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Whitefly (Bemisia tabaci) in cotton and chilli

Bemisia tabaci is a polyphagous aleyrodid (whitefly) and one of the most economically important hemipteran pests of cotton and chilli in India. It is a key component of the Sucking Pest Complex Cotton and the principal vector of cotton leaf curl virus (CLCuV) and chilli leaf curl virus.

Identification and symptoms

Adults are small, 1-2 mm, with a yellow body and two pairs of white wax-dusted wings; they typically rest on the underside of leaves and fly up in clouds when disturbed. Nymphs and pseudopupae are flat, scale-like and translucent. Direct feeding causes leaf chlorosis, premature senescence and copious honeydew which is colonised by sooty mould fungi. Persistent, circulative transmission of Begomovirus species causes leaf curl, vein thickening and severe stunting in cotton and chilli.

Host crops and life cycle

The pest is polyphagous on Malvaceae, Solanaceae and many other families. Several overlapping generations occur each season; build-up is rapid under warm humid conditions. As with other sap-feeders, Bt Cotton Bg Ii does not control it because the Cry toxins target only lepidopterans, in contrast to the bollworm complex including Pink Bollworm.

Damage and economic impact

Beyond direct sap loss and honeydew/sooty-mould fouling, virus transmission is the principal economic concern. Cotton leaf curl virus epidemics — historically severe in the north-Indian cotton belt — and chilli leaf curl virus outbreaks in Telangana and Andhra Pradesh have caused severe yield losses. In chilli, whitefly-transmitted virus losses have been documented at very high levels in epidemic years.

Management

  • Cultural: avoid contiguous host crops, rogue out virus-symptomatic plants, manage alternate-host weeds, use yellow sticky traps for monitoring.
  • Biological: conserve Encarsia parasitoids and Chrysoperla predators.
  • Chemical: ETL-based sprays of insect growth regulators (pyriproxyfen, buprofezin), diafenthiuron, flonicamid or acetamiprid; rotate modes of action.
  • Resistance management: avoid back-to-back applications of the same chemistry; integrate with the IPM package for the broader sucking-pest complex.

See also Sucking Pest Complex Cotton, Jassid Leafhopper Cotton, Bt Cotton Bg Ii, Pink Bollworm.

References

  1. Whitefly Management Strategies for Sustainable Agriculture. MDPI Agriculture.
  2. Bemisia tabaci interaction with Cotton Leaf Curl Virus. Springer.