Resistance of Colorado potato beetle to insecticides of different groups in Koprivnica-Križevci and Međimurje county

Najznačajnijim štetnikom krumpira smatra se krumpirova zlatica koja je zbog intenzivnog suzbijanja razvila rezistentnost na 56 djelatnih tvari insekticida. Cilj istraživanja bio je utvrditi stanje rezistentnosti populacija zlatice sa šest lokacija iz Koprivničko-križevačke i Međimurske županije. Laboratorijskim testovima utvrđena je učinkovitost četiri doze pripravaka na osnovi djelatnih tvari klorpirifosa, cipermetrina, tiakloprida i spinosada nakon 48 sati te metaflumizona nakon 72 sata. Populacije su klasificirane u pet kategorija temeljem učinkovitosti preporučene doze pripravka kao visoko osjetljive, osjetljive, blago rezistentne, rezistentne i visoko rezistentne. Na klorpirifos je pet populacija bilo visoko rezistentno, a jedna blago rezistentna. Cipermetrin je bio učinkovit samo na jednoj lokaciji u Međimurskoj županiji, dok je na ostalima utvrđena rezistentnost. Tiakloprid je bio učinkovit na populacije s tri lokacije, no u svakoj županiji utvrđene su i rezistentne populacije. Metaflumizon se pokazao kao učinkovit u Koprivničko-križevačkoj županiji, gdje je samo jedna populacija bila blago rezistentna, dok je u Međimurskoj županiji imao slabiji učinak, jer su dvije populacije bile rezistentne do visoko rezistentne. Spinosad se pokazao kao najučinkovitiji insekticid za suzbijanje krumpirove zlatice: sve istraživane populacije zlatice bile su osjetljive do visoko osjetljive. Rezultati ukazuju da se stanje rezistentnosti na organofosforne insekticide i piretroide nije promijenilo zadnjih 30 godina, ali i da neke populacije postaju rezistentne i na novije insekticide, tiakloprid i metaflumizon. To pokazuje da zlatica relativno brzo postaje rezistentna, što u budućnosti može dovesti do proširenja rezistentnosti na druge insekticide istog ili sličnog mehanizma djelovanja, ali i na druga uzgojna područja krumpira, ukoliko se isti insekticidi budu intenzivno primjenjivali.The most important potato pest is Colorado potato beetle (CPB), which became resistant to 56 active substances due to intensive insecticide application. The aim of the study was to determine the resistance status of CPB populations from six locations from Koprivnica- Križevci and Međimurje counties. In laboratory tests, the efficacy of four different doses of chlorpyrifos, cypermethrin, thiacloprid and spinosad was determined after 48 hours and metaflumizone after 72 hours. Populations were classified into five categories based on the efficacy of the recommended dose of the preparation as highly sensitive, sensitive, mildly resistant, resistant and highly resistant. Five populations were highly resistant to chlorpyrifos and one was mildly resistant. Cypermethrin was effective in only one location within Međimurje County, while all other populations were resistant. Thiacloprid was effective on populations from three locations, but resistant populations were also found in each county. Metaflumizone proved to be very effective in the County of Koprivnica-Križevci, where only one population was mildly resistant, while in Međimurje County it had a weaker effect because two populations were resistant to highly resistant. Spinosad proved to be the most effective insecticide for the CPB control: all the populations studied were sensitive to highly sensitive. The results indicate that the resistance status to organophosphorus insecticides and pyrethroids has not changed in the last 30 years, but also that some populations are becoming more resistant to newer insecticides, thiacloprid and metaflumizone. This shows that CPB becomes resistant relatively quickly, which in the future may lead to an extension of resistance to other insecticides of the same or similar mechanism of action, as well as to other potato growing areas if the same insecticides are intensively applied