Gn. Mbata, EVALUATION OF SUSCEPTIBILITY OF VARIETIES OF COWPEA TO CALLOSOBRUCHUS-MACULATUS (F) AND CALLOSOBRUCHUS-SUBINNOTATUS (PIC) (COLEOPTERA, BRUCHIDAE), Journal of Stored Products Research, 29(3), 1993, pp. 207-213
Twenty-six varieties of cowpea some of which are among those distribut
ed for international trials by the International Institute of Tropical
Agriculture (IITA), Ibadan, Nigeria were evaluated in comparison with
Ife Brown, a known susceptible variety, for susceptibility to Calloso
bruchus maculatus (F.) and Callosobruchus subinnotatus (Pic.). The mos
t susceptible varieties to C. maculatus were TVu 310, TVu 2896, TVu 99
44 and TVu 9836. Some varieties were found to be moderately susceptibl
e to C subinnotatus and these included TVu 18, TVu 36, TVu 2896 and IT
81D-1020. Most varieties were found to be more susceptible to C. macul
atus than to C subinnotatus. However, the median developmental periods
of the bruchids on the cowpea varieties were comparable in most cases
. Some varieties were found to be consistently less susceptible to att
ack by the two bruchids and these included TVu 2027, IT81D-1064, IT81D
-1157 and IT86-498. The weight losses due to infestation by the bruchi
ds correlated very strongly to the susceptibility indices (SI) of the
varieties to the bruchids. The losses in weight caused by C. subinnota
tus were comparable with those caused by C. maculatus even though the
number of F1 adults of C. maculatus that emerged from the varieties wa
s higher than those of C. subinnotatus.