Bangladesh is a sub-tropical and humid country. That is why, the infestation of insects during storage is very common here. The maize weevil, Sitophilus zeamais Motschulsky (Coleoptera: Curculionidae), locally known as “Katta Poka”, is one of the most serious cosmopolitan pest of stored cereal grain, especially of maize (Zea mays L.), in tropical and subtropical regions including Bangladesh. Considering the issue, the study was conducted in the laboratory of Department of Entomology, Bangladesh Agricultural University (BAU) following completely randomized design (CRD) with three replications to evaluate the efficacy of four locally available botanicals and chemicals. The botanicals used were: Neem (Azadirachta indica) leaf, Datura (Datura stramonium) leaf, Nishinda (Vitex negundo L) leaf and Garlic (Allium sativum L.) tablet powders at three different doses (3, 4 and 5gm)/100g of grain seed against maize weevil. The results revealed that all test materials at 5g doses exhibited higher mortality action against maize weevil while at 3g doses it gave the lowest percentage efficacy. Powdered leaves of neem and datura at 4 and 5gm were showed statistical significant (P<0.01) differences while powdered leaves of nishinda at the similar rates were observed with moderately effectiveness and powdered tablet of garlic gave the lowest mortality rate within 28 days of exposure in all tested doses. These findings suggest that botanical treatments exerted better mortality of maize weevil and reduced maize seed weight loss with higher germination capacity compared to the untreated control. It was also observed that the highest mortality percentage, lowest seed weight loss and highest germination capacity in the seeds which were treated with Sevin 85SP at the rate of 0.25g/100g maize seeds. Maize grains treated with botanicals, indicated that insect reproduction and development were impaired in all botanical pesticides. It is suggested that datura leaf, neem leaf powder can be used as good alternatives to chemical insecticides against S. zeamays due to their higher mortality, lower seed weight losses and higher germination capacity.
Efficacy of Cymbopogon citratus Stapf leaf extract as seed protectant against Sitophilus zeamais Motschulsky (Coleoptera: Curculionidae) on stored maize (Zea mays L.)