RESISTANCE TO IVERMECTIN IN POPULATIONS OF MUSCA DOMESTICA (DIPTERA: MUSCIDAE) FROM POULTRY FARMS

ABSTRACT Larvicidal effect and resistance to ivermectin in 10 populations of Musca domestica from poultry farms was evaluated by concentration-response bioassays. For this purpose, the larval growth medium was treated with different concentrations of ivermectin (0.015, 0.03, 0.06, 0.125, 0.25 and 0.5 ppm). As a result, larvicidal activity of ivermectin was observed and some anomalies were detected in pupae. The population from Monte Mor, SP, was the most resistant to ivermectin (LC50 = 0.262 ppm and RF = 13.1). Fly populations from Campinas, SP (LC50 = 0.141 ppm and RF = 7.1), Promissão, SP (LC50 = 0.110 ppm and RF = 5.5), Santa Cruz da Conceição, SP (LC50 = 0.102 ppm and RF = 5.1), Holambra, SP (LC50 = 0.071 ppm and RF = 3.6) and Hortolândia, SP (LC50 = 0.068 ppm and RF = 3.4) were more resistant than the ones from Sumaré, SP (LC50 = 0.052 ppm and RF = 2.6), Sarapuí, SP (LC50 = 0.050 ppm and RF = 2.5), and Itanhandu, MG (LC50 = 0.047 ppm and RF = 2.4). The population most susceptible to ivermectin was that from Grande Porto Alegre, RS (LC50 = 0.020 ppm and RF = 1.0). The results indicate that ivermectin can be effective against larvae ofM. domestica. However, since resistance was suspected in some of the populations studied, it is important to carry out new studies in these places.