Biological and Biochemical Effects of Coach 20% (Fipronil) Insecticide Against Un-Irradiated and Irradiated Spodoptera littoralis (Boisd.)

Fipronil (coach) has shown toxic activity against numerous insects. We tested the biological and biochemical effects of fipronil (phenylpyrazole) against Spodoptera littoralis pupae. The toxicity of various coach insecticide concentrations (2, 4, 6 and 8%) against both unirradiated and irradiated full grown pupae of S. littoralis with substerilizing dose 100Gy was assessed using the pupae spraying technique. The findings demonstrated that as concentrations in either irradiated or unirradiated pupae increased, the percentage of treated pupae that emerged reduced. Male and female emergence and adult lifespans decreased as pesticide concentrations increased, and the lifespan of adults developed from irradiated pupae was less than that of unirradiated adults. To evaluate biological activity, males from treated pupae were mated with normal females. Four groups were organized; normal adults, male resulted from pupae treated with LC50, male resulted from 100Gy irradiated pupae and male resulted from treated and irradiated pupae. The least number of hatched larvae, larval duration and percent pupation were in the LC50 with irradiated pupae (100Gy) group. Biochemical study revealed that a highest significant catalase activity was found in the case of treatment at LC50 with irradiated pupae (100Gy). This was in contrast to glutathione-s-transeferase (GST) which showed significant decrease in the case of treatment with LC50 with irradiated pupae (100Gy). In general, the combination of gamma radiation and coach could be utilized as integrated program to control S. littoralis.