Leaf Eating Beetle
Both adults and larvae feed on the leaves and can cause serious damage. Feeding damage of the green tissue between the leaf veins is the initial symptom. Later, a characteristic pattern of damage called skeletonization occurs whereby only the hard parts of the leaves (main veins and petioles) are left. There may be shallow holes on fruit surfaces, too. Seedlings can be destroyed and the growth of more mature plants can be stunted. The pest can lead to heavy defoliation and high yield loss and is therefore one of the most dangerous eggplant pests.
The adults are oval, dull orange in color with 28 black spots and short soft hairs on the back. The female beetle lays oval, yellow eggs (0.4-1 mm) upright and in small groups usually on the lower side of the leaves. After about 4 days the pale yellow-whitish larvae with long, dark-tipped split spines on the backs hatch. The larvae grow to about 6 mm within about 18 days, depending on temperature. They then move to the underside of the leaves and pupate. After an additional 4 days, the new generation of adult beetles emerges from the cocoons. During the reproduction period (March-October), cooler temperatures favor lifecycle and population growth. The beetles can overwinter in the soil and in piles of dry leaves.
Parasitoid wasps of the Pediobius family can be used to control the pest. These wasps also attack beneficial ladybirds, so it is important to identify the pest carefully before using them. Pathogenic microorganism can help to control the population of leaf eating beetle, too. Biopesticides containing the bacterium Bacillus thurengiensis or the fungus Aspergillus spp. can be used as foliar spray applications. Leaf extracts of Ricinus communis (castor oil), Calotropis procera and Datura innoxia can be sprayed foliarly. Applying ash can effectively reduce the infestation in early stages.
Always consider an integrated approach first. If insecticides are needed, products containing dimethoate, fenvelarate, quinalphos, chloropyriphos, malathion, fenitrothion can be applied on the foliage.