Latest evidence in hunt for beetles’ resistance
- Credit: Eastern Daily Press © 2013
Latest research has suggested, as many oilseed rape growers feared, that resistance to pyrethroids in UK populations of cabbage stem flea beetle is widespread.
Following a pre-harvest call for suspected pyrethroid resistant beetle samples to be sent to Rothamsted Research for analysis, knock-down resistance (kdr) to pyrethroids has now been confirmed in every UK sample tested so far.
The HGCA is now calling for more growers and agronomists to send suspected resistant samples to Rothamsted Research to build an even more robust picture of resistance in the UK.
Caroline Nicholls, HGCA research and knowledge transfer manager, said: 'The researchers at Rothamsted developed a genetic test to look for the mutation associated with kdr resistance previously reported in Germany. The results found resistant beetles in all samples tested so far.
'This is a cause for concern as this type of resistance is likely to cause control problems with all pyrethroids applied at recommended field rates.'
You may also want to watch:
The frequency of resistant individuals has also been surprisingly high, according to the analysis.
This may in part be down to a potential bias caused by the fact samples were typically taken where resistance was suspected.
- 1 Body found in search for missing 87-year-old Margaret Smith
- 2 'I can't carry it' - Shock as plant starts growing eight inches a day
- 3 WATCH: 'Selfish' drug-driver ploughs into police detective's vehicle
- 4 Norfolk man who had sexual relationship with teen jailed
- 5 Two Norfolk businesses star in TV show
- 6 Fly-tipper travelled from Welsh border to dump in Norfolk
- 7 Aldi planning four new stores in Norfolk
- 8 The Range confirms new store at former Outfit on retail park
- 9 Funeral held for much loved windsurfer after body found in Sweden
- 10 Man charged with attempted murder after serious Norwich assault
Further to the genetic test, live beetles were also placed in glass vials coated with lambda-cyhalothrin, the pyrethroid which is found in a number of insecticides authorised for use in oilseed rape.
A range of doses, including the equivalent of recommended field rate, were tested. Once again, resistance was detected in all samples.
Researchers now need more adult beetle samples to continue their work.
'We have been contacted by a number of growers concerned about cabbage stem flea beetle in emerging oilseed rape crops wanting to send in samples for analysis,' said Miss Nicholls.
'Unfortunately, there isn't a tried-and-tested approach for collecting live samples in the field at this time of year.
'We found the best way to catch live beetles is to go out at night with a torch to find beetles. Once located, beetles can then be trapped using a jar.'
HGCA's revised cabbage stem flea beetle publication provides further information on assessing the need to spray larvae as well as adult beetles.