Abstract

The potyviruses Bean common mosaic virus (BCMV) and bean common mosaic necrotic virus (BCMNV), and to a lesser extent cucumber mosaic virus (a cucumovirus) are major constraints to bean production in Africa. Beans are important because they can be inter-cropped with other crops saving on space and fertilizer due to their ability to fix nitrogen naturally. Nutritionally, beans also constitute a substantial part of the protein intake. Unfortunately, genetic options for virus control are limited because plants carrying a major dominantly inherited resistance gene to BCMV are susceptible to systemic necrosis induction by BCMNV , which is endemic in Africa. Recessive resistance genes are too strain-specific to provide broad resistance. BCMV and BCMNV are both transmitted by aphids. Aphid-transmitted viruses prove increasingly problematic due to the evolution of pesticide resistance in aphids and increases in the geographical range of aphids and the viruses they spread due to climate change. Previous studies with CMV , and the potyvirus potato virus Y (PVY) in model plants (tobacco and Arabidopsis thaliana) and crops (potato) have shown that virus infection affects aphid behaviour by altering the attractiveness of the plant host. Based on the results and the techniques developed from these studies we shall seek to understand more about how BCMV , BCMNV and CMV influence bean-aphid interactions. I present preliminary data on free choice experiments carried out using a bean specialist aphid (Aphis fabae) and a generalist (Myzus persicae) on BCMV and, BCMNV infected beans and this how affects aphid behaviour.