Dr. John F. Carroll is a Research Entomologist with the U. S. Department of Agriculture, Agricultural Research Service, for which he has conducted research on ticks and mites since the 1980s. In 1990, he was directed to work on the blacklegged tick (a.k.a. deer tick), I. scapularis, vector of the pathogen causing Lyme disease. His research has been on the behavior, ecology and control of I. scapularis and other species of ticks of medical and veterinary importance. As part of the USDA Northeast Tick Control Project, he was responsible for testing the efficacy of the ‘4-Poster’ deer self-treatment bait stations in reducing populations of I. scapularis at three 2 square mile field sites in Maryland 1998-2002. Currently his research is focused largely on tick repellents.
He earned a BA from Siena College and MS and PhD in entomology from the University of Florida. He is employed in the Invasive Insect Biocontrol and Behavior Laboratory at the USDA, ARS, Beltsville Agricultural Research Center, Beltsville, MD.
Some of the results of Carroll’s tick research (alone and with cooperators):
Developed the tick sweep, a more effective and durable modification of the tick flag for sampling and collecting ticks. Described of the distribution of host-seeking nymphal and adult I. scapularis at woods-pasture boundaries. Discovered that I. scapularis nymphs and particularly adults disperse distances several times greater than previously thought. Demonstrated that silt fence barriers treated with acaricide prevent dispersal of I. scapularis adults. Discovered that substances associated with external leg glands of white-tailed deer act as kairomones influencing the selection of host-ambush sites by adult I. scapularis. Discovered that urine from white-tailed deer in certain reproductive states elicits arrestant responses in adult I. scapularis. Discovered that substances from different types of deer leg glands elicit different responses in I. scapularis. Described attachment site pattern of adult I. scapularis on white-tailed deer. Showed that weather-based and economic models can ascertain optimum winter operation of ‘4-poster’ devices. Compared efficacies of the widely used repellent deet and numerous natural and synthetic chemicals in repelling ticks. Demonstrated that I. scapularis and lone star ticks, Amblyomma americanum, detect deet and SS220 by olfaction without needing to contact treated surfaces. Evaluated efficacy of cream, spray and lotion formulations of repellents against A. americanum in 12-h duration trials with human volunteers. Other relevant research on ticks includes: first electrophysiological study of tick vision, study of population dynamics of host-seeking Dermacentor variabilis, ruled out D. variabilis as vector of agent causing Potomac horse fever, showed that host-seeking ticks can survive laundering (even hot cycle) in automatic clothes washer.