Mobility of pesticides in water, sediment, plants and soils, including soil columns

Understanding mobility of pesticides is an important part of environmental toxicology and chemistry. Pesticides need to be mobile enough to allow them to be transported to the site of action. On the other hand, pesticides that are too mobile will rapidly dissipate once applied to the target area and contaminate water and sediment. Many factors can affect the mobility of pesticides in soil and water including soil characteristics, pesticide properties, and timing of application.

Picture of a soil column experiment. The packed soil column is placed vertically in a formulated insecticide which moves up the column through capillary action, to determine how far a pesticides will travel in soil.Research in the lab has primarily focused on the transport of herbicides and their metabolites through soil profiles and into groundwater and surface water bodies. Recent research has focused on testing various formulations for their ability to increase the mobility of insecticides. Using formulations to increase mobility is essential for ensuring that insecticides are capable of moving through the soil to reach the habitats of ground-dwelling insect pest such as termites.


Some relevant publications:

Zhao, S., J.B. Belden, J.H. Cink, and J.R. Coats. 2010. Mobility of five termiticides in soil columns. Chapter in Proceedings of the 2010 NCUE. NCUE, Portland, OR, pp 169-174

Arthur, E.L., P.J. Rice, P.J. Rice, T.A. Anderson, and J.R. Coats.  1998.  Mobility and degradation of pesticides and their degradates in intact soil columns, Chapter 7 in Environmental Behavior of Pesticides:  The Lysimeter Concept.  F. Führ, J. Plimmer, R. Hance, and J. Nelson, eds.  American Chemical Society, Washington, D.C. pp. 88-114.

Kruger , E.L., B.  Zhu, and J.R. Coats. 1996. Relative mobilities of atrazine, five atrazine degradates, metolachlor, and simazine in soils of Iowa.  Environ. Toxicol. Chem. 15: 691-695.

Kruger, E.L., P.J. Rice, J.Anhalt, T.A. Anderson, and J.R. Coats. 1996. Use of undisturbed soil columns under controlled conditions to study the fate of [14C]deethylatrazine, J. Agric. Food Chem. 44: 114-1149.

Somasundaram, L., J.R. Coats, V.M. Shanbhag, and K.D. Racke. 1991. Mobility of pesticides and their hydrolysis metabolites in soil. Environ. Toxicol. Chem. 10: 185-194.

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.

Degradation and persistence of insecticides, herbicides, fungicides, including natural products

It is important to understand the degradation and persistence of pesticides in soil and water in order to maximize pesticide efficacy while minimizing any detrimental effects they may have on the ecosystem. Degradation and persistence of pesticides can be affected by a wide variety of factors including properties of the pesticides (water solubility, volatility, polarity), properties of the soil or water (pH, temperature, soil composition), and resistance to degradation (biological, chemical, photo).

The lab has an extensive history of studying the degradation and persistence of pesticides in terrestrial and aquatic ecosystems. Though much of the research has focused on conventional herbicides, such as atrazine and metolachlor, the fate of natural insecticides, like thymol, has also been studied.


Some relevant publications:

Hu, Dingfei, Keri Henderson, and Joel Coats. 2009. Fate of transformation products of synthetic chemicals. Chapter  in The Handbook of Environmental Chemistry, vol. 2, Part P. Alistair Boxall, editor, Springer-Verlag, Berlin, Germany. pp. 103-120.

Hu, Dingfei, and Joel Coats. 2008. Evaluation of the environmental fate of thymol and phenethyl propionate in the laboratory. 2008. Pest Manag. Sci. 64: 775-779.

Rice, P.J., T.A. Anderson, and J.R. Coats. 2004. Effect of sediment on the fate of metolachlor and atrazine in surface water. Environ. Toxicol. Chem. 23: 1145-1155.  

Coats, J.R. and H. Yamamoto, Editors.  2003.  Environmental Fate and Effects of Pesticides.  American Chemical Society, Washington, D.C., 300 pp.

Arthur, E.L., B.S. Perkovich, T.A. Anderson, J.R. Coats. 2000. Degradation of an atrazine and metolachlor herbicide mixture in pesticide-contaminated soils from two agrochemical dealerships in Iowa. Water Air Soil Pollut. 119: 75-90.

Dr. Joel R Coats

Profile photograph of Joel Coats
Principal Investigator
Charles F. Curtiss Distinguished Professor of Entomology
Area of Expertise: 
Insecticide Toxicology
Environmental Toxicology