RESISTANCE IN GERMAN HOUSEFLY POPULATIONS (MUSCA DOMESTICA L., DIPTERA) -SUMMARY OF RECENT STUDIES

Abstract:
The housefly Musca domestica L. belongs to the most important hygiene pests world-wide - especially in livestock. Due to its fast development and high reproductive rate the housefly has developed severe resistance against commonly used insecticides. Sometimes resistance problems against new active ingredients occur even after the first treatment because of cross resistance to previously used insecticides. Populations of the housefly Musca domestica L. were collected from farms in different German districts with severe resistance problems and compared to laboratory populations with different resistance spectra. Their resistance, in comparison to a susceptible housefly strain (origin WHO), against pyrethroids, organophosphates and carbamates was determined using impregnated filter papers and by topical application . Different groups of insect growth regulators (juvenile hormone analogues, chitin synthesis inhibitors and triazine derivatives) were tested in a special larvicidal test. Additionally, the insecticides were combined with different synergists (e.g. piperonyl butoxide, a mixed function oxidase inhibitor and S,S,S.- tributyl phosphorotrithioate (DEF), an esterase inhibitor) in order to evaluate relevant detoxification mechanisms. The results were incorporated into fly control programmes, taking into account the different resistance spectra and existing fly control strategies, especially for animal production. Increasing resistance to insect growth regulators indicates that not only adulticides but also larvicides should be utilised in a rotation programme.