Insecticide resistance in house fly populations is a major problem faced by livestock producers worldwide. A survey of insecticide resistance levels and frequencies of pyrethroid resistance alleles in the United States was conducted in 2008-09, but little is known about how resistance levels have changed over the last 10 years. In addition, new <i>voltage-sensitive sodium channel</i> resistance alleles that confer high levels of resistance have been recently identified, and their frequencies in field populations are unknown. Our aim in this study was to reassess the resistance status of house flies from select locations in the United States by examining resistance levels and frequencies of known resistance alleles. House flies were collected from animal production facilities in five different states between 2016 and 2018. Resistance levels to three three classes of insecticides (pyrethroids, organophosphates and carbamates) varied geographically. The recently identified <i>1B</i> pyrethroid resistance allele increased dramatically in frequency compared to previous reports, most notably in populations from Kansas and Maryland, indicating that it may already be widespread around the United States. Based on comparison with historical data, the population collected from Kansas represents one of the most highly permethrin resistant strains ever collected. If the alleles responsible for this level of resistance spread, pyrethroids may be of limited use for house fly control in the United States in the near future.

Will resistance render pyrethroids ineffective for house fly control in the near future?

2019 Fall National Meeting

The official archive and repository for all ACS Meetings & Expositions abstracts and select posters or presentations.