Eggplant Integrated Pest Management AN ECOLOGICAL GUIDE

__________________________________________________________________________________Major Eggplant Insect PestsThe insects can be found during the day at the base of the plant, on the underside of the leaves, at thesections with healthy tissue that border areas of brown or damaged tissue. Pupae are found in the soil.Thrips move frequently to new locations to make more feeding incisions. They fly weakly, but they maybe carried great distances on wind and air currents.Life cycleEggs are laid in notches of up to 100 eggs within the tissue of the leaves and stems of young plants.They are white, and take 4-10 days to hatch.Thrips develop through two nymphal instars, a prepupal form and one or two more or less immobilepupa-like stages. These developmental stages are of similar general appearance to the adults butwithout wings.Life cycle of thrips (from: Kerruish et al, 1994)Nymphs mould twice in about five days, they are white or yellow. The nymphs usually can be foundamong debris or in the surface layers of the soil before changing to prepupae. After about 2 days,prepupae change into pupae. These resting stages do not feed but are capable of slow movement inresponse to suitable stimuli e.g. they tend to avoid light. Pupation occurs in the soil, usually at the baseof the plant.The life-cycle spans about 3 weeks. There are generally several generations per year. Warm, dryweather favors thrips development.Host rangeThrips are polyphagous and have been recorded on more than 300 species of plants, includingwatermelon, muskmelon, bottle gourd, cucumber, chili pepper, tomato, eggplant and potato crops.Plant damage and compensationBoth nymphs and adults rasp the surface tissue of the leaves causing wounds from which flows the sapon which the thrips feeds. Damage is most obvious on the underside of the lower leaves, where areasappear brownish and dried up. Similar damage is seen along the mid-vein on the upper leaf surface.The leaves of attacked plants are silvered with blotches and may shrivel. Heavy attacks lead to stuntedleaf-growth, wilted shoots, reduced fruit size and in extreme cases, death of the plants. Fruits can bedamaged by small necrotic spots.87Eggplant Ecological Guide