Whiteflies (Bemisia tabaci and Trialeurodes vaporariorum)
Whiteflies are important pests of beans. Both the larvae and the adults pierce and suck the sap from leaves, which may cause reduced plant growth, yellowing of leaves, and wilting of the plant when present in large numbers. They produce honeydew, which may lead to growth of sooty mould on leaves and pods. Heavy growth of sooty mould reduces photosynthesis affecting plant growth. French bean pods contaminated with sooty mould are unmarketable.
Control measures on beans are justified if large whitefly numbers attack the plants during the early stages of the crop. Whitefly infestations after the onset of flowering usually do not affect yield.
Adults are small (1-3 mm long), with two pairs of wings that are held roof-like over the body. They resemble very small moths.
- Conserve natural enemies. Parasitic wasps are very important for control of whiteflies.
- Whenever necessary spray crop with neem products. Neem-based pesticides are reported to inhibit growth and development of immature stages, and to reduce egg laying by adult whiteflies