Bioactivity of Selected Plant Parts in the Control of Cowpea Bruchid (Callosobruchus maculatus L.) on Stored Cowpea (Vigna unguiculata L. Walp.)

Abstract

Cowpea bruchid (Callosobruchus maculatus) is a very serious primary pest of stored cowpea grains with 30 – 100% loss potential. This study is therefore aimed at evaluating the efficiency of some plants in the management of the bruchid. The treatments evaluated were pulverized (dusts) eucalyptus leaves - Eucalyptus globulus Lab., neem leaves – Azadirachta indica A. Juss., neem stem bark, neem seed kernel, ginger rhizome – Zingiber officinale Rosc., pawpaw leaves – Carica papaya L. (all at 2 g/kg of seeds), and control (untreated). The experiment was laid out in a Completely Randomized Design (CRD) with three replicates. Data collected included mortality of adult insects, number of eggs laid, grain damage, grain weight loss, and germination percentage on SAMPEA-11 infested seeds. Data were analyzed using Analysis of Variance (ANOVA), and significantly different means were separated using Duncan’s New Multiple Range Test (DNMRT) at p ≤ 0.05. Results indicated that neem seed kernel followed by eucalyptus leaves dusts effected the highest mortality rate throughout the assessment period. The control (untreated seeds) had the highest number of F1 progeny produced (84.7±6.0), seed damage (92.8%±1.4), and grain weight loss (33.4±0.3%). Neem seed kernel dust had the highest germination percentage (77.2%±3.3) followed by eucalyptus leaves dust (74.5%±1.7). The study showed therefore that the botanical dusts evaluated, particularly neem seed kernel and eucalyptus leaves dusts, had promising potentials in the control of C. maculatus in stored cowpea.