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Cotton jassid (Amrasca biguttula biguttula)

The cotton jassid, Amrasca biguttula biguttula (Ishida), is a cicadellid leafhopper and one of the most damaging sap-feeders in Indian cotton. It is the principal component of the Sucking Pest Complex Cotton alongside whitefly, thrips and aphid.

Identification and symptoms

Adults are pale green wedge-shaped leafhoppers, 2.5-3 mm long, with two characteristic black spots on the forewings; nymphs are smaller, wingless and crawl sideways when disturbed. Feeding occurs on the underside of leaves with the insect inserting its stylet and injecting phytotoxic saliva. The characteristic injury — termed "hopper burn" — appears as downward leaf curl, marginal yellowing progressing to reddish-brown, and ultimately necrosis of leaf margins.

Host crops and life cycle

The jassid is polyphagous on Malvaceae and on okra (bhindi), brinjal, potato and cotton. Several generations occur each season with rapid build-up under warm humid conditions. The Bollgard-II trait (Bt Cotton Bg Ii) does not control it because the Cry toxins are active only on lepidopteran pests.

Damage and economic impact

Severe infestations cause leaf necrosis, reduced photosynthesis, premature defoliation and stunted plants. The TNAU/CICR economic threshold is 1-2 nymphs per leaf or first appearance of hopper-burn symptoms. Crop susceptibility correlates with leaf trichome density: glabrous (hairless) cotton genotypes are highly susceptible, while hirsute varieties show field tolerance. Varieties like Mahyco's Bahubali series (Mayko Bahubali Plus) are marketed with claimed sucking-pest tolerance.

Management

  • Cultural: choose hirsute genotypes; remove alternate-host weeds; avoid excess early nitrogen.
  • Biological: conserve coccinellid predators and Chrysoperla.
  • Chemical: at ETL, neonicotinoids (imidacloprid, thiamethoxam, acetamiprid) and methyl-O-demeton are widely used; flonicamid provides an alternative mode of action for resistance management.
  • Rotate modes of action to delay resistance.

See also Sucking Pest Complex Cotton, Whitefly In Cotton Chilli, Bt Cotton Bg Ii, Mayko Bahubali Plus.

References

  1. Cotton pests. TNAU Agritech Portal.
  2. Effects of plant morphology on sucking insect pests of cotton. ScienceDirect.