Two plant extracts protect stored maize against infestation of Sitophilus zeamais in Northern Ghana

Abstract

Botanicals have been encouraged as substitutes for conventional pesticides to reduce the impact of the latter on the environment. In line with that, we studied the effects of two plant extracts in controlling Sitophilus zeamais Motsch (Coleoptera: Curculionidae) attacks on stored maize (Zea mays L. Poales: Poaceae). The experiment was conducted under a normal room temperature of 27⁰C to 30⁰C and relative humidity of 74–76 % in a completely randomized experimental design. We infested the stored maize seeds in glass jars with S. zeamais F₁ under a 12-hour day and 12-hour night within 24 hours period. This was after 50 g of the seeds were mixed with 2 g each of the two botanicals separately in different glass jars. There were 5 treatments and 10 replications in total. The data taken for this study were quantitative. To ascertain the efficacy of the botanicals we compared the number of dead and live weevils, of seeds damage and weight loss caused by weevil attacks under each of the different treatments by determining percentage mortality, percent weight loss, seed damage and progeny production. Our results showed that the different botanical formulations significantly controlled S. zeamais population resulting in reduced damage, better protection and improved storage of maize seeds. However, there were no significant differences in protections offered between shade dried neem seed powder and rice husk powder although the latter was the most efficacious with 85 % mortality compared to the former with 65 % with sundried neem seed powder being the least with a little above 40 % mortality. We concluded from this study that the formulated botanicals were very effective in controlling S. zeamais populations and therefore recommended that it be used as a cost effective and environmentally friendly protection of stored maize against S. zeamais attacks, especially in rural poor areas and places known for continuous seed production and storage, such as the case of the study community.