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Title: Simultaneous detection of Pyrethroid, Organophosphate and Cyclodiene target site resistance in Haematobia irritans (Diptera: Muscidae) by multiplex Polymerase chain reaction

Author
item DOMINGUES, LUISA - Louisiana State University Agcenter
item Guerrero, Felicito
item FOIL, LANE - Louisiana State University Agcenter

Submitted to: Journal of Medical Entomology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 7/14/2014
Publication Date: 9/2/2014
Citation: Domingues, L.N., Guerrero, F., Foil, L.D. 2014. Simultaneous detection of pyrethroid, organophosphate and cyclodiene target site resistance in Haematobia irritans (Diptera: Muscidae) by multiplex polymerase chain reaction. Journal of Medical Entomology. 51(5):964-970.

Interpretive Summary: The horn fly, Haematobia irritans irritans, is an important pest that causes significant economic losses to the livestock industry, but insecticide resistance in horn fly populations has made horn fly control increasingly difficult to achieve. In this study, we developed a DNA-based assay to simultaneously detect the most serious types of insecticide resistance found in horn fly populations, target site resistance. Our assay detects individual gene mutations that cause resistance to pyrethroids, organophosphates and cyclodienes. We used the assay to follow the progression of these resistance-causing gene mutations after exposure to different insecticide pressure. We assayed flies collected at the Macon Ridge research station, Winnsboro, Louisiana, from 2008 to 2012. The pyrethroid resistance-causing mutation remained at high frequencies during all years, even after 4 years with no use of pyrethroids. The organophosphate resistance-causing mutation fluctuated from 7.5% to 23.8% during the studied years while the cyclodiene resistance-causing mutation was rare in 2008, 2009 and June 2010 and then significantly increased after the first use of endosulfan. The possibility of screening for all the known target site resistance mutations in a single DNA assay makes this assay a useful and affordable tool that can be used to help diagnose and manage insecticide resistance in horn flies.

Technical Abstract: The horn fly, Haematobia irritans irritans (Linnaeus, 1758), is an important pest that causes significant economic losses to the livestock industry, but insecticide resistance in horn fly populations has made horn fly control increasingly difficult to achieve. In this study, we developed a multiplex PCR assay to simultaneously detect target site resistance to pyrethroids (kdr mutation), organophosphates (G262A AChE mutation) and cyclodienes (Rdl mutation) and used the new procedure to follow the progression of these three mutations after exposure to different insecticide pressure. We assayed flies collected at the Macon Ridge research station, Winnsboro, Louisiana, from 2008 to 2012. The multiplex PCR showed robust results in all our assays. The kdr mutation remained at high frequencies during all years, even after 4 years with no use of pyrethroids. The G262A AChE mutation fluctuated from 7.5% to 23.8% during the studied years while the Rdl mutation was rare in 2008, 2009 and June 2010 and then significantly increased after the first use of endosulfan. The possibility of screening for all the known target site resistance mutations in a single PCR reaction makes the multiplex PCR a useful and affordable tool that can be used to help diagnose insecticide resistance.