Publisher: Bachudo Science Co. Ltd

Analysis of Insect Populations In Stored Crops In Cross River State, Nigeria

Donald A. Ukeh, Idorenyin A. Udo
KEYWORDS: stored-prOduct insects, cassava. maize, groundnuts, cowpea.


A survey of stored cassava, maize, groundnuts and cowpea insect pests and their natural enemies was conducted in Obudu, Cross River State, Nigeria from October 2006 to March 2007. For each product 3 storage facilities were sampled to give a monthly total of 12 locations 500g of dried cassava tubers, maize, groundnuts or cowpea seeds was measured out from each sample and adult insect pests and beneficial insects were sieved out and identified monthly. Eight insect pest species were found associated with these stored products namely; the maize weevil, Sitophilus zeamais, the red flour boetle, TriboNum castaneum. the cowpea weevil, Cal/osobruchus maculatus, the lesser grain borer, Rhyzopertha dominica, the Indian meal moth, Plod1a interpunctella. the Angoumois moth, Sitotroga cerealella. the kapra beetle, Trogoderm'a granar(um and the rusty grain beetle. Cryptofestes ferrugineus. The predominant insect species in all crop samples were T. castaneum and, S. zeamais with mean numbers of 30.6 and 28.2 respectively. T castaneum was recorded in all the crop products sampled, C. macu/atus was sampled only from cowpea seeds, whereas T granarium, P interpunctella and C. ferrugineus were all found in stored groundnut R. dominica and S. cerealella were recorded as insect pests of stored cassava. while S. zeamais was primarily associated with maize and occasionally found in, cassava. The beneficial insects recovered from these stored products were Anisopteromalus ca/andrae, Theocolax elegans and Dinarmus basalis all Pteromalid Hymenopterans. Results from this study showed that stored commodities are often infested with various insect pests, and frequent sampling and sanitation are required to prevent infestations.

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