Response of introduced cowpea breeding lines to bruchid Callosobruchus rhodesianus infestation in South Africa

To expedite the development of high yielding and pest resistant cowpea varieties in South Africa, elite cowpea lines were introduced and screened for bruchid resistance. This paper reports the response of cowpea breeding lines to bruchid infestation. Thirty-six elite cowpea breeding lines, with Ife-brown (susceptible check) and IT84S-2246 as resistance check, were screened in a laboratory trial at University of Limpopo using a completely randomized design (CRD) with six replications. Batches of ten seeds of each breeding line were artificially infested with 2 female and 2 male bruchids. Data were collected for a period of 45 days after infestation, and the variables include adult emergence, days to insect emergence, mean and total insect developmental time, seed damage, insect growth and susceptibility indices as well as seed weight loss. Data were collected between December 2013 to February 2014. Results showed significant reactions (P 40 days), susceptibility (<4.50) and seed damage (<60%) were designated as bruchid resistant. The varieties include, IT98K-690, IT86D-1010, IT99K-316-2, TVu 13464, Jana Fod and IT99K-494-6. These varieties were recommended for cultivation and breeding programmes in South Africa. The study also showed highly significant correlations between seed damage and other variables which could be used as criteria for selecting resistance of cowpea varieties to bruchid infestation.