Eggplant Integrated Pest Management AN ECOLOGICAL GUIDE

__________________________________________________________________________________Major Eggplant Insect Pests5.8 Whitefly - Bemisia tabaciBemisia tabaci is a very common species of whitefly. However, there are several other species ofwhitefly, for example Aleurodicus dispersus (spiraling whitefly), and Trialeurodes vaporariorum (commonwhitefly).Other common names: tobacco whitefly, cotton whitefly or sweet potato whitefly.Description and life cycleThe adult whitefly is very small: about 1 mm long, silvery-white in color and withwings of a waxy texture. It is found often on the underside of the foliage where itsucks the plant sap.When a plant containing whiteflies is shaken, a cloud of tiny insects flutter out butrapidly resettle. The adult has 4 wings and is covered with a white, waxy bloom.Adults can fly for only short distances but may be dispersed over large areas by wind.Females usually lay their first eggs on the lower surface of the leaf on which theyemerged, but soon move upwards to young leaves. The female may lay 100 or moreeggs. The egg is pear-shaped and about 0.2 mm long. It stands upright on the leaf.The eggs are anchored by a stalk which penetrates the leaf through a small holemade by the female. Water can pass from the leaf into the egg, and during dryperiods when there are high numbers of eggs, the plant may become water-stressed.Adult whitefly(from: Kerruishet al, 1994)Eggs are white when first laid but later turn brown. Early in the season, eggs are laid singly but later theyare laid in groups. They hatch in about 7 days.When the nymphs hatch they only move a very short distance before settling down again and starting tofeed. Once a feeding site is selected the nymphs do not move. All the nymphal instars are greenishwhite,oval and scale-like. The last instar (the so-called “pupa”) is about 0.7 mm long and the red eyes ofthe adult can be seen through its transparent back. The total nymphal period lasts 2 - 4 weeks dependingon temperature. Nymphs complete 3 moulds before pupation.(from: Kerruish et al, 1994)Eggs and early instar nymphs are found on the young leaves and larger nymphs are usually morenumerous on older leaves.Attacks are common during the dry season. Whiteflies disappear rapidly with the onset of rain.Host rangeWhitefly species currently are known to attack over 500 species of plants representing 74 plant families.They have been a particular problem on members of the squash family (squash, melons, cucumbers,pumpkins), tomato family (tomato, eggplant, potato), cotton family (cotton, okra, hibiscus), bean family(beans, soybean, peanuts), and many ornamental plants.Plant damage and plant compensationDirect crop damage occurs when whiteflies suck juices from the plant. With high populations plants maywilt, turn yellow and die.91Eggplant Ecological Guide