Insect Pests of Vegetable, Tuber and Spice Crops

Cabbage Aphid

3. Cabbage aphid, Brevicoryne brassicae (Aphididae: Hemiptera)

Host range: All cruciferous crops

Nature of damage:

• Suck the cell sap from tender leaves/shoots
• Stunted growth and poor head formation.
• Under severe infestation the entire plant may dry up.
• When seedlings are infested they loose vigor, gets distorted and become unfit for transplanting.
• Excrete honeydew which attracts sooty mould and interferes with photosynthesis.
• If attack starts early, heavy losses can occur

Identification:

• Eggs: Pale-yellow with greenish tinge.
• Nymphs: 1-1.5 mm long and yellow green with light ash grey tinge.
• Adults: About 2 mm in length and ash grey in colour

Life cycle:

• Active from October to April
• In mid hills of HP it appears in the last week of January with peak during first week of April
• Reproduces through parthenogenetic vivipary however, during severe winter, sexual reproduction also occurs.
• Overcrowding coupled with high temperature and low humidity results in appearance of alates for migration.
• The nymphs mature in 10-15 days and immediately start laying
• There are 4 nymphal instars
• A single female can produce 40-45 young ones.
• Total life cycle is completed in 10-45 days
• Many generations in a year.

Management:

• Cut and destroy the infested leaves/ shoots mechanically as soon as the aphid attack appears.
• Spray of fine pulverized mica powder @ 0.2 per cent to repel the alates.
• Conventional insecticides like malathion (0.05%) or oxy- demeton methyl (0.025%) or dimethoate (0.03%).
• Predators like coccinellids, syrphids and chrysopids; and parasitoids like Aphidius spp also reduce the population.
• Cabbage cultivars like Red Drum Head and KK cross were moderately resistant to this aphid (Lal, 1991) and can be used.