Insect pest damage to leaves of cowpea (Vigna unguiculata L. Walp): comparative effects of aqueous extracts of Piper guineensis, Allium sativum and Myristica fragrans

Abstract

Utilization of plant extracts in pest management is a cheap, environmentally friendly alternative to chemical pesticides. This study was designed to investigate the effects of aqueous extracts of Piper guineensis, Allium sativum and Myristica fragrans on field insect pest damage to leaves of cowpea, prior to flowering. Ife brown cowpea seeds were cultivated on beds assigned to four treatment groups (including a control), in a completely randomized design. 200g/litre of each plant material was used to prepare the stock solution. Field application of extracts was done in the evenings, thrice a week for two months, and data on leaf parameters was collected monthly. Analysis of variance revealed significant differences between the treatment groups at 5% probability level. Only Piper guineensis treated cowpea plants had significantly higher total number of leaves and total leaf area than the control, as well as significantly lower number of damaged leaves, percentage leaf damage, and damaged leaf area, in both months. Piper guineensis was more effective in controlling insect pest damage to leaves of cowpea than Allium sativum and Myristica fragrans.