Hyptis suaveolens seed powder as a repellent against Callosobruchus maculatus (Coleoptera: Bruchidae) on cowpea

Hyptis suaveolens is a common weed that can be found growing on wasteland in The Gambia. It is traditionally used as a mosquito repellent in many homes in the rural areas and belongs to the Labiatae family, a rich source of compounds with anti-insect activity. In this study, the anti-insect activity of ground H. suaveolens seeds on the cowpea seed weevil Callosobruchus maculatus was investigated using a two choice ‘Y’ olfactometer. Six concentrations of 1, 2, 4, 6, 8, and 10% w/w were prepared. Ten adult insects of mixed sexes were released into the response chamber and each test was replicated eight times. A high repellency action of up to 80% was recorded on the highest concentration of 10% w/w when the weevils were allowed to choose between cowpea seeds treated with ground H. suaveolens seed powder and the untreated seeds which served as control. Results from this research strongly suggest that H. suaveolens seed powder can be used as a botanical pesticide to reduce C. maculatus infestation in storage. Since, it is easily available, farmers can make their own formulation at little or no cost.