Pyrethroid resistance of insect pests in oilseed rape in Germany since 2005
Pyrethroid resistant pollen beetles (Meligethes aeneus) are now widely distributed in Germany since the first resistant beetles were detected about 15 years ago. Over half (53%) of sensitive populations in biotests in 2005 had declined to 0% by 2011. Very clear resistance increased from 33% in 2005 to 100% in 2015. Monitoring of the other insect pests of oilseed rape in Germany showed no resistance yet in pest species including Ceutorhynchus napi and C. pallidactylus, Dasineura spp. and Phyllotreta spp., but resistance to pyrethroids has recently developed in C. obstrictus and Psylliodes chrysocephala. Resistance of both species has spread over many parts of Germany but resistance factors in laboratory biotests are far below resistance values known for M. aeneus.