Resistance of Meligethes aeneus to pyrethroids in Lithuania

The pollen beetle (Meligethes aeneus F.) is the most important pest in winter and spring oilseed rape crops in Lithuania. Laboratory experiments were conducted with the aim of testing the sensitivity of populations of pollen beetle, collected in different regions of Lithuania to different active substances of pyrethroids (lambda-cyhalothrin, alpha-cypermethrin, deltamethrin and tau-fluvalinate). During 2008-2010, 101 populations (46 collected from winter and 55 from spring oilseed rape fields) were tested. Many Lithuanian pollen beetle populations showed decreased susceptibility to lambda-cyhalothrin, alpha-cypermethrin, deltamethrin, especially those, collected from the Central agroecological zone, where winter and spring oilseed rape has been grown intensively for 20 years. Resistance of pollen beetle populations to tau-fluvalinate was lower. It was estimated that during 2008-2010 the sensitivity of pollen beetle to all active substances tested tended to decrease and resistance tended to increase.