Different methods of monitoring susceptibility of oilseed rape beetles to insecticides

The resistance of oilseed rape pollen beetles to lambda-cyhalothrin has increased in Germany over the period 2002 to 2007. Oilseed rape pollen beetles are very good at dispersing, therefore field results should always be compared with those of laboratory experiments. The response of oilseed rape pollen beetles to active substances may not be the same as that to formulated products. Bioassays in which beetles are exposed to insecticides on either complete inflorescences or flower buds give different results. It is evident that samples of the genus Meligethes collected in the field can include several different species. Monitoring for insecticide resistance should be done using only the true oilseed rape pollen beetle.