Delayed reproductive behavioral responses in Drosophila melanogaster (Diptèra: Drosophilidae) following exposure to aqueous extract of Peganum harmala and the insecticide Spinosad

Abstract

This study aims to evaluate the delayed effects of two treatments spinosad (a commercially available insecticide) and a natural bioinsecticide (aqueous extract of Peganum harmala) on the sexual behavior and oviposition of vinegar flies (Drosophila melanogaster). Sublethal concentrations (86 mg/ml P. harmala, 0.020 mg/ml Spinosad) of each product were administered via ingestion to second-instar (L2) larvae of D. melanogaster. The results indicated that exposure to Spinosad significantly reduced sexual activity in D. melanogaster, as evidenced by prolonged mating latency and a lower copulation rate. Moreover, its repellent properties alter female oviposition site preference and a marked decrease in the number of eggs laid. In contrast, the natural bioinsecticide (aqueous extract of P. harmala) exerted a milder effect: it reduced the frequency of courtship behaviors; it prevented mating in most individuals. Its moderate repellent effect also influenced oviposition site selection, leading to reduction in egg deposition.