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ARS Home » Plains Area » Kerrville, Texas » Knipling-Bushland U.S. Livestock Insects Research Laboratory » LAPRU » Research » Publications at this Location » Publication #364620
Research Project: Cattle Fever Tick Control and Eradication

Location: Livestock Arthropod Pests Research

Title: Impacts of various long-term insecticide treatment regimes on skdr and kdr pyrethroid resistance alleles in horn fly field populations

Author
item DOMINGUES, LUISA - Department Of Energy
item Guerrero, Felicito
item FOIL, LANE - Louisiana State University

Submitted to: World Association for the Advancement of Veterinary Parasitologists
Publication Type: Abstract Only
Publication Acceptance Date: 6/21/2019
Publication Date: N/A
Citation: N/A

Interpretive Summary:

Technical Abstract: In a six-year study, we evaluated the effect of different control strategies on the incidence of the pyrethroid target site resistance alleles, superkdr (skdr) and kdr, at four field populations of Haematobia irritans irritans (Linnaeus, 1758) (Diptera: Muscidae) in Louisiana, USA. The continuous use of pyrethroid ear tags for six years (treatment 1) caused a significant increase in the resistance ratio to pyrethroids as well as the frequencies of both skdr and kdr resistance alleles (%R allele), mainly by increasing the frequency of the skdr-kdr SS-RR and SR-RR genotypes. At treatment 2 (use of pyrethroid ear tags for three consecutive years, followed by one year with no treatment, and followed by two years with organophosphate ear tags), the resistance ratio for pyrethroid was not significantly affected. The %R-skdr significantly dropped while the %R-kdr allele remained relatively high and stable at the conclusion of the six years of the study. Similarly, at treatment 3 (use of pyrethroid ear tags for three consecutive years, followed by one year with no treatment, and followed by two years with endosulfan ear tags), the %R-skdr significantly dropped while the %R-kdr allele remained relatively high and stable after the six years of the study. However, unlike treatment 2, treatment 3 resulted in a slight increase in resistance ratio to pyrethroids. In a mosaic, treatment 4, the resistance ratio for pyrethroids showed a 2.5-fold increase but the skdr-kdr genetic profiles did not change, as the %R alleles (skdr and kdr) remained low and stable through the six years. In treatments 2 and 3, where pyrethroids ear tags were used for the first three years, the percentage of the SR-RR genotype (skdr-kdr) significantly dropped, which was likely caused by overwintering fitness costs associated with the skdr allele and the RR-kdr genotype.