A comparison of effectiveness of plant-based and synthetic insecticides in the field management of pod and storage pests of cowpea

Optimal cowpea (Vigna unguiculata L. Walp) yields in Uganda are constrained by a complex of insect pests that attack and damage the crop both in the field and in storage. Insecticide application is one management option that can substantially reduce yield losses associated with these insect pest infestations. This study evaluated the effectiveness of two synthetic insecticides (cypermenthrin and fenitrothion) and three plant-based insecticides (aqueous extracts of tobacco, tagetes and tephrosia) for the control of Callosobruchus spp. field infestation, damage by pod flies, pod borers, and pod suckers. Whenever pest populations of pod flies, pod borers and pod bugs were high, cowpea sprayed with insecticides registered significantly lower damage than the unsprayed cowpea, with minor differences among the insecticides efficacy. Insecticide application did not significantly (P>0.05) reduce Callosobruchus spp. field infestation except during the first season of 2003. Damage by insect pests contributed to poor seed germination.