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Botanicals to enhance effectiveness of synthetic pyrethroid insecticides; funded by the U.S. Department of Defense, Deployed War Fighter Protection Program

Since the beginning of the project in April 2012, our lab has screened a wide array of plant essential oils for baseline toxicity and in combination with various synthetic pyrethroids against Aedes aegypti, the yellow fever mosquito, and Anopheles gambiae, the African malaria mosquito. To date, we have identified essential oil candidates that enhance the toxicity of various synthetic pyrethroids, and some that cause greater enhancement than the most commonly used commercial synergist in synthetic pyrethroid formulations, piperonyl butoxide (PBO). Future directions for Photograph of cone tests that are utilized in the Deployed War Fighter Protection project.this project include whether or not these essential oil candidates enhance different synthetic pyrethroids to different degrees, isolating components from the most promising oils which impart the ability to enhance synthetic pyrethroids, mode/mechanism of action studies to determine how these essential oils/components are causing this enhancement, and whether or not these essential oils/components can enhance the efficacy of synthetic pyrethroids against insecticide-resistant mosquito populations.

Natural Terpenoid repellents with activity against mosquitoes, flies, cockroaches, ticks, and bed bugs

It is well established that insects and plants have shared a long evolutionary history with one another. Due to this evolutionary “arms race,” plants have developed some truly fascinating ways to deter insects from feeding upon them, such as production of various terpenoid compounds that repel or kill insect pests. Our lab is interested in isolating plant-derived compounds that may act as natural repellents. We have demonstrated that many of these plant-derived compounds cause significant repellency against mosquitoes and various other arthropod pest species, some of which rival n,n-diethyl-m-toluamide (DEET), the commercial standard for repellency. It is our goal to continue isolation of novel repellent compounds from plants to potentially create stronger repellents and to gain insight into how these repellent compounds act on various insect olfactory receptors.

Photograph of clear glass tubes used for testing natural terpenoid repellencyPhotograph of irritancy and spatial repellency chambers used for testing natural terpenoid repellency

Some relevant publications:

Paluch, G.E. and J.R. Coats, Editors. 2011. Recent Developments in Invertebrate Repellents. American Chemical Society, Washington, DC. 186 pp.  DOI: 10.1021/bk-2011-1090     

Paluch, G.E., L.C. Bartholomay, and J.R. Coats.  2010. Mosquito repellents: a review of chemical structure diversity and olfaction. Pest Manag. Sci. 66: 925-935.

Peterson, Christopher J., and Coats, Joel R. 2011. Catnip essential oil and its nepetalactone isomers as repellents for mosquitoes, Chapter 4 in Recent Developments in Invertebrate Repellents, Paluch, Gretchen E. and Coats, Joel R., American Chemical Society Books, Washington, DC. pp 59-65.

Paluch, Gretchen E., Junwei Zhu, Lyric C. Bartholomay, and Joel R. Coats. 2009. Amyris and Siam-wood essential oils: Insect activity of sesquiterpenes, in Pesticides in Household, Structural and Residential Pest Management, C.J. Peterson, and D.M. Stout II, eds., ACS Books, Washington, DC. pp 5-18.

Schultz, G., C. Peterson, and J.R. Coats. 2006. Natural insect repellents: Activity against mosquitoes and cockroaches. Chapter 13 in Natural Products for Pest Management, A.M. Rimando & S.O. Duke, eds.  American Chemical Society, Washington D.C. pp. 168-181.