Insecticides and predatory lady beetles: Characterization of lambda-cyhalothrin resistance in Eriopis connexa
Agna Rita dos Santos Rodrigues
IF Goiano – Câmpus Rio Verde, Brazil
: Forensic Toxicol Pharmacol 2015, 4:3
Abstract
Natural enemies are considered the major natural mortality factor of pests in different agricultural ecosystems. Despite resistance in natural enemies is a rare phenomenon, the occurrence of resistant populations of natural enemies could be beneficial because this biological control agents could prevent the population growth of the pests by control the escaping pests of insecticide exposure. Eriopis connexa is a key predator of soft-bodied arthropods mainly aphids. To control pest complex in many agro ecosystem are required multiple insecticide applications or broad-spectrum insecticides recommendation. The pyrethroid lambda-cyhaothrin is a broad-spectrum insecticide recommended against defoliators, but lacking efficacy against aphids; requiring the preservation of such predators as E. connexa . Recently, four populations of E. connexa were recorded as resistant to pyrethroid insecticide lambda- cyhalothrin. The lambda-cyhalothrin resistance in E. connexa is inherited as autosomal factor with incomplete dominance so heterozygous individuals could present resistant phenotype. The reduction of the level of resistance to lambda-cyhalothrin in E. connexa using piperonyl butoxide (PBO) and S, S, S-tributyl phosphorothioate (DEF) synergists indicated metabolic mechanism of resistance. Also, in vitro assays and native-PAGE pointed to high B-type carboxylesterase activity of resistant population being decreased by eserine, PBO, and methyl paraoxon inhibitors. In addition, resistance to lambda-cyhalothrin in E. connexa has allowed high survival under field rate of this insecticide applied against boll weevil in cotton and to field rate of other pyrethroids. Thus, physiological selectivity mediated by resistance to lambda-cyhaothrin has been detected in populations of E. connexa from Brazil. agna.
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