Insecticide impact on natural populations of parasitoids associated with diamondback in Central Brazil

The diamondback moth (DBM) Plutella xylostella (L.) (Lepidoptera: Yponomeutidae), is the most serious pest of cabbage in Central Brazil and its control is primarily based on pesticide sprays. Over the past years a number of new pesticide compounds were introduced onto the market and some of them may cause adverse effects on natural populations of parasitoids associated with DBM, which was the objective of this research. Spinosad, Thiacloprid, Indoxacarb, Bacillus thuringiensis var. kurstaki and a strain of B. thuringiensis developed at Embrapa Genetic Resources and Biotechnology were tested in the field. Three insecticides: Spinosad, Indoxacarb and Bacillus thuringiensis var. kurstaki provided outstanding control of DBM populations. The rate of total parasitism of larvae recovered from cabbage leaves was not significantly different among treatments. The most frequent parasitoid species recovered were Diadegma, leontidinae Brethés; Apanteles sp.: Actia sp., and Oomyzus sokolowskii (Kurdjumov). (Résumé d'auteur