engleski

Resistance of the Colorado potato beetle to organophosphorus insecticides and pyrethroids in Croatia

Colorado potato beetle (CPB ; Leptinotarsa decemlineata, Say) is the most important potato pest in Croatia and worldwide and is resistant to 56 active ingredients of insecticides ; more than 300 cases of resistance are registered. During the 1990s, systemic monitoring of CPB resistance was conducted in Croatia. The appearance of resistance to organophosphates (OP) was shown after 16 years, and resistance to pyrethroids (P) after 7 years of their widespread use. Of current interest is whether populations from resistant locations are still resistant to OP and P insecticides. From 2017 - 2019, laboratory experiments were used to investigate the resistance of CPB to organophosphorus insecticides (chlorpyrifos) and pyrethroids (cypermethrine). Insecticide efficiency was determined in 27 populations of beetles collected from central and north-western Croatia. Efficiency of recommended dose, half and 1/5 of the dose were determined. Classification of populations was undertaken according to the IRAC method, no. 1132, where populations were classified into 5 categories on the basis of the efficiency of recommended dose determined 72 hours after treatment as: 1) highly susceptible (E = 100 %) ; 2) susceptible (100>E≥95 %) ; 3) slightly resistant (95>E≥90 %) ; 4) resistant (90>E ≥50 %) ; and 5) highly resistant (E<50). Results of the experiment showed that CPB resistance to OP and P insecticides has not changed in the last 25 years.

Colorado potato beetle, resistance, chlorpyrifos, cypermethrin

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