Search Menu Abstract Sublethal insecticide exposure may affect foraging of insects, including natural enemies, although the subject is usually neglected. The lady beetle Eriopis connexa Germar, Coleoptera: Coccinelidae is an important predator of aphids with existing pyrethroid-resistant populations that are undergoing scrutiny for potential use in pest management systems characterized by frequent insecticide use. Therefore, our objective was to assess the effect of sublethal lambda-cyhalothrin exposure on three components of the prey foraging activity i. Both lady beetle populations exhibited similar walking patterns without insecticide exposure in noncontaminated arenas, but in partially contaminated arenas walking differed between strains, such that the resistant insects exhibited greater walking activity. Behavioral avoidance expressed as repellence to lambda-cyhalothrin was not observed for either the susceptible or resistant populations of E.

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Balcarce, Discussion Our analysis of the population density of E. The results showed that increasing the structural complexity of the habitat surrounding wheat crops resulted in a higher abundance of E. Similar conclusions were reached in previous studies, where the increase in plant diversity in wheat crops increased the number of larvae of hoverflies and coccinellids [ 26 ] and aphid parasitism [ 34 , 37 ].

In the current study, the regression models indicated that adults and larvae of E. Unsurprisingly, the numerical responses of E. The positive effect of plant diversity on the reproductive numerical response is a consequence of the dependence of emerged ladybeetles in early spring on prey in hibernation areas when aphid densities in the fields are still low.

Since the level of food supply affects the fecundity [ 39 — 41 ] and migration behavior of ladybeetles [ 39 ], the availability of aphids in noncrop landscape elements is likely to impact the numbers and distribution of ladybeetles and associated biocontrol in agro-ecosystems [ 13 ].

Moreover, prey availability in shelter habitats in early spring can influence postoverwintering mortality, the fecundity of surviving coccinellids, and the phenology of dispersal into the crop [ 42 ]. In this study, we registered this type of effect, because during , we recorded an increase in the abundance of E. This increase in the density of E. Even if the abundance of cereal aphids could not account for that of E. During the autumn of , an increase in the abundance of aphids on M.

The presence of aphids in the refuges favored predator survival and increased their abundance before the early stage of wheat sowing. Furthermore, the presence of aphids in the refuges could be explained by the better reproductive performance of adult E.

Egg production in aphidophaga is usually related solely to the availability of prey. However, some studies have indicated that fecundity is also influenced by the prey quality [ 43 ].

Our results are consistent with those of Bianchi and van der Werf [ 44 ], who established that reproduction and the associated control of pest aphids are affected by both the availability of nonpest aphids in noncrop habitats and the infestation date of pest aphids in wheat fields. When the infestation of wheat by pest aphids occurs early in the season, the prey availability of pest aphids alone is sufficient to allow C. However, when the infestation by pest aphids is somewhat delayed, C.

Therefore, prey availability in noncrop habitats might play a significant role in the conservation of ladybeetles and directly affect the numerical response of predators and consequently the biological control of cereal aphids in agroecosystems. It might be possible to enhance the population of coccinellids in the agricultural landscape by increasing plant diversity. Plant diversity supports prey diversity and provides refuge and additional resources such as pollen and nectar fecundity [ 13 , 31 — 33 ].

As a result, coccinellids and other natural enemies should be able to respond better to the change in aphid densities in diverse habitats. In agricultural landscapes, it might be possible to enhance populations of coccinellids by manipulating plant diversity. The presence of refuges near wheat crops is particularly important in determining the local abundance of E.

The augmentation of prey availability in noncrop habitats is one of the habitat management strategies that might preserve predators in agricultural landscapes and increase their effectiveness [ 13 ]. Moreover, individual predators might not need to travel far to obtain essential resources. This suggests that the potential of E. Conclusions In summary, we observed an increase in the numerical response of E. For E. Even though an increase in plant diversity in the agroecosystems and its maintenance represents an additional cost for farmers, predator efficacy would increase over time and consequently, pest attack would be less likely to cause economically important damage.

Acknowledgments The authors are grateful to the editor Jean-Guy Godin and one anonymous reviewer for the valuable comments on earlier drafts of this paper.

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Eriopis connexa

Pestic Biochem Physiol. Epub Mar 5. Enzymes mediating resistance to lambda-cyhalothrin in Eriopis connexa Coleoptera: Coccinellidae. Electronic address: agnarodrigues yahoo. Resistance to widely used insecticide, lambda-cyhalothrin, was recently reported in the predatory lady beetle Eriopis connexa Germar Coleoptera: Coccinellidae.


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