Economic Rationale of Using African Weaver Ants, Oecophylla longinoda Latreille (Hymenoptera: Formicidae) for Sustainable Management of Cashew Pests in Tanzania

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Cashew nut, Anacardium occidentale Linnaeus, is an important crop to the African economy, contributing to livelihood of many families. It is among the top foreign-currency-earning crops in East and West African countries. The crop is attacked by several sucking pests that survive on multiple host plants. These include: Pseudotheraptus wayi, Helopeltis anacardii, H. schoutedeni, and Selenothrips rubrocinctus. Management of these pests is usually a challenge which triggers irrational use of synthetic pesticides. Excessive use of pesticides concerns human health and pollution in the environment. The use of African weaver ants, Oecophylla longinoda, has presented an alternative to pesticides for sustainable cashew pest management. The predator was found to be as highly effective (P < 0.0001) as the recommended insecticide (Lambda cyhalothrin) (P < 0.0001) in controlling cashew pests. The several economic analyses on the profitability of the technology over the recommended pesticides by partial budgeting, marginal rate of returns, benefit-cost ratio and net present value proved O. longionda to be superior to pesticides. The partial budgeting indicated a net benefit of US$7.72 per cashew tree by changing from insecticides to O. longinoda within two seasons. The dominance analysis for marginal rate of returns indicated a net profit of US$11.39 per tree in two seasons compared to US$5.74 per tree gained from Lambda cyhalothrin. If adopted for use, the predator will provide a sustainable solution to cashew pest management and overcome the pesticide residue threats in marketed cashew from Africa.

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... The present study exposed the erceness of major workers foragers encounter with any intruders and other weaver ants from different colonies, showing that foraging and colony defense is a risky duty, impairing substantially the survival ability and therefore incurring high mortality rates in ants (Chapuisat & Keller, 2002). This is particularly true in the Oecophylla genus, where major workers aggressively defend extensive territories, by performing permanent foraging duties, against con-speci c individuals from different colonies seen as competitors or intruders in the case of O. smaragdina (Peng et al., 1999;Saarinen, 2006;Peng & Christian, 2009) and O. longinoda (Rwegasira et al., 2020). The same strategy is systematically adopted as soon as the colony expands its territory by performing initially extensive foraging activity to explore suitable new areas (Hölldobler & Wilson, 1990). ...
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Asian weaver ant, Oecophylla smaradigma is a nuisance species, effect the plantation employee due to their painful bites. The O. smaragdina was reported as one of the potential predators for the invasive bagworm species, Pteroma pendula in the oil palm plantation. Despite their important role in the plantation, however the study on the ecology and behaviour of the O. smaragdina is still lacking and not discovered. The objectives of this study were to investigate the relationships between the foraging daily activities of the O. smaragdina with the weather parameters. In 2018-2022, this study investigates the trunk foraging activity pattern of O. smaragdina colonies (9 days per colony) from selected plantations, as an effort of mitigation. In 2020-2022, a targeted field study was undertaken to examine the daily trunk foraging activities of major workers in relation to air temperature (AT), relative humidity (RH), air pressure (AP) and rainfall (RI). Ground forager behaviours were observed and examined from the trunk trail split covering an average frontal fluctuating angle from base palms. It is suggested that O. smaragdina is a diurnal ant species with much lesser crepuscular intensity. It is demonstrating similar daily foraging activity patterns featuring higher intensity during the warmest daily periods in relation to population size relative abundance. This was irrespective of the dry-wet seasons corresponding to low activity from late scotophase to early photophase, exhibiting a bimodal foraging pattern. Throughout the overnight period, foraging activity ceased. O. smaragdina is a visual light dependent hunter for efficient intensive foraging. Active foragers reached peaks at around 1100 to 1530 hours, and from 1745 to 1845 hours. Between 1620 and 1650 hours, foragers demonstrated a two-fold daily decline in intensity on average. There was a strong positive correlation between foraging activity, AT and AP but negatively correlated with RH. Sustained RI stopped the trunk-ground trail activity of O. smaragdina, exposing outbound foragers withdrawing massively to the canopies. Defensive territorial layers are established from the base palm trunks reaching an average 5 m distance featuring two distinct spatial arrangements. Major workers trunk trails split into several new lines on an average 3 m radius showing higher foraging density. The trails broke off to expand into a web shape figure occupation reaching on average 5 m. The avoidance of forager relentless attacks can be achieved during the daily low activity periods (before 1000 hours) for pruning and harvesting tasks if the adoption of O. smaragdina is implemented to control the invasive Metisa plana bagworm species.
... In Zanzibar, O. longinoda was reported attending Saissetia zanzibarensis (Way, 1954), as was observed in this study. The ant has also been found in close association with other mealybugs and scale insects (Dwomoh et al., 2008;Olotu et al., 2013); it is used as a biological control agent against other, non-scale pests' elsewhere (Way, 1954;Mele et al., 2007;Olotu et al., 2013;Carrillo et al., 2017;Rwegasira et al., 2020). ...
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A survey of citrus orchards was conducted in Kilifi, Kwale, Machakos and Makueni counties, Kenya to collect and identify ants (Hymenoptera: Formicidae) and natural enemies associated with scale insects (Hemiptera: Coccomorpha) feeding on citrus trees (Sapindales: Rutaceae). Nine ant species were found associated with nine scale insect species feeding on three citrus species (Citrus limon, C. reticulata and C. sinensis) for their honeydew. The ants associated with the scales in the study areas were: Cataulacus brevisetosus (Forel), Camponotus rufiglaucus (Jerdon), Crematogaster castanea (Smith), Cr. sjostedti (Mayr), Monomorium afrum (Andre), Myrmicaria opaciventris (Emery), Oecophylla longinoda (Latreille), Pheidole megacephalla (Fabricius), and Technomyrmex albipes (Fr. Smith). The ant Myrmicaria opaciventris was recorded attending four scale insects’ species: Coccus hesperidum, Co. viridis, Pulvinaria polygonata (Hemiptera: Coccidae) and Pseudococcus cryptus (Hemiptera: Pseudococcidae) in Kilifi County. Host-plant identities and localities surveyed are also presented. These new data for citrus-growing areas in Kenya will contribute to the development of integrated pest management programs on citrus
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Cashew production in Tanzania is severely constrained by sucking insect pests such as the coreid coconut bugs (Pseudotheraptus wayi Brown), the mirid bugs, Helopeltis spp. and thrips spp. These pests damage flushing foliar and floral shoots as well as young cashew fruits and nuts. Farmers rely heavily on insecticides in controlling these pests and there are no suitable alternative control methods compatible with organic cashew production. Weaver ants, Oecophylla longinoda Latreille have for long been considered as effective biological control agents against sap-sucking pests of cashew, but studies on their effectiveness as compared to conventional insecticides had never been conducted. The current study evaluated the efficiency of O. longinoda as compared to the recommended conventional insecticide, lambda cyhalothrin (Karate®) in controlling major cashew insect pests and compared the resulting cashew yield. The damage caused by each pest was significantly lower (P < 0.0001) on trees with weaver ants and in the plots treated with Karate® than was the case on the control trees. There was no significant difference (P > 0.05) in the damage between O. longinoda and Karate® treated trees suggesting that the two treatments are equally effective. The difference in the damage levels was directly reflected in the mean cashew yield. The two season’s results showed an average yield increases of 58.2 and 60.7 % in the insecticide-treated and in the O. longinoda-protected trees, respectively, in relation to untreated control plots. Thus, O. longinoda can serve as an alternative to chemical insecticides in Tanzanian cashew protection.
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The predatory efficiency of African weaver ants Oecophylla longinoda and their utilisation in protein production is a function of ant abundance. Reliable control of insect pests in tropical crops is achieved when ant populations are constantly high. Transplanted populations of weaver ant colonies containing egg-laying queens are more stable than those without. Achieving such stability through collection of colonies established in the wild is usually difficult because of uncertainty in locating the nest containing the egg-laying queen. In this study, we investigated four methods that may be used to collect mated queens that subsequently can be used to stock ant nurseries. The catch efficiencies of (1) leaf traps, (2) paper traps (both types providing a refuge for founding queens), (3) random search for queens and (4) light trapping were compared. Light trapping was the most efficient way to collect queens followed by leaf traps, random search and, last, paper traps. Light trapping and random search, though, required the presence of a person throughout the ant's mating season (several months), whereas this was not required when using leaf and paper traps.
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In Benin cashew plantations, yields and nut quality are lost mainly as a result of insect pests. In the present study, we investigated the effectiveness of the African weaver ant Oecophylla longinoda as a biocontrol agent against Beninese cashew pests.In a 2-year study, nut yield and quality were compared among: (i) trees with weaver ants O. longinoda; (ii) trees where weaver ants were sugar-fed; (iii) integrated pest management (IPM) trees with weaver ants combined with fruit fly bait spray; and (iv) control trees receiving no control measures.All treatments with ants showed significantly higher yields than the control, with the IPM treatment leading to the highest yield. Compared with the control trees, the ants, ant sugar-fed and the IPM trees produced 78%, 122% and 151% more nuts, respectively. Nuts produced on control trees were of a higher quality on average because they were less damaged by thrips (probably because the fruit fly bait worked as a contact poison on thrips); this was also the case for the IPM treatment. In absolute numbers, however, trees in ant treatments produced more first-quality nuts.To achieve a broader and effective control of both coreid bugs and thrips, a combination of weaver ants and supplementary compatible control measures is recommended.
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Cashew (Anacardium occidentale L.) is a very important source of income for more than 200,000 farmer households in Vietnam. The present cashew productivity in Vietnam is low and unstable, and pest damage is partly responsible for this. Cashew farmers rely on pesticides to minimize the damage, resulting in adverse impacts on farm environment and farmers' health. Weaver ants (Oecophylla spp) are effective biocontrol agents of a range of cashew insect pests in several cashew-growing countries, and these ants are widely distributed in Vietnam. The aim of this study is to evaluate the potential of weaver ants in cashew orchards in Vietnam. Field surveys and field experiment were conducted in five cashew orchards from July 2006 to January 2008 in Binh Phuoc, Dong Nai, and Ba Ria Vung Tau provinces, Vietnam. Based on the field surveys, the most important pests that damage flushing foliar and floral shoots and young cashew fruits and nuts were mosquito bugs, brown shoot borers, blue shoot borers, and fruit-nut borers. The damage caused by each of these pests was significantly lower on trees with weaver ants compared with trees without the ants, showing that the ants were able to keep these pest damages under the control threshold. Regular monitoring of the field experiment showed that weaver ants were similar to insecticides for controlling mosquito bugs, blue shoot borers, fruit-nut borers, leaf rollers, and leaf miners. Aphids did not become major pests in plot with weaver ants. To manage insect pest assemblage in cashew orchards, an integrated pest management using weaver ants as a major component is discussed.
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We interviewed half of the mango-growers in northern Benin, including 15 farmers involved in a regional fruit fly project, and held focus group discussions with women fruit-pickers. They were asked about pest management and their knowledge of a weaver ant, Oecophylla longinoda. All considered low yields due to fruit flies to be the principal constraint upon mango production, estimating economic losses to be between 20 and 45%. None could recognize damage during the first 2 days after fruit fly egg deposition. On-farm research persuaded farmers to stop using insecticides and it also changed negative perceptions of Oecophylla. Over 80% of the farmers involved in on-farm research, compared to 25% of those not involved, reported Oecophylla to be beneficial. All fruit-pickers knew that ants protected mango from fruit flies, with 60% attributing better mango quality in terms of appearance, shelf-life and sweetness to the presence of Oecophylla. Nevertheless, 40% of the pickers still considered weaver ants a nuisance pest during harvest. Ways of reducing this nuisance need to be developed for Oecophylla to gain wider acceptance by mango-growers.
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Fruit flies are causing extensive socioeconomic losses in citrus orchards in Ghana. The flies as quarantine pests have detrimental effects on the export market due to international trade regulations. Oecophylla species have been tested as biological control agents on other crops, and have shown great potential in reducing the effects of pests. The effectiveness of Oecophylla as a biocontrol agent of fruit flies was compared with insecticide, Cypermethrin + Dimethoate (Cydim super®) at Forest and Horticultural Crops Research Centre, Kade, in the Eastern Region of Ghana. The results have shown that trees colonized by Oecophylla had between 6%-10% fly infestation and Cypermethrin + Dimethoate (1614 mg a.i. mL-1 tree-1) recorded 3.0% infestation. Cypermethrin + Dimethoate treatment recorded 3.50 ± 0.87 dropped fruits, and Oecophylla colonized-trees recorded 15 to 19.20 ± 3.61. Oecophylla colonized-trees recorded yield values from 12.90 to 15.20 tons ha-1 whilst Cypermethrin + Dimethoate treatment recorded 27.90 tons ha-1 fruit yield. Total number of fly landings in the presence of Oecophylla (72.00) was significantly lower than the absence of Oecophylla (114.20). Setup with no Oecophylla recorded the highest infestation index (71.17) while the presence recorded 45.83. These results suggest that Oecophylla longinoda can be used as a biocontrol agent for IPM programs in citrus orchards.
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As damage by the fruit flies Bactrocera invadens and Ceratitis cosyra is significantly reduced in mango trees with weaver ants, but we rarely observed adult flies being captured, we investigated whether Oecophylla pheromones affect fruit fly oviposition behaviour. Mangoes were collected within 1 m and 1–3 m distance from ant nests, and from ant-free trees. Using both choice and no-choice tests, fruit flies were allowed to oviposit on fruits for 72 h in the absence of ants. Flies landed significantly more and spent more time on fruit from ant-free than from ant-colonized trees. The density of ant pheromone sources significantly affected the oviposition time and the number of fruit fly pupae collected per kg fruit under greenhouse conditions. However, field data did not show any difference in damage for fruit collected within 1 m and 1–3 m distance from ant nests, suggesting that physical or visual mechanisms complement the repellencey effect of ant pheromones against fruit flies.
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Mango is the most important commercial fruit crop in the Northern Territory, Australia. Growers currently rely on insecticides to control insect pests of mango, resulting in environmental and social problems. To reduce dependency on insecticides, a suitable IPM programme is needed. Previous work showed that weaver ants can control the major mango insect pests, but they protect soft scales, damage fruits by their formic acid and annoy operatives during fruit harvest. Further research addressing these constraints showed that certain chemicals can reduce soft scale numbers without seriously affecting weaver ant populations, the isolation of ant colonies reduces fruit damage by formic acid, and water spray reduces the ant activity during harvest. A field experiment with two treatments, weaver ants plus soft chemicals (WPS) and weaver ants plus chemical insecticides (CI), was conducted at Howard Springs in the Northern Territory. In two out of the three years, the yield of first class fruit was 20% higher in WPS than in CI. This was mostly explained by lower insect pest damage, lower incidence of mango scab disease and lower infestation of lenticels in WPS. Trees in WPS produced significantly more fruits than in CI in 2002. Overall, trees in WPS resulted in a profit of A$14.50/tree per year, but trees in CI produced only A$8.38/tree per year. During harvest, farmers experienced only minor problems with ant disturbance. An IPM model using weaver ants as a key element is discussed with respect to ‘organic’ production.
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Oecophylla species are among the most iconic tropical ants, but a broad review of their biology has been lacking. The two living species of Oecophylla are widespread in the Old World tropics and are similar in presenting the most sophisticated nest-building activities of all weaver ants. Workers draw leaves together, often forming long chains, and glue them together with larval silk. Chain formation promises to provide a major subject for the development of models of the self-organization of complex behavior. The colonies are very large and highly polydomous. Queens are pre-dominantly though not exclusively once-mated and colonies are usually single-queened, but most Northern Territory (Australia) colonies are polygynous. The workers are highly polymorphic (seen also in a fossilized colony), show complex polyethism, and present a much-studied rich pheromonal repertoire for the colony's tasks. Colony odor is partly learned, showing a "nasty neighbor" effect in reactions to other colonies of this highly territorial ant, and partly intrinsic to each individual. The odor varies over time and differs between the nests of a colony. Not surprisingly, Oecophylla ants are hosts to a variety of inquilines, such as spiders, which mimic the colony odor to escape detection. In addition, a con-stellation of Homoptera benefit from ant protection, yet the activities of the ants in controlling pest species make these ants beneficial insects (they are also human food in some areas). We speculate that the existence of Oecophylla blocks other weaver ants from evolving highly complex social organization, an idea which could be tested with further knowl-edge on the timing of ant adaptive radiations.
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Six mango, Mangifera indica L., plantations around Parakou, northern Benin, were sampled at 2-wk intervals for fruit fly damage from early April to late May in 2005. Mean damage ranged from 1 to 24% with a weaver ant, Oecophylla longinoda (Latreille), being either abundant or absent. The fruit fly complex is made up of Ceratitis spp. and Bactrocera invadens Drew et al., a new invasive species in West Africa. In 2006, Ceratitis spp. peaked twice in the late dry season in early April and early May, whereas B. invadens populations quickly increased at the onset of the rains, from mid-May onward. Exclusion experiments conducted in 2006 with 'Eldon', 'Kent', and 'Gouverneur' confirmed that at high ant abundance levels, Oecophylla significantly reduced fruit fly infestation. Although fruit fly control methods are still at an experimental stage in this part of the world, farmers who tolerated weaver ants in their orchard were rewarded by significantly better fruit quality. Conservation biological control with predatory ants such as Oecophylla in high-value tree crops has great potential for African and Asian farmers. Implications for international research for development at the Consultative Group on International Agricultural Research level are discussed.
The purpose of this article is to outline a simple economic procedure, based on the economic principles of marginal analysis, to assist the researchers in decision making. It was made popular at CIMMYT (Perrin, et al., 1988) and is summarized in the article. CIMMYT is the acronym for Centro Internacional de Mejoramiento de Maiz y Trigo (International Maize and Wheat Improvement Center), located in Mexico. This is EDIS document FE565, a publication of the Department of Food and Resource Economics, Florida Cooperative Extension Service, Institute of Food and Agricultural Sciences, University of Florida, Gainesville, FL. Published June 2005. FE565/FE565: Marginal Analysis: An Economic Procedure for Selecting Alternative Technologies/Practices (
The African Weaver Ant, O. longinoda Latreille is an important and successful biological control agent of numerous important pests of tree crops including cashew. There are hundreds of nests in a colony but only a single nest contains a queen with the role of laying eggs which ultimately produce viable offspring. The introduction of weaver ant colonies in a plantation is sustainable when a reproductive queen is included. Therefore, locating weaver ant colonies that contain a queen nest is essential, particularly during relocation of a mature colony in a plantation. We investigated locating queen nests in 52 colonies of O. longinoda. This study revealed that a tree with a queen nest (i) was not infested by weaver ant antagonists (ii) had more weaver ant trails with more active/aggressive workers than was the case with other trees (confirmed in 96% of cases). The queen nests was identified by aggregation of workers on or near the nest surface and the presence of workers on the exterior surface of the queen nest forming a chain/bridge like structure when queen nest is slightly disturbed. Furthermore, the queen nest is constructed with thick silk threads tightened between the queen nest leaves. Significantly (p < 0.0001), more queen nests were of smaller size and were located at the middle or lower position inside the tree canopy. It took an average of 5.6 min with a success rate of 99.6% to locate a O. longinoda queen nest. These new findings may facilitate the application of weaver ant technology in IPM-programs.
Oecophylla spp. are used as biocontrol agents for many types of insect pests. A large and stable population is essential for effective control of pests. Colonies of Oecophylla spp. can be transplanted from wild habitats into orchards. Transplanted colonies can only survive in the presence of egg laying queens. It is difficult to locate nests with egg laying queens in large colonies that may sometimes contain more than 100 nests. Therefore, the need to explore and develop methods for rearing newly mated queens in nurseries may not be over emphasized, hence the current study. In the first experiment, we tested three rearing methods on queen survival and colony establishment. In the second experiment, we compared feeding techniques of different weaver ants on young colony growth. We observed that queens were best reared under continuous, indirect access to water. The first workers emerged earlier (32 days on average) in indirect and direct continuous access to water methods than on limited access to water (sprinkled) (38 days on average). Moreover, rearing mated queens under continuous indirect access and continuous direct access to water methods saved labour and time, because of limited attendance to the colonies. Availability of water, sugar solution and different sources of protein throughout improved the growth of young colonies. Likewise, the number of workers increased rapidly. Therefore rearing mated queens in nurseries is possible and would minimize hustles in hunting for the colonies and their queens in the wilderness.
Cashew (Anacardium occidentale) is an economically important cash crop for many rural households in Tanzania. However, its production is constrained by some insect pests and diseases. As a prerequisite for the development of a more sustainable integrated insect pest and disease management strategy for cashew, information on the biology and ecology of the key insect pests and diseases in a changing environment, and on influencing biotic and abiotic factors, is needed. Surveys were conducted in the major cashew nut-producing areas of Tanzania for two seasons: August to December, 2009, and August to December, 2010. Data on number of infested and infected shoots by key insect pests and diseases, natural enemies and associated farmer practices, namely synthetic pesticide use and intercropping systems, were collected from different subzones within agroecological zones. Our data showed that abundance and diversity of key cashew insect pests and diseases were influenced by agroecological zones and subzones. Intercropping was more commonly practised in the northern than in the southern zone. Agrochemicals were most frequently used in the southern agroecological zone and affected the occurrence of natural enemies, notably the weaver ant that was more abundant in the northern zone. Furthermore, our findings revealed that Helopeltis sp. and the powdery mildew remained the major constraints to cashew nut production in Tanzania.
In tropical Africa and Asia, two species of the predatory ant genus, Oecophylla, play a crucial role in protecting tree crops against pests and enhancing the quality of fruits and nuts. As predatory effectiveness is influenced by the presence of other dominant ant species, understanding the ecological factors at work in agroecosystems lies at the basis of conservation biological control. Over three and a half years, the effect of ground vegetation management on the beneficial tree-nesting ant Oecophylla longinoda (Latreille) and its competitor, the ground-nesting ant, Pheidole megacephala (Fabricius), was studied in a citrus orchard in Tanzania. When ground vegetation was present, P. megacephala tolerated O. longinoda and to some extent cohabited with this ant in citrus trees. However, after clean cultivation, P. megacephala displaced O. longinoda from tree crowns and became the sole occupant of the majority of trees. Displacement could be reversed by reversing the weed management regime, but this took time. Two years after the establishment of ground vegetation about half of the trees were colonized by Oecophylla only. Maintaining ground vegetation in tree crop plantations benefits the establishment and abundance of Oecophylla over Pheidole and is recommended in order to improve the efficiency of biological control of tree pests. The use of Amdro ant bait (hydramethylnon) to control P. megacephala is discussed. Boosting agroecological innovations, such as the one described in this paper, could benefit smallholder producers.
Following a questionnaire survey and field studies, the weaver ant, Oecophylla smaragdina (Fab.), was found to inhabit much of the coastal area of tropical Australia. With discriminant analyses, the observed distribution pattern was explained by the combination of two physical parameters, mean annual rainfall and average minimum temperature. These may limit Oecophylla distribution in at least two ways: (1) low temperatures directly inhibit larval development; (2) both rainfall and temperature levels limit the distribution of the forest-woodland vegetation required by this arboreal ant.
Summarizes relevant aspects of ants' feeding habits and general ecology, followed by discussion of beneficial species and their attributes, and of how ecological conditions favoring their use can be manipulated for improved pest management. The stability, social organization, and foreging behavior of some predatory ants enable them to react quickly to increasing prey density, and also make them uniquely able to protect crops from low-density pests. Such qualities require dependence on honeydew-producing Homoptera that may sometimes be made harmful by ant attendance. Cost-benefit judgements are therefore needed when such ants are to be used. Predacious ants also affect other natural enemies, but less than might be expected, and may indeed benefit some. Ants tend to overlap the food niches of other predators and may force them into one competitive system. Whether overall biological control is benefited by such interactions is unknown. -from Authors
Cashew, Anacardium occidentale, is an economically important cash crop for more than 300 000 rural households in Tanzania. Its production is, however, severely constrained by infestation by sap-sucking insects such as Helopeltis anacardii, H. schoutedeni and Pseudotheraptus wayi. The African weaver ant, Oecophylla longinoda, is an effective biocontrol agent of hemipteran pests in coconuts in Tanzania, but its efficacy in the control of Helopeltis spp. and P. wayi in Tanzanian cashew has not been investigated so far. The aim of this study was therefore to evaluate the efficacy of O. longinoda in the management of these insect pests in the cashew crop at different sites of the Coast region of Tanzania. Colonisation levels of O. longinoda, expressed as weaver ant trails, varied from 57.1 to 60.6% and from 58.3 to 67.5% in 2010 and 2011 respectively. The mean number of leaf nests per tree varied from five to eight nests in 2010 and from five to nine nests in 2011. There was a negative correlation between numbers of nests and pest damage. Oecophylla longinoda-colonised cashew trees had the lowest shoot damage by Helopeltis spp. of 4.8 and 7.5% in 2010 and 2011, respectively, as opposed to uncolonised cashew trees with 36 and 30% in 2010 and 2011 respectively. Similarly, nut damage by P. wayi was lowest in O. longinoda-colonised trees, with only 2.4 and 6.2% in 2010 and 2011 as opposed to uncolonised trees with 26 and 21%. Oecophylla longinoda is an effective biocontrol agent of the sap-sucking pests of cashew in the Coast region of Tanzania and should be considered as an important component of IPM.
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.
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.
1 Although the weaver ant Oecophylla is the first written record of biological control, dating from 304 ad, there have been fewer than 70 scientific publications on this predator as a biological control agent in Asia, from the early 1970s onwards, and fewer than 25 in Africa.2 Apart from crop-specific ecological and perceptual factors, a historical review shows that political and market forces have also determined the extent to which Oecophylla was incorporated into research and development programmes.3 In Africa, research on weaver ants in biological control concentrated on export crops, such as coconut and cocoa, whereas, in Asia and Australia, research focused on fruit and nut crops, primarily destined for domestic markets.4 Increased evidence of pesticide inefficiency under tropical smallholder conditions, changing paradigm shifts in participatory research and a growing scientific interest in local knowledge in the early 1990s opened up new avenues for research on conservation biological control.5 Lobbying and advocacy have been needed to ensure that Oecophylla was recognized as an effective biological control agent.6 With an increased market demand for organic produce, holistic approaches such as conservation biological control, particularly the use of Oecophylla, are increasing in importance.7 Multi-stakeholder strategies for collaborative learning are proposed for a better control of major fruit, nut and timber tree pests in Africa, Asia and Australia.
Cashew (Anacardium occidentale L.) is the fourth most valuable Tanzanian export crop after coffee, cotton and tea. Following a steady increase in production from the middle of this century, there was a dramatic decline from 145,000 t in 1973 to 16,500 t in 1986. This was caused by a complex of socio-economic (low producer prices, inefficient marketing, villagisation) and biological factors (cashew powdery mildew disease, low tree yields, overcrowding of trees). Recently, higher cashew prices and liberalised marketing have created favourable conditions that have encouraged farmers to tackle several of the biological constraints on production. As a result, cashew production has risen steadily from 16,500 t in 1986 to 70,320 t in 1994.
The present study has been formulated to study the cost of cultivation of stevia to encourage the farmer regarding cultivation of this plant and also provide information regarding profitability of cultivation. Stevia become a potential and renewable raw material in the food market because the increase in the number of diabetic and health conscious individual boost up the international market of high quality stevia leaves which is a non-caloric natural sugar. Lack of information regarding the cost of cultivation of stevia specially in Indian context generate plenty of confusion with regard to cultivation of this plant and also about selection of the profitable propagating material. The present study thus concerned with calculating the cost of cultivation, return and cost benefit ratio to identify economic viability and technical feasibility of stevia cultivation through cutting and tissue culture propagated planting material. For this an experimental plot size of 100x100 m each was used for cultivation for 3 years with cutting and tissue cultured plantlets as propagating material. The cost of cultivation refers to the total expenses incurred in cultivating stevia, expressed on a per hectare basis and worked out using operation wise approach in both the cases for three years. Lastly benefit cost ratio was incurred which is the ratio of the present worth of gross costs and represents the economic viability of the two projects. From the two project it was revealed that fixed as well as variable cost was more in tissue culture plantlets propagated field but tissue cultured plants favour disease free clean cultivation with high foliage production as compared with cutting where disease and pest infection was severe. For this during three years of economic life total sales of dry stevia leaves was generate more income in tissue cultured propagule established fields than cutting propagated field. From the cost benefit ratio of the two projects it was clear that profit of the two projects was comparable with each other and was technically feasible and economically viable.
The beneficial effects of ants in agriculture and forestry have already been reviewed in Chapter 11. In the following pages I discuss the methods by which ants have been utilized in crops to limit maladies and highlight the strengths and weaknesses of the various approaches. Arising from this review a checklist of points to consider when promoting beneficial is presented so that future ant manipulation attempts can draw on these experiences. This account distinguishes between species that are physically "introduced" into an area from outside and resident species that are "encouraged" to spread their range or utilize an enemy species more effectively. The term "promoted" collectively refers to both methods.
Cashew (Anacardium occidentale L.) has become a very important non-traditional tree crop in Ghana. The crop is, however, attacked by sap-sucking insects, particularly the mosquito bug, Helopeltis schoutedeni Reuter, the leaf-footed bug, Pseudotheraptus devastans (Dist.), and the coreid bug, Anoplocnemis curvipes (F.), which feed on shoots, panicles and fruits. Their damage is characterised by withering of the latter. In Ghana, Oecophylla longinoda Latr. occurs in large numbers on cashew and other native plants, but little is known about its relationship with insect pests. The relationship between O. longinoda and shoot and panicle damage by sap-sucking bugs and the effectiveness of O. longinoda as a biocontrol agent in the protection of cashew as compared with two chemical insecticides, lambda-cyhalothrin (Karate) and cypermethrin + dimethoate (Cyperdim), were therefore investigated at Bole in the northern region of Ghana. There was a negative correlation between numbers of O. longinoda nests and pest damage. Trees treated with cypermethrin + dimethoate (969 mg AI mL(-1) tree(-1)) and lambda-cyhalothrin (100 mg AI mL(-1) tree(-1)) recorded the smallest bug numbers, followed by O. longinoda. Trees infested by Oecophylla longinoda and trees treated with cypermethrin + dimethoate and with lambda-cyhalothrin had less than 6% pest damage to shoots, panicles and fruits, while water-sprayed trees recorded damage as high as 36.8% (shoots) in February, 32.9% (panicles) in February and 37.8% (fruits) in March. Cypermethrin + dimethoate again recorded the highest (485.0 kg ha(-1)) nut yield, followed by O. longinoda (431.0 kg ha(-1)), with water recording the lowest (93.0 kg ha(-1)) nut yield. The results indicate that O. longinoda can be used to control some sucking bugs as effectively as some insecticides.
Weaver ant, Oecophylla longinoda Latreille (Hymenoptera: Formicidae) as biocontrol agent on major insect pests of cashew and mango in Tanzania
  • N R Abdulla
A study of the weaver ant
  • A C Cole
  • J W Jones
A masterpiece evolution-Oecophylla weaver ants (Hymenoptera: Formicidae)
  • R H Crozier
  • P S Newey
  • E A Schluns
  • S K Robson
  • RH Crozier
Cashew nuts and production development in Nigeria. Am -Euras
  • L A Hammed
  • J C Anikwe
  • A R Adedaji
  • LA Hammed
Deutsche Gesellschaft für Internationale Zusammenarbeit GmbH and The Advisory Service on Agricultural Research for Development
  • Icipe
Utilizing economically beneficial ants. In: Bradleigh S (ed) Economic impact and control of social insects
  • J D Majer
  • JD Majer
Insect pests of cashew and their management
  • R Maruthadurai
  • A R Desai
  • Hrc Prabhu
  • N P Singh
Integrated cashew improvement program using weaver ants as a major component - photo book for cashew growers in Vietnam
  • R K Peng
  • K Christian
  • L P Lan
  • N T Binh
  • RK Peng
Definition of Marginal Rate of Return
  • C Ryan
Compendium of lectures delivered during the Advanced Training Course on “Novel Approaches in Pest and Pesticide Management in Agro-Ecosystem”
  • R K Saini
  • G S Yadav
  • B Kumari
Partial budgeting: a tool to analyze farm business changes
  • R Tigner
Economic Value of Using African Weaver Ants as Biological Control in Fruit Production and Export in Tanzania
  • J G William
Partial budgeting analysis of different strategies for management of insect pests in cashew and mango orchards in Tanzania
  • J G William
  • J Hella
  • Lars E Offenberg
  • J Mwatawala
  • M Rwegasira
  • JG William
A guide to IPM in mango production in Kenya
  • A M Varela
  • A Seif
  • B Nyambo
  • AM Varela
Survey of insect species associated with cashew
  • E A Dwomoh
  • J B Acknor
  • Jvk Afun
The effectiveness of using weaver ant biocontrol in Southern Asian citrus and mango
  • J Offenberg
  • T B Nguyen
  • D Wiwatwitaya
An economic analysis of Stevia
  • Amb Das
  • M Mandal