Cotton trichomes, acting as a resistance factor to Aphis gossypii Glover, can also affect its natural enemies, reducing the efficacy of the control agents and increasing prey searching time. The effects of different trichome densities, observed in three cotton cultivars (Antares - low pilosity; CNPA 7H - hirsute and Deltapine Acala 90 - high pilose), on biological aspects and predatory ability of Chrysoperla externa (Hagen), fed on A. gossypii reared on IAC-22 cotton seedlings, were evaluated. Developmental period and viability of C. externa larva were not significantly affected by trichome densities. However, C. externa oviposition period was longer when larva were fed on A. gossypii reared on Antares leaves. Also, daily and total egg numbers laid by C. externa were not influenced by any cotton cultivars on which it was maintained during the larval phase. Highest longevity of C. externa females was observed when they were fed, during the larval phase, on leaves of the lowest pilosity cultivar (Antares). During larval period, C. externa consumed, respectively, 540.0; 494.3 and 454.8 aphids, when it was maintained on CNPA 7H, Antares and Detapine Acala 90 cultivars leaves. Cotton cultivars showed good compatibilities with the predator species; the results clearly indicate the feasibility of A. gossypii aphid control through the use of C. externa on cotton cultivars with proper trichome densities.
host-plant resistance; tritrophic interaction; predator; aphid
