FIELD INFESTATION OF PIGEONPEA (CAJANUS-CAJAN (L.) MILLSP.) BY CALLOSOBRUCHUS-CHINENSIS (L.) IN UGANDA

Studies were conducted in Uganda to determine the importance of field infestation of pigeonpea by bruchids, and whether or not the susceptib ility of the pigeonpea pod to infestation changes during pod and seed development, A survey of farmers' fields in the major pigeonpea growin g areas in northern Uganda showed that bruchids did infest pigeonpea i n the field. In all three districts surveyed (Apae, Gulu and Lira), in festation levels were similar and by one species only, Callosobruchus chinensis, Once harvested, infestation of stored seeds was four times greater than stored pods. In a separate study, caged pigeonpea pods we re infested at seven different developmental stages by C. chinensis. T he number of eggs laid increased with development, from pod formation to the mature yellow stage, but declined thereafter. When pods were in cubated, there was no adult emergence from pods infested after they ha d matured and started to dry. The frequency of C, chinensis adult emer gence varied significantly over time; a bimodal frequency pattern of e mergence was observed from pods infested at mature green stage and, to a lesser extent at the preceding late pod filling state, suggesting t he occurrence of polymorphism. (C) 1998 Elsevier Science Ltd. All righ ts reserved.