Toxicological and Biochemical Studies on Use of Neonicotinoids and Bioinsecticides Against the Egyptian Cotton Leaf Worm. Spodoptera littoralis (Boisduval) (Lepidoptera: Noctuidae)

The cotton leaf worm, Spodoptera littoralis (Biosduval) (Lepidoptera: Noctuidae) is one of the most serious cotton pests in Egypt. New control methods are needed to diminish reliance on conventional insecticides as part of IPM programs. In the present study, the effect of Bacillus thuringiensis and NPV as bioinsecticides as well as the two neonicotinoid compounds, imidacloprid and acetamiprid were evaluated. Imidacloprid was recommended to be used over acetamiprid for both 2nd and 4th larval instars due to its low LC50 values, while profect and viruset showed the same virulence toward 2nd and 4th instars. Successive application of LC25 of profect, followed by LC25 of acetamiprid was superior in reducing the number of 2nd instar larvae, while treatment of 4th instar larvae with viruset, followed by acetamiprid was superior in reducing larval population. The total protein content and activity of enzymes that may play a role in insect immune response were determined.