Detoxifying enzyme profiles in pesticide tolerant strains of Trichogramma chilonis Ishii, a hymenopteran parasitoid

Abstract

Investigation on enzyme assays were carried out for carboxyl esterase (á and â esterase) and glutathione s-transferase in the susceptible and pesticide tolerant Trichogramma chilonis Ishii strains such as TCT1, TCT4, TCT5 and TCCb tolerant to endosulfan, spinosad, lamda-cyhalothrin and indoxycarb respectively. The electrophoretic profile of á-esterase enzyme in the susceptible Trichogramma strain showed 3 alleles in comparison with tolerant Trichogramma strains TcT5, TCT1, TCCb and TCT4 which depicted 5, 4, 3 and 2 alleles respectively. Similarly, â-esterases profile in the susceptible indicated 4 alleles compared to TCT5, TCT1, TCCb and TCT4 strains which showed 6, 5, 3 and 3 alleles respectively. The results of the quantitative analysis showed an increased enzyme activity in the tolerant strains. The increase in á-esterase activity in the tolerant strains TCT1, TCT4 and TCT5 was 2.07, 1.53 and 1.51 times more than the susceptible one and the mean difference was statistically significant and â-esterase activity in the tolerant strains TCT1, TCT4 and TCT5 was 1.41, 1.69 and 1.16 times more than the susceptible one. In the glutathione s-transferase enzyme activity, the mean value of the susceptible strain was 0.029?M and in tolerant strains, TCT1, TCT4 and TCT5 the values were 0.0243, 0.0289 and 0.023?M respectively indicating that the tolerant strains had lesser activity than the susceptible one. Such an increase in enzyme activity indicated the elevated production of detoxifying enzymes such as carboxylesterase to sustain the parasitoid in the field.