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Sucking pest complex in cotton

The sucking-pest complex of cotton comprises sap-feeding insects whose feeding and virus transmission can cause substantial yield losses, particularly on Bt cotton, where the Bollgard-II trait provides no protection because the Cry toxins are active only on lepidopteran bollworms.

Identification and symptoms

The complex includes:

  • Jassid (leafhopper): Amrasca biguttula biguttula — downward leaf curl, marginal yellowing progressing to reddish-brown necrosis ("hopper burn"). See Jassid Leafhopper Cotton.
  • Whitefly: Bemisia tabaci — honeydew, sooty mould, vector of cotton leaf curl virus. See Whitefly In Cotton Chilli.
  • Thrips: Thrips tabaci — silvery streaks on leaves, deformed seedlings.
  • Aphid: Aphis gossypii — leaf curl, honeydew, sooty mould.

Host crops and life cycle

All four species are polyphagous on Malvaceae and on a wide range of vegetable hosts. Populations build rapidly under warm humid conditions in the kharif season. Because Bt Cotton Bg Ii does not control them, sucking pests have become disproportionately important on Indian Bt cotton.

Damage and economic impact

Beyond direct sap loss, the complex causes virus transmission — particularly cotton leaf curl virus by whitefly — and indirect yield loss through sooty-mould-coated leaves with reduced photosynthesis. Severe outbreaks can defoliate Bt cotton crops in the absence of intervention.

Management

ICAR-CICR's validated IPM package for the complex includes:

  • Cultural: timely sowing, removal of alternate-host weeds, balanced nutrition (avoiding excess early nitrogen), use of hirsute trichome-rich genotypes (e.g. Mayko Bahubali Plus is claimed to have sucking-pest tolerance), and adequate spacing for airflow.
  • Biological: conservation of Encarsia parasitoids (35-46% parasitisation of whitefly nymphs in CICR field studies), Chrysoperla predators, and coccinellid beetles.
  • Chemical: ETL-based sprays of imidacloprid, thiamethoxam, acetamiprid, flonicamid, diafenthiuron, pyriproxyfen or buprofezin, rotated by mode of action.
  • Foliar nutrition: potassium nitrate sprays to improve plant tolerance.

Validated IPM has reduced active-ingredient use by approximately 86% and the number of sprays by approximately 58% relative to farmer practice, with higher seed-cotton yields.

See also Jassid Leafhopper Cotton, Whitefly In Cotton Chilli, Bt Cotton Bg Ii, Mayko Bahubali Plus, Pink Bollworm.

References

  1. Sucking pest complex of cotton and their management. The Pharma Journal.
  2. Large-scale IPM validation in whitefly. ICAR Indian Journal of Agricultural Sciences.