|Geden, Christopher - Chris|
Submitted to: Pest Management Science
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 8/10/2009
Publication Date: 11/10/2009
Citation: Kaufman, P.E., Nunez, S., Mann, R.S., Geden, C.J., Scharf, M.E. 2009. Nicotinoid and pyrethroid insecticide Resistance in house Flies (Diptera: Muscidae) Collected from Florida dairies. Pest Management Science. 66:290-294. Interpretive Summary: House flies continue to major pests of livestock, poultry and humans throughout the world. Fly control is a difficult matter in part because of the rapidity with which house flies have developed resistance to insecticides that are used to control them. In recent years several new insecticides with novel modes of action have been introduced for fly control, yet some farmers have reported that these novel products are already showing decreased potency in the field. The purpose of this study, conducted by scientists at the University of Florida and ARS’s Center for Medical, Agricultural and Veterinary Entomology (Gainesville, Florida), was to document the status of resistance of house flies to pyrethroid insecticides (permethrin and betacyfluthrin) and to two recently-introduced products (imidacloprid and nithiazine). As expected, most of the fly populations tested showed moderate to high tolerance for pyrethroids, which have been a mainstay for fly control for many years. Resistance to imidacloprid was surprisingly high in many cases, probably due to the widespread popularity of sugar baits containing this insecticide. There was little evidence for resistance to nithiazine except on one of the farms. The results strongly suggest that farmers should rotate use of imidacloprid and nithiazine with other management methods in order to prevent resistance from reaching levels that would result in fly-control failures in the field.
Technical Abstract: The house fly, Musca domestica L., continues to be a major pest of confined livestock operations. House flies have developed resistance to most chemical classes and new chemistries for use in animal agriculture are increasingly slow to emerge. Five adult house fly strains from four Florida dairy farms were evaluated for resistance to four insecticides (betacyfluthrin, permethrin, imidacloprid and nithiazine). Significant levels of tolerance were found in most field strains to all insecticides, and in some cases, substantial resistance was apparent (as deduced based on comparison to prior published results). At the LC90 level, greater than 20-fold resistance was found in two of the fly strains for permethrin and one fly strain for imidacloprid. Betacyfluthrin LC90 resistance ratios exceeded 10-fold resistance in three fly strains. The relatively underutilized insecticide nithiazine had the lowest resistance ratios, however, 4-fold LC90 resistance was observed in one southern Florida fly strain. Farm insecticide use and its impact on resistance selection in Florida house fly populations are discussed. In conclusion, house fly resistance to pyrethroids is widespread in Florida. Imidacloprid resistance is emerging and tolerance was observed to both imidacloprid and nithiazine. If these insecticides are to retain efficacy, producer use must be restrained.