Eggplant Integrated Pest Management AN ECOLOGICAL GUIDE

__________________________________________________________________________________Major Eggplant Insect PestsEpilachna beetle: adult, pupa and larva (from: Kar et at, 1995, CARE Bangladesh)Life cycleThis insect continues its life cycle throughout the year and has 4 to 5 generations per year.Eggs are pale yellow, elongate-oval and are 0.5 mm long. The eggs are laid in clusters, usually on theunderside of the leaves and placed vertically. Each female lays on average 12 clusters, each with up to50 eggs. The egg stage lasts about 4 days in summer and 9 – 10 days in winter. The larva is sometimescalled a grub. Larval development takes about 2 weeks.Pupation generally takes place on the upper parts of the shoots and lower surface of the leaves. Thepupa is dark yellow.Host rangeMain hosts are cucurbits such as cucumber, melon and gourd and solanaceous crops like eggplant,tomato and potato. Alternative hosts may include maize, sorghum, millet, rice, wheat, cotton, sesame,lettuce, soybean, cowpea, beans.Plant damage and compensationBoth adults and larvae damage the leaves by eating the soft outertissue and leaving “windows” in the leaves. Leaf tissue is eatenbetween the veins, sometimes being completely stripped to themidrib. When leaves are damaged, less area is left for the energyproduction (photosynthesis). This results in weaker plants orproduction delay. In a heavy attack, young plants may be killed.Sometimes, holes are eaten in fruits.Epilachna beetles are very visible, easy to spot and damage is veryobvious. However, plants compensate for loss of leaf area byproducing new leaves. When plants are young, severe defoliationmay result in death of the plant or serious delay in production. Howmuch defoliation an eggplant can tolerate at a certain growth stagecan easily be tested in a small experiment. See section 4.5 and thereference to exercises below.Epilachna larvae feeding on leafEpilachna population dynamics, an exampleThe population dynamics of Epilachna vigintioctopunctata were studied on eggplants in Indonesia in1981-82. After planting, adult beetles soon colonized and reproduced massively, resulting in rapidpopulation growth for 1-2 months; thereafter, the population increase slowed down due to defoliation.Three to four months thereafter the plants recovered their leaves (compensation!), but leaf quality wasless suitable for the Epilachna beetle and, as a result, the population remained low during the rest ofthe study period.A life table showed that parasitism, and starvation by overcrowding, contributed most to mortality ofthe Epilachna beetles in the immature stages (Nakamura, 1988).77Eggplant Ecological Guide