2007 Annual Report 1a.Objectives (from AD-416) To elucidate critical, but poorly understood, elements of tick behavior mediated by chemical and physical factors. Develop ecologically based strategies and systems using kairomones, pheromones, attractants, toxicants and repellents to reduce tick populations and tick bites. 1b.Approach (from AD-416) Behavioral and electrophysiological responses of ticks to chemical stimuli will be ascertained by means of laboratory bioassays, time lapse videotaping and field trials. Chemicals suspected of affecting ticks will be evaluated by behavioral bioassays as attractants, arrestants, repellents and toxicants. Host-targeted tick control devices (4-posters) modified to discourage squirrel usage will be evaluated in the field for their effectiveness in reducing squirrel consumption of the corn bait. 3.Progress Report In laboratory bioassays, isolongifolenone was found to be as effective as deet, the most widely used repellent approved for use on the skin, against blacklegged ticks and lone star ticks. Five analogues of isolongifolenone were also tested against blacklegged ticks and one compound was about equivalent in repellency to isolongifolenone. A patent application for the use of isolongifolenone as tick and insect repellent has been submitted. Laboratory bioassays showed that compounds associated with of bovid integument are repellent to lone star ticks. Further testing of these compounds is planned. Twenty-three compounds known to occur in citrus were tested in laboratory bioassays against host-seeking lone star tick nymphs as repellents and for their capacity to cause adverse effects on basic behaviors involved in tick host acquisition and pre-feeding activity. Citrus compounds were found that repelled lone star ticks, inhibited their ability to right themselves if turned upside down, inhibited their tendency to climb (important in host acquisition) and inhibited locomotion 18-24 h after exposure. In cooperation with Iowa State University we showed in laboratory bioassays that elemol and amyris oil were repellent to blacklegged ticks and lone star ticks. Behavioral bioassays were conducted to determine whether blacklegged tick adults can find one another by means of a trail-type pheromone. The results thus far have not proven conclusive. Carbon dioxide is a strong attractant of some species of ticks and has been used in tick surveillance and population studies. Dry ice has often been used as the CO2 source in field work, but has some drawbacks. In cooperation with Walter Reed Army Institute of Research, preparations have been completed for a field test of four CO2-generating technologies to evaluate their efficacy compared to dry ice in attracting lone star ticks. The ‘4-poster’ deer self-treatment tick control device was used experimentally on Gibson Island, MD in connection with the USDA Northeast Area-Wide tick Control Project from 1998-2002. About 1.5 years after the experimental treatments ended, the Gibson Island community purchased ‘4-posters’ and has operated them until the present. Blacklegged tick and lone star tick populations were reduced dramatically by 2001. Our annual sampling of host-seeking populations of blacklegged ticks and lone star tick nymphs has shown that densities of both species of ticks remain at low levels. At the NASA Space Flight Center, Greenbelt, MD, where ‘4-posters’ have been used for several years annual monitoring has shown the populations of lone star ticks and blacklegged ticks remain low and that they are now much reduced in an area of the center where we started treatments in 2004. 4.Accomplishments Novel tick repellent Identifying drug alternatives to tick control is necessary to expand the arsenal of drugs used against ticks and that can be applied to human skin. In cooperation with the Invasive Insect Biocontrol and Behavior Laboratory (formerly Chemicals Affecting Insect Behavior Laboratory), we found that isolongifolenone repelled deer tick and lone star tick nymphs as effectively as Deet, the most widely used repellent approved for use on human skin. Because isolongifolenone was also shown to be effective in deterring mosquito feeding and it has a history of use in products used on human skin, a patent application has been submitted. Isolongifolenone could be developed into a product that can be used to protect humans or animals from ticks and biting insects. This addresses the need for protecting humans and domestic animals from ticks and tick-borne disease, and is relevant to ARS National Program 104, more particularly, in Component 4, with repellent studies falling in 4.1.1, 4.1.2 and 4.1.3. Sustained tick control by ‘4-poster’ technology. It is important to continue monitoring the effectiveness of‘4-poster’ technology in controlling the regional expansion of the tick populations. In this regard, the populations of deer ticks and lone star ticks on Gibson Island (in Chesapeake Bay) were found reduced by ‘4-poster’ technology as part of the USDA Northeast Tick Control Project from 1998-2002. After the conclusion of the experimental treatments, the Gibson Island Corporation purchased ’4-posters’ and has operated them until the present. We monitored populations of host-seeking nymphs of both species of ticks by annual sampling 1998-2007. These findings substantiate the long term effectiveness of ‘4-poster’ technology in controlling tick populations when used by persons with a non-research background. This addresses the need for protecting humans and domestic animals from ticks and tick-borne disease, and is relevant to ARS National Program 104, more particularly, in Component 4, with toxicant studies falling in 4.1.1, 4.1.2 and 4.1.3. Citrus compounds affect ticks. Natural products are often good sources of insect repellents. Compounds occurring in citrus were found to repel and adversely affect host-seeking behaviors (righting, climbing and host-acquisition) by lone star ticks. These findings show that these compounds may have protective effects beyond repelling ticks. Some compounds may have potential for use in commercial products to protect against tick bites. This addresses the need for protecting humans and domestic animals from ticks and tick-borne disease, and is relevant to ARS National Program 104, more particularly, in Component 4, with repellent studies falling in 4.1.1, 4.1.2 and 4.1.3. 5.Significant Activities that Support Special Target Populations None 6.Technology Transfer Number of U.S. patents granted 1 Number of non-peer reviewed presentations and proceedings 4 Number of newspaper articles and other presentations for non-science audiences 3 Review Publications Carroll, J.F. 2007. A note on the occurrence of the lone star tick, Amblyomma americanum (Acari: Ixodidae) in the greater Baltimore-Washington area. Proceedings of the Entomological Society of Washington. 109(1):253-256. Carroll, J.F., Cantrell, C.L., Klun, J.A., Kramer, M.H. 2007. Repellency of two terpenoid compounds isolated from Callicarpa americana (Lamiaceae) against Ixodes scapularis and Amblyomma americanum ticks. Experimental and Applied Acarology. 41:215-224. Weldon, P.J., Carroll, J.F. 2007. Vertebrate chemical defense: secreted and topically acquired deterrents of arthropods. In: Debboun, M., Frances, S.P., and Strickman, D., editors. Insect repellents: principles, methods, and uses. Boca Raton, FL:CRC Press. p. 47-75.