Relative susceptbility of stored cowpea, Vigna unguiculata walp and soyabean, Glycine max (L.) merrill, to infestation by the cowpea seed beetle, Callosobruchus maculatus (Fab.) (Coleoptera: Bruchidae)
Pessu P.O.1, Umeozor O.C.*
Department of Animal and Environmental Biology, University of Port Harcourt Box 384, Uniport Post Office, Port Harcourt, Nigeria.
* Corresponding Author.
1Present address: Nigerian Stored Product Research Institute P. M. B. 5063, Port Harcourt, Nigeria.
Cowpea, Vigna unguiculata Walp was significantly more susceptible than soybean, Glycine max (L.) Merrill, to Callosobruchus maculatus (Fab.) infestation; indices of susceptibility were 7.4 and 2.7 on cowpea and soybean, respectively. In addition, the developmental period of C. maculatus on soybean was more titan double the period on cowpea; the developmental periods were 24.3±3.0 days and 58.5±1.0 days on cowpea and soybean, respectively. Furthermore, thenumbers of F1 and F2 adults from soybean were significantly fewer, smaller, and weighed less than those from cowpea. Significantly higher percent damage and weight 1055 were observed on cowpea; percent damage were 16.7±8.6 and 5,3±1.4 for cowpell and soybean, respectively for F1 and 66.7±4.9 and 7.5±1.0 for cowpea and soybean, respectively for F2 while weight losses were 1.33±0.5g and 0.08±0.5g for cowpea and soybean, respectiyely for F1 and 5.16±0.2g and 0.11±0.5g for cowpea and soybean, respectively for F2. The implications of these results on the sources of plant proteins in the tropics are discussed.