Infestation Patterns of The Cowpea Weevil and The Common Bean Weevil on Cowpea and Common Bean

Rebecca Thole, Swivia Hamabwe, Modreen Chinji, Isabel Mugovu, Kennedy Zimba and Kelvin Kamfwa*
Department of Plant Sciences, University of Zambia, Great East Road, P.O Box 32379, Lusaka Zambia
*Corresponding Author: Kelvin Kamfwa, Department of Plant Sciences, University of Zambia, Great East Road, P.O Box 32379, Lusaka Zambia.

Published: September 22, 2025

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Abstract  

Callosobruchus maculatus (CM) (Cowpea weevil) and Acanthoscelides obtectus (AO) (Common bean weevil) are major post-harvest pests of cowpea and common bean, respectively. The objective of this study was to investigate the infestation patterns of these two weevils on common bean and cowpea. Twenty-four cowpea and 14 common bean genotypes were evaluated for resistance to CM and AO in a laboratory at the University of Zambia. CM successfully infested and damaged seed of all 24 cowpea genotypes. However, CM laid eggs on common bean, but no larvae hatched  from the eggs, therefore, there was no seed damage. Significant variation was observed in the reaction of the 24 cowpea genotypes to infestation with AO. Of the 24, cowpea genotypes, 14 were resistant while ten were susceptible at 60 days post-infestation, demonstrating that AO successfully infested and damaged cowpea seed. However, the infestation and seed damage on cowpea by CM was more severe than by AO. The results of this study suggests that in common bean and cowpea production environments where both CM and AO are prevalent, the damage on cowpea is likely to be higher than on common bean because both CM and AO will damage cowpea while common bean may only be damaged by AO.

Keywords: Common bean weevil; cowpea weevil; common bean; cowpea; infestation

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