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 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.
We perform various bioassay tests for various companies and agencies to quantify the ability of new insecticidal formulations to kill and repel a wide array of arthropod pest species. Some of the species we utilize in our testing includes, but is not limited too: house flies, cockroaches, ticks, bed bugs, mosquitoes, fleas, crickets, corn rootworms, corn borers, cutworms, aphids, and spider mites. The fees for service, as well as the types of testing to be performed, are negotiated via a contract basis.
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.
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.
Octopamine and tyramine are essential biogenic amines that have been implicated in numerous physiological systems in arthropod species, such as reproduction, the nervous system, and learning-and-memory, to name a few. We have successfully created two stably-transfected Chinese Hamster Ovary cell lines (CHO) with a functional octopamine receptor from Periplaneta americana, the American cockroach, and a functional tyramine receptor from Rhipicephalus microplus, the southern cattle tick. Our hope is to characterize plant-derived compounds that may function as agonists, antagonists, or modulators of these two arthropod receptors. This research may lead to the identification of plant-derived compounds that possess activity at these two receptors and may act as insecticidal compounds with a novel mode of action that has yet to be exploited in the field of insect toxicology.
Some relevant publications:
Gross, Aaron D., Michael J. Kimber, Tim A. Day, Paula Ribeiro, and Joel R. Coats. 2013. Quantitative structure-activity relationships (QSARs) of monoterpenoids at an expressed American cockroach octopamine receptor, Chapter 7 in Pest Management with Natural Products, J.J. Beck, J.R. Coats, S.O. Duke and M.E. Koivunen, Editors, American Chemical Society, Washington, D.C. 247 pp. DOI: 10.102/bk-2013-1141.ch007.
Tsao, R., S. Lee, P.J. Rice, C. Jensen, and J.R. Coats. 1995. Monoterpenoids and their synthetic derivatives as leads for new insect-control agents. Chapter 28, in Synthesis and Chemistry of Agrochemicals - IV, D.R. Baker, J.G. Fenyes, and G.S. Basarab, eds., pp. 312-324. American Chemical Society, Washington, D.C.