Weevil populations have increased exponentially each season since 2021, with entomologists describing it as an impactful pest.
Key Details
- A native insect, the bicoloured weevil, has been observed feeding on cotton plants in the Northern Territory since 2021.
- Populations have increased each season, appearing earlier and in larger numbers.
- The weevils cause damage when females lay eggs in bolls, leading to boll shedding and potential yield loss.
- The weevils have also been found in Queensland and Western Australia's Ord Irrigation Scheme, but not in the same numbers.
Background
- The bicoloured weevil is native to Australia and is distinct from the exotic cotton boll weevil from the Americas.
- No pesticides are currently registered specifically for this pest in cotton.
Current Status
- Approximately 6,000 hectares of cotton are planted in the Northern Territory this season, down from about 10,000 hectares last year.
- Harvest is expected to begin in late May.
- The NT Department of Agriculture and Fisheries is investigating future control options.
Statements
NT Department of Agriculture entomologist Simon Ong reported that weevil numbers have increased exponentially each season since 2021, describing it as an impactful pest.
"Growers are aware of the weevils and can sometimes control them when spraying for other pests." – Cotton Australia chief executive Adam Kay recommended an "alert but not alarmed" approach.
Mr. Ong advised growers to maintain good field hygiene between seasons, as ratoon cotton can support weevil populations.