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United States Department of Agriculture

Agricultural Research Service

Research Project: SUSTAINABLE PEST MANAGEMENT SYSTEMS FOR BLOOD-FEEDING FLIES AFFECTING LIVESTOCK

Location: Tick and Biting Fly Research

Title: A sustained release gel formulation of Doramectin for control of Lone Star Ticks (Acari: Ixodidae) and Horn Flies (Diptera: Muscidae) on cattle

Authors
item Lohmeyer, Kimberly
item Miller, John - USDA RETIRED
item Pound, Joe
item Klavons, Jerome

Submitted to: Journal of Economic Entomology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: December 19, 2008
Publication Date: April 1, 2009
Citation: Lohmeyer, K.H., Miller, J.A., Pound, J.M., Klavons, J.A. 2009. A sustained release gel formulation of Doramectin for control of Lone Star Ticks (Acari: Ixodidae) and horn flies (Diptera: Muscidae) on cattle. Journal of Economic Entomology. 102(2):804-808.

Interpretive Summary: A study was conducted at the Knipling-Bushland U.S. Livestock Insects Research Laboratory, Kerrville, TX to determine if a gel formulation could provide long-lasting delivery of doramectin to cattle for control of lone star ticks and horn flies. Doramectin was incorporated in a 10% hydroxypropl methylcellulose aqueous solution and injected subcutaneously in the neck of cattle. The doramectin concentration in the serum of steers receiving 600 µg/kg declined from 21.9 ppb at 0.5 wk to below detectable at 8 wks post-injection. For those steers treated with a1200 µg/kg injection, doramectin concentrations in the serum declined from 29.1 ppb at 0.5 wk and declined to 0.5 ppb at 8 wks post-injection. Both 600 µg/kg and the 1200 µg/kg injections provided 100% inhibition of adult lone star ticks through the 8th wk after which there was a decline in effectiveness to 79.4 % and 45.3 %, respectively, during the 12th wk post treatment. The mortality of adult horn flies feeding on the blood from steers treated at 600 µg/kg declined from 16.9 during wk 2 to 3.1 % during wk 7 post injection. The blood from those steers treated at 1200 µg/kg resulted in a similar decline in horn fly mortality from 29.4 % during wk 1 to 4.0 % during wk 7. Additionally, the 600 µg/kg treatment provided complete control of larval horn flies in the manure for 9 wks; whereas, the 1200 µg/kg injection gave complete control for 14 wks post treatment. The gel formulation provided long-lasting delivery of doramectin to cattle and extended control of lone star ticks and horn flies. Such a simple and inexpensive formulation could prove useful in tick eradication programs by reducing the frequency of gathering cattle.

Technical Abstract: A gel formulation was formed by incorporating technical doramectin in a 10% hydroxypropyl methylcellulose aqueous solution. Six Hereford steers held in indoor stanchions were divided into groups of 2 steers each and treated with a 5 mL subcutaneous injection of the gel formulation at dosages of 0, 600 and 1200 µg/kg body wt. The doramectin concentration in the serum of the 2 steers receiving 600 µg/kg declined from 21.9 ± 5.4 ppb at 0.5 wk to below detectable at 8 wks post-injection. The 1200 µg/kg injection resulted in doramectin concentrations in the serum of 29.1± 24.2 ppb at 0.5 wk and declined to 0.5 ± 0.7 ppb at 8 wks post-injection. Both 600 µg/kg and the 1200 µg/kg injections provided 100% inhibition of adult lone star ticks through the 8th wk after which there was a decline in effectiveness to 79.4 ± 28.1% and 45.3 ± 0.9%, respectively, during the 12th wk post treatment. For those steers treated at 600 µg/kg, corrected mortality of adult horn flies feeding on blood declined from 16.9 ± 1.5% during wk 2 to 3.1 ± 2.3 % during wk 7 post injection. The blood from those steers treated at 1200 µg/kg resulted in a similar decline in mortality from 29.4 ± 16.7% during wk 1 to 4.0 ± 5.7% during wk 7. The 600 µg/kg treatment provided complete control of larval horn flies in the manure for 9 wks; whereas, the 1200 µg/kg injection gave complete control for 14 wks post treatment. By the 16th week, the corrected larval mortality had declined to 16.7 ± 19.9% in the manure of the steers treated at 600 µg/kg and 54.6 ± 41.9% in the manure of those treated at 1200 µg/kg. The gel formulation provided long-lasting delivery of doramectin to cattle and extended control of lone star ticks and horn flies. Such a simple and inexpensive formulation could be useful in tick eradication programs by reducing the frequency of gathering cattle.

Last Modified: 7/23/2014
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