• Aphid, winged formAphid, winged form
  • “Aphids are vectors of more than half of all economically important plant viruses”

Aphids are a major threat to global agriculture; they feed on economically important grain, pasture and horticultural crops, causing physical damage and economic losses. They are the largest group of insects that feed on sap from plant phloem, and can severely affect the growth of many host plants resulting in shoot distortion, stunting, loss of vigour, reduction in photosynthesis and reduction of crop yield and quality. These sucking pests are also vectors of more than half of all economically important plant viruses. The virus diseases they transmit compound the losses they cause by feeding.

Strategies employed to control damage caused by aphids include planting resistant varieties of crops, if available, and the application of insecticides (often in conjunction with aphid forecasting data). Although chemical insecticides may provide considerable control, they can be expensive and are not environmentally friendly. It is also well documented that insecticide-resistant phenotypes occur (eg to carbamates, organophosphates, cyclodienes, chlorinated hydrocarbons and pyrethroid insecticides). Genetically modified crop plants expressing a crystalline bacterial protein, Cry toxin, derived from Bacillus thuringiensis (Bt) have been widely deployed, but this strategy is only effective against chewing insects.

There is considerable market demand for new approaches to controlling aphids and the use of RNAi technology opens the door to developing novel and robust forms of genetic resistance.