Insect Pests of Vegetable, Tuber and Spice Crops

Cabbage butterfly

2. Cabbage butterfly, Pieris brassicae (Pieridae: Lepidoptera)

Distribution: All over the world

Host range: Cabbage, cauliflower, knol khol, turnip, raddish, mustard, toria, etc.

Nature of damage:

• Young caterpillars feed gregariously and skeletonise leaves
• Late instars disperse and move to adjacent plants/ fields and feed on the leaves voraciously.
• Plants are sometimes completely defoliated resulting in heavy yield losses

Identification:

• Eggs: Yellow cylindrical eggs are laid in clusters of 50-90 on ventral surface of leaves
• Larvae: Pale yellow when young and become greenish yellow later on. The head is black and the dorsum is marked with black spots and short hairs.
• Adults: Butterflies are pale white having smoky shade on the dorsal side of the body. The wings are pale white with a black patch on the apical angle of each hind wing. The females measure about 6.5 cm across the wings and have two conspicuous black spots on the dorsal side of each fore wing. The males are smaller than females and have black spots on the underside of each fore wing.

Life cycle:

• Incubation period: 3-7 days.
• Larvae period: 15-20 days (summer) and 30-40 days (winter).
• Pre-pupal period : 1.5-2
• Pupal periods : 8-10 days
• Adult longevity: 3-12 days.

Salient features:

• Eggs are laid in clusters of 50-90 on ventral surface of leaves.
• P. brassicae prefers clumped vegetation for oviposition
• Five larval instars.
• Pupate on the leaves and stems of the host.
• Temperature between 15 and 30 is ideal
• The pest remains active from October to April in plains and from May to September it breeds only in the mountains.

Management:

• Collection and destruction of the egg masses and early gregarious caterpillars
• NSKE @ 4.0 % and Bt @ 500g/ha are also effective.
• Need based spraying of the crop with insecticides like malathion (0.05%) or cypermethrin (0.01%).
• In nature, Cotesia glomerata has been reported as major mortality factor of this pest.