Efficacy of onion (Allium cepa) extracts on the black bean aphis (Aphis fabae) and red spider mite (T. evansi) on black nightshade (S. nigrum) cultivars when planted with different manure regimes

Abstract

Black nightshade, Solanum nigrum Linnaeus (Solanaceae), is a tropical plant used as a nutritive vegetable and herbal medicine, it expresses high levels of secondary metabolites such as steroidal glycoalkaloids and phytoalexins which offer protection against pests and microbial pathogens. However, pests such as the black bean aphid Aphis fabae (Homoptera, Aphididae) and the red spider mite Tetranychus evansi Linnaeus (Acarina, Tetranychidae) have become a major problem for improved S. nigrum Linnaeus cultivars, especially in regions such as western Kenya. The current research is aimed at developing an integrated pest management approach based on Allium cepa Linnaeus extracts and farmyard manures to control the aphid A. fabae Linnaeus and a mite T. evansi Linnaeus infesting improved S. nigrum Linnaeus cultivars in western Kenya. The experiment was a randomized block design. Data was analyzed using SAS version 9.1. Onion extracts reduced pest populations and cattle manure had significant positive effects.