Additive effects of the biopesticide azadirachtin combined with linalool on the life table parameters and behaviour of <i>Drosophila melanogaster</i>

Abstract Excessive use of insecticides contributes to environmental pollution, degrades soil quality, and promotes the development of resistance in insect pests. Botanical compounds are considered effective, safe, and eco‐friendly alternatives to synthetic products for the management of insect pests and vectors. This study aimed to evaluate the efficacy of azadirachtin, applied individually or in combination with linalool at sublethal and lethal doses (LD 25 and LD 50 ), on the life table and behaviour of Drosophila melanogaster larvae. Results showed that the bioinsecticide activity of the mixture applied at a 3:1 ratio and tested at both the LD 25 and LD 50 levels exhibited an additive effect on larval mortality. The results showed that azadirachtin, when applied individually, significantly inhibited the growth rate, reduced fecundity, and altered oviposition and larval preference, indicating a marked repellent effect. Binary combinations of azadirachtin with linalool were more effective than azadirachtin alone, leading to greater reductions in growth rate and fecundity, as well as enhanced repellency. Females exhibited increased oviposition aversion in azadirachtin–linalool‐treated mediums, showing a clear preference for untreated zones. Larvae also exhibited significant repellency to the azadirachtin–linalool arenas, remaining predominantly in untreated arenas rather than moving to treated ones. These results suggest that azadirachtin combined with linalool at a 3:1 ratio may serve as an effective strategy for controlling insect populations while simultaneously reducing reliance on the inappropriate and excessive use of harmful chemical insecticides.