Biological activity of azadirachtin-enriched neem kernel extracts against r hyzopertha dominica (F.) (coleoptera: bostrichidae) in stored wheat

Abstract

The residual activity of an ethanolic neem kernel extract, containing azadirachtin, was evaluated in the laboratory against Rhyzopertha dominica (F.) on wheat stored for up to 48 weeks. All treatments in both fresh and residual studies did not have any effect on mortality of the parents. On freshly treated grain, the application rate of 5 mg kg −1 of azadirachtin was effective in inhibiting F1 progeny production by >98% against three test strains. The minimum application rate for >95% reduction of F1 progeny of the multi-resistant strain throughout the 48-week storage period was 25 mg kg −1, with complete prevention estimated to occur with 75 mg kg −1. The effectiveness of azadirachtin was not synergised by piperonyl butoxide. The results indicate the persistency of this emulsifiable neem formulation, and the potential for field evaluation as a grain protectant.