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United States Department of Agriculture

Agricultural Research Service

Title: Release of piperonyl butoxide and permethrin from synergized ear tags on cattle and effects on horn fly mortality

Authors
item Li, Andrew
item Miller, John
item Klavons, Jerome

Submitted to: Journal of Economic Entomology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: May 22, 2008
Publication Date: October 3, 2008
Citation: Li, A.Y., Miller, J.A., Klavons, J.A. 2008. Release of piperonyl butoxide and permethrin from synergized ear tags on cattle and effects on horn fly mortality. Journal of Economic Entomology. 101(5):1697-1703.

Interpretive Summary: A study was conducted at the Knipling-Bushland U. S. Livestock Insects Research Laboratory, Kerrville, TX to determine the release rates of piperonyl butoxide (PBO) and permethrin from synergized insecticidal ear tags and effects of those release rates on mortality of the horn fly. PBO was released from the ear tags at a higher rate than permethrin in both the winter and summer trials. Both PBO and permethrin were released from ear tags at a higher rate in the summer than in the winter. There was a linear relationship between cumulative PBO or permethrin release and time (week) in for the entire period of the winter trial. Such linear relationship existed only for the first 8 wks in the summer trial. Little release of either PBO or permethrin was observed afterward. There was a significant correlation between the cumulative daily high ambient temperature (oC) and the cumulative release of both PBO and permethrin. Results of bioassays of horn flies using filter paper wipes from the shoulders of cattle treated with the PBO synergized permethrin tags from the summer trial revealed reduced mortalities in the resistant strain. Significant correlations were found between fly mortalities and the ratio of PBO:permethrin released from the tags. The results from this study may help design the new generation of insecticidal ear tags that have more regulated synergist release to achieve and maintain best synergist : insecticide ratio, therefore achieving long-lasting control of the pest.

Technical Abstract: A study was conducted to determine the release rates of piperonyl butoxide (PBO) and permethrin from synergized insecticidal cattle ear tags and effects of those release rates on mortality of the horn fly, Haematobia irritans irritans (Diptera: Muscidae). PBO was released from the ear tags at a higher rate than permethrin in both the winter and summer trials. The cumulative release of PBO and permethrin from the ear tags at the end of 18 wks in the winter trial was 50.4% and 30.3 %, respectively. The cumulative release of PBO and permethrin from the ear tags at the end of 18 wks in the summer trial was 66.7% and 44.7 %, respectively. There was a significant correlation between the cumulative daily high ambient temperature (oC) and the cumulative release of both PBO and permethrin. Compared to the susceptible horn fly strain at the levels of LC50 and LC90, the permethrin resistant strain demonstrated 7.9- and 12.8-fold resistance to permethrin, respectively. When exposed to filter paper wipes taken from the shoulders of cattle treated with the PBO synergized permethrin tags from the summer trial, the resistant strain demonstrated reduced mortality in comparison with the susceptible strain. The mortality of the resistant strain at 2 and 3 h exposure exhibited a pattern of declining fly mortalities as a result of the decreased release of PBO and permethrin, as well as the decline in the ratio of PBO:permethrin released from the tags after 8 wks. A similar decline in horn fly mortalities was observed in the susceptible strain at 30 min. exposure time that coincided with the pattern of reduced release of PBO and permethrin from the ear tags over the course of summer trial.

Last Modified: 7/30/2014
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