Comparative Effects of Rice and Melon Wastes on Sitophillus Zeamais, Storage Pest of Maize Grains in Nigeria

Abstract

World’s calories supply from maize accounts for 20% but global postharvest grain loss caused by insect pests was estimated to be 10%. Control is mostly by synthetic insecticides with consequences such as insect resurgence and resistance and negative effect on non- target organisms. Maize grain losses to weevils are so enormous that effective local solution has to be sought. Thus this research aimed at assessing the effectiveness of powders and ash of rice husk and melon shell in controlling Sitophillus zeamais (Mots) in stored maize. Four treatments, Rice husk powder (RHP), Rice husk ash (RHA), Melon shell powder (MSP) and Melon shell ash (MSA) were applied at eight levels of 0 - 2.0 g 20 g-1 maize grain in three replicates. Five pairs (males and females) of freshly emerged S. zeamais were introduced into each treatment. Mortality test was carried out on the insects at 48 and 96 hours after introduction. Germination test was conducted on ten randomly selected grains after weevil emergence. Significantly higher (p≤0.05) mortality was recorded in treated seeds than the control. Virtually 100% mortality of S. zeamais was attained in both RHA and MSA treated maize in 96hrs at all application rates. Mean adult emergence in maize treated with both RHA and MSA were zero, with no weight loss like those of grains treated with standard control of P. guinensis. Also maize grain treated with Rice husk ash (RHA) and Melon shell ash (MSA) recorded a mean WPI of zero irrespective of application rates as in P. guinensis. The mean percentage germination of maize grain was significantly higher (p≤0.05) in P. guinensis than those recorded on treatments, while germination of treated maize is higher than the control. Thus rice husk and melon shell are effective alternatives to insecticides against S. zeamais in stored maize.