Breeding plants for resistance to aphid infestation

This chapter discusses the breeding of plants for resistance to aphid infestation. Aphids damage crops both directly by their feeding and by spreading viruses, and the relative importance of each has often been a source of friendly disagreement between entomologists and virologists. A single viruliferous aphid can, by infecting a plant, cause as much damage in one feed as is done during prolonged feeding by several non-viruliferous aphids, especially if the plant is very young. There is apparently tremendous potential for restricting virus spread by breeding aphid-resistant cultivars, but the realization of this potential depends on understanding how the plant host, aphid, and virus interact. Tolerance to large aphid populations may prevent aphid damage but not restrict virus spread. Increased mobility of aphids caused by host characters such as a repellent or poor nutritional status may provoke dispersal with consequent virus spread. Infestation by aphids and the subsequent infection of a crop by virus is a dynamic process that can be hampered, diverted, or stopped at various stages. There is opportunity to use accumulated knowledge to change the balance in the plant's favor and this requires the collaboration of various disciplines concerned with increasing agricultural output