats. The coconut mite Aceriaguerreronis Keifer (Acari: Eriophyidae) lives hidden beneath the perianth, which is appressed to the coconut fruit surface, where they feed on the meristematic tissue. Its natural enemy, the predatory mite Neoseiuluspaspalivorus De Leon (Acari: Phytoseiidae), is larger than this pest and is believed to gain access to the refuge only after its opening has increased with coconut fruit age. In the field, experimentally enlarging the perianth-rim-fruit distance beyond the size of the predators resulted in earlier predator occurrence beneath the perianth and lower numbers of coconut mites. On non-manipulated coconut fruits, the predators gained access to the prey weeks later than on manipulated ones, resulting in higher pest densities of coconut mites. Successful biological control thus critically hinges on the size of the predator relative to the opening of the prey refuge.
Humans have used weaver ants, Oecophylla smaragdina, as biological control agents to control insect pests in orchards for many centuries. Over recent decades, the effectiveness of weaver ants as biological control agents has been attributed in part to deterrent and oviposition inhibiting effects of kairomones produced by the ants, but the chemical identity of these kairomones has remained unknown. We have identified the kairomone responsible for deterrence and oviposition inhibition by O. smaragdina, providing a significant advance in understanding the chemical basis of their predator/prey interactions. Olfactometer assays with extracts from weaver ants demonstrated headspace volatiles to be highly repellent to Queensland fruit fly, Bactrocera tryoni. Using electrophysiology and bioassays, we demonstrate that this repellence is induced by a single compound, 1-octanol. Of 16 compounds identified in O. smaragdina headspace, only 1-octanol evoked an electrophysiological response from B. tryoni antennae. Flies had greatly reduced oviposition and spent significantly less time in an olfactometer arm in the presence of 1-octanol or a synthetic blend of headspace volatiles containing 1-octanol than in the presence of a synthetic blend of headspace volatiles without 1-octanol, or clean air. Taken together, our results demonstrate that 1-octanol is the functional kairomone component of O. smaragdina headspace that explains repellence and oviposition deterrence, and is hence an important contributor to the effectiveness of these ants as biological control agents.
A tubular survey of ant-plant symbioses worldwide summarizes aspects of the evolutionary ecology of these associations. Remarkable similarities between ant-plant symbioses in disjunct tropical regions result from convergent and parallel evolution of similarly preadapted ants and plants. Competition among ants has driven evolutionary specialization in plant-ants and is the principal factor accounting for parallelism and convergence. As habitat specialization accompanied the evolutionary radiation of many myrmecophytes, frequent host shifts and de novo colonizations by habitat-specific ants both inhibited species-specific coevolution and co-cladogenesis. and magnified the diversity of mutualistic partners.
The comparatively high species diversity of neotropical plant-ants and myrmecophytes probably results from two historical factors. Most importantly, influenced by Andean orogeny, greater habitat disturbance by fluvial systems has created a mosaic of habitat types unparalleled in other tropical regions; both myrmecophytes and plant-ants have diversified across habitat boundaries. Second, the arrival of a new wave of dominant ants (especially Crematogaster) may have condensed the diversity of relatively timid plant-ants to a greater degree in Africa and Asia than in the more isolated Neotropics. Regular trajectories in the evolutionary histories of plant-ants appear to be driven principally by competition, in a manner analogous to the taxon cycles or pulses proposed for other
groups.
p>A survey of southern Guinea Savanna at Mokwa, Nigeria revealed the presence of 63 species of ants; 5tti were recorded as being predators of termites. The majority of these ants were opportunist predators.The two obligate termite predators, Meganonera foetens (Fab.) and pecamorium uel.ense (Santschi) showed specific adaptations in their recruitment and foraging regimes to secure their prey. Wacrotermes hel.licosus (Sm.) and Ce.ontotermes spp. were the main prey of IH.foetens and Microter.-.:es spp. of D.uelense. Both ant species used a scout ant to locate foraging termites. M.foetens scouts then recruited columns cf 200-500 ants which were guided by the scout ant to the termites ¢.tong scent trails originating from the poison (,land. D.uelense scouts recruited small groups of ants which attacked and immobilized their prey; a miss recruitment phase then occurred to secure the prey.The scout ants of ti.foetens located foraging termites through chemical cues contained in the protective soil sheeting over their prey. The chemical cues were solvent extractable and originated from the anterior region of worker termites. Chemicals were also involved in the coordination of attacks on termites. Ants finding groups of termites release alkyl sulphide pheromones from their mandibular glands which attract sister workers who dig, in response to other pheromones, into the termite galleries.The specialized predator, M.foetens, took 141 M.bellicosus per square metre per year and 42 Odontoterr:es spp. per square metre per year. With a termite standing population of i23 M.bellic:osus and 260 Odontotermes spp. per square metre, M.foetens can turn over the worker-soldier copulation of these two species in 0.9 and 6.2 years respectively. Other Macrotermitinae accounted for only a small proportion of the prey (7 Ancistrcter:nes, 3 Microterres and < 1 iiacroternes subh alinus per square metro per year). It uas concluded that the efficiency of predation on different termite species was controlled through termite foraging regimes and density, the response of ants to termite soldier defence secretions and the responses of termites to ant secretions.The repellent responses of termites to ants were partially controlled through glandular secretions from the predator. Successful specialised predators, such as D.neirnse, produce non-repellent compounds (aliphatic alcohols) in their mandibular glands, whereas less successful opportunist predators produce compounds (aliphatic ketonos, aldehydes and alkyl pyrazines) which are repellent to termites. it was concluded that inter-specific pressures were one of the reasons for the great diversity of exocrine secretions in the Formicidaa.</p
Diversity, permanence, and activity of terrestrial arthropods were investigated in four areas of different land use in the lowlands of the Pacific coast of Colombia with the aim to identify potential predator species for the palm root borer, Sagalassa valida. Ten pitfall traps were established along a 100 m transect in four areas: a secondary forest, a 20 year.-old peach palm plantation, and two hybrid oil palm plantations of three and seven years of age, respectively. Twenty-two collections were made covering a whole year. All ants were identified to species or morphospecies level, the other arthropods to order or where possible to family level. In total, 50,603 arthropods were captured, the most abundant were ants (37.0 %), followed by Collembola (35.4 %), Acari (10.6 %), Coleoptera (7.0 %) and Diptera, Hemiptera and Araneae in almost equal numbers (around 2.5 %). Orthoptera (92 % Gryllidae) were present in all collections, always at low numbers. The highest number of ants were recorded in the oil palm transects; Diptera, Hemiptera and Orthoptera were more numerous in the secondary forest, Acari, Araneae and Collembola in the palm transects. Ectatomma ruidum was by far the dominant ant species (84.9 % of all specimens) and absent from only 20 of the 880 captures. The second most frequent ant genus were army ants with two species, Labidus praedator and L. coecus. Rainfall, even area-wide flooding, and temperature did not explain variability in captures of any taxonomic group satisfactorily. We conclude that E. ruidum might be the predator to provide control of the root borer and recommend further studies on its efficiency.
The ant mosaic is a concept of the non-random spatial distribution of individual ant species in trees built upon the assumption of interspecific behavioural associations. However, colony identity and environmental variance may also play a role in species distribution. Here we assess the presence of ant mosaics in a primary forest ecosystem and whether they are structured by species' aggressive behaviours or by habitat filtering.
We sampled arboreal ants from vertically stratified baits exposed in 225 canopy trees in a 9-ha plot of primary lowland forest in Papua New Guinea, the largest forest area surveyed to detect ant mosaics. We performed behavioural tests on conspecific ants from adjacent trees to determine the territories of individual colonies. We explored the environmental effects on the ant communities using information on the plot vegetation structure and topography. Furthermore, we created a novel statistical method to test for the community non-random spatial structure across the plot via spatial randomisation of individual colony territories. Finally, we linked spatial segregation among the four most common species to experimentally assessed rates of interspecies aggression.
The ant communities comprised 57 species of highly variable abundance and vertical stratification. Ant community composition was spatially dependent, but it was not affected by tree species composition or canopy connectivity. Only local elevation had a significant but rather small effect. Individual colony territories ranged from one tree to 0.7 ha. Species were significantly over-dispersed, with their territory overlap significantly reduced. The level of aggression between pairs of the four most common species was positively correlated with their spatial segregation. Our study demonstrates the presence of ant mosaics in tropical pristine forest, which are maintained by interspecific aggression rather than habitat filtering, with vegetation structure having a rather small and indirect effect, probably linked to microclimate variability.
The ants associated with cacao (Theobroma cacao L.) suspected as predators of the cacao mirid bug, Helopeltis bakeri Poppius were surveyed using four collecting methods, namely: (1) beating the canopy; (2) handpicking; (3) pitfall trapping, and (4) ground surface food-baiting in regularly pruned trees and weeded farm (site 1) and irregularly pruned trees and weedy farm (site 2) in Santo Tomas, Batangas, Philippines during the month of January 2018. A total of 2,072 ant individuals (1,019 in site 1 and 1,053 in site 2) belonging to 13 species in 13 genera under four subfamilies were recorded. These are Myrmicinae with 1,182 individuals (57.04%) in five species represented by Solenopis geminata Fabricius 1804; Tetramorium sp.; Carebara diversa Jerdon 1851; Pheidole sp. and Crematogaster sp.; Formicinae with 793 individuals (38.27%) in four species-Nylanderia sp.; Oecophylla smaragdina Fabricius 1775; Anoplolepis gracilipes F. Smith 1857 and Polyrhachis sp.; Dolichoderinae with three individuals (0.15%) in Tapinoma melanocephalum Fabricius 1793, and Ponerinae with 94 individuals (4.54%) in three species-Odontoponera denticulata F. Smith 1858; Odontomachus simillimus F. Smith 1858, and Leptogenys sp. Of all taxa, C. diversa and O. smaragdina were most preponderant, followed by Crematogaster and Odontoponera in the second group; whereas, Anoplolepis, Pheidole, Nylanderia and Solenopsis were the least preponderant. Our findings showed that Shannon-Weaver function of diversity (H’) was slightly higher in weedy and irregularly pruned farm (H’=1.18) compared to the weeded and regularly pruned one (H’=1.08). On the other hand, alpha diversity (α) index showed diversity highest in soil (α =1.9) > trunk (α =1.7) > foliage area (0.6). Sorensen’s Coefficient index (CI) of similarity of ant species was high (0.86) denoting that at least nine taxa are common in the same orchard irrespective of farmers practice. A new scoring system was developed based on ant’s attraction to food baits. Of all taxa, only O. smaragdina and Solenopsis geminata preyed on the cacao mirid bug and demonstrated potential use as biological control agents in cacao farms.
The cover/green manure crops can be considered as the backbone for any annual cropping system to be sustainable. They are responsible for sustainable farming because of enhancement of organic matter, improvement of soil structure, nitrogen fixation, nutrient enhancement, rooting action, soil and water conservation, soil microbial activity, and pest management. This chapter summarizes different management aspects of insect and mite pests (pollen and nectar source for predators, overwintering habitats for generalist predators, and understory cover crops in orchards), disease pathogens, nematode pests, and weed suppression using cover/green manure crops. The mechanisms involved in insect pest, disease, and weed suppression are also discussed.
A study entitled “An ecological study of Pteroma pendula (Lepidoptera: Psychidae) in oil palm plantations with emphasis on the predatory activities of Oecophylla smaragdina (Hymenoptera: Formicidae) on the bagworm was conducted at the MPOB Research Plantation at Teluk Intan, Perak, Malaysia from 11.11.2010 to 31.01.2013. The main objectives of the study was to assess the infestation of P. pendula and investigate a
correlation between pest density fluctuations with abiotic factors in the study area and to elucidate O. smaragdina occupancy pattern and its predatory behaviours towards P. pendula as well as assessing the productivity of palm trees occupied and not occupied by the weaver ants.
Results of the survey showed that there was an infestation of the bagworm with peak outbreak from October to November 2010 which coincides with the ending of the dry season (Pearson correlation coefficient r = 0.474, p <0.05).
O. smaragdina shows a high preference for tall trees where 92% of sampled palms were
occupied with a Preference Index (Pi) of 1.84 but avoid short palms where none were
occupied (Pi =0). Forty percent of the occupied palms harbours nests of various types
ranging from 1-13 nest per palm with an average of 3.98 ±1.74 and uniquely the number
was always odd. The weaver ants exhibited a bimodal foraging circadian cycle with two
peaks: midday (12:00 h-15:00 h) and around dusk (17:30 h-18:30 h).
O. smaragdina showed a moderate positive correlation of foraging activity with increase in air temperature (r=0.874, p < 0.001). However it is negatively correlated to relative humidity (r = - 0.921, p < 0.001). The attack tactic deployed by O. smaragdina towards the bagworm larva can be simplified into four main stages: Foraging and detection of prey; physical attack & securing of prey; piercing and releasing of formic acid and finally the lifting of paralyzed prey followed by transporting it to the nest. O. smaragdina shows no aggressive behavior towards Elaeidobius kamerunicus, the principal pollinators for oil palm.
O. smaragdina had a high preference for pupae (Pi = 1.73) over larvae (Pi = 0.13) when the former was in abundance within the cut-off period of 90 minutes (U = 0; P < 0.01). A log-rank test demonstrated a statistically significant difference in survival ability between pupae and larvae (for equivalence death rates X2 = 3.42, d.f =1; P = 0.06). The degree of infestation by the bagworm was significantly different between the occupied and unoccupied palms (X2= 406.30, d.f = 4, p < 0.001). Among the tall occupied palms, none were infested to Level 3 and 4 with 84% not infested at all (Level “0”). But 40% of the tall unoccupied palms were infested to Level 3 and 25% to Level 4.
For the short unoccupied palms 31% were infested to Level 2 and 28% to Level 3 with only 2.2% showed no evidence of infestation. The degree of foliar injury is significantly less severe for the occupied palms (X2= 439.2), d.f = 4, p < 0.001). There is positive correlation between the level of infestation and the degree of foliar injury (rs= 0.952; d.f= 48; P < 0.01) in occupied palms and unoccupied palms (rs= 0.848; d.f = 48; P < 0.01).
The productivity of DFB/FFB is significantly higher for the occupied palms (z ≥ 4.16, p< 0.0003) compare to shorter unoccupied palms. Similarly, the difference between tall occupied and tall unoccupied palms was highly significant at P < 0.002 (U=1). Based on the finding of this study, O. smaragdina holds a promising potential as biological control agent for the bagworm pests particularly against the increasing concern for sustainable
oil palm industries.
While swamps perform valuable functions in coastal ecosystems, terrestrial invertebrates in these fragile habitats are poorly known. The aims of this study were to (1) uncover the ant diversity and functional groups of Cypress-Tupelo swamps; (2) examine the differences of ant assemblages across vertical strata within trees and across tree species within swamps; and (3) determine if the ant mosaic hypothesis applies to observed patterns of arboreal ant distribution. Pitfall traps were set in tree crowns and on trunks to collect the arboreal ants in three swamps in Louisiana. A total of 21 species from 11 genera were collected. Contrary to our hypothesis, ant diversity on trunks was higher than that in the canopy. A multivariate analysis revealed that the canopy and trunk support distinct ant assemblages, whereas ant species composition was not consistently different among the three dominant tree species- bald cypress, water tupelo, and red maples. In addition, evidence of ant mosaic distribution patterns were not detected. Moreover, we did not find dramatic changes of ant diversity or community structure in trees that were infested with invasive red imported fire ants. Our study provides a benchmark to evaluate the effects of disturbances and conservation management in swamp ecosystems.
The distribution of ants in a 2·25-ha cocoa plantation at the University of Ghana Agricultural Research Station, Kade, was recorded in December 1970. The 44 species of ants found could be grouped as dominant, co-dominant, sub-dominant and nondominant. Oecophylla longinoda (Latr.) and Macromischoides aculeatus (Mayr) were mutually exclusive as were six Crematogaster spp.; the latter were also exclusive of O. longinoda and M. aculeatus. Camponotus acvapimensis Mayr became dominant under insolated conditions, and Platythyrea frontalis Emery for reasons unknown. The distribution of these ant species in cocoa plantations resembles a three-dimensional mosaic which is preserved by their aggressiveness and by competition for food and nesting sites. It is suggested that this mosaic is due to vegetative succession.(Received April 20 1971)(Revised February 09 1972)
Sampling by light trap, insecticide knockdown and other methods has given data on seasonal population changes in many insects and a few spiders in an area of semideciduous high forest largely devoted to cocoa growing at Tafo, Ghana. Populations of most species showed seasonal change and in every month some species were in a period of major increase. There are several characteristic seasonal population curves which, when associated with botanic and climatic events, lead to the conclusion that six seasons should be recognized. These can be defined by a combination of mean rainfall (more or less than 4 in./month) and mean monthly sunshine (more or less than 5.5 h/day). The seasons, listed together with some of the events we have discussed, are: (1) Dry sunny. Maximum fruit production, abundance of fruit-feeding and seed-feeding insects, continuing into the following season. Species thought to be favoured by effects of drought and related stress factors on host-plant nutrition also increase. (2) First wet sunny. Maximum leaf production; abundance of leaf-feeding insects and their predators. Maximum breakdown of leaf litter; abundance of litter-feeding and fungus-feeding insects. (3) First wet dull. Decline in leaf feeders and their predators. Abundance of timberborers. (4) Dry dull. Biologically similar to wet dull seasons; forms with numbers closely correlated with rainfall, for example timber-borers, may decline. (5) Second wet dull. (6) Second wet sunny. Shorter than the first wet sunny season, but period of submaximum leaf production; abundance of leaf feeders and their predators. Species that depend for food on primary production of plant tissues in the form of leaves or fruits have maximum numbers in the three sunny seasons. Their populations appear to respond directly to seasonal changes in the amount of food.
(1) Forty-eight general and 128 species of ants are listed from various microhabitats in 250 m2 of a cocoa-farm locality in Ghana. (2) The ant faunas of the microhabitats are compared, and it is noted that the majority of the species nest in dead wood and forage in the litter. (3) Two broad categories of foraging microhabitat are recognized--exposed and cavity. (4) Three species of ant invaders into the forest zone from savannah were taken in the locality. (5) The relative distributions of species' foraging territories in insolated cocoa canopy were investigated. (6) The frequencies of sixty-seven species in 168 samples are given, and may be taken as a rough guide to the relative abundance of territories of these species. (7) The mechanisms underlying numerical dominance in cocoa-farm ants are discussed and some implications for the use of ants as biological control agents are suggested. (8) It was shown that the five common dominant ants of the microhabitat had significantly different numbers of subdominant ants associated with them. It is suggested that this reflects the relative specializations of those dominant ants. (9) Unmodified chi2 analysis of the data was found to give a meaningful grouping of species into communities. It is suggested, along very general lines, how these communities function and interact with those species not included in them. (10) The extremely close association between Oecophylla longinoda and Crematogaster castanea?, and its significance, are briefly discussed.
1. Studies on a nest of the leaf-cutting ant Atta cephalotes in tropical rain forest in Guyana were continued for 58 days and showed that the ants were nocturnal. 2. The directional distribution of attacked plants about the nest was uneven, but the pattern was consistent throughout the study period. The distribution of foraging effort was similarly uneven, and the pattern varied. 3. The distance distribution from the nest of attacked plants revealed constant area exploitation up to 31.2 m, a zone of increased exploitation from 31.3 to 46.8 m and thereafter a falling off; this pattern was consistent throughout the study period. The distribution of foraging effort was broadly similar, but varied with time. 4. 62% of all new foraging records were in the 0-3 m height range although the majority (37%) of foraging activity was in the high canopy over 12.2 m. 5. 25% of all plants attacked were cut on more than one occasion, one tree being exploited on nineteen consecutive nights. 6. The pattern of usage of the six main trails leading from the nest varied markedly with time. 7. Of the seventy-two species of woody plants identified in the nest area, thirty-six were attacked; this ratio did not differ significantly from 1/1 when comparable sampling effort was taken into account. Evidence of selectivity in the degree to which the ants exploited the species was apparent. 8. The ants did not cut the nearest specimen of the exploited species to the nest, there being on average at least 6.2 nearer intact specimens. 9. There was evidence of changes with time in the pattern of species attacked. 10. It is suggested that A. cephalotes has developed a conservational grazing system which prevents it from over-exploiting, and so destroying the vegetation in the area around the nest. It is further argued that the introduction of agriculture disrupts this pattern, and may contribute to the animal's pest status.
1. Some notes on the distribution of Oecophylla sp. are given. 2. Larvae failed to develop at 33.3 degrees C but developed at 30 degrees C, and the eggs failed to hatch at 16 degrees C. It takes 25 days for the first workers to emerge at 28 degrees C. 3. Colonies fed solely on honey produced mostly small yellow non-aggressive workers; those fed on insect food produced deep red large worker or soldier ants and were very aggressive. 4. Both insect food and sugars appear essential for the survival and reproduction of a colony. 5. Field experiments in rearing Oecophylla colonies are described. 6. All attempts to introduce a `queen' Oecophylla to a `queen-less' colony failed. 7. In the field Oecophylla colonies vary in colour, composition, feeding habits and aggressiveness; unless destroyed by antagonistic ants the life of a colony exceeds 5 years. 8. Oecophylla sp. are monogynous and the `queens' move from nest to nest to oviposit. 9. The size of a colony was estimated by feeding with radio-phosphorus. It is estimated that the `queen' must have been producing over 900 eggs a day and that the average life of the workers was between 68 and 140 days. 10. The most important antagonist of Oecophylla in Zanzibar is Pheidole sp.; two alien species of ant, Anoplolepis longipes and A. custodiens, established in parts of Zanzibar prey on Oecophylla. Most species of ant prey on the young `queens'. 11. Oecophylla colonies are infested with a mimicking spider Myrmarache sp. and a pseudo-scorpion Hansenius sp. and other insects. 12. Some observations on the prey of Oecophylla are given. Unless the colony is numerically strong, it does not completely protect the palm from damage by Pseudotheraptus wayi. 13. A list of membracids tended by Oecophylla is given. 14. Solar movements influence the siting of leaf-nests more than the prevailing wind. 15. About 1% of colonies move to a new location during each year; these are usually heavily infested with arachnids. 16. Oecophylla is not selective in its choice of palms, but frequently occurs in groups; where all ant species were eradicated, re-colonization was at random. 17. Strong colonies of Oecophylla only give about 50% protection from Pseudotheraptus wayi damage and none from Diocalandra frumenti damage. 18. Insecticidal formulations containing lindane or dieldrin quickly reduce or eradicate Oecophylla from an area. The effects of some formulations of D.D.T. and other insecticides were also studied. 19. Some insecticides caused a considerable movement of Oecophylla colonies. 20. Although Oecophylla is a useful predator of Pseudotheraptus wayi and should not be destroyed, it is doubtful whether it could be used to obtain economical control of the pest.
Four species of ants, Oecophylla smaragdina, Iridomyrmex cordatus, Anoplolepis longipes and Pheidole megacephala, are involved in the control of a coreid bug, Amblypelta cocophaga, which causes nutfall of coconuts in the Solomon Islands. The ants compete to occupy coconut palms and are mutually exclusive. The competition between them is complex, continuous and one-sided with relative numbers a major factor in the outcome of any interaction. In the competition for palms between established colonies the species can be ranked in an order of competitive ability: Iridomyrmex cordatus>Pheidole megacephala and Anoplolepis longipes>Oecophylla smaragdina>other minor species. This ranking depends on the size of individuals, population structure and the main nest site and food source of each species. In the species' ability to colonize vacant palms this order is reversed. Although Iridomyrmex cordatus is dominant to any single ant species it has a low rate of increase. This is thought to be due to the nature of its food and also to the effects of competition from several other species together. The frequencies of the four species in certain Guadalcanal plantations have been recorded, at 2-3 year intervals, by a series of workers since 1948. Results have not been reported since 1958 and they are brought up to date here. Pheidole megacephala, the dominant species before World War II, was still common, although declining, in 1948. It was followed by Oecophylla smaragdina and then from 1952 until the late 1960s Anoplolepis longipes was frequent. An account of these changes is given and of the subsequent fluctuations in frequency of Oecophylla smaragdina, Pheidole megacephala and minor species. Throughout the 20-year-period populations of Iridomyrmex cordatus have typically remained, stable or increased slowly. Previously it was not possible to account for these frequency variations, and some suggestions are made here. In Oecophylla smaragdina there is evidence of a cycle of approximately 8 years, observations on individual colonies indicating that this is their average life span. The probable effects of a wartime vegetation change on the diversity of ant faunas is discussed and it is concluded that the postwar return to well-maintained plantations affected ant frequencies and was responsible for a sequence of population fluctuations which is still continuing.
Experiments on lime saplings under controlled conditions have revealed that the roots of aphid infested saplings do not grow. However, the growth above ground in girth, height increment, leaf number and leaf size is normal. Saplings infested with aphids shed their leaves earlier, the leaves are heavier per unit area, and they contain more nitrogen. Aphid infestation in one year results in smaller leaves in the following year, and these leaves are a darker green and have a net production 1.6 times greater than the leaves of previously uninfested saplings. Lime tree growth and the way aphids affect its realization are discussed.
Undisturbed ant faunas of islands in the Moluccas-Melanesian arc are for the most part "saturated," that is, approach a size that is correlated closely with the landmass of the island but only weakly with its geographic location (figure 1). In the Ponerinae and Cerapachyinae combined the saturation level can be expressed approximately as F=3A0.6, where F is the number of species in the fauna and A the area of the island in square miles. Interspecific competition, involving some degree of colonial warfare, plays a major role in the determination of the saturation curve. It deploys the distribution of some ant species into mosaic patterns and increases the diversification of local faunas. Perhaps because of the complex nature of the Melanesian fauna, differences between local faunas appear that give the subjective impression of randomness. Despite the action of species exclusion, the size of local faunas occurring within a set sample area increases with the total size of the island (figure 2). Water gaps br...
For both of the important cacao Mirids, Sahlbergella singularis Hagl. and Distantiella theobroma (Dist.), there is a well-marked annual population cycle. Numbers are at their lowest in March and, although showing fluctuations from month to month, remain low until July. After this period, there is an increase in numbers to a peak level which may be bimodal, an earlier peak corresponding with the maximum numbers on pods and a later peak on stems alone in January or February. This is followed by an abrupt drop in the dry season to the minimum values of March.
The period of increasing numbers is, at first, associated with the presence of more cacao pods but evidence is given to prove that Mirid increase is nor determined by pod increase but that both reflect the action of some common cause. The final peak population is associated with the symptoms of seasonal blast, but although Mirid numbers beneath the canopy are at their maximum at this time, there is no corresponding increase in the resident canopy population, the blast symptoms being produced by a transient population of adults from the sub-canopy levels.
Even at their highest the numbers of Mirids are small compared with most crop pests, the normal maximum being of the order of 1,000 per acre in mature stands of cacao.
Such aspects of mortality as could be studied from field observations are described. There is a steady loss during nymphal life, more dying during the later stages because these last longer. Parasitism, food supply and predation appear to be the main controlling factors, but, of these, only predation is examined quantitatively. Mantids, ants and Reduviids kill between 16 per cent. and 21 per cent. of the nymphs with which they are associated and the proportion of Mirids killed by such predators increases as the number of Mirids increases. Predation plays an important part in the natural controla of Mirid populations but, although optimum conditions for predation exist in Mirid pockets, economic control is not effected.
The use of ants as a Mirid control measure is examined and rejected. Infestation of healthy trees by ants does not protect nearby attacked trees and the association between ants and healthy trees is due to the colonisation of such trees as the only ones suitable in an area subject to Mirid damage. A single instance is quoted where Oecophylla longinoda (Latr.) appeared to exert a control but only at a level where the ants were so numerous as to constitute a hazard to humans in the plot.
A final discussion of the three papers of the series is included to focus attention upon those aspects of Mirid biology which need immediate investigation. These include an evaluation of the loss caused by Mirids and the need for experimental work to determine the effect of physical factors on Mirids. Suggestions are made for sampling which could be employed in any future field observations.
In British East Africa Oecophylla longinoda (Latr.) var. textor Santschi is locally common in the costal region. Inland it is absent from higher altitudes and from areas where there is a pronounced dry season.
In Zanzibar Island, O. longinoda at least 89 species of trees and shurbs; the largest populations occur on the clove ( Jambosa caryophyllus ), Citrus spp., Bridelia micrantha and Canthium zanzibaricum .
The nesting habits and colony composition of O. longinoda are such that one colony may spread over a number of adjacent trees; it contains only one gravid queen.
Winged virgin sexual forms are released at the beginning of the wet seasons and new colonies are initiated by a single queen, who uses her food reserves to bring the first batch of brood to maturity.
In Zanzibzr, O. longinoda tends a wide range of Homoptera that produce honey-dew, but apparently “ prefers ” certain Coccids, notably Saissetia spp.
The degree of attention afforded by an ant species determines the species of Homoptera which it is able to attend.
The insect species preyed upon by O. longinoda include the honey bee, Apis mellifera , and the driver ant, Dorylus nigricans , of which large numbers may be destroyed.
O. longinoda is of undoubted value for controlling certain coconut pests, notably Theraptus sp. (Coreidae), and its efficiency in coconut plantations could probably be much enhanced.
The most important species of Pseudoeoccid transmitting the swollen-shoot virus disease in the Gold Coast is Pseudococcus njalensis Laing. It is almost always attended by ants of the genus Crematogaster . These ants usually build their nests in the cavities and galleries that have already been excavated by wood-boring insects in the dead branches of cacao trees. The only apparent advantage of this association to the ants is to imbibe the honeydew secreted from the anal orifice of the mealybugs; if this is allowed to accumulate it becomes a medium for bacteria and fungi which seems to kill the mealybugs eventually.
Attempts were made to break the link between the mealybugs and ants by spraying six cacao trees, not in contact with each other or any other trees, each with 3·5 litres of 0·2 per cent. DDT emulsion, twice at two-week intervals. All dead branches containing nests of ants were cut out, and a band of grease painted, on the trunk, one foot above the soil level to prevent the ants climbing up. Four weeks after the first application of spray, the population of mealybugs was brought down to 1·2 per cent, of its size before treatment. Unfortunately locating the ant nests, especially in the crevices and under the bark, is very difficult. Experiments were therefore carried out in which the trees were sprayed without previously eliminating all the sources of ants. The results were unsatisfactory, the size of the mealybug population, compared with that before treatment, after four, six and eight weeks was 16·9, 39·4 and 92·3 per cent., respectively, in the case of 0·2 per cent. DDT emulsion, and 11·6, 64·3 and 58·8 per cent., respectively, in the case of a treatment consisting of 3·5 litres per tree of a mixture of 0·2 per cent. DDT and 0·02 per cent, parathion active material. Cutting off the dead branches containing ant nests, followed by either painting the cut end of the dead branches with DDT (16·7 per cent, emulsion) or painting the trunk with a band of the same emulsion also gave poor results.
The unsatisfactory results obtained by spraying are attributed to the fact i that only the ants that happen to be exposed are affected by the application of ithe insecticide; the immature stages inside the nests are not touched.
The efficiency of dimefox when applied to the soil at 0·8 gm. active material per inch of tree girth was not increased when the ants had previously been partially eliminated.
Treated cacao trees could not in practice be completely isolated from forest jtrees and climbers containing nests of Crematogaster ants and these provide a continuous source of large populations. It is, therefore, considered that the icomplete elimination of ants is not possible.
It was also found that there is a relationship between the population of mealybugs and ants. Trees were usually free from mealybugs if no ants were found on them. The examination of isolated cacao trees with different sizes of dead branches containing nests of ants suggests that the number of mealybugs 38 in proportion to the size of the nests.
Pupulations of the West African cocoa capsids Distantiella theobroma (Dist.) and Sahlbergella singularis Hagl. were sampled in 1966–67 by several methods: fast knockdown over sheets with pyrethrum, mercury-vapour light-trap, direct counts in a small artificially established area of high population, and observations of presence or absence in randomly selected inspection squares.
A population build-up in mature cocoa accompanies and probably directly depends on development of the main crop from July or August to October. When pods become scarce after harvesting there is in S. singilaris a period of dispersal in which the species becomes more widespread as feeding is transferred to vegetative tissues, and in D. theobroma a more local change of feeding sites.
Subsequent events vary greatly between areas and between years. It is suggested that the extent to which capsids are able to utilise vegetative tissues varies and depends on nutritional changes in the external parenchymatous tissues from which their food is obtained.
Low humidities during spells of harmattan in January and February almost certainly kill larvae in exposed situations, but feeding conditions following such periods may be particularly favourable to capsids as large rapid population increases can occur locally. The factors involved are obscure but may be related to processes of regeneration stimulated by leaf loss and other damage in dry conditions.
The densities and seasonal patterns found are discussed in relation to results of previous workers and some implications for control briefly considered.
Data were obtained on survival and development of larvae of Distantiella theobroma (Dist.) on cocoa seedlings maintained under three water régimes, high (HW), intermediate (IW) and low (LW). Recorda were taken of plant growth and damage by feeding. The water régimes of some plants were reversed in the latter part to the experiment.
Larvae soon completed development on HW plants, but on LW plants a large number died, possibly because they were unable to take up fluid fast enough to offset loss by evaporation. There was intermediate mortality on IW plants.
Larvae took longer to develop on IW than on HW plants, probably because they imbibed nutrients at a reduced rate.
More larvae survived on LW plants that were regenerating after increase in water status than on plants that had received abundant water continuously. They fed mainly on the old wood and very little on the soft regenerative shoots, so were apparently favoured by some change in the peripheral tissues of the main stem.
On HW plants, nearly all feeding took place on woody or partially hardened tissue; newly flushing tissue was not fed on if it was growing normally. On IW plants, the expansion of new terminal leaves was often slow, and these tissues were then attacked by young larvae. This happened much more on LW plants, where the apical region was killed by persistent feeding. On all plants larvae older than second instar fed only on hard tissues.
Later effects of feeding were splitting of the wood where lesions had been made and sometimes the development of fungal infecdtions. The most severe infections occurred when the upper part of the old stem died back on LW plants that were regenerating after increase in water status.
The geographical ranges of Sahlbergella singularis and Distantiella theobroma overlap, and the Gold Coast lies in the zone common to both. The respective northern limits remain to be determined, and should be investigated to the north of the main cacao belt, from Kintampo to the Afram plain.
The same area should also yield information on the possible importance of alternative hosts in the dispersal of cacao Mirids, as the small stands are well separated from each other.
Earlier records, that D. theobroma is confined to seedlings and S. singularis to mature trees, are erroneous. D. theobroma is found on pods and, particularly, chupons. The feeding range of S. singularis includes fan branches in addition, but breeding is confined to chupons and pods.
Observations suggest that there is competition for breeding sites on chupons. Of the many chupons in an area only a small number is available to Mirids, and the proportion of nymphs reaching maturity is limited by their sedentary habit and the destructiveness of their feeding.
Co-existence of the two species is possible by their slightly different habits. S. singularis produces more eggs, but is more diffusely distributed. D. theobroma is virtually restricted to chupons, but can quickly build up a large population in favourable areas by its greater rate of egg production.
In Nigeria, the rate of egg production by D. theobroma is less than that by S. singularis , and this, together with the sparsity of chupons, may account for the unimportance of D. theobroma in that country.
In the coastal region of British East Africa three ant species, Anoplolepis custodiens, A. longipes and Pheidole punctulata may destroy the ant Oecophylla longinoda which is a valuable predator on the coconut pest Theraptus sp. (Coreidae). The three first-named species do not prey on Theraptus , which may severely damage palms occupied by them.
Nesting habits of the three ant species and their behaviour towards O. longinoda and certain other insects are described.
O. longinoda has been exterminated in the limited areas occupied by the two Anoplolepis species. P. punctulata is widespread and is usually common in areas occupied by O. longinoda and is also present, though relatively less common, in A. longipes areas.
The distribution of the Anoplolepis species, particularly A. custodiens , is correlated with sandy soils bearing a sparse ground vegetation. Where there are heavy soils or a thick ground vegetation of grasses and creepers the Anoplolepis species are absent and O. longinoda is usually present. It is suggested that the Anoplolepis species are limited by the relatively low temperature of soils shaded from sunlight by thick vegetation.
The Ponerine ant Odontomachus haematodus (L.) tendsthe aphid Toxoptera aurantii (Boy.) and a StictococcidStictococcus sjostedti Ckll. on cocoa in Ghana but predates the mealybug Planococcoides njalensis (Laing). Tents are built over the first two, largely of soil particles. Honeydew is collected in the mandibles and carried to the nest or may be accumulated and eventually drunk. Some of the soil used in the tents is infected by blackpod sporangia. Tending homopters is restricted to the immediate vicinity of the nest. The mutualism practised has evolved independently of its occurrence in higher ants.(Received July 19 1971)
Counts were made of Microdiptera hatching in emergence traps from samples of organic substrates from cacao plantations in Bahia, Brazil. Rotten cacao pods provided the best substrate with regard to species diversity and total numbers of insects collected, and also for the subgenus Thyridomyia. Leaf-litter was found to be an important breeding place for the subgenus Forcipomyia, especially F. {F.} genualis (Lw.), and for Atrichopogon species. Epiphytic bromeliads may be an important breeding place for the pollinating subgenus Proforcipomyia.(Received December 06 1971)
A method for the routine quantitative estimation of mealybug populations on cacao trees is described and the results obtained from 24 successive monthly samples are tabulated.
The quantitative results obtained are of such variability that only gross differences in population density are shown as statistically significant.
From a series of analyses based on the survey data the following conclusions have been reached with regard to P. njalensis , the most important mealybug vector of swollen shoot virus :—
(a) The species is almost invariably attended in the field by Crematogasterine ants, the most important ant species building protective carton tents over the mealybug colonies.
(b) Crematogaster density is closely correlated with mealybug density and the ants construct their carton tents in relation to the numbers of mealybugs to be protected. Some of the arboreal Crematogasterine groups investigated are shown to be consistently associated with higher mealybug populations, and to have a more advanced tent building habit, than others.
(c) Tree to tree variation in mealybug density is shown to be largely dependent on the identity of the dominant ant group.
(d) No direct correlation is apparent between mealybug density and incidence of swollen shoot though populations in areas devastated by virus are usually smaller than in areas in which virus is actively spreading.
(e) The factors of importance in the natural control of P. njalensis populations have been discussed in some detail. It is clear that the species is maintained by ant protection at a density level considerably above that prevailing amongst closely related pseudococcid species which are not ant attended to the same extent. At this level of “ protected steady density ” balance is maintained partly by losses during crop harvesting, and partly by swollen shoot rendering the host plants unsuitable as feeding stations. It is concluded, however, that natural enemies must, in the last analysis, be responsible for maintaining balance.
(f) Since the protected density of P. njalensis is a direct result of ant associations it follows that factors tending to control the attendant ant species will have a delayed effect on mealybug density. In this respect it is believed that Oecophylla , which is strongly negatively correlated with Crematogaster spp., is of importance. Any attempts that may in the future be made to control the mealybugs by killing the ants will have to be designed as specific against the Crematogasterini and non-lethal to Oecophylla and the other large predatory ants common on cacao.
In the British Solomon Islands Protectorate, the incidence of immature nutfall of cococuts that is caused by the Coreid bug, Amblypelta . (chiefly A. cocophaga China ), depends indirectly upon certain species of ants, some of which protect the palms against Amblypelta , whilst others do not. There is evidence that populations of the ants can sometimes change quite rapidly, and that local fluctuations in nutfall are largely dependent on such changes.
Observations on ant populations were maintained over a period of 2½ years (1954—1956) to find out if such changes are of common occurrence and to attempt to explain their cause.
An account is given of ideas, current at the beginning of the author's investigation, on the effect of vegetation and other factors on changes in ant populations, and in particular of the cover-crop or creeper theory, the advocates of which suggest that the presence of such vegetation, prevalent in plantations during and after the war, provided conditions favourable to beneficial species of ants.
The actual progress of recorded changes in ant populations is described and discussed. Rapidly changing populations usually involve the ants, Pheidole megacephala (F.), Oecophylla smaragdina (F.), and sometimes also Anoplolepis longipes (Jerd.); more stable populations usually involve Iridomyrmex myrmecodiae Emery, and occasionally Oecophylla and Anoplolepis . An account is given of the ‘battles’ which often occur during replacements of one species by another.
An account is given of the vegetation found in coconut plantations in the Solomon Islands, with special reference to the plant communities associated with each of the four species of ant of special importance in immature nutfall, and also with mixed ant populations. It is concluded that heavy creeper growth is not particularly associated with O. smaragdina (as was thought by supporters of the creeper theory), nor with the other beneficial species A. longipes , but rather, if anything, with P. megacephala , a non-protective or harmful species; there is thus no good reason to suppose that a growth of creepers will encourage beneficial species. Iridomyrmex myrmecodiae is the only species of the four which tends to be associated with a characteristic type of vegetation, including several species of epiphytes and often heavy creeper growth. But there are exceptions even to this, and there is evidence that the epiphytic vegetation may to some extent be the result rather than the cause of the presence of Iridomyrmex . There are, in fact, exceptions to every rule, and it is concluded that vegetation is not an important factor controlling ant distribution, except in so far as heavy growth of creepers and other plants may encourage a more mixed ant population in general, including several indigenous species which are not normally conspicuous in well-maintained plantations; if there is any effect on the four ‘major’ species, it is to encourage Pheidole and Iridomyrmex at the expense of Oecophylla and Anoplolepis .
An account is given of two experiments which involved control of creepers and other vegetation by repeated cutting down or ‘brushing’ in marginal zones between areas occupied by two different ant species, to see if this practice would alter the course of changes in population that were already taking place. One experiment involved a marginal zone between I. myrmecodiae and A. longipes , and the other between O. smaragdina and P. megacephala . It was found that in both cases there was no appreciable difference in the course of events between ‘brushed’ plots and plots adjacent to them in which the vegetation was not controlled. This bears out the previous conclusions that the presence or absence of creepers and other vegetation has little, if any, effect upon changes in ant populations.
At Rua Vatu, where an extensive replacement of P. megacephala by O. Smaragdina was taking place, accompanied by recovery from a condition of heavy nutfall, detailed studies revealed that this replacement was not a direct one, but that, at all events for the most part, a succession of normally unimportant ‘transition’ species first replaced Pheidole , and were in turn replaced by Oecophylla . The details of this succession are described and discussed. Evidence is produced to suggest that a similar succession may have been involved in recorded examples of recovery from nutfall in other places, notably in that which occurred in the Kukum/Lunga/Tenaru group of plantations after the second world war. These conclusions present a picture not so much of direct antagonism between Pheidole and Oecophylla , but rather of the initial disappearance of Pheidole owing to unknown intrinsic factors, followed later by the infiltration of Oecophylla in the wake of a variable succession of indigenous ‘transition’ species, which have been allowed to increase in numbers temporarily during the interim period when the area is not dominated by either of the two major species. In view of this, it is not so surprising that a factor such as vegetation should have little or no direct effect upon the change as suggested in terms of the creeper theory.
As regards the reverse change, the replacement of Oecophylla by Pheidole , there is little evidence to go on, but such as there is suggests that the replacement in this case is more in the nature of a direct one.
The fact that recovery from nutfall took place recently at Rua Vatu, at a time and place where insecticides had not been applied, contradicts the theory that the earlier and similar recovery in the ukum/Lunga/Tenaru group of plantations was the result of a differential effect upon ant species of the application of insecticides during the war for mosquito control .
The entomology of swollen shoot of cacao is a complex and unique problem involving the inter-relations in the field of over 120 insect species of four insect and two arachnoid orders. Briefly, there are 17 species of pseudococcids, 75 species of ants, 16 species of hymenopterous parasites, three predatory beetles, one predatory dipteran, and three arachnid species involved in vector relationships directly, with a further 18 Coccid species involved indirectly (it is possible, of course, that further work will show that some of these 18 species are directly concerned as vectors).
In the present paper an attempt has been made to reduce this assemblage of insect material to some semblance of order. The Coccid species are named and a series of preliminary observations on their biology and field behaviour detailed. The ant species, some of which are obligatorily associated with certain vector species, have been sorted into groups where specific determination has proved impossible or unnecessary and information has been included on their field habits and relative abundance.
There are three distinct but complementary ecological niches involved in the problem. The first, and most important, is the association between the mealybug virus vectors and the Myrmicine coccid-tending ants. The second is the association between mealybugs of the genera Paraputo and Formicococcus and the wild forest tree hosts of swollen shoot virus, and the third is the negative association between the mealybug tending Myrmicine ants and Oecophylla and Macromischoides , the latter species acting in certain circumstances as barriers to the spread of the mealybugtending species and hence to the spread of mealybugs and virus. These problems will be dealt with on a quantitative basis in a further paper.
A close association exists between the ant Oecophylla longinoda (Latr.) and the scale insect Saissetia zanzibarensis Williams.
Several factors cause the scale to be rare in the absence of the ant. Contamination by honey-dew and sooty moulds prevents increase of the S. zanzibarensis population above a relatively low level, while, in addition, insect parasites and probably predators virtually exterminate the scale. A fungal parasite may destroy honey-dew-contaminated S. zanzibarensis under humid conditions.
The attendant O. longinoda prevents contamination of the scale by honeydew. It gives absolute protection from Coccinellid predators and, although parasitism by Coccophagus spp. and predation by Eublemma spp. is not prevented, the mortality of S. zanzibarensis which they cause is thought to be of little significance.
O. longinoda workers benefit S. zanzibarensis in other ways. They remove débris from the scale clusters; they transport the nymphs and establish them at suitable feeding sites. The effect of these benefits is most marked when the ant population is high relative to that of the scale.
The silken shelters built by O. longinoda over S. zanzibarensis clusters protect the ant during adverse weather and may only incidentally benefit the scales.
S. zanzibarensis and other honey-dew-producing Homoptera are the major food source for O. longinoda . Other sources are sufficient to maintain only relatively low populations of the ant.
Certain species of COCCIDAE that excrete honeydew and are attended by ants or enclosed in their nests are quite prevalent on tea bushes and seed trees in the plains of Assam and West Bengal but those which are not attended by ants are kept under considerable check by the activities of their natural enemies. In Darjeeling, where the natural enemies are fewer, a number of species occur abundantly and are often responsible for serious damage to tea.
From the studies of the relative population of the ant, Crematogaster dohrni Mayr and the Coccid, Saissetia formicarii (Green), occurring on tea bushes it is doubtful if more than a small portion of the food requirement of the vast ant population in the nests which contain sexual forms could be met from the honeydew excreted by the small number of Coccids enclosed therein. The major part of food must, therefore, come from other sources. Insects attacking or visiting the tea bushes and tea seed trees or even those found on the ground appear to constitute the major part of the food of the ants, C. dohrni and Oecophylla smaragdina (F.).
Several factors are responsible for the decrease in the population or disappearance of the Coccids in the absence of attendant ants. In the plains, Eriochiton theae Green, Coccus hesperidum L. and S. formicarii entirely disappear in the absence of attendant ants either due to the activities of their natural enemies or by contamination with honeydew accumulation or both. Parasitism may be slightly higher in ant-free colonies, but no estimation was possible since, in the absence of ants, the Coccids are quickly destroyed by predators.
The ants do not protect the Coccids from Hymenopterous parasites; but their active movements hinder the parasites in their efforts to oviposit, and this leads to a reduction in the rate of parasitisation.
In the presence of the ants, O. smaragdina and Crematogaster dohrni , predators are rare; they are destroyed as are any other insects or any foreign bodies that happen to be near their nests, whether they constitute food or not. The larvae of predators which have a protective covering or which resemble Coccids, if they happen to have gained access to the Coccid colonies, are not attacked by the ants, because they are not recognised as different from the Coceids.
O. smaragdina does not normally transport Coccids, though young nymphs of E. theae and Coccus hesperidum may be aided in their dispersal, but Crematogaster dohrni and Crematogaster sp. are primarily responsible for the dispersal of S. formicarii and this takes place when an occasion arises to remove the Coccid to more favourable sites.
O. smaragdina does not destroy the nymphs and sedentary form of Coccus hesperidum for food, but sedentary forms which are unable to establish themselves on transfer from withered leaves to a new nest are eaten.
With the control of the attendant ants, the honeydew-producing Coccids disappear or at least they become rare. Conversely, where the Coccids are controlled, the ants automatically disappear.
The two species of Mirids, Sahlbergella singularis Hagl. and Distantiella theobroma (Dist.), are important pests of cacao ( Theobroma cacao L.) in the Gold Coast. The damage sustained by the cacao is due, in part, to the direct effects of feeding by these insects, but more to the subsequent invasion of the resulting lesions by the weakly pathogenic fungus, Calonectria rigidiuscula (Berk. & Br.) Sacc.
In the field, Mirid damage may be classified into three categories. “Blast” is the result of light diffuse attack and is so named because of its similarity to fire damage. “Stagheaded cacao” is more severe, the trees showing numeroussmall crown branches but forming a poor canopy. “Mirid pocket” describes severe damage, normally limited to a small area, the trees losing the crown completely and the polelike trunks bearing numerous lateral chupons. In general, stagheaded symptoms are more prevalent where cacao is grown without shade, and pockets where cultivation of cacao utilises shade trees.
Consideration of the factors associated with Mirid damage shows that it is correlated with breaks in the cacao canopy. Evidence is brought forward to suggest that such breaks normally precede, rather than result from, Mirid attack. The canopy itself is unsuitable for the development of either species, the major part of the population being confined to the sub-canopy levels. The initial causes of the breaks are, most frequently, the die-backs associated with swollen shoot or with adverse water relations. The falling of shade trees causes a number of breaks, and, where cacao is grown without shade, the Mirids themselves may be a cause.
The most important single factor influencing the form of the cacao canopy, and thus the course of Mirid attack, is the amount of overhead shade, particularly that provided by trees little taller than the cacao itself. Shade which is too dense causes etiolation of the cacao and thus renders it susceptible to attack, the resulting damage generally taking the form of a pocket. Shade which is too sparse does not shield the cacao from the adverse effects of exposure. The Mirid damage in such areas generally assumes the stagheaded form.
It is suggested, from field experiments, that the invasion by Mirids of areas suitable for colonisation is not by random movements, but is determined by the change in some physical factor resulting from the broken canopy. Changes in light intensity are the most obvious results of such breaks, but further experiments are needed to determine which is the operating factor.
Degraded cacao is prevented from recovery, not by Mirid attack alone, but by the interaction of it with the presence of C. rigidiuscula , and by increased exposure.
The sampling methods employed are described, and the bearing of the results upon control measures is discussed.
The anatomy and development of a typical Tapinanthus bangwensis-cocoa association is described, and it is shown how the mistletoe haustorium grows obliquely through the xylem of its host, causing the cocoa distal to it to die gradually from desiccation. In early development the mistletoe haustorium forms a plate of tissue between the host xylem and phloem, having roughly equal areas of contact with both. Later the ratio of phloem: xylem haustorial contact decreases.
Two experiments using ¹⁴C showed that the mistletoe took products of photosynthesis from its hosts, in one case against the expected direction of flow in the host phloem. A third experiment showed that no labelled photosynthates produced by the mistletoe were translocated into cocoa. It is suggested that in this case host hypertrophication is stimulated by the stresses set up by haustorial growth, rather than by mistletoe-produced hormones.
Phytophthora palmivora (Butl.) Butl., the causal agent of black pod of cocoa (Theobroma cacao L.), accounts for an estimated 19% crop loss in Ghana1, and losses are considerably higher in wetter countries such as Nigeria and the Cameroun Republic. The epidemiology of the disease is still uncertain but rain-splash from soil is considered by some workers2,3 to trigger-off disease cycles.
Six dolichoderine species have haploid numbers: 9 (Iridomyrmex pilifer, I. sp. nr. pilifer, Dorymyrmex ?thoracicus, D. ?pulchellus), 13 (D. bicolor) and 16 (Forelius foetidus). Robertsonian changes could account for the differences between the Dorymyrmex numbers. The Iridomyrmex species, both Neotropical, have a different karyotype from Australian 9-chromosome Iridomyrmex. The species with numbers 13 and 16 have relatively more acrocentrics per karyotype than those with lower numbers. Five formicine species have haploid numbers: 8 (Oecophylla smaragdina), 9 (Brachymyrmex sp.), 15 (Lasius nearcticus), 21 (Polyrhachis rastellata), and 26 (Camponotus (Colobopsis) sp. (impressus gp.)). Although thelytoky has been reported for Oecophylla spp., a queenless greenhouse colony died out after producing an all-male brood; further work is suggested on Oecophylla populations where thelytoky has been reported. The 8- and 9-chromosome formicines have all chromosomes metacentric, while acrocentrics predominate in the higher-numbered species. The ponerine Proceratium silaceum has n = 18. Nine myrmicine species have haploid numbers: 10 (Pheidole dentata, P. dentigula), 11 Solenopsis molesta, Monomorium minimum, M. viridum, Meranoplus sp. (hirsutus gp.)), 12 (Leptothorax longispinosus), and 16 (Solenopsis aurea, S. geminata). Monomorium karyotypes have a small acrocentric, while all 11-chromosome Solenopsis chromosomes are metacentric. Reviewing the 92 known ant karyotypes supports some present taxonomic schemes but not others. Imai's (1966) suggestions, that polyploidy occurred in formicine evolution and that high numbers occur more frequently at 'high' latitudes, are not supported by present evidence.
A genetical mathematical model is described which allows for interactions between relatives on one another's fitness. Making use of Wright's Coefficient of Relationship as the measure of the proportion of replica genes in a relative, a quantity is found which incorporates the maximizing property of Darwinian fitness. This quantity is named “inclusive fitness”. Species following the model should tend to evolve behaviour such that each organism appears to be attempting to maximize its inclusive fitness. This implies a limited restraint on selfish competitive behaviour and possibility of limited self-sacrifices.
Special cases of the model are used to show (a) that selection in the social situations newly covered tends to be slower than classical selection, (b) how in populations of rather non-dispersive organisms the model may apply to genes affecting dispersion, and (c) how it may apply approximately to competition between relatives, for example, within sibships. Some artificialities of the model are discussed.
Grounds for thinking that the model described in the previous paper can be used to support general biological principles of social evolution are briefly discussed.Two principles are presented, the first concerning the evolution of social behaviour in general and the second the evolution of social discrimination. Some tentative evidence is given.More general application of the theory in biology is then discussed, particular attention being given to cases where the indicated interpretation differs from previous views and to cases which appear anomalous. A hypothesis is outlined concerning social evolution in the Hymenoptera; but the evidence that at present exists is found somewhat contrary on certain points. Other subjects considered include warning behaviour, the evolution of distasteful properties in insects, clones of cells and clones of zooids as contrasted with other types of colonies, the confinement of parental care to true offspring in birds and insects, fights, the behaviour of parasitoid insect larvae within a host, parental care in connection with monogyny and monandry and multi-ovulate ovaries in plants in connection with wind and insect pollination.
Two worker ants preserved in amber of Upper Cretaceous age have been found in New Jersey. They are the first undisputed remains of social insects of Mesozoic age, extending the existence of social life in insects back to approximately 100 million years. They are also the earliest known fossils that can be assigned with certainty to aculeate Hymenoptera. The species, Sphecomyrma freyi, is considered to represent a new subfamily (Sphecomyrminae), more primitive than any previously known ant group. It forms a near-perfect link between certain nonsocial tiphiid wasps and the most primitive myrmecioid ants.
The role of Anoplolepis longipes Jerdon (Hymenoptera: Formicidae) in the entomology of cacao in the Northern District of Papua New Guinea. Abstr. 14th Int. Congr. Ent, Canberra
- G Baker
- Maclaren P. I. R.
- Dunn J. A.
The ant mosaic: a fundamental property of cocoa farms
- D Leston