Mineral oils: Non-conventional chemicals in the control of insect pests and yield of cowpea (Vigna unguiculata (L) WALP) at Asaba and Abraka during the early season, Delta State, Nigeria

Abstract

Mineral oils are refined petroleum products. They have been employed as contact insecticides to control insect pests on various crops in many parts of the world. Three types – premium motor spirit (PMS), dual purpose kerosene (DPK) and automotive gas oil (AGO) at 0.4% were evaluated to assess their efficacy in the control of major insect pests of cowpea in two locations – Asaba and Abraka, Delta State. Influence of pest control on grain yield was also determined and comparison of the two agro-ecological zones in terms of insect species and yield was made. The study was conducted at both locations during the early cropping season (May – July) of 2005. The experiments were conducted at Asaba in the Teaching and Research Farm of the Agronomy Department, Delta State University while at Abraka on a piece of land about 100 metres to Campus 2 of Delta State University, Abraka. The experimental design was a randomised complete block design with five treatments and three replications. The results indicated that all the tested mineral oils effectively controlled M. sjostedti at 0.4% concentration. Similarly, M. vitrata was subdued by PMS and AGO at both locations. Grain yields were high in the two locations; however, Abraka yields were significantly (P<0.05) higher than Asaba. The present study provides the evidence that mineral oils are suitable bio-chemicals for cowpea insect pests control in Nigeria and should be tested further so that it could be incorporated into the pest management programme.