Submitted to: Meeting Proceedings
Publication Type: Proceedings
Publication Acceptance Date: May 30, 2005
Publication Date: June 8, 2005
Citation: Li, A.Y. 2005. Use of synergists for elucidation of resistance mechanisms and management of resistant ticks and horn flys. In: Proceedings of 30th Anos al Servicio de la Granderia Nacional, 1975-2005, June 8-9, 2005, Jiutepec, Morelos, Mexico. 2005 CDROM. Interpretive Summary: Resistance to pesticides in the cattle fever tick Boophilus microplus and the horn fly Haematobia irritans has made the control of these two major pests of cattle increasingly difficult in many countries, including Mexico and the United States. The development of resistance to the organophosphate acaricide coumaphos in Mexican tick populations poses a significant risk to the Cattle Fever Tick Eradication Program of the United States. Significant progress has been made during the past decade in the development of resistance diagnostic techniques and the understanding of resistance mechanisms. Synergists have played a major role in the elucidation of resistance mechanisms in many arthropod pest species, including the horn fly and ticks. Synergists are currently being used for the control of resistant horn flies in the United States. There have been relatively few reports on using synergists for tick control. We conducted a research at USDA ARS Knipling-Bushland Livestock Insects Research Laboratory to explore the possibility of using synergized acaricides to control resistant ticks. The study evaluated both the benefits and limitations of the synergist strategy for resistance management.
Technical Abstract: Resistance to acaricides/insecticides in the cattle fever tick Boophilus microplus and the horn fly Haematobia irritans remains a major problem for the successful control of these economically important ectoparasites of cattle in many countries, including Mexico and the United States. In order to develop effective strategies to control resistant ticks and horn flies, extensive research has been conducted on bioassays, biochemical and molecular techniques for resistance detection and monitoring and understanding of resistance mechanisms. Synergists played an important role in the elucidation of resistance mechanisms in both pest species. The use of synergists (TPP, PBO and DEM) that specifically inhibit particular classes of detoxifying enzymes (esterases, mixed function oxidases, and glutathione S-transferases) allowed determination of the role of specific enzymes to organophosphate and pyrethroid resistance in various tick and horn fly populations. The current use of synergists in commercial insecticide formulations for horn fly control was reviewed, and potential strategies and benefits of using synergists for the control of resistant cattle ticks were also discussed.