Screening for resistance to cowpea aphids (Aphis craccivora Koch.) In mutation derived and cultivated cowpea (Vigna unguiculata L. Walp.) genotypes

Research studies aimed at screening cowpea genotypes against Aphis craccivora K. commonly known as black aphids, under the no-choice infestation condition, were conducted in the greenhouse at Natural Resource Development College (NRDC), Lusaka, Zambia in 2021. The main objective was to discern the cowpea genotype that is resistant to Aphis craccivora K that would aid the reduction of yield losses encountered in cowpea production. The most resistant genotype BBBT1-11 across all parameters investigated recorded an average aphid score of 1.0, compared to LT11-3-3-12 which recorded the highest score of 7.0. The aphid population build-up of BBBT1-11 was 1.0 compared to the highest recorded by LT11-5-1-1-4 at 3.54. The highest plant vigour of 3.0 was recorded by BBBT1-11, BB10-4-3-2, and LT11-5-1-1-4, and the lowest was recorded by Sanzi (1.2). BBBT1-11 recorded a survival percentage of 100% at 21DAI compared to the lowest recorded by TVu 2027 (20%). Mutant line BBBT1-11 emerged as a resistant genotype across all parameters tested including weight of seeds/plant and number of seeds/plant. BBBT1-11 could further be assessed for the possible presence of biochemicals and traits, that could explain the basis of the observed differences among the genotypes in their reaction to Aphis craccivora K. Besides, BBBT1-11 can also be incorporated in the breeding program with the target of breeding cowpea varieties that are resistant to aphid infestation to address the yield losses experienced in cowpea production as a result of A. craccivora K