Chrysoperla externa is a good candidate for predation of Aleurodicus cocois in cashew crop

What is it about?

A potential alternative to the use of chemicals for controlling phytophagous arthropods in agricultural environments is the use of biological control agents of natural occurrence. This study evaluated the functional response of frst-instar larvae of Chrysoperla externa-fed eggs and nymphs of Aleurodicus cocois, as well as the olfactory response of the third-instar larvae of this predator to the volatiles of two genotypes (CCP 76 and PRO 143/7) of dwarf cashew induced by the herbivory of A. cocois. The volatile compounds emitted by the leaves of the two cashew genotypes, infested and non-infested by A. cocois, were analyzed by solid-phase microextraction coupled to GC–MS. Logistic regression indicated that frst-instar larvae of C. externa exhibited a type II response when fed eggs and nymphs of A. cocois. The value of the attack rate (a') did not difer between prey, but the handling time (Th) was longer when the predator fed on nymphs. In the behavioral tests third-instar larvae of C. externa were able to distinguish and select the volatile signals emitted after the infestation of A. cocois, regardless of the cashew genotype evaluated. According to the volatile profles of cashew genotypes infested by A. cocois, the compounds β-caryophyllene, allo-ocimene, neo-allo-ocimene, α-copaene, γ-muurolene, and δ-cadinene were released in large amounts by genotypes CCP 76 and PRO 143/7. Therefore, these compounds may be involved in the attractiveness of the predator. The results indicate that C. externa may be an efective biocontrol agent of A. cocois in cashew crop.

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