Experiments were conducted to study the bioefficacies of different plant/weed derivatives that affect the development of the pulse beetle, Callosobruchus maculates F. (Coleoptera: Bruchidae) fed on black gram, Vigna mungo, seeds. Plant extracts, powder, ash and oil from nishinda (Vitex negundo L.), eucalyptus (Eucalyptus globules Labill.), bankalmi (Ipomoea sepiaria K.), neem (Azadirachta indica L.), safflower (Carthamus tinctorius L.), sesame (Sesamum indicum L.) and bablah (Acacia arabica L.) were evaluated for their oviposition inhibition, surface protectant, residual toxicity and direct toxicity effects on C. maculates. The results showed that plant oils were effective in checking insect infestation. The least number of F1 adults emerged from black gram seeds treated with neem oil. The nishinda oil extract was the most toxic of three extracts tested (nishinda, eucalyptus and bankalmi). Bablah ash was the most effective compared to the powdered leaves of nishinda, eucalyptus and bankalmi. The powdered leaves and extracts of nishinda, eucalyptus and bankalmi, at a 3% mixture, provided good protection for black gram seeds by reducing insect oviposition, F1 adult emergence, and grain infestation rates. The oil treatment did not show adverse effects on germination capability of seeds, even after three months of treatment.

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Laboratory experiments were carried out to investigate the efficacy of seed extracts of pithraj,Aphanamixis polystachya (Wall & Parker), a locally grown plant in Bangladesh, against the red flour beetle,Tribolium castaneum (Herbst.). Results of three different bioassays showed that crude extracts of pithraj seeds have strong repellent effects and moderate feeding deterrent and insecticidal (direct-contact) effects on adultTribolium castaneum.

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Ground leaves, bark, seeds, and four seed extracts of pithraj,Aphanamixis polystachya (family Meliaceae), a locally grown plant in Bangladesh, were evaluated for their repellency, contact toxicity, and food protectant efficacy against adult pulse beetle (Callosobruchus chinensis L.). The seed extracts showed poor repellent effects, but high contact toxicity to adults at 72 hr after application. The ground leaves, bark, and seeds provided good protection for mung beans against pulse beetles, and the seed powder greatly reduced the F1 progeny and seed damage rates.

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Conventional pesticides are being used as the major tools for stored grain and food protection. Many conventional pesticides have created problems including pesticide resistance, toxic residues in the treated products, handling hazards, health hazards to operatives and pest resurgence. Among these, the incidence of pesticide resistance is a growing problem in stored product protection. Problems associated with synthetic pesticides, especially pesticide resistance, have created a worldwide interest in the development of alternative biorational strategies. Plant-derived materials, biological control agents, insect growth regulators, solar disinfestation systems, use of inert dusts and diatomaceous earth, etc., are potential viable alternatives. Most of these alternatives have low toxicity or are not toxic to humans, making them environmentally acceptable and enabling them to be incorporated in stored product protection.