Larval exposure to azadirachtin induced locomotor deficits, and impairs olfactory and gustatory preference in adults of Drosophila melanogaster (Diptera: Drosophilidae)

Azadirachtin, a tetranortriterpenoid botanical insecticide, has a variety of sub-lethal effects against many insect pests, including insect fitness, growth and development inhibition, antifeedancy and repellency. Despite extensive studies of the mechanisms that underline physiological effects, little attention has been given to effects of azadirachtin on olfactory and gustatory perception, and locomotor reactivity considering as an integral part of most insect behaviors. Azadirachtin was applied topically at two doses LD 25 (0.28 μg) and LD 50 (0.67 μg) on early third instar larvae of Drosophila melanogaster (Meigen) (Diptera: Drosophilidae) as a model organism. Results showed that previously treated flies (3rd instar larvae) showed a clear preference for solvent odor avoiding azadirachtin. The biopesticide significantly inhibited the proboscis extension response in the adults of both sexes with more marked effects in previously treated flies. These findings provide clear evidence that azadirachtin induced olfactory and taste aversion behavior suggesting a learned avoidance memory. Moreover, azadirachtin was found to affect Drosophila adult’s locomotor reactivity. These results may reflect interference of azadirachtin with the modulation of behavioral avoidance and locomotion in Drosophila which may contribute as repellent strategies and reinforce the action of azadirachtin in integrated pest management programs.