Evaluation of resistance to black bean aphid (Aphis fabae) in selected varieties and mutant genotypes of common bean (Phaseolus vulgaris)

Common bean (Phaseolus vulgaris) is an important food crop across sub-Saharan Africa. In Zambia, actual common bean yields are typically lower than potential yields because of the impact of invertebrate pests and plant diseases. Black bean aphids (Aphis fabae) (Hemiptera: Aphididae) negatively impact bean productivity directly by ingesting plant assimilates and indirectly by vectoring diseases such as bean common mosaic virus. Current breeding programmes aim to develop bean cultivars with improved yield and tolerance to pests. The objective of this study was to screen five common bean varieties (Rozi Koko, Mwezi Moja, Majesty, KK25 and AO-1012-29-3A) and four mutation-derived genotypes (CA 3, CA 15, CA 24 and CA 38) for resistance to black bean aphid. Commercial bean cultivars such as Kabulangeti and Carioca (variety from which all mutants were derived) were used as controls for the selected varieties and mutant genotypes, respectively. Several parameters of aphid resistance traits were assessed. Deterrence to aphid was assessed by settling preference while physical barriers to aphid feeding were evaluated by nymph survival. Reduction in palatability of phloem sap was evaluated by nymph development and mean relative growth rate. Electrical penetration graph recordings of feeding behaviour were performed in order to localise aphid-resistant factors. Nymph development was significantly longer on AO-1012-29-3A compared to Kabulangeti despite the fact that there were significantly fewer glandular trichomes on this line. The variety AO-1012-29-3A can be used in genetic improvement of common bean for aphid resistance.