Researcher 2013;5(12) http://www.sciencepub.net/researcher 240 Efficacy of Moringa oleifera leaf powder against Callosobruchus maculatus (F.) (Coleoptera: Chrysomelidae) on stored cowpea (Vigna unguiculata L. Walp) Ojo J. A. 1* , Olunloyo A. A. 2 and Akanni E. O. 2 1 Department of Crop Production, Kwara State University, Malete, Kwara State, Nigeria 2 Department of Crop Protection and Environmental Biology, University of Ibadan, Nigeria. *jamesadebayoojo@gmail.com Abstract: Cowpea is a very important grain legume that serves as a source of dietary protein for human consumption, however the grain is widely infested by a number storage insect pests among which Callosobruchus maculatus is a primary field to store pest causing considerably great losses to farmers. Laboratory study was conducted to assess the efficacy of Moringa oleifera leaf powder, used as protectant against C. maculatus F. infesting stored cowpea. The bioassays were conducted at six levels of concentrations (0.2, 0.4, 0.6, 0.8, 1.0 and 2.0 g/20g seed) of test plant leaf powder and the untreated control (0g/20 g seed). All the different levels of concentrations considerably reduced oviposition and emergence of F1 progeny compared to the control. The mortality of the cowpea beetles was assessed at two days after infestation (2 DAI), 4 DAI, 6 DAI and 7 DAI and the results indicated that the mortality increased with increasing amount of M. oleifera leaf powder, with concentration of 2.0g /20g seed has significantly higher (p > 0.05) mortality compared to the control. Also, different level concentrations significantly protected the seeds in relation to seed damage and seed weight loss caused by C. maculatus compared to the control. [Ojo J. A., Olunloyo A. A. and Akanni E. O. Efficacy of Moringa oleifera leaf powder against Callosobruchus maculatus (F.) (Coleoptera: Chrysomelidae) on stored cowpea (Vigna unguiculata L. Walp). Researcher 2013;5(12):240-244]. (ISSN: 1553-9865). http://www.sciencepub.net/researcher . 34 Keywords: Callosobruchus maculatus, leaf powder, protectant, concentration Introduction Cowpea (Vigna unguiculata L. Walp) is one of the most important grain legume in the farming systems of Nigeria and West Africa at large (Singh et al., 2002). It accounts for about 60% of human protein intake in Nigeria (Oparaeke, et al., 1998). The potential yields of improved varieties of cowpea can be as high as 3 tonnes per hectare, resource poor farmers who are the predominant growers of this important crop seldom harvest up to 500 kg per hectare of grain even when they grow such varieties. Farmers obtain low yields averaging 200 – 300 kg/ha in Nigeria (Alghali, 1992). Biotic factors are responsible for these losses in the field, most importantly insect pests infestations at all stages of the plant growth in the field and also in the store (Oparaeke, et al., 2004). Callosobruchus maculatus is a major primary pest of stored seeds of cowpea in Nigeria (Ofuya, 2001). Infestation usually starts from the field and continues in the store where the seeds are severely damaged, leading to reduced weight, low viability and poor marketability (Ofuya, 1986), these losses constitute a major threat to food security and availability. The common control method of storage pests is with synthetic insecticides such as pirimiphos methyl, fenithrithion, methyl bromide and phosphine fumigant (Cardona and Karel, 1990; Monford, 2006). Although these chemicals appear to be effective, their use is being discouraged due to associated human health and environmental problems such as pest resistance to insecticide, environmental pollution, high cost of purchase, non-availability as well as hazards to farmers (Talukder and Howse, 1995). These drawbacks have necessitated the need for sustainable alternatives that are easily biodegradable, environmentally friendly and safe to both producers and consumers (Ewete et al., 1996; Akob and Ewete, 2007). The challenge of finding a good alternative to replace these conventional insecticides has led to bio- prospecting for plants with natural insecticidal potency. Some plants which their parts like leaves, stems, roots have been used include Azadirachta indica, Piper guineense, Allium cepa, Anethum graveolens, Senna species, Annona senegalensis (Ewete et al., 1996, Ofuya, 2001) among others. The pulverized leaves of moringa have been found to be effective against storage pest like Tribolium castaneum (Herbst.) (Anita et al., 2012). This study seeks to assess the efficacy of powdered leaves of Moringa oleifera against cowpea beetle, Callosobruchus maculatus (F). Materials And Method The experiment was conducted in the Entomology Research Laboratory of the Department of Crop Protection and Environmental Biology, University of Ibadan at an ambient temperature of 27