Antifeedant activity and some biochemical effects of garlic and lemon essential oils on Spodoptera littoralis (Boisduval) (Lepidoptera: Noctuidae)
The present study was aimed to evaluate the larvicidal activity, antifeedant activity and some biochemical studies of garlic and lemon essential oils on Spodoptera littorals (Boisduval) larvae by leaf dipping method. The results showed that both garlic and lemon oils have larvicidal effects against S. littoralis larvae, with LC90, LC50 and LC30 of 39.18, 19.95 and 16.60% for garlic oil, respectively; and it was 47.04, 24.20% and 20.09 for lemon oil, respectively. The antifeedant activity and the starvation percentage decreased significantly in larvae treated with garlic and lemon oils. Biochemically, the total midgut proteins and lipids contents decreased significantly while the carbohydrate levels increased in larvae treated with LC30 of both garlic and lemon oils. a amylase and lipase decreased significantly in treated larvae. The present study showed that both garlic and lemon essential oils were toxic to S. littoralis larvae and these results could be useful for the development of new insecticide formulations to control this pest. The effects of essential oils on larvicidal and antifeedant activities are discussed.