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Title: Control of Culicoides Sonorensis (Diptera: Ceratopogonidae)blood feeding on sheep with long lasting repellent pesticides

item Reeves, Will
item Stith, Charles
item Miller, Myrna
item Bennett, Kristine
item JOHNSON, GREG - Montana State University

Submitted to: Journal of Economic Entomology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 5/1/2010
Publication Date: 9/1/2010
Citation: Reeves, W.K., Lloyd, J.E., Stobart, R., Stith, C.E., Miller, M.M., Bennett, K.E., Johnson, G. 2010. Control of Culicoides Sonorensis (Diptera: Ceratopogonidae)blood feeding on sheep with long lasting repellent pesticides. Journal of Economic Entomology. Vol 26:3, 302-305.

Interpretive Summary: Bluetongue disease is sporadic and unpredictable in the northern Rocky Mountains. Outbreaks can be separated by years of with little to no disease. Woolgrowers need access to control technologies that can be used after an outbreak is detected. We tested 6 formulations of midge repellent pesticides against Culicoides sonorensis, the primary vector of bluetongue in the western USA. Synthetic pyrethroids with PBO (a synergist) applied with both ear tags and a low volume spray were effective in repelling biting midges for up to 5 weeks. These pesticides are low cost and can be applied during an outbreak and might protect sheep during the autumn until freezing weather sets in and kills the biting midges.

Technical Abstract: Culicoides sonorensis is the primary vector of bluetongue and epizootic hemorrhagic disease viruses in North America. Bluetongue disease is considered one of the most economically important arthropod-borne diseases of sheep in North America because it causes significant morbidity and mortality and can lead to local and international trade restrictions and quarantines. In the northwestern USA, sheep are exposed to bites of C. sonorensis in the late summer and early fall when they move from mountain pastures to ranches at lower elevations. While at lower elevations, sheep are exposed to potentially infectious bites from vectors until the first killing frost. Long lasting repellent pesticides could be applied to sheep as they are moved down from mountain pastures to protect them from biting midges until the first frost. We tested long lasting pesticides on sheep as repellents against C. sonorensis. Both PYthon ear tags (Y-TEX) with 10% zeta-cypermethrin (9.8 g/tag) and 20% piperonyl butoxide (PBO) and a low volume spray application of Ready-to-use Sheep Insecticide (Y-TEX) with 2.5% permethrin and 2.5% PBO (10 ml) in an oil based formulation were repellent to C. sonorensis for at least 3-5 weeks after a single application.