Laboratory bioassays were carried out to study the insecticidal, antifeedant, developmental, and reproductive effects of three commercial neem oil-based formulations (Pure Neem Oil, Azatrol, and Triple Action Neem) on Spodoptera eridania when used at recommended concentrations. Neem-derived insecticides significantly reduced the food intake of all instars tested, often limiting the feeding activity on neem-treated leaf areas to a fraction of that occurring on controls, in both choice and no-choice bioassay tests. Pure neem oil, followed by Azatrol, demonstrated up to 96% antifeedant activity against larvae; consequently, both biopesticides are effective antifeedants. A two-day feeding period on leaves treated independently with pure neem oil and Azatrol induced the prolongation of the second larval instars by 4.5 and 2.7 days, and by 2.4 and 1.3 days for fourth larval instars, respectively. Mortality and pupal ecdysis of S. eridania were also negatively impaired by neem-based biopesticides, with the greatest efficacy attributable for pure neem oil. When administered orally, commercial formulations induced significant reduction in longevity by 0.8-4.1 days, and fecundity of adults was significantly reduced compared to those fed on untreated diet.
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