Urgent research to understand the nature and extent of insecticide resistance in an increasingly damaging pest of peas and beans is underway at Rothamsted Research.
The work is in response to reports of failure to control the pea and bean weevil (Sitona lineatus) with pyrethroid sprays, which are a special chemical class of active ingredients found in many modern insecticides used by growers.
Rothamsted’s Dr Steve Foster has tested samples collected recently from Hertfordshire, Lincolnshire, Northamptonshire, Nottinghamshire and Warwickshire. He has found they contain adult weevils that are resistant to a representative pyrethroid when it is applied at a similar dose to that which is used in the field.
Dr Foster said: “The next step is to find and understand the cause of this resistance which is likely to exist in other pyrethroid insecticides used. In the meantime, growers should be aware that treatment with these compounds against this pest may not be effective.”