Chronic toxicity of rynaxypyr 20%EC, an anthranilic diamide insecticide, on the egg parasitoid, Trichogramma chilonis Ishii

Pupal stages of T. chilonis Ishii were repeatedly exposed (once in each generation) to the recommended field dose (0.008%) and half of recommended field dose (0.004%) of rynaxypyr 20%SC, an anthranilic dyamide group of insecticide, up to 10^th generation by dipping parasitized egg cards of Corcyra cephalonica Stnt. to insecticidal preparations. After adult emergence, 10 pairs of adults were collected and each pair were placed separately in a small glass tube along with small egg cards, containing about 100 Corcyra eggs for parasitisation. The remaining adults were provided with a large egg card @ 30 eggs / adult for continuation of the bulk culture for the experiment.  After each exposure, observations were taken on various biological parameters of the treated population and their off springs. Effect of insecticidal treatments was compared with the control in each generation and also among different generation. Data were subjected to test of significance following General linear model using SPSS and SAS packages. The mortality of treated pupae, longevity of emerged adults, fecundity, and egg hatchability, percent pupation, percent adult emergence and sex ratio of off springs were adversely affected due to exposure to insecticidal treatments that intensified gradually with increase in the number of exposures. Duration of life cycle of the off springs was not adversely affected by insecticidal treatments.