Physical and Biochemical Basis of Resistance in Some Cowpea Varieties against Callosobruchus maculatus (F.)

Abstract

Four varieties of the cowpea seeds (Local, Dokki331, Kareem7 and Aswany) were screened for their resistance to the bruchid, Callosobruchus maculatus F., a serious pest of stored pulses. Morphological characters like seed coat texture, volume and weight, were not found to be responsible for offering resistance to C. maculatus. Data revealed that the female weevil preferred the smooth surface for egg oviposition. The results also showed that Aswany was found to reduce the growth and development of C. maculatus, which were indicated by different parameters; larval penetration %, adult emergence %, total developmental time, susceptibility index and growth index. Seeds were analysed for protein profiles (SDS-polyacrylamide gel electrophoresis) to study the chemical basis of resistant to bruchid infestation. A negative correlation was indicated between the seed total protein content and the susceptibility index. SDS-PAGE analysis of seeds protein for the fore mentioned varieties revealed the presence of antinutrient chemicals that might impart resistance to C. maculatus. The role of these antinutritionals in relation to C. maculatus infestation is discussed.