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Test for predation effects of single versus multiple species of generalist predators: Spiders and their insect prey
Abstract
The prediction that single spider species (as exemplary generalist predators) limit associated prey populations to the same extent that species assemblages do was tested in a well controlled and replicated old field experiment involving the following treatments: (1) the natural spider assemblage (2) a numerically prominent web building spider, (3) a numerically prominent wandering spider, (4) a biomass prominent web-builder, and (5) a biomass prominent wandering spider. Pest insect numbers were significantly higher in spider removal controls than in any spider treament over the four month period of the study, both in terms of total numbers and per spider effects. The individual spider species, in general, showed reduced prey limitation effects relative to that of the spider assemblage, though the magnitudes of these differences were small when compared to those exhibited between the various treatments and the spider removal control. When insect numbers were partitioned according to taxa, no treatment was found to have limited the predaceous insects nor the phytophagous hemipterans. All treatments, however, showed significant limiting effects on the phytophagous homopterans, coleopterans, and dipterans in the old field system, and other taxa were significantly reduced in at least one treatment in addition to the spider assemblage as a whole.
... To produce organic vegetables and other crops, it is essential to utilize indigenous natural enemies of pests in combination with strategic cultivation techniques, such as planting flowering plants that attract beneficial insects and applying organic fertilizers. True spiders are effective natural predators in field crops, but their effects depend on their densities in agroecosystems (Riechert and Lawrence 1997, Marc et al. 1999, Landis et al. 2000, Symondson et al. 2002, Schmidt et al. 2003. They kill and consume a large number of prey daily Lawrence 1997, Riechert andMaupin 1998). ...
... True spiders are effective natural predators in field crops, but their effects depend on their densities in agroecosystems (Riechert and Lawrence 1997, Marc et al. 1999, Landis et al. 2000, Symondson et al. 2002, Schmidt et al. 2003. They kill and consume a large number of prey daily Lawrence 1997, Riechert andMaupin 1998). ...
... Hunting spiders decreased numbers of herbivorus Coleoptera in an old field in Tennessee (Riechert and Lawrence 1997). The quality of organic materials and the plant structure are very important to increase the soil organism densities (Yeates et al. 1997). ...
The main goal of this study was to identify the treatment that increases the populations of spiders, which are effective predators in agroecosystems. In 2013 and 2014 the experimental eggplant (Solanum melongena L.) field was two different treatments, organic fertilizers and chemical fertilizer treatment, and in 2014 we surrounded organic fertilizer plots with the flowering plants mealy cup sage (Salvia farinacea Benth.), spearmint (Mentha spicata L.), and basil (Ocimum basilicum L.). Analysis using repeated measures ANOVA revealed significant influences of fertilizer type on the numbers of linyphiid spiders and Collembola in 2013. In 2014, the numbers of Collembola, thrips, and lycosid and linyphiid spider were higher in organic fertilizer with flowering plants treatment comparing with the chemical fertilizer treatment. Moreover, the numbers of Henosepilachna vigintioctopunctata (F.) were significantly lower in the organic fertilizer with flowering plants treatment than in chemical fertilizers treatment. Finally, we expect that Thysanoptera and Collembola were important alternative prey for linyphiid and lycosid spiders and the use of organic fertilizer and flowering plants enhanced the density of these spiders, and may increase their effectiveness in suppressing the populations of H. vigintioctopunctata (F.).
... in laboratory studies (Marc et al. 1999). Both web-weaving and hunting spiders limited populations of phytophagous Homoptera, Coleoptera, and Diptera in an old field in Tennessee (Riechert and Lawrence 1997). Spiders have also proven to be effective predators of herbivorous insects in apple orchards, including the beetle Anthonomus pomorum Linnaeus, and Lepidoptera larvae in the family Tortricidae (Marc and Canard 1997). ...
... Provencher and Riechert (1 994) used computer simulations and field tests to show that an increase in spider species richness leads to a decrease in prey biomass. Riechert and Lawrence (1997) found that insect numbers were lower in test plots that contained a sheetweb weaver (Florinda coccinea (Hentz)), an orb-web weaver (Argiope trifasciata (Forskal)) and two wolf spiders (Rabidosa rabida (Walckenaer) and Pardosa milvina (Hentz)) than in plots that contained only one of these species. ...
... The typical diversity of spiders in an agricultural ecosystem is such that there will probably be one or more species that will attack a given pest (Marc et al. 1999). Since different spiders feed on different insects at different times of the day, a loss in community diversity can result in some prey species being released from predation pressure (Riechert and Lawrence 1997). Variation in body size of both predator and prey species also contributes to prey reduction, with larger spiders taking larger prey and smaller spiders taking smaller prey (Nentwig and Wissel 1986;Nyffeler et al. 1994a). ...
The ecology of spiders (Araneae) in lowbush blueberry (Vaccinium angustifolium (Aiton)) fields in Washington County, Maine, was studied during the summers of 2000 and 2001. The abundance and distribution of spiders was investigated, and predation by one family of spiders, the wolf spiders (Lycosidae) was evaluated. The abundance and distribution of spiders was examined by capturing spiders using pitfall traps. Traps were set in conventionally managed, reduced input, and organic fields at different distances from the field edge (forest border or windbreak). The most commonly captured spiders were in the family Lycosidae. More lycosids were captured in May, June, and July than in August. Lycosids were more abundant in reduced input fields than in conventional fields in 2000 and 2001. No differences in capture were detected among conventionally managed, reduced input, and organic fields for samples taken in the later part of the season in 2001. Species composition of lycosid communities were not significantly different among fields and management practices in 2000, but the proportion of each species captured differed among management practices in 2001. Significantly more lycosids were captured at field edges than the field interior. In both 2000 and 2001, there was a significant linear contrast with lycosid capture decreasing as distance from the edge increased. In each year, one conventional field showed this linear decline in lycosid capture as distance from the edge increased, but the reduced input and organic fields did not. There were no significant differences in community composition between distances from the edge, but some species were associated with specific distances. Field edges may be a more important habitat from lycosids in blueberry fields that are more intensely managed. Predation by wolf spiders (Lycosidae) on pest and non-pest insects found in blueberry fields in Washington County, Maine, was investigated in the laboratory, greenhouse, and field. In laboratory experiments, four taxa of prey insects were evaluated as prey in no-choice arenas. Prey examined were blueberry spanworm ltame argillacearia (Packard) (Lepidoptera: Geometridae), blueberry flea beetle larvae, Altica sylvia Malloch (Coleoptera: Chrysomelidae), grasshopper (Acrididae) adults and nymphs, and field cricket (Gryllus pennsylvanicus Burmeister) (Orthoptera: Gryllidae) adults and nymphs. Lycosids consumed blueberry flea beetles, grasshopper nymphs, and field cricket nymphs but not blueberry spanworm, grasshopper adults, or field cricket adults. In greenhouse mesocosms, both grasshopper and house cricket (Acheta domestica Linnaeus) densities were lower in no-choice cages containing a single lycosid compared to control cages with no spiders; blueberry spanworm larvae densities remained the same. Two field experiments were conducted in which cages received known quantities of several prey species and either zero (control), four, or eight lycosids. Significant differences in numbers of grasshoppers or house crickets recovered were not detected among treatments. There were significant differences in field crickets recovered. Less field crickets remained in cages containing more predators (lycosids, carabid beetles, and ants). Although lycosids consumed some blueberry pest species, pest populations were not significantly lower in field cages containing lycosids.
... To maximize the contribution of arthropod predators (including spiders) in integrated pest management, a detailed knowledge of their biodiversity and population dynamics is necessary (Furlong et al 2004 andDevotto et al 2007). Several studies have shown that assemblages of many predator species may be more effective in controlling agricultural pests than single species augmentation (Chiverton 1986 andRichert andLawrence 1997). To find out the assemblages of spiders in different agricultural ecosystems, several collecting methods should be used. ...
... To maximize the contribution of arthropod predators (including spiders) in integrated pest management, a detailed knowledge of their biodiversity and population dynamics is necessary (Furlong et al 2004 andDevotto et al 2007). Several studies have shown that assemblages of many predator species may be more effective in controlling agricultural pests than single species augmentation (Chiverton 1986 andRichert andLawrence 1997). To find out the assemblages of spiders in different agricultural ecosystems, several collecting methods should be used. ...
... Spiller (1986) suggested such a negative effect of greater predator diversity, based upon his finding that a single web-building spider suppressed prey more effectively than in combination with a second web-building spider species. In contrast, Provencher and Riechert (1994) and Riechert and Lawrence (1997) manipulated spider species richness in field-cage experiments and found that herbivore abundance was negatively correlated with increasing predator diversity. Lang (2003) removed ground beetles from cages in winter wheat resulting in a two-fold increase of wolf spider (Lycosidae) abundance. ...
... Wise (2004) herbivore groups in maize and winter wheat. Spider removal also resulted in significantly higher herbivore abundance when compared to single spider species treatments or spider assemblages in an old-field (Riechert and Lawrence, 1997). The low impact of predator removal in our experiment could be a consequence of the limited experimental period (31 days from establishing treatments to the end of sampling) and/or high immigration rates of herbivores into plots independent of Pardosa treatment. ...
... Se estima que la tasa global y anual de consumo de presas por parte de la comunidad de arañas es de entre 400 a 800 millones de toneladas, y entre las presas que componen su dieta, los insectos y los colémbolos representan el 90% (Nyffeler & Birkhofer, 2017). Las arañas tienen importancia en las comunidades naturales donde mantienen las poblaciones de insectos bajo control y en las comunidades artificiales, como cultivos, donde moderan, al menos en cierto grado, el incremento poblacional de plagas durante los brotes (Riechert, 1974;Riechert & Lawrence, 1997;Mishra et al., 2020). ...
Los objetivos de esta tesis fueron: 1) caracterizar la estructura de las
comunidades de Salticidae en los hábitats bosque y pastizal, con diferentes condiciones de protección (protegido o no protegido), naturales o antropizados, en términos de abundancia, riqueza de especies y diversidad (alfa, beta y gamma) para el área estudiada del Chaco Oriental Húmedo; 2) identificar especies de Salticidae indicadoras de calidad ambiental en las distintas condiciones (conservación o alteración ambiental); y 3) lograr un listado de especies e identificar y describir potenciales nuevas especies.
The aims of this thesis were: 1) to characterize the structure of the Salticidae communities in forest and grassland habitats, with different protection conditions
(protected or unprotected), natural or anthropized, in terms of abundan ce, the richness of species and diversity (alpha, beta, and gamma) for the studied area of the Humid Eastern Chaco; 2) identify species of Salticidae that are indicators of environmental quality in different conditions (conservation or environmental alteration); and 3) achieve a list of species and identify and describe potential new species.
... Spiders (order: Araneae) are highly efficient predators in sugar beet fields, as well as other crops (Riechert and Lawrence, 1997;Lang et al., 1999;Sunderland,1999). It is known that spiders rank seventh in the global diversity after Coleoptera, Hymenoptera, Lepidoptera, Diptera, Hemiptera, and the arachnid order, Acari (Kingdom: Animalia) (Nyffeler et al. 1994). ...
... Ambusher 11.22 11 6 Foliage runner 1.05 1 Total 98 Riechert& Lawrence, 1997;. Spiders prevent and suppress pest outbreaks in arable crops (Riechert & Lockley, 1984;, and can persist even when pest numbers are low by feeding on alternative prey items within the agroecosystem (Settle et al., 1996;. ...
Spiders are successful natural enemies of pests occurring throughout the different strata of an agroecosystem. The study of their functional responses can provide information related to the potential effectiveness of different species and guilds on reducing a pest population. The present paper deals with a study of diversity and distribution of spiders
... Many field experiments performed over the last 35 years have demonstrated that spiders can reduce insect populations and crop damage they cause (Reichert and Lawrence, 1997). The effect of spiders on pest population may be enhanced if their population increase rapidly in response to rich supply of nutritous alternative preys (Axelsen et al., 1997;Khan and Misra, 2003a). ...
Combining ability analysis of a 10 x 10 diallel, excluding reciprocals was
undertaken for fruit yield per plant, yield components, quality and
physiological characters in egg-plant during summer, rainy and late
summer seasons. Non-additive gene action was noticed to be preponderant
for all the traits studied, during all the seasons. A perusal of the
gca effects revealed the lines PLR 1 and JBPR 1 to be good general
combiners for fruit yield per plant, during all the seasons studied. These
parents had also recorded high per se performance for these trait, during
all the seasons, indicating their suitability and importance in breeding
programmes for the development of widely adaptable and high yielding
hybrids. PLR 1 was also noticed to be a good general combiner for total
soluble sugars during all the seasons indicating its potential in the
development of adaptable and high yielding hybrids with high total soluble
sugars, greatly desired by the consumers. Among the 45 hybrids studied,
22 crosses during summer, 14 crosses during rainy season and 22
crosses during late summer had exhibited significant and desirable sca
effects for fruit yield per plant. Of these, eight crosses during summer, nine
crosses during rainy season and nine crosses during late summer season
had recorded desirable sca effects in addition to high per se performance
for the trait. An analysis of these crosses revealed the involvement of a
good and a poor general combiner parent for the majority of the crosses;
and both good or poor in a few cases. The hybrid, PLR 1 x JBPR 1, involved
both good combiner parents for fruit yield per plant were identified as a
potential and widely adaptable hybrid for commercial cultivation during all
the three seasons, while KS 224 x PLR 1 was identified for specific
cultivation during contingency situations of late summer
... Moreover, studies have previously demonstrated the adverse impact insecticides can have on spider population dynamics and diversity, with very few at the species level (Pedro et al., 2020;Pekár, 2012). Therefore, for the preservation of the spider assemblage and the associated ecosystem services they provide, it is necessary to understand the species level impacts of insecticides (Riechert & Lawrence, 1997;Sharma et al., 2013). ...
Orb‐weaving spiders are abundant predators in agroecosystems and serve as key natural enemies for pest control. However, studies have demonstrated that many insecticides can negatively affect the predatory behaviours of spiders when exposed to sublethal concentrations, thus disrupting their biocontrol potential and subsequent ecosystem dynamics. Understanding how insecticides impact spiders is, therefore, of great importance.
This study investigated the effects of two conventional insecticides (thiamethoxam and deltamethrin), and a common biopesticide (neem oil) compared to a tap water control on the functional response of a common orb‐weaver Araneus diadematus .
Spiders were collected from the wild and maintained under laboratory conditions in containers (20 × 20 × 5 cm) to allow for web production. Spiders were then exposed to one of the four treatments and Drosophila melanogaster were added to the webs as prey at densities of 1, 3, 5, 10, 20, and 40, with the number of consumed prey quantified after 16‐h to determine the functional response.
Overall, A. diadematus exhibited a type II functional response when exposed to the control, thiamethoxam and neem oil treatments, with comparable consumption rates, search coefficients and handling times. This contrasted with deltamethrin‐treated spiders which exhibited a type III functional response and a lower consumption rate of prey compared to the control.
This study demonstrates that deltamethrin, unlike thiamethoxam and neem oil, is capable of negatively affecting the biocontrol potential of A. diadematus . However, further research is required to fully understand the impact insecticides have on the predatory behaviours of orb‐weaving spiders.
... The effectiveness of single predators, such as Pardosa (syn= Lycosa pseudoannulata (Araneae: Lycosidae) and Verania (syn= Micraspis) lineata (Coleoptera: Coccinellidae) has been reported widely (IRRI, 1982;Heong et al., 1990;Preap et al., 2001;Laba, 2001;Syahrawati et al., 2015). P. pseudoannulata is a generalist predator that does not have specific preferences for prey and tends to catch the closest abundant prey (Reissig et al., 1985;Riechert and Lawrence, 1997;Foelix, 2011). Furthermore, P. pseudoannulata is polyphagous predator, very generalist, and time generalist, i.e., this species consumes the prey without time limitations (Suana and Haryanto, 2013). ...
Pardosa pseudoannulata and Verania lineata are two generalist predators commonly found in rice fields. Only a few references indicate their presence as joint predators resulting in positive interactions to brown planthopper without competition. The research aimed to determine the predation rate of joint predators in competitive conditions. The research was conducted in the laboratory using a Completely Randomized Design (CRD) with different combinations of joint predators. The density of P. pseudoannulata (P) and V. lineata (V) were 1, 3, 5 individuals per treatment (P1V1, P1V3, P1V5, P3V1, P3V3, P3V5, P5V1, P5V3, and P5V5). Each treatment had five replications. The results showed that competition and cannibalism factors indicate a negative interaction that affected the predation rate of joint predators. The ability of P. pseudoannulata to survive in competitive conditions was lower than V. lineata. The suitable and safe combination was using one (1) P. pseudoannulata and three (3) V. lineata (P1V3) with 89.6% predatory rate on Nilaparvata lugens Stål on the first day, and with the lowest death rate of two predators. The P1V3 combination also had an increase in bodyweight of P. pseudoannulata and a competition model that resulted in draw conditions. Therefore, before using some predators to control the BPH optimally, there is a need to minimize the impact of competition and cannibalism on them.
... Even if generalist predators are usually considered poor biocontrol agents (Snyder &Wise, 1999;Polis and Holt,1992) increasing evidence shows that they can sometimes reduce pest populations in agro-ecosystems (Mansour et al., 1980;Riechert & Lawrence, 1997;Nyffeler & Benz, 1998;Young & Edwars,1990;Maloney et al., 2003;Picchi et al., 2016;Camerini, 2017). Therefore, in order to test such an hypothesis, we planned a rese-arch aimed at identifying the community of agrobiont spiders which can prey on D. virgifera in corn fields, assessing the extent of predation and the influence of landscape, if any, on natural enemies' response to the invader. ...
The response of spiders (Araneae) to the introduction of the corn rootworm (Diabrotica virgifera, Coleoptera
Chrysomelidae, LeConte, 1868) was studied in 2010 and 2011 in two study areas in the Padana Plain (Northern
Italy). The research was aimed at identifying the community of spiders which can prey on D. virgifera in corn fields,
the rate of predation and the influence of landscape on the natural enemies’ response to the invader. The two
study areas were different in terms of both land use and agricultural patterns.
... Different spiders feed on different insects at different times of the day, so a loss in community diversity of spiders can result in some prey species being released from predation pressure (Riechert and Lawrence, 1997). Variation in body size of both predator and prey species also contributes to prey reduction, with larger spiders taking larger prey and smaller spiders taking smaller prey (Nentwig and Wissel, 1986;Nyffeler et al., 1994). ...
Large numbers of a wide range of spider species inhabit agricultural fields. Their presence limits the habitats open to insect pests. Spiders threaten insect pests with various foraging strategies. As well as consuming large numbers of insect pests as prey, they have the trait of killing all insects living in their territory. For this reason, spiders are a favorable biological control agent in the agricultural ecosystem and can be successfully used to check pest population in the field.
... However, in our study the contribution of Diptera to the diet of striders and web-building spiders, as indicated by detection frequency, was similar (12.8% and 17.5% of tested spiders, respectively), suggesting that striders may feed on soil and litter living larvae of the same groups of flying insects that are caught into by web building spiders. Thus, along with published data (Nentwig, 1987;Riechert & Lawrence, 1997;Foelix, 2011), our results highlight that the diet between striders and web-building spiders overlaps widely despite the different hunting strategies at least if they share the same habitat (i.e. leaf litter). ...
Generalistic interactions between predator and prey may vary with ecosystem type, predator traits, and prey traits, but the interplay of these factors has not been assessed in ground food webs.
We investigated trophic interactions of ground‐dwelling spiders across eight forests in European Russia associated with body size, hunting strategy, microhabitat specialization, potential prey type, potential prey population density, and forest type (coniferous vs. broadleaved). We analyzed 128 individual spiders, including juveniles, all identified to the family level with two complementary methods: molecular gut content analysis, and stable isotope analysis of carbon and nitrogen.
The results suggest that feeding frequency of spiders is affected by predator body size and by selection of certain prey type. Stable isotope analysis showed similar trophic niches among spider families, varying moderately with forest type. Larger spiders had higher Δ13C values than smaller ones, but similar Δ15N values, suggesting that different size classes of spiders belong to different food chains. Results based on stable isotope and molecular gut content analyses were weakly linked, indicating them targeting different trophic niche dimensions.
At least for the group‐level interactions, family identity and hunting strategy of predator has little predictive power while predator body size and prey traits affected trophic niche dimensions calling for future studies in this direction. Large spiders feed more and rely on different basal resources than small spiders, suggesting that including small species and juveniles provides a more comprehensive picture of food web organization.
... In the current study, six spider species were surveyed. Richert and Lawrence (1997) concluded that assemblage of several species of predators may be more effective in controlling insect pests than single or few species augmentation. ...
Seed watermelon, Citrulus lanatus (Thumb) is an early summer crop, which is a subject to infestations by several insect pests resulting in damage and losses in the crop production. A study was undertaken at Rasheed region, Beheira Governorate during 2015 and 2016 summer seasons to detect the true spider species occurring in seed watermelon plantations, and monitor the population fluctuation of the most dominant ones. In addition, a comparison study was conducted to find out the efficiency of traps, used in spider catch, as related with spider species. Six true spider species were surveyed beginning from first of May up to mid-July. Paradosa sp. and Lycosa sp. (Fam. Lycosidae) and Thanatus albini (Fam. Philodromidae) were captured throughout the season; May to July. On the other hand, Clubiona sp. (Fam. Clubionidae), Singa sp. (Fam. Araneidae) and Thomisus sp. (Fam. Thomisidae) were trapped only during July. The most dominant spider species in 2015 season was Thanatus albini (43.77%), followed by Pardsoa sp. (42.64%), and then Lycosa sp. (4.91%). A reverse situation was found in 2016 season, as the most dominant spider was Pardosa sp. (45.14%), followed by Thanatus albini (41.32%) and the third rank was occupied by Lycosa sp. (4.17%). However, the dominance percentages of the remaining spiders ranged between 0.17 and 4.17% in both seasons. Tools used for capturing spiders were variable in their efficiency. Pardosa sp. was captured mainly by pitfall traps, with values of 90.27 and 93.08%, out of total catch of different traps, in the first and second seasons, respectively. Lycosa sp. was not captured by the sweep net, and captured in low numbers by each of pitfall and water pan traps. Thanatus albini was captured by the sweep net (39.66 & 41.86%) and water pan trap (47.41 & 50.39%) in 2015 and 2016 seasons, respectively, but was captured in low numbers in the pitfall traps. Clubiona sp., Singa sp. and Thomisus sp. were all not detected in the pitfall traps, and were found in low numbers in each of sweep net and water pan traps.
... In the current study, six spider species were surveyed. Richert and Lawrence (1997) concluded that assemblage of several species of predators may be more effective in controlling insect pests than single or few species augmentation. ...
... Spiders are considered one of the most important groups of natural predators of insects worldwide. Indeed, spiders are abundant generalist predators in crop fields (Nyffeler & Sunderland, 2003) and it has been well documented that they contribute to the suppression of several agricultural pests (Michalko et al., 2017;Michalko, Pekár, Dul'a, & Entling, 2019;Riechert & Bishop, 1990;Riechert & Lawrence, 1997;Symondson et al., 2002). Moreover, a recent meta-analysis corroborated their role as effective pest predators and it was shown that they improve crop performance (Michalko et al., 2019). ...
Agricultural landscapes include patches of cropped and non‐cropped habitats. Non‐cropped fragments are often source habitats for natural pest predators which colonise less suitable agricultural fields. The goals of the present study were: (a) to evaluate the contribution of non‐cropped fragments to agro‐ecosystems as biodiversity reservoirs and ecosystem service providers, by assessing the abundance of spider species and their diversity and (b) to quantify the spatial variation in spider communities across different non‐cropped fragments and crops. We hypothesised that non‐cropped fragments function as spider diversity reservoirs with better conditions for reproduction than crops. We collected spiders from 10 restored fragments having had no disturbance for 20 years and four field edges, along a gradient inside the crop adjacent to each fragment. Overall, we collected 3,591 spiders belonging to 49 species/morphospecies in 14 families. Non‐cropped fragments had a central role in the spider community, as estimated through species–habitat networks. We found differences in the diversity and abundance of spiders between non‐cropped and cropped fragments. However, these differences were only for immature spiders, whose abundance decreased from non‐cropped fragments towards the inside of crops. Our results highlight the importance of non‐cropped fragments in agro‐ecosystems as important source habitat patches, reservoirs of biodiversity and sites where spider reproductive success is possibly higher.
... Their polyphagous diet (Marc & Canard, 1997), high resistance to insecticides (Hoque et al., 2002) and coexistence capability in different niches (Norma-Rashid et al., 2014) make them potential agents for effective biological control in agriculture ecosystems. Previous studies have demonstrated the importance and benefits of different spider species in pest control (Riechert & Lawrence, 1997;Motobayashi et al., 2007;Tahir et al., 2009). These studies revealed that different spider species have specific roles and thus, higher spider species diversity can provide more effective control of pest populations (Marc et al., 1999). ...
Thirty adult female individuals of each of the four orb-web spider species namely Araneus sp. (Araneidae), Gasteracantha kuhli Koch, 1837 (Araneidae), Gasteracantha hasselti Koch, 1837 (Araneidae) and Opadometa grata (Simon, 1877) (Tetragnathidae) were randomly sampled between 1000 and 1400 h from May to July 2017 in an oil palm plantation in Perak, Malaysia. Morphological and web characters of these orb-web spiders were obtained and analyzed using principal component analysis (PCA) and bootstrapping methods. For the morphological characters, the PCA results captured a total of 99% of the variance and indicate that the Araneid species have distinct clustering. For the web characters, the PCA captured 76% of the total variance and did not show any distinct clustering with significant overlapping between them. Moreover, the mean and 95% confidence intervals using bootstrapping identified significant
differences in the morphological and web characters for most spider species with little overlap. This study indicates that the four orb-web spider species could coexist in terms of their spatial territory and food resources in the oil palm plantation, suggesting that these resources were not a limiting factor.
... 12% para el cultivo convencional y 15% en transgénico. Esto es acorde con lo evidenciado por Riechert et al. (1997); Greenstone (1999), quienes en experimentos en campo en cultivos transgénicos de soja y trigo han demostrado la capacidad que presentan las arañas para reducir algunas poblaciones de insectos plagas. A pesar de las grandes preferencias y comportamiento de las especies en nuestro estudio la prueba de Mann-Whitney no mostró diferencias significativas entre la diversidad de especies y el tipo de cultivo (U = 638,00 p = 0,91). ...
La adopción de los cultivos genéticamente modificados (OGM) ha llevado a la necesidad de evaluar los impactos sobre los organismos no objetivos. Para ello se estudio el impacto del cultivo transgénico maíz (Zea mays) sobre la entomofauna benéfica. Se colectaron artrópodos en ocho lotes de maíz convencional y transgénico mediante las técnicas de Berlesse, Pitfall, Jama y Trampas amarillas. El análisis de diversidad se realizó utilizando el método propuesto por Jost (2006) a través de tres valores q = 0, 1 y 2 y se construyeron curvas de rango-abundancia. Para la formación de los grupos funcionales, se realizó un análisis de conglomerados empleando el método de encadenamiento jerárquico de Ward. Se colectaron 6,932 individuos entre cultivos convencionales y transgénico, registrando 102 taxones discriminados en 6 especies, 42 géneros y 54 familias. El cultivo transgénico registró la mayor abundancia con 51,60% y el convencional un 48,39%. La curva de rango-abundancia no indica diferencias entre los cultivo para las localidades de Cereté y San Pelayo. El dendrograma arrojo ocho (8) grupos funcionales. Al analizar la diversidad alfa verdadera 0D, se obtuvo en ambas localidades los ocho (8) grupos funcionales; la diversidad verdadera en el cultivo convencional fue 1D = 6,76 y el transgénico 1D = 6,83. Para el orden 2D fue 6,17 en convencional y 6,21 en transgénico; se puede concluir que en estos resultados no se observaron diferencias significativas con relación a los tres perfiles de diversidad entre los cultivos convencional y transgénico.
... However, our field cages excluded other generalist predators and parasitoids, which would act in concert with lynx spiders and potentially contribute to an effective conservation biological control regime. Enhanced predator diversity has been shown to contribute to increased pest suppression (Snyder et al., 2006;Straub and Snyder 2008), and spiders are likely to provide more effective pest control when natural assemblages are used instead of single species (Riechert and Bishop 1990;Riechert and Lawrence 1997). Thus, the inclusion of multiple predator species may provide early season control of BMSB, preventing late season population outbreaks. ...
Conservation biological control manipulates habitat characteristics to enhance natural enemy populations and ultimately reduce pest density. These practices can be most effective early in the growing season when pest populations are low. Early season predator impacts on these pests can include both direct consumption of herbivores and non-consumptive effects such as superfluous killing, both of which provide pest suppression. We combined laboratory feeding trials, and a field cage experiment with molecular gut-content analysis to explore the effects of striped lynx spiders (Oxyopes salticus Hentz) on brown marmorated stink bugs (Halyomorpha halys (Stål)). The laboratory feeding trials revealed that lynx spiders did attack stink bugs but that stink bug DNA had a short DNA detectability half-life within lynx spider guts. To simulate field conditions where these two species could interact in both early and late season, we manipulated the density and relative abundance of stink bug nymphs and adults in the presence and absence of lynx spiders. There was no effect of treatment on recovery of either adult stink bugs or nymphs. Although dead stink bugs were recovered, we found no evidence of consumption through molecular gut-content analysis. Contrary to expectations that generalist predators would have the greatest impact on pests early in the growing season, our results suggest that lynx spiders are unlikely to exert substantial early season control. Biological control might be most effective when utilizing multiple predator species as part of a complex of natural enemies, so spiders acting in concert with other generalist predators could be capable of suppressing pest populations.
... This is because the effectiveness of pest biocontrol is strongly determined by the ecological balance between species assemblages characterizing ground-and soil-dwelling insect herbivores and arthropod predators in agricultural landscapes (Huffaker et al., 1976;May and Hassell, 1988). In general, a diverse and abundant community of arthropod natural enemies is better able to control insect pests (Riechert and Lawrence, 1997;Straub and Snyder, 2006;Tscharntke et al., 2007;Straub et al., 2008;Letourneau et al., 2009;Tylianakis and Romo, 2010). Thus, the effectiveness of controlling insect pests by arthropod natural enemies in cropping systems could be quantitatively assessed by using the calculated density-and richnessbased ratios of ground-and soil-dwelling arthropod predators and insect herbivores (Letourneau et al., 2009;Zhao et al., 2013). ...
... Grounddwelling spiders, in particular, are the dominant arthropod predators in many terrestrial ecosystems (Uetz 1977, Weeks and Holtzer 2000, Cardoso 2008). These top predators affect the diversity and abundance of other arthropods in a range of experimental systems, including sage-steppe, agricultural, old-field, and forest litter communities (Wing 1984, Hurd 1990, Riechert and Lawrence 1997, Wise 2004. The relevance of spiders has been established in managing insect communities and as useful indicators of habitat change (Sanders et al. 2008, Maleque et al. 2009, Woodcock et al. 2009, Petillon et al. 2010. ...
... Under this context, structurally diverse infrastructures, such as woodland hedges, support greater richness values that could improve the effectiveness of spiders in biological control. This is because the role of spiders in this process is a community phenomenon, and more successful cases of pest suppression have been reported where spiders act as multi-species assemblages (Marc and Canard, 1997;Riechert et al., 1999;Riechert and Lawrence, 1997;Riechert and Lockley, 1984). Nevertheless, the differences in family richness between grass strips and rosaceous hedges, are not as evident as those observed in terms of abundances, suggesting that both infrastructures are heterogeneous enough to harbor multiple families and produce similar richness values. ...
Within agricultural landscapes, ecological infrastructures like hedges, grass strips or wildflower strips, can be essential for the provision of ecosystem services, and their role in maintaining and promoting functional biodiversity has been widely demonstrated in temperate zones. However, although the Mediterranean basin is considered to be a biodiversity hotspot, there is a lack of information about the role played there by these elements in biodiversity conservation. Spiders are generalist predators that are considered important components of biodiversity in vineyard ecosystems, where they can play a prominent role in the natural control of pest populations. Nevertheless, the influence that ecological infrastructures have on driving spider assemblages in Mediterranean vineyard agroecosystems is practically unknown. In a study conducted in an area exclusively devoted to traditional vineyard crops (La Rioja, northern Spain), we analyzed spider assemblages across four types of linear ecological infrastructures differing in their structural diversity: woodland hedges, rosaceous hedges, grass strips and flower strips. Spider assemblages were examined across three levels of organization (taxon, guild and body-size group). Taxonomic composition was different among infrastructures, as was guild composition and the distribution of body sizes. Abundance and richness of spiders were higher in more structurally diverse infrastructures. The response to habitat type differed among guilds but, overall, higher densities of spiders from different guilds were found in hedges. Body-size groups had a more balanced distribution in strips and hedges with higher levels of structural diversity. Our results suggest that it is crucial to preserve varied typologies of ecological infrastructures, with an optimal level of complexity and heterogeneity, to maintain diversified assemblages of these important biocontrol agents within Mediterranean vineyard agroecosystems.
... This is because biological pest control strongly depends on the ecological balance between populations of predators and insect herbivores (Huffaker et al. 1976;May and Hassell 1988). In general, a diverse and abundant predator community is better able to control insect pests (Riechert and Lawrence 1997;Straub and Snyder 2006;Tscharntke et al. 2007;Straub et al. 2008;Letourneau et al. 2009;Tylianakis and Romo 2010). In addition, predators and insect herbivores also play a key ecological role as prey for other taxa, especially insectivorous birds, reptiles, and bats. ...
Background and aims
Irrigation-maintained artificial oases (AO) in arid regions of northwestern China provide vital human settlement sites. Recent human population increases has caused rapid AO expansion, mainly through transforming natural grassland to arable and afforested land. Here, we assessed how soil biodiversity is affected by various AO expansion strategies, each representing historical land-use regimes.
Methods
We sampled six dominant functional groups of soil biota, covering multiple trophic levels: macrofauna consumers (predators and insect herbivores), mesofauna decomposers (Oribatida and Collembola), and microbial decomposers (bacteria and fungi). Sampling was carried out in three AO sites of northwestern China, each containing distinct land uses: natural grasslands (NG; non-irrigated), shrub (Haloxylon ammodendron) plantations (SP; non-irrigated), tree (Populus gansuensis) plantations (TP; irrigated), and arable lands (AL; irrigated).
Results
The conversion of NG to SP, TP, and AL eliminated or reduced the abundance of some NG-adapted taxa. Their replacements were exotic species better suited for anthropogenic habitats. As a result, community composition shifted in all six functional groups, with greater differences between NG and TP and AL than between NG and SP. Based on taxonomic gains and losses within each group, we determined that NG to SP conversion positively affected diversity among predators, Collembola, and fungi, but negatively affected diversity of insect herbivores and Oribatida. Bacterial diversity remained unaffected. However, converting NG to TP and AL significantly promoted diversity in all six functional groups, although effect sizes differed.
Conclusions
Our results suggest that different AO expansion strategies differentially affected the diversity and structure of belowground communities, which in turn, cascaded down to ecosystem functioning differently. These findings not only contribute to a better understanding of how the diversity and community composition within soil food-webs respond to land-use change but also provide key insights into the development of management strategies for AO ecosystems in drylands to mitigate the negative impact of land-use change on soil biodiversity and ecosystem functioning.
... The effects of predator diversity on pest regulation are usually enhanced when they act at different spatiotemporal scales (Schmidt et al., 2003;Straub et al., 2008). The effectiveness of biological control is strongly influenced by the structure and composition of predator communities (Riechert and Lawrence, 1997;Menalled et al., 1999;Griffin et al., 2013;Rusch et al., 2015). In addition, investigating both community structure and species composition allows to better understand agroecosystem functioning (Bommarco et al., 2013), which argues to use these parameters as key response variables. ...
Despite the role generalist predators may play in biological regulation, the influence of landscape composition in shaping their assemblages remains little studied, especially when landscape interacts with local factors. In this study, we investigated the effects of farming systems along gradients in landscape elements on the structure and composition of carabid and spider assemblages. Twenty pairs of organic vs. conventional spatially-matched fields were sampled in 2013 along increasing percentage covers of organic farming and semi-natural habitats in the landscape. A total of 24241 spiders and 27767 carabids belonging to 120 and 75 species respectively were collected by pitfall traps. Farming systems locally had a strong influence on the community structure (activity-density and species richness) and composition for both spiders and carabids. Structure of spider assemblages was mostly affected by local and landscape factors, whereas that of carabids was more driven by landscape variables and the interaction of the two levels. Spider and carabid community compositions were mostly determined by field farming systems and wood percentage around the field. Our study underlines the importance of landscape context in shaping assemblages of predatory arthropods, and suggests that mechanisms behind the distribution of individual species strongly differ between spiders and carabids.
... As generalist predators, spiders are not an insignificant component of terrestrial ecosystems and they can play a role in the biological control of insect pests in agro-ecosystems (Riechert & Bishop, 1990;Wyss et al., 1995;Riechert & Lawrence, 1997;Maloney et al., 2003;Thorbek et al., 2004;Sanders et al., 2008;Picchi et al., 2016). ...
The planthopper Metcalfa pruinosa (Say, 1830) (Homoptera: Flatidae) was unintentionally introduced from North America to Europe and started its invasion from Italy in 1979. During 2004, a survey was carried out in a study area located in the central western Po floodplain (Northern Italy) in order to identify spiders feeding on M. pruinosa. Fourteen species of spiders preying upon the planthopper were recorded. The community of spiders mainly included species belonging to Agelenidae (27.4%), Linyphiidae (26.7%) and Araneidae (15.6%). Almost all remains of M. pruinosa found in the webs were adults of the pest, while the predation of juvenile stages was negligible.
During summer 2005 and 2006, more specific observations were carried out, respectively, on Agelena labyrinthica and Linyphia triangularis that were identified in 2004 as the most common planthopper predators.
M. pruinosa was regularly found in the webs of A. labyrinthica; predation rate was maximum in July and around the half of August, while it tended to decline during September.
L.triangularis modulated its density in response to the increase of M. pruinosa density. M. pruinosa was recorded as the dominant prey in L. triangularis webs all summer long as far as the prey could be available.
... Marc et al. (1999) and Harwood et al. (2001) describe the aggregation of spiders in prey rich areas as a possible numerical response. Furthermore, prey switching can occur, when spiders change their prey preferences in favour of the most abundant prey (Nyffeler et al. 1994a;Riechert and Lawrence 1997). In the studied case, spiders follow the density of their prey. ...
Spiders are omnipresent, occurring in almost all terrestrial habitats. They are generalist predators and important for conservation biocontrol in agricultural fields, helping to reduce pesticide applications. In this study, we examined how spider families and spider web types in rice fields are related to local and landscape management. Samples were taken in differently managed rice fields adjoining either homegarden polycultures or banana monocultures. Furthermore, landscape structure, prey abundance, herb richness and cover were taken into account. The results showed that prey availability explained most of the variation in spiders and their web’s abundance, indicating that spiders in the rice fields can potentially contribute to pest control. Adjacent habitat had no effect on the spider populations, but maintaining fallow fields in the surrounding landscape seems to be a useful measure to promote Erigoninae in rice fields. There was no evidence that local management practices such as fertiliser and pesticide use had an impact on spider families, which appeared to be due to the low level of these inputs. Spider web sampling can complement spider sampling as it detects spiders hidden at the base of the rice tillers, which are likely to be missed by sweep netting. Additionally, tetragnathid webs are easy to observe and thus can be used as an indication for farmers not to spray pesticides as spiders are potentially controlling the pest species. Interviews with farmers made clear that many farmers in the study area showed their interest in management methods that promote biological pest control.
... We chose a common native angiosperm species, coyote bush (Baccharis pilularis de Candolle; Fig. 1), a dioecious perennial shrub that is abundant in California coastal sage scrub (Rudgers & Whitney, 2006), that hosts crab spiders (Bolger et al., 2008) and that is visited by a wide variety of insect pollinators (Fig. 2). For our predator, we used a native crab spider, Xysticus elegans Keyserling (Aranae: Thomsidae), which is a generalist ambush predator (Riechert & Lawrence, 1997) and which we commonly found on B. pilularis. These small spiders are among the most common and widespread Xysticus species in North America, are brown in colour ( Fig. 1) and have a carapace that is approximately 2.7 mm long (Turnbull et al., 1965). ...
1. The ability of pollinating insects to discover and evade their predators can affect plant–pollinator mutualisms and have cascading ecosystem effects. Pollinators will avoid flowers with predators, but it is not clear how far away they will move to continue foraging. If these distances are relatively small, the impact of predators on the plant–pollinator mutualism may be lessened. The plant could continue to receive some pollination, and pollinators would reduce the time and energy needed to search for another patch.
2. A native crab spider, X ysticus elegans , was placed on one cluster in a small array of B accharis pilularis inflorescence clusters, and the preferred short‐range foraging distances of naturally visiting pollinators was determined.
3. Nearly all pollinator taxa (honey bees, wasps, other H ymenoptera, and non‐bombyliid flies) spent less time foraging on the predator cluster.
4. The key result of this study is that inflorescences within 90 mm of the crab spider were avoided by visiting honey bees and wasps, which spent three‐ and 18‐fold more time, respectively, foraging on more distant flower clusters.
5. Whether honey bees can use olfaction to detect spiders was then tested, and this study provides the first demonstration that honey bees will avoid crab spider odour alone at a food source.
... la complex . In Hawaii, Bach and Tabashnik (1990) found that the presence of tomato next to cabbage significantly increased parasitism of P. xylostella by C. plutellae. The impact of spiders in vegetationally diverse crucifer plantings has received limited attention, and spiders are probably the most overlooked predators in Brassica agroecosystems. Riechert and Lawrence (1997) suggested that conservation via habitat manipulation could increase spider species richness in agroecosystems. A literature review by Sunderland and Samu (2000) showed that diversification increased spider abundance in 63% of the studies reviewed. Frank and Nentwig (1995) found that the presence of weed strips increased the density and ...
Numerous studies have examined the responses of pest and beneficial arthropods to plant diversification in ephemeral cropping habitats. Cruciferous crops, mainly cabbage and broccoli, are probably the most studied plants with respect to evaluating the impact of plant mixtures on insect population dynamics. This review examines the mechanisms influencing arthropod responses to floral diversification, specifically focusing on cruciferous crops. In many instances, mechanisms accounting for herbivores and natural enemy responses to plant mixtures are not thoroughly tested. Biological parameters of herbivores impacted by crop diversification were mainly related to the behavior of the insects studied. Mechanisms accounting for herbivore responses to plant mixtures include reduced colonization, reduced adult tenure time in the marketable crop, and oviposition interference. Tactics used for choosing companion plants, and the future perspective for mixed-crucifer crops usage are discussed. Manipulative studies involving cruciferous crops provide some evidence that habitat manipulation techniques (e.g., intercropping, undersown nonhost plants, vegetation borders) impact crop growth. However, the indirect role habitat manipulation plays in the population dynamics of insect pests and natural enemies still remains unclear in many systems. Quantitative data are needed to determine the level of change in plant quality brought about by companion planting that alters arthropod behavior.
... Studies showed that spiders exhibit significant levels of density-dependent switching (Nyfeller et al., 1994;Riechert and Lawrence, 1997). They kill more prey than (Riechert and Lockley, 1984). ...
Present study was designed to assess the predatory interaction of orb-web spider Neoscona theisi (Araneae: Aranidae) against its prey brown plant hoppers (Sogatella furcifera). N. theisi is the highly abundant on folliage in all agro-ecosystems of Punjab, Pakistan. Its feeding efficiency was studied in laboratory and in microcosm under different prey densities. The amount of prey consumed at different densities of prey represents type II functional response. Handling time and attack rate was calculated by linear regression. The attack rate and efficiency of attack per hour were high in lab as compared to microcosm experiment but handling time was opposite of this. The observed feeding strategy of N. theisi suggested that spiders can have positive role in controlling agricultural pest such as brown plant hopper in a density sensitive way.
... A number of studies have focused on combining and releasing several biocontrol agents simultaneously (such as predators, parasitoids and pathogens) in outdoor agro-ecosystems and on studying their interactions with their prey/host (Sih et al., 1998;Roy and Pell, 2000;Griffen, 2006;Agboton et al., 2013). Because of varied effects, the benefits of introducing single or multiple natural enemy species for biological control has been debated by ecologists and biocontrol researchers (Riechert and Lawrence, 1997;Lang, 2003;Vance-Chalcraft and Soluk, 2005;Letourneau et al., 2009;Messelink et al., 2012;Albendin et al., 2015). Several authors have favored the use of one effective agent (Briggs, 1993;Denoth et al., 2002). ...
Interactions between multiple natural enemy species are relevant to biological control of agricultural pests. The first part of the study evaluated the effects of single and combined applications of the entomopathogenic fungus Beauveria bassiana and the predatory mite Neoseiulus barkeri for controlling western flower thrips, Frankliniella occidentalis on greenhouse cucumber. Results revealed that a separate application of either B. bassiana or N. barkeri significantly reduced both larval and adult F. occidentalis populations. The control effects from the fungal application occurred more rapidly than those attributable to predation during the 7-week experiment. However, the thrips population fluctuations and non-additive effect of the B. bassiana and N. barkeri combination treatment suggest possible negative interactions may have occurred between the fungus and the predators. The second part of the study investigated the interaction between B. bassiana and N. barkeri in the laboratory. We confirmed the presence of B. bassiana conidia on mites by scanning electron microscopy and bioassays. Though a benefit of this procedure was dissemination of the pathogen to the target pest resulting in 77.5% mortality of adult thrips, mites also spent a considerable amount of time engaged in self-grooming behavior. Any potential benefits of fungal dissemination by the predatory mites were possibly weakened by increased mite grooming time, which likely reduced the searching activity and predation rates of N. barkeri. Overall, our results suggest that simultaneous application of B. bassiana and N. barkeri would not be recommended for effective biological control.
... Spiders in general are important components of agricultural systems since they help in controlling pest insect and mite populations in fruit, vegetable, and field crops [1][2][3]. Therefore, understanding the ecology of spiders in agroecosystems is important given the role these arachnids play as generalist predators [4,5]. ...
... Spiders in general are important components of agricultural systems since they help in controlling pest insect and mite populations in fruit, vegetable, and field crops [1][2][3]. Therefore, understanding the ecology of spiders in agroecosystems is important given the role these arachnids play as generalist predators [4,5]. ...
... Biological control can be more effective if antagonists perform in a synergistic or additive mode. On the contrary, Intraguild predation (where two predators that share a common prey species also feed on each other) results in less effective biological control (Riechert & Lawrence, 1997;Rosenheim, 1998Rosenheim, & 2005Venzon et al., 2001;Rosenheim, 2005;Xu et al., 2006). Snyder and Ives (2003) reported that increasing the diversity of natural enemy species on crops lead to progressive declines in herbivore equilibrium density. ...
Aeolothrips intermedius (Bagnall) and Orius niger (Wolff) feed on larvae-I-II and adults of the onion thrips (Thrips tabaci Lind.) in the potato fields of Ardabil region. Predation by O. niger, one female and one nymph-V and A. intermedius, three adults and three larvae-II, was determined in the separated and combined uses at three densities of larvae-II onion thrips with a aim to investigate the additive effect and intraguild predation of O. niger and A. intermedius in the combined uses and compared with the separated uses at three densities of prey. In the separated uses O. niger, one female and one nymph-V, consumed more prey than A intermedius, three adults and three larvae-II, at three densities of prey. Prédation in the combined uses of O. niger and A. intermedius at the 50 and 100 prey densities were higher compared to the separated uses of each predator alone. These results indicated that at the 50 and 100 prey densities, additive effects were occurred on the mortality of prey when two predators were used synchronously. Whereas predation in the combined uses of O. niger and A intermedius at the 10 prey density, were not higher than the separated uses of each predator alone. Interaguild predation of O. niger, female and nymph V, on A intermedius, adults and larvae-II, were observed also at the 10 prey density. The combined uses of O. niger and A. intermedius at high population density of onion thrips compare to low density can be successful in biological control of this pest.
... Conserving predators and parasitoids from different guilds means conserving a wide range of searching and feeding strategies (Koul & Dhaliwal 2003), which may in turn insure against a broader range of potential pest strategies. While intra-guild predation and functional redundancy have been highlighted as possible drawbacks of natural enemy diversity for biological control (Chong & Oetting 2007;Denoth et al. 2002;Lang 2003;Rodriguez & Hawkins 2000;Straub et al. 2008), other studies have detected synergistic effects of natural enemy diversity on pest suppression (Cardinale et al. 2003;Losey & Denno 1998;Riechert & Lawrence 1997;Sunderland et al. 1997). To gain a better understanding of the complex relationship between natural enemy diversity and biological control it is useful to study specific effects of a natural enemy complex on a prey/pest species (Letourneau & Bothwell 2008;Straub & Snyder 2006). ...
Fruitspotting bugs (FSB) Amblypelta nitida Stål and Amblypelta lutescens lutescens Distant (Hemiptera: Coreidae) are major native pests in subtropical and tropical horticultural crops in Australia, and key pests in avocado. Until now, using a single targeting approach, namely broad-spectrum insecticides, has been the only management option for growers. However, this approach is not sustainable in the long-term. A single strategy approach from different research teams has also not been able to find a solution, and therefore a multi-target approach is needed. In March 2011, a multi disciplinary collaborative project commenced. Team members included state government agencies from New South Wales and Queensland, the University of Queensland, BioResources Pty. Ltd., and private consultants. Major components of the management strategy under investigation are the following: 1. Chemical control 2. Monitoring and trap cropping a. Trap cropping and monitoring using alternative host and highly susceptible cultivars b. Pheromone traps 3. Biological control a. Investigation of biological control agents (ecology and biology) b. Mass-rearing of FSB and biological control agent 4. Integrated Pest Management (IPM) case studies - demonstrations on commercial farms 5. Area Wide Management (AWM) - management tested and coordinated on an areawide- scale 6. Industry adoption The project has made progress in all different components, and progress results will be presented. Different new management tools will become available at different times with new chemicals most likely to be the first new tool. The project is guided by industries including avocado, macadamia, lychee and papaya, passionfruit, and custard apples, with the avocado and macadamia industries being the major contributors.
... However, Luczak also suggests that spider competition should be lower in littoral and agroecosytems than in ecosystems with higher spider species diversity (1979). Riechert & Lawrence (1997) on the other hand, found evidence that a multispecies spider assemblage would better reduce pest insect abundances because a group of species would occupy a wider range of niches than any single species could. In our own studies we uncovered limited evidence that Hogna could affect both Pardosa densities as well as foraging efficiency. ...
Spider competition has long been an elusive phenomenon for ecological study. Because most spiders are generalist predators, they are predicted to overlap in resource use wherever they overlap in space use and activity periods. However, despite this obvious potential for competition, the empirical evidence for competition has been weak. Spider competition could potentially limit densities in agricultural ecosystems, which would limit their effectiveness as biological control agents. We summarize the results of five studies in a type of ecosystem which may be considered to be analogous to row crops in both the physiognomy of vegetation and cyclic disturbance regimes, namely, wetlands. In addition, we summarize the results of our own work in a soybean ecosystem.
... Because both the leafminer fly and the bud midge pupate in the soil, ground-dwelling predators play an important role in the regulation of populations of these insects. Generalist predators are regarded as an indispensable complement to specialized parasitoids, buffering outbreaks of pests, when populations of parasitoids and oligophagus predators are still low (Riechert and Lawrence 1997). Only few studies on soil dwelling predators in agroecosystems of the central coast of Peru have been conducted, showing the dominance of spiders (Araneae), ground beetles (Carabidae, 4 spp.), rove beetles (Staphylinidae, 16 spp,) and earwigs (Labiduridae, e.g. ...
Potato (Solanum tuberosum L.) is cultivated in diverse agroecosystems, which may harbor different insect pests; accordingly, potato farmers need to have appropriate site-specific pest control solutions. We developed Integrated Pest Management (IPM) strategies for potato production systems of the high Andes and the coast of Peru. This required considering all economically important pests and developing technological innovations to replace farmers' pesticide applications with equal efficacy. Examples are the use of plastic barriers that effectively prevent infestations of migrating Andean potato weevils (Premnotrypes spp.), the use of attract-and-kill for managing potato tuber moths [Phthorimaea operculella (Zeller), Symmetrischema tangolias (Gyen.)], or the rational use of insecticides to control flea beetles (Epitrix spp.) in the Andean highlands, or the leafminer fly [Liriomyza huidobrensis (Blanchard)] and the bud midge [Prodiplosis longifila (Gagne)] in the coastal lowlands. Moreover, the resilience of potato agroecosystems can be increased through augmentation strategies for natural enemies at the field level and inoculative biological control to recuperate species lost through the intensive use of pesticides. Potato IPM showed clear economic and ecological benefits at pilot sites. Strong public-private partnerships will be crucial for technology delivery, and well-trained field advisors are required to support the specific needs of farmers to adopt IPM. © 2012 Springer Science+Business Media B.V. All rights reserved.
... Spiders are among the most abundant predators of terrestrial ecosystems. Under favourable conditions they can establish high population densities and therefore are supposed to have an important impact as regulators or stabilising agent of insect populations (Nentwig 1987;Sengonça & Klein 1988;Temerak 1981;Nyffeler & Benz 1982Bogya 1995;Riechert & Lawrence 1997;Wisniewska & Prokopy 1997a;Holland & Thomas 1997). One of the main pests in apple orchards is the codling moth, Cydia pomonella (Lepidoptera, Tortricidae). ...
1. Conservation biocontrol, the regulation of crop pests by naturally-occurring biocontrol agents (e.g., predators and parasitoids), is predominantly monitored throughout periods of primary crop growth when pests exert the most observable impact on yields. Pest-focused agricultural biomonitoring often overlooks post-harvest, winter and even early-season biocontrol, despite the significant predator-pest interactions during these periods that profoundly affect pest abundance and, consequently, crop yields. Rapid advances in biomonitoring, particularly in the detection of predator-pest interactions that underpin biocontrol, provide an opportunity to reconsider how and when we monitor these interactions.
2. Advances in agricultural biomonitoring must transcend methodological innovation and encompass conceptual changes in monitoring of agricultural systems. Here, we assess existing evidence supporting the importance of periods beyond primary crop growth for biocontrol, and how predator-pest interactions are likely to evolve during these periods, subsequently influencing pest population dynamics during the primary crop growth period.
3. We advocate for a greater concerted effort to establish continuous monitoring of biocontrol interactions, particularly beyond primary crop growth periods in temperate climates. To facilitate this, we also summarise the methodological approaches that can make it possible, and explore how extending sampling across the full annual cycle might impact the practicalities and outcomes of these approaches.
4. Year-round monitoring of biocontrol interactions, both in crops and adjacent semi-natural habitats, will provide a previously intractable understanding of predator-pest dynamics, offering significant potential to enhance our ability to optimise and manipulate these systems for improved crop yields.
أُجريت الدراسة لتعريف فصائل العناكب المتواجدة في بعض مناطق طرابلس والتي تقع كجزء من الساحل الغربي لليبيا بمختلف تنوع بيئاتها من القربولي شرقاً إلى جنزور غرباً ومن 12 موقعاً على مدار فصول السنة خلال الفترة من أبريل 2018 إلى مارس 2019 ف. تم تجميع كافة العينات بطرق التجميع المختلفة من بيئات متنوعة. حيث جُمعت 654 عنكبوت صُنفت جميعها الى 22 عائلة و8 منها عُرفت لمستوى الجنس والنوع، حيث كانت أكثر العائلات وفرة عائلة Theridiidae مُثلت بـ 200 فرد وSalticidae بـ 117 فرد وكل من Pholcidae، Araneidae، oecobiidae بـ 60 فرد أو أكثر من العناكب بينما سُجل أكثر من 20 فرد لكل منLycosidae، Gnaphosidae وHersiliidae، في حين كان تمثيل بقية العائلات قليلاً جداً تراوح بين 1-7 عنكبوت. تُمثل الكثافة العددية للإناث 556 عنكبوت والذكور 98 عنكبوت، وبكثافة عددية للأفراد البالغة 258 فرد وغير البالغة 396 فرد من العناكب. اتضح حسب الإجمالي العام للفصول الأربعة أن فصل الصيف أكثر عدداً من بقية الفصول الاخرى حيث مُثل بـ 284 فرد والربيع 269 فرد مقارنة بفصلي الخريف 59 والشتاء 42 عنكبوت. كانت معظم العائلات الأكثر كثافة عددية متواجدة في فصلي الربيع والصيف بينما قلْت خلال فصلي الخريف والشتاء. كافة الدراسات للعناكب تشير إلى أهمية هذه المجموعة الحيوانية على مستوى العالم وفي كافة الأنظمة البيئية ولعدم وجود أبحاث مستفيضة عن أجناسها وانواعها وبيئاتها بليبيا أُجريت هذه الدراسة لتحديد عائلات العناكب وتسجيل توزيعها الجغرافي والفصلي في الأنظمة البيئية وقد رصدت الدراسة المعلومات البيولوجية لهذه العائلات وتم تعريف العينات المُجمعة في منطقة الدراسة لعائلات وأجناس وبعضها لمستوى النوع.
مفاتيح الكلمات: ليبيا، طرابلس، العناكب، التنوع البيولوجي، التصنيف.
A survey was carried out at farms of Rasheid, Beheira gavernorate during two successive rice seasons,2009 and 2010. Two sowing dates were studied; the first is the normal date of sowing (early May), the second sowing date is the late one (early June) using three traps (sweep net,pit fall and water pan). 10 species of true spiders were belonging to 6 families surveyed from the Egyptian rice fields. The spiders were recorded for the first date 9 species of true spiders were surveyed from rice fields at from Rasheid EL-Behira governorate. 6 spider families were surveyed, with 807 individuals belonging to 9 spider Species. The surveyed spiders and Families and their percentages were as follows: Thomicidae (Thomisius sp) with 3.46 % Lycosidae (Lycosa sp., Pardosa spp., Trochosa sp.,) with 9.04 % 25.65 % and 7.89 %, respectively. Tetragnothridae had two species (Tetragnatha javana, Tetragnatha nitens) with 40.89 %. Philodromidae (Thanatus Albini)) with 4.08% Araneidae (Singa sp.) with 6.44 % and Pisawridae (Dolomedes sp.) with2. 72 % and the second 7 spider families were surveyed, with 719 individuals belonging to 10 spider Species. The surveyed spared and Families and their percentages were as follows: Thomicidae (Thomisius sp.) with2.78% Lycosidae (Lycosa sp., Pardosa spp., Trochosa sp.,) with 9.59 % 17.52 % and 3.47 %, respectively. Tetragnothridae had if two species (Tetragnatha javana, Tetragnatha nitens) with 54.65 % Philodromidae (Thanatus Albini)) with 3.33% Araneidae (Singa sp.) with 5.98 % and Pisawridae (Dolomedes sp.) with 2.50 % and Salticidae Mendoza sp with 0.13 %.
Use of spiders in the field to control the cotton leaf-worm Spodoptera littoralis
This is a biological control test, conducted in the field where the spiders were released under greenhouse condition to control the pest Spodoptera littoralis, the most we can talk about, that made a great result.
Argiope bilali, a new specie of spiders was described from Dadu, Sindh, Pakistan.
A quick glance at the biological diversity reveals that the arthropods are the most diverse group of organisms' The arachnid constitutes the second largest class "t a'"""*t'i1;tll:ry9::fl"1ff:::f"t:iit:,:H,ffi:[X; Ilg"ilXTJi:Jlli.]1,,1,:.=,Ji; most diverse sroup on in" "rrtn *ni.n has received 7ri rankins in srobat diversitv after the six largest inseci 'orders. Spiders have. tigtifi";tt role to play in ,ecology be being exclusively predatory they regutate tn.""i popur"t,on, spiders .l:;';^;g; ;r oiotogicaicontrol agents' In spite of several applied values, spiders n.r" t""Jr"O "ri.ory attention.Gir is one of the seven identified protected areas (PA) by global Environment fu.i ot wo1Jernt "ni u"ing d; ;; abode of nslatic lion' Gir PA has been well explored for its floristic components and its vertebrate fauna. ii" r.J"og" of diversity and distribution of spiders in lndia as such is sparse and nil in the Gir PA. Hence an;tt";;i is niaOe to make a preliminary survey and know the status of the spider diversity in Gir PA. n totar oioo genera belonging to 39 families are represented' Taxonomy of spiders is an ambiguous area and *n.o]iO.Liinformation L fJcking' Our observations therefore ,iiir" onfy at the family level or best at the genus level
Biodiversity is one of the most important issues discussed worldwide, and each country has various policy measures to preserve its diversity. Efforts to preserve and improve our ecosystems have been an important issue in the agricultural sector. Especially, rice paddies are recognized in the scientific community as an important wetland system globally by the Ramsar convention. Rice paddies have formed a typical agricultural landscape for centuries in many areas including Asia.
Spiders can contribute to control of pest insects. Web-weaver spiders are common in many agroecosystems and, being sedentary, they are adequate for this type of studies. This paper deals with prey selection by four species of spiders, two orb-weavers (OW) and two cob-weavers (CW) and differences in diets, among species and among guilds, were analyzed. Field work was done in a cocoa plantation in Chiapas, Mexico, where the potential and actual preys for each spider species were sampled. Composition and proportion of captured prey differ from that of potential prey, showing a biased predation from their environmental availability. Spiders showed differences in diet composition and amplitude. OW had more specializaed diets than the CW, but overlap analyses shown higher similitude among CW, revealing that OW share a lower number of prey in common than the CW. Each of the four spider species over-predated several families of pest insects, but CW over-predated a higher proportion of these.
Pardosa pseudoannulata (Araneae: Lycosidae) and Verania lineata (Coleoptera: Coccinellidae) are common predator found in agro ecosystem. Several studies have described the ability of these predators to prey on Nilaparvata lugens (Hemiptera: Delphacidae). However, the study that explained the density impact of N.lugens on the ability predation in competition condition by both predators have not been completely known. A research had been conducted in the laboratory to study the predation and model of competition on different densities of N.lugens. The study used a completely randomized design in 10 replications. The prey densities for single predation were 5, 10, 15, 20 and for predation by competition were 10, 20, 30, 40 and without prey. This study revealed that the density of prey influenced the ability of predation of the two predators, which in turn, it also affected their growth. The impact of prey behavior on the predation and competition process between the two predators was also discussed in this article.
Biological control has come a long way towards adapting to the changing needs of agricultural pest suppression. Current trends in agriculture towards reduced pesticide use and ecological sustainability have led to surge of interest in spiders as potential biological control agents. This is because spiders have the capacity to exist in various conditions, with wide-ranging food webs, and are able to exploit the various stages of their prey life cycles. These habit diversifications portray them as efficient predators; the web weavers skewed towards phytophagous pests mainly from Diptera and Hymenoptera, whereas the non-web weavers foraged for foliage-dwelling pests such as Coleoptera and Homoptera. Since different spider species play different predating roles for a specific pest in its life cycle, it may be reliable to sustain the diversity of spider species within the specific area. This will be further discussed in this chapter together with our current results obtained from the botanical garden, dragon fruit, and herbal garden plantations which are suggesting some potential biocontrol agents for agricultural ecosystems belonging to the family groups of Araneidae, Lycosidae, Oxyopidae, Tetragnathidae, Thomisidae, and Salticidae. We further discussed the correlation of spider existence with the crop vegetation structures and architectural features.
A mathematical model demonstrates that a complex of polyphagous non-synchronized predators and parasites is likely to control only low-density cereal rust populations. Nonetheless, control at low rust density can delay epidemic development and thus substantially reduce yield losses. Methods of lengthening this delay are discussed. These methods involve adjusting the complex of background natural enemies directly or changing some characteristics of the agricultural environment to allow the complex to assert itself more forcefully. A program for further research is outlined.
