Significant levels of resistance to pyrethroid insecticides have been detected in cabbage stem flea beetle populations in the UK this summer.
Rothamsted Research scientists Dr Steve Foster and Dr Martin Williamson have been testing adult beetles collected from oilseed rape, either at harvest or from seedlings this autumn, in order to monitor resistance levels to pyrethroid insecticide lambda-cyhalothrin.
Samples were sent in by growers and agronomists from 73 sites in England.
The data for this year are said to show significant levels of pyrethroid resistance in cabbage stem flea beetle, particularly in the south east of England.
Dr Foster says: "Growers who do not have access to neonicotinoid-treated seed are likely to encounter problems controlling cabbage stem flea beetle in areas where there is a high frequency of pyrethroid resistance.”
Widespread knockdown (kdr) resistance to pyrethroids was confirmed in 2014 following a screening programme funded as part of an AHDB Cereals and Oilseeds project.