East Anglia's oilseed rape growers have been asked to submit live samples of cabbage stem flea beetles (CSFB) so the damaging crop pests can be tested for resistance to insecticides.
The monitoring work funded by the AHDB (Agriculture and Horticulture Development Board) has tracked the rise of beetles with resistance to pyrethroid insecticides over the last few years.
The pest was previously controlled with neonicotinoid seed treatments before the controversial chemicals were banned by the EU due to concerns over their impact on the health of bees.
The AHDB is looking for beetle samples with suspected resistance to pyrethroid insecticides from across the UK's winter oilseed rape production area.
It says the screening evidence assessed so far reinforces the point that any decision to apply pyrethroid insecticides must be based on risk. If a pyrethroid application is deemed necessary, full recommended field rates should be used.
If the application is not effective and cannot be explained by factors, such as poor spray coverage, then it is likely that the population is resistant. In such cases, further pyrethroids should not be applied.
• For more details and sampling guidelines, see the AHDB website.
• The AHDB is also asking farmers to guide investment in pest monitoring services over the next five years by completing a short survey, which closes on November 30.
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