INSECT AND MITE PESTS - WHITEFLY

Whitefly - Trialeurodes vaporariorum (Greenhouse whitefly), Bemisia tabaci (Genn.) (Sweet Potato whitefly)

• Appearance: (Insect) Both are white in color. Trialeurodes holds its wings out giving it more of a triangular shape, whereas Bemisia appears more linear.

• Life cycle: Essentially 7 stages: Egg: on a stalk on the leaf underside, sometimes with several in a circle. 4 larval stages: initially with legs, but lose their legs after they pierce the leaf tissue and begin to feed. Pupal (or false pupa) stage: sedentary stage; adult red eye color appears. Adult: emerges from the pupa. This stage also feeds.

• Damage: Larvae and adults pierce and suck juices from plant cells causing reduced photosynthesis and growth, leaf drop and reduced harvest. Larvae and adults excrete honeydew onto leaves and fruit. Molds colonize the honeydew reducing photosynthesis and transpiration on leaves and leaving sticky, “dirty” deposits on fruit (unmarketable).Both whiteflies have been shown to transmit viruses (see Viruses below).

• Control/Natural enemies: Parasitic wasps: An egg is laid in the whitefly larvae (3rd or young 4th stages preferred). The egg hatches and the wasp larvae devours the whitefly larvae, then uses the host’s shell to develop to adult which emerges through a small round hole in the host’s shell. The wasp Encarsia formosa prefers the whitefly Trialeurodes. Upon entry the wasp larvae turns the w.f. pupa black. The wasp Eretmocerus eremicus prefers the whitefly Bemisia. Upon entry the wasp larvae turns the w.f. pupa golden. Verticillium lecanii: A fungus that parasitizes and ultimately kills whitefly