The potentials of mineral oils for controlling the major insect pests of cowpea (Vigna unguiculata (L.) Walp in Asaba, Nigeria

Abstract

Three mineral oils - premium motor spirit (PMS), dual purpose kerosene (DPK) and automotive gas oil (AGO) at 0.4% concentration each, were evaluated for efficacy in the control of major insect pests and yield of cowpea. Insect pests studied were the cowpea aphid, Aphis craccivora Koch, legume bud thrips Megalurothrips sjostedti Tryb, legume pod borer, Maruca vitrata Fab. and pod sucking bugs. The trials were carried out in the teaching and research farms at the Agronomy department, Asaba Campus, Delta State University, Nigeria. The results showed that the tested mineral oils effectively controlled M. sjostedti damage and PMS and AGO controlled M. vitrata during the early season. In the late season study, DPK was effective against A. craccivora. All the tested mineral oils controlled pod sucking bugs. Moderate yields of 224.70 kg ha-1, 238.20 kg ha-1 and 397.00 kg ha-1 for PMS, DPK and AGO respectively were obtained in the early season. Yields in the late season were lower compared to early season yield. There was delay and reduced flowering of cowpea in the field with mineral oil application. The study provides the information that mineral oils can be reliable insecticides for cowpea growers if these factors - delay and reduction of flowering are removed, they could be new components in the overall management of cowpea pests in Nigeria.