Frequency of kdr and kdr-his alleles in stable fly (Diptera: Muscidae) populations from the United States, Costa Rica, France, and Thailand

Authors: Olafson, Pia; KAUFMAN, PHILLIP - University Of Florida; DUVALLET, GERARD - University Of Montpellier; SOLORZANO, JOSE ARTURO - Costa Rica Institution; Taylor, David; TROUT FRYXELL, REBECCA - University Of Tennessee

Submitted to: Journal of Medical Entomology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 2/15/2019
Publication Date: 2/15/2019
Citation: Olafson, P.U., Kaufman, P.E., Duvallet, G., Solorzano, J., Taylor, D.B., Trout Fryxell, R. 2019. Frequency of kdr and kdr-his alleles in stable fly (Diptera: Muscidae) populations from the United States, Costa Rica, France, and Thailand. Journal of Medical Entomology. Vol 56(4):1145-1149. https://doi.org/10.1093/jme/tjz012.
DOI: https://doi.org/10.1093/jme/tjz012

Interpretive Summary: Anecdotal evidence of pyrethroid insecticide product failure for the control of stable fly populations in the US and worldwide prompted us to evaluate the frequency of the kdr-his allele, associated with permethrin resistance, in field collected individuals. The kdr-his allele was detected in stable flies from ten states in the US, as well as from Costa Rica and France (Toulouse). In Tennessee (Spring Hill), evidence of a shift in the kdr-his frequency over a three month period was reflective of a response to insecticidal pressure, and a high frequency of kdr-his from a region in Costa Rica experiencing product failure suggests the allele may contribute to this phenotype. Resistance to permethrin at two sites in California and one site in New York did not appear to strictly associate with frequency of the kdr-his allele, suggesting there may be additional resistance mechanisms accounting for the phenotype in these states. Given the expansive cytochrome P450 gene family in stable flies, metabolic detoxification mechanisms will be of interest in future studies. The kdr allele was detected for the first time in stable flies originating in France and Thailand, and an improved, DNA-based diagnostic assay was developed to further screen for kdr and kdr-his allele frequencies in field collections. Absence of kdr in US populations suggests the allele is currently restricted to Europe and Asia.

Technical Abstract: Anecdotal evidence of pyrethroid insecticide product failure for the control of stable fly populations in the US and worldwide prompted us to evaluate the frequency of the kdr-his allele, associated with permethrin resistance, in field collected individuals. The kdr-his allele was detected in stable flies from ten states in the US, as well as from Costa Rica and France (Toulouse). In Tennessee (Spring Hill), evidence of a shift in the kdr-his frequency over a three month period was reflective of a response to insecticidal pressure, and a high frequency of kdr-his from a region in Costa Rica experiencing product failure suggests the allele may contribute to this phenotype. Resistance to permethrin at two sites in California and one site in New York did not appear to strictly associate with frequency of the kdr-his allele, suggesting there may be additional resistance mechanisms accounting for the phenotype in these states. Given the expansive cytochrome P450 gene family in stable flies, metabolic detoxification mechanisms will be of interest in future studies. The kdr allele was detected for the first time in stable flies originating in France and Thailand, and an improved, DNA-based diagnostic assay was developed to further screen for kdr and kdr-his allele frequencies in field collections. Absence of kdr in US populations suggests the allele is currently restricted to Europe and Asia.