Joaninha predadora resistente a piretroides : contribuição para o controle da traça-das-crucíferas

Abstract

The conservation of natural enemies and the use of insecticides are crucial for pest management. Therefore, the physiological selectivity obtained through insecticide resistance can aid in the integrated management of pests in conventional crops, in special when the natural enemy and the insecticide act against different pests or complement one another in the control of a common target. Thus, in this work was evaluated the potential of predation of Eriopis connexa (Germar) (Coleoptera: Coccinelidae) population resistant to deltamethrin on diamond back moth (DBM) Plutella xylostella (L.) (Lepidoptera: Plutellidae), also resistant to pyrethroids. Adult of the lady beetle were exposed to the dry residue of deltamethrin on cabbage leaves to determine the rate of predation, the predation behavior at different densities of larvae in treated and untreated environment, the choice between leaves of cabbage treated and not treated with deltamethrin, the potential for population reduction of P. xylostella, and the preference between DBM larvae and the aphid Lipaphis erysimi (Kalt.) (Hemiptera: Aphididae). Resistant and susceptible E. connexa, consumed during 24h exposure, an average of 9.8 and 6.0 DBM`s larvae, respectively. In addition, lady beetle resistant exhibited similar predation on treated and untreated environment and higher predation than susceptible beetle under treated environment as function DBM`s larvae availability. Adults resistant of E. connexa showed no preference between treated and untreated surfaces for prey consumption. In greenhouse, resistant and susceptible E. connexa exhibited similar survival after 10 days of confinement on plants treated with recommended dosage of deltamethrin and both populations consumed about 95% of DBM in deltamethrin treatments. Despite preying more aphids, E. connexa also consumed DBM`s larvae even under high availability of the aphid. Thus, we conclude that resistant population of E. connexa survives the exposure to deltamethrin and, does not present alteration in the behavior of predation under treatment with deltamethrin.