SUSCEPTIBILITY OF THE COLORADO POTATO BEETLE (LEPTINOTARSA DECEMLINEATA SAY, COLEOPTERA: CHRYSOMELIDAE) TO APPLIED INSECTICIDES IN THE REPUBLIC OF SERBIA

In the locality of Dobanovci (Belgrade), several years of research (1992 – 1995) under field conditions showed the decreasing mortality of L. decemlineata Say. to be a result of the use of insecticides from the group of carabamates, pyrethroides and organophosphorous compounds. In the investigations under laboratory conditions with larvae (L₃), collected in the same locality and from Skela (Obrenovac) revealed significant changes in the L. decemlineata's susceptibility to insecticides from the mentioned chemical groups.

In 1995, also a susceptibility check with regard to carabamates, pyrethroides and organophosphorous compounds on the populations of the L. decemlineata from five different localities in Serbia (Dobanovci, Starcevo, Vršac, Sjenica and Ivanjica) was carried out. Very irregular changes in the susceptibility level of the L. decemlineata to the investigated insecticides were detected. The population from Starcevo manifested the highest resistance to carabamates (LC-50 for carbaril was 3200,4 ppm, for carbosulfan it was 11038 ppm). The resistance factor of this population for carabamates in relation to the population from Sjenica (the one most susceptible to carabamates) is 31.331, and for carbosulfan it is 144.361. The highest resistance to pyrethroides was displayed by the population from Ivanjica (LC-50 for cypermetrine is 38,3 ppm) with a resistance factor of 48.784 in relation to the population from Dobanovci. The population from Dobanovci was the most resistant to organophosphorous compounds (LC-50 for quinalphos 23.571 ppm) with a resistance factor 113.375 in relation to the population from Sjenica.