1a. Objectives (from AD-416):
Objective 1: Develop new toxicants and application methods (e.g., attract-and-kill formulations) that provide novel modes of action or that have other properties desirable for efficacy, safety, and commercialization. Objective 2: Develop new repellent active ingredients and combinations that provide protection and product potential. Objective 3: Determine the fine scale elements of mosquito behaviors (e.g., host-seeking) and associate them with particular chemicals (agonists and antagonists) and physiological detection mechanisms, in order to develop novel behavior-altering chemicals. Objective 4: Develop and refine bioassay methodologies for blood-sucking arthropods that can serve as standards for EPA labeling of toxicant and repellent compounds.
1b. Approach (from AD-416):
Applied research will use the expertise of entomologists and a synthetic organic chemist to produce, develop and evaluate new toxicant and repellent products effective against blood-sucking arthropods. Fundamental research will elucidate the underlying mechanisms involved in mosquito attractancy and repellency, thereby leading to the discovery of even newer classes of chemicals that alter arthropod behavior. Consistent with these efforts, bioassays will be developed and refined that can be used by the research community and industry for discovery, product development, and federal registration purposes.
3. Progress Report:
The focus of our research is to discover and develop new methods to protect people from blood-sucking arthropods. Priority arthropod targets are mosquitoes, ticks, and the common bed bug. ARS scientists in Beltsville, MD have identified natural products obtained from plants that act as mosquito repellents, which relate directly to our objective to develop new repellent active ingredients. ARS scientists in Beltsville have also conducted more fundamental research on the objective relating to the fine scale elements of mosquito behavior. In this regard, scientists have shown that the mechanisms involved in repellents exerting their ultimate effect are quite complicated, and the research effort has resulted in a better understanding of how repellents change or interfere with mosquito behavior. Tick research by ARS scientists at Beltsville in collaboration with other ARS units and industry has addressed objectives to develop new toxicants and repellents, while scientists at Beltsville have also refined tick bioassay protocols to serve as standards for the EPA. Specifically, insecticides synthesized by ARS scientists were shown to be as effective as some commercial insecticides against three types of ticks that attack animals and humans. Tick repellent studies, utilizing either synthetic chemicals or natural plant oils, have had mixed success, with some compounds performing better than others depending on the type of tick used in the assay. This has led to a more fundamental study of repellents and ticks, and has shown that the solvents (usually considered inert) used to dilute tick repellents can affect the outcome of laboratory repellent assays. In an effort to develop new toxicants, research with bed bugs has continued to revolve around efficacy testing of proprietary compounds obtained from ARS chemists, and compounds obtained from industry. While most compounds tested have proven ineffective in killing field-collected bed bugs, three compounds obtained from ARS scientists are quite toxic to bed bugs and are being further evaluated. ARS knowledge of the bed bug chemical ecology was instrumental in a collaboration with industry. Because bed bug infestations can be difficult to detect in dwellings, particularly when populations are low, pest control companies are using dogs in their inspection efforts. While a canine’s keen sense of smell is well-documented, little information existed on the underlying chemical basis for bed bug detection by dogs. ARS scientists at Beltsville, MD were able to show that bed bug-sniffing dogs detect particular chemical compounds produced by the bed bug to alert other bed bugs.
1. Mosquito repellents. ARS researchers at Beltsville, MD showed that not only do repellents activate or inhibit odor detectors found in mosquitoes, a repellent may work together with an attractant to greatly enhance responses of the mosquito to the attractant. This enhanced effect on the response to an attractant provides a novel mechanism for development of behaviorally disruptive tools for use in management of mosquito pests. These results also contribute to a better understanding of fundamentals involved in mosquito attraction, and will ultimately contribute to the design of new repellents.
2. Reaction response to bed bug bites. A study was designed and conducted to examine the one reaction response to bed bug bites. While bed bug infestations are annoying and cause discomfort, these blood-sucking insect pests of humans have not been shown to transmit disease, and reactions to their bites are generally considered to be of minor medical importance. However, in collaboration with The University of Mississippi Medical Center and Harvard Medical School, ARS researchers at Beltsville, MD have shown that bed bug bites can cause a very severe, localized inflammation of blood vessels. Moreover, the type of inflammation that occurs has the potential to affect major body organs. The results of this research will alter the way bed bug infestations and their bites are viewed by regulatory officials, public health professionals and the medical community at large.
Carroll, J.F., Tabanca, N., Kramer, M.H., Agramonte, N.M., Wedge, D.E., Bernier, U.R., Coy, M.R., Becnel, J.J., Demirci, B., Can Baser, K., Zhang, J., Zhang, S. 2011. Essential oils of Cupressus funebris, juniperus communis, and j. chinensis (cupressaceae) as repellents against ticks (Acari; Ixodidae) and mosquitoes (diptera; Culicidae) and as toxiants against mosquitoes. Journal of Vector Ecology. 36(2):258-268.