Seeds of Neem Tree (Azadirachta indica A. Juss). Promising Biopesticide in the Management of Cowpea Insect Pests and Grain Yield in the Early Cropping Season at Asaba and Abraka, Delta State, Nigeria

Literature on the use of neem extract as biopesticide in the management of field insect pests on cowpea in Nigeria is scanty. The present study evaluated the efficacy of extract of neem seeds at 5 percent concentration for the control of the cowpea aphid, Aphis craccivora Koch, flower bud thrips, Megalurothrips sjostedti Tryb, legume pod borer, Maruca vitrata Fab, and a spectrum of pod sucking bugs (Coreidae bugs) all key field insect pests of cowpea. The experiments were conducted in the early cropping season in two locations – Asaba and Abraka, Delta State, Nigeria. At Asaba, the study took place in the Teaching and Research Farm of the Agronomy Department, Asaba Campus and at Abraka on a plot of land situated close to the Agricultural Sciences Department, Delta State University, Abraka. The experiments consisted of two calendar sprays – 7 days’ spray intervals at 5 times and 10 days’ spray intervals at 4 times and monitored spray and a control. There were 4 treatments and 3 replicates, organised into a randomised complete block design (RCBD). The results indicated that more insect pests occurred at Asaba than Abraka plot. The calendared spray treatments significantly (P<0.05) reduced M. sjostedti at Asaba and A. craccivora colonies at Abraka plot compared to control. Grain yield was significantly higher at Abraka (1630.70kg ha-1) compared to Asaba (404.90 kg ha-1). The neem seed extract at 5 percent concentration in the management of the cowpea insect pest is quite attractive. However, the botanical causes delay in cowpea flowering.