Resistance to Pyrethroids and DDT in a Field-Mixed Population of Argentinean Black Flies (Diptera: Simuliidae)

Abstract

Field-mixed populations of Simulium bonaerense (Coscarón & Wygodzinsky) and S. wolffhuegeli (Enderlein) from an agricultural region of northern Patagonia (Argentina) were tested for insecticide resistance. High levels of resistance at the LC50 were found toward DDT (59.2-fold) and the pyrethroids deltamethrin (90.0-fold), fenvalerate (88.2-fold) and cypermethrin (22.9-fold). There was no evidence of resistance to the organophosphates azinphosmethyl and malathion and the carbamates carbaryl and carbofuran. Even though further investigation is required to determine the mechanism of insecticide resistance, the current results are indicative of target site resistance by means of a kdr-like mechanism in the test insects.