The adult insects feed voraciously on the leaves, flowers and fruits. The beetle produces large holes in the plant tissues (between the veins), causing growth retardation and eventually death of the plant. The damage done to young seedlings is often devastating as it delays crop maturity. If flowers are affected, it will result in reduced fruit setting. The grubs of this pest remain in the soil and feed on roots and underground stem of the plants, which causes rotting and withering of the stems and roots. Adults feeding on seedlings may retard the development and even lead to death, thus resulting in bare patches in the field. Beetles sometimes aggregate and gnaw on the foliage of older plants. Flower parts can also suffer some damage, resulting in reduced fruit setting. Lower parts of young fruits show scars caused by adult feeding, enabling the invasion by rot causing micro-organisms.
Damage is caused by the grub as well as the adult beetle of Aulacophora foveicollis, which feed on the leaves, flowers and fruits. Full-grown larvae are usually creamy white and the size of a human fingernail. Eggs are usually oval, yellow and are laid singly or in clusters of 10 in moist soil at the depth of a human finger near the base of the plant. Adults are orange-red and the same size as a housefly. The larvae hatch after 1 or 2 weeks and attack the plant and its roots before going into the soil to pupate. Pupation takes place in an earthen cocoon from 7 to 17 days. Optimal environmental conditions for pupation are met when the temperature is 27-28°C.
Natural enemies attack the beetle, including members of the tachinid family and the reduviid Rhynocoris fuscipes. Mix half a cup of wood ash and half a cup of lime in 4 litres of water, and leave to stand for a few hours. Strain and test this mixture on a few infested plants before applying on your field. Apply the mixture as a foliar spray on your crop. Alternatively, you can use plant-derived products such as neem (NSKE 5%), derris or pyrethrum (add soap with it) @ 7-day interval. Apply Triciderma Trichoderma as seed and nursery treatment and Pseudomonas fluorescens as seed, nursery treatment and soil application. Use trap crops that were treated with a strong insecticidal spray to attract and kill the adult beetles.
Always consider an integrated approach with preventive measures together with biological treatments, if available. Deltamethrin @ 250 ml/acre can be used when 1 adult/10 plants is detected in the nursery. Synthetic pyrethroids are likely to be effective but are at the same time harmful to natural enemies. Use of trap crops that were treated with a strong insecticidal spray can attract and kill the adult beetles. Spray fenitrothion as soon as the pest is detected and repeat the process at 15 days interval.