Abstract

Chelonus oculator Panzer is an egg-larval parasitoid of the cotton leaf worm, Spodoptera littoralis (Boisd.) with a broad geographical area. Four botanical insecticides - azadirachtin (Neem Azal), pyrethrum (Spruzit Neu), capsaicin (Hotpepper wax) and d-Limonene (Orange guard) - were investigated regarding their side effects on C. oculator. Sub-lethal concentrations (LC₂₅ and LC₅₀) were determined for azadirachtin and pyrethrum. Then, the parasitized third larval stage of S. littoralis was treated with LC₂₅ and LC₅₀ values for the same insecticides. Behavioural effects of the botanical insecticides on C. oculator were performed by choice tests using a Y-tube olfactometer. The results revealed that LC₅₀ value of pyrethrum was very harmful causing 100% mortality to C. oculator. LC₅₀ and LC₂₅ values of azadirachtin and LC₂₅ values of pyrethrum prolonged development time whilst reducing the longevity, emergence rate and adult dry mass. The behavioural test indicated that the tested botanical insecticides have strong repellent effects on the parasitoid. Thus, this study contributes to the amelioration of the safe use of botanical insecticides against the natural enemy in integrated pest management programs.

Key words: Chelonus oculator, side effect, azadirachtin, pyrethrum, capsaicin, d-Limonene.