Development of resistance in field housefly (Musca domestica):: Comparison of effects of classic spray regimes versus integrated control methods

The development of resistance in the housefly (Musca domestica) to azamethiphos, pirimiphosmethyl, bendiocarb, permethrin, cypermethrin and deltamethrin was investigated on pig farms over a 4-year period. The results obtained in laboratory tests were compared with those obtained under practical conditions in pig houses. An intensive use of insecticides induced resistance in the course of 2 to 3 seasons. The classic spray regimes of insecticides led to the development of hi-h resistance after one or two seasons. Integrated control, based on rotational application - organophosphate, pyrethroid, carbamate, pyrethroid, organophosphate - retained the resistance at low to moderate levels. Because of the variability of resistance factor (RF) in the field populations observed, the monofactorial and rotational selective pressure of insecticides was investigated. The rotational application of azamethiphos and permethrin or cypermethrin having sufficient insecticidal effect retained the resistance at low to moderate levels over a 4-year period. Although the alternation of insecticides cannot prevent the development of resistance, it can extend several times the period of their successful application on farms. This knowledge can help to formulate the strategies for fly control programmes.