ABSTRACT
The chapter presents pertinent information related to the whitefly’s bio-ecology and the nature and extent of the damage the insect causes. The eggs are stalked and laid on the undersurface of leaves. The egg is provided with a pedicel through which it attaches itself to the leaf surface. After the hatching of eggs within about a week, the crawlers move out of the egg, settle on a suitable spot, and remain sessile throughout their life till their emergence as adults. In this process, the insect passes through four instars in about two weeks. The 4th instar nymph is termed as a pseudo pupa or red-eye nymph. Additionally, the biology of whitefly is also discussed with relation to weather parameters. Being a poikilothermic animal, the profound influence of temperature on the life cycle of whitefly, Bemisia tabaci is evident. The ecological conditions were studied taking into consideration the profound influence of the changing weather. The two weather parameters, temperature, and relative humidity are discussed. Also, three more important species (Trialeurodes abutilonea, Trialeurodes vaporariorum, and Tetraleurodes perseae) are discussed in this chapter. The detailed information on the extent and nature of damage caused by the whitefly has also been presented. The insect sucks the sap and exudes a huge quantity of honeydew on the leaf, post which a black sooty mold develops which interferes in the photosynthetic activity of the plant. As a result, the plants becomes weak due to the draining of its sap and reduced photosynthesis. Recently, the immature ripening of tomato fruits due to the whitefly has also been reported. This is because the whitefly is a vector of several dreaded Geminiviruses in nature and is a limiting factor in the successful cultivation of many crops. The loss in yield due to insect pests is not that alarming in crops but the insect is much more important as a vector of viruses. The cent percent loss in some of the crops suffering from viral diseases has been common. Crop failures have also been reported at many locations. The premature boll opening in cotton (responsible for weak fiber and reduction in seed germination) has also become common due to whitefly-spread viruses.
