Shoot webbers and defoliating caterpillars

Shoot webbers and defoliating caterpillars

• O. exvinacea shoot damage .
• Bombotelia jacosatrix Guenee (Noctuidae: Lepidoptera),
• Orthaga exvinacea Hampson (Pyralidae: Lepidoptera) and
• Euthalia aconthea Moore (Nymphalidae) are the common defoliators in cashew.

Besides, the larvae of Spodoptera litura F., Helicoverpa armigera Hubner (Noctuidae: Lepidoptera) and bag worm, Dappula tertia Templeton (Psychidae: Lepidoptera) also defoliate cashew in certain pockets of India.

In few cashew pockets in Karnataka and Kerala, the caterpillars of Tassar silk moth (Antherea mylita Linnaeus) and Circula trifenestrata Helfer (Saturniidae: Lepidoptera) respectively, are sometimes noticed on cashew that defoliates voraciously.

Pest appearance:

Larvae of B. jacosatrix are greenish, stout, striped with reddish-brown spots. Adult is a medium sized stout moth, black coloured with white specks throughout.

Caterpillars of O. exvinacea are slender and pale-green with dark bands, remains inside the webs and moves vibrantly upon disturbance.

Eggs of E. aconthea are laid singly on leaves, greenish in colour and beautifully articulated. The larvae are spiny caterpillars, green in colour, lie along the midribs. Moth is big sized, bluish black in colour with white patches.

Symptoms of damage:

B. jacosatrix feeds the tender leaves from the margins. Early instars are gregarious and during the later stages they feed on the entire leaf, leaving behind only the midribs. During certain periods, it also feeds on inflorescences.

Caterpillars of O. exvinacea mostly attack young cashew plants, web together tender shoots and leaves, live within the webs and feed on the leaves. Several caterpillars are found in a single webbed-up cluster of leaves. Presence of silken webs reinforced with pieces of plant parts on terminal portions and blossoms as well as dried up appearance are the symptoms of its infestation.

In Kerala, stout reddish brown caterpillar of the wild silk moth C. trifenestrata occurs during September-October and causes severe defoliation. They feed voraciously for more than a month and pupate in golden yellow hairy-spiny silken cocoons which are found in masses inside group of leaves during November.

Similarly, A. mylitta occur on cashew in Karnataka and parts of Kerala during July-October causing defoliation.