Occurence of pyrethroid resistant pollen beetle (Meligethes spp.) in Croatian oilseed rape (Brassica napus L.) crops

Repičin sjajnik (Meligethes spp.) najvažniji štetnik je uljane repice. Oštećuje cvjetne pupove dok su još zatvoreni i pokriveni lišćem. Ponovljena sjetva uljane repice na istim parcelama ili blizu njezinih prošlogodišnjih parcela i sjetva na velikim površinama svake godine povećala je populaciju repičinoga sjajnika. Zbog česte uporabe piretroida tijekom zadnjih desetak godina zabilježena je rezistentnost repičinoga sjajnika na djelatne tvari iz te skupine insekticida. Odrasli oblici repičinoga sjajnika skupljani su u usjevu uljane repice tijekom 2007. i 2008. na lokalitetima Županja, Komarnica i Kutina. Prema IRAC test metodama br. 011 i br. 025 rabljene su djelatne tvari lambda-cihalotrin kao standardni test te alfa-cipermetrin i klorpirifos-metil kao alternativne djelatne tvari. Rezultati pokazuju da su sve tri testirane populacije repičinog sjajnika umjereno rezistentne do rezistentne na djelatnu tvar lambda-cihalotrin i djelomično rezistentne na djelatnu tvar alfa-cipermetrin iz skupine piretroida.Pollen beetle (Meligethes spp.), as one of the most important oilseed rape pests, damages flower buds while they are completely closed in tight raceme and covered by leaves. Successive sowing of oilseed rape on the same fields or close to last year\u27s fields and sowing on the great areas every year have contributed to the increase of the pollen beetle population. Due to frequent use of pyrethroids for pollen beetle control in the last decade, the resistance of pollen beetle to this group of insecticides was confirmed. Adult forms of pollen beetle were collected from oilseed rape fields in 2007 and 2008 at Zupanja, Komarnica and Kutina. In a laboratory experiment, according to IRAC Susceptibility Test Methods No: 011 and 025, active ingredient lambda - cyhalothrin as standard test and alpha - cypermethrin and chlorpyrifos methyl as alternative active ingredients were used. Results show that all of three tested Croatian populations of pollen beetle are moderately resistant to resistant to the pyrethroid lambda-cyhalothrin and partly resistant to the pyrethroid alpha¬cypermethrin