Location: Invasive Insect Biocontrol & Behavior Laboratory
2025 Annual Report
Objectives
Objective 1: Expand the current repertoire of tools for surveillance of human-biting ticks in order to target their populations more efficiently.
Sub-objective 1.A: Develop new surveillance tools targeting mouse reservoir hosts.
Sub-objective 1.B: Develop new surveillance tools targeting ticks.
Sub-objective 1.C: Develop population genetic tools for source tracing of Invasive tick populations.
Sub-objective 1.D: Assess acarological risk at representative public use areas in urban or suburban settings.
Objective 2: Develop and evaluate new control technologies like natural products and integrated pest management approaches for control of ticks of medical importance.
Sub-objective 2.A: Test host targeted control strategies directed at the mouse reservoir host.
Sub-objective 2.B: Test existing chemicals and new natural products for activity against ticks.
Sub-objective 2.C: Develop demonstration tick IPM projects using new approaches with commercially available products and incorporating a public outreach component.
Objective 3: Discover innovative tick control strategies by utilizing technology for fundamental research on vector-host-pathogen interactions.
Sub-objective 3.A: Develop an understanding of the core microbiome for human-biting ticks.
Sub-objective 3.B: Understand the physiological mechanisms of tick feeding and the modes of action of existing and novel compounds.
Approach
New surveillance tools will be developed for human-biting ticks, their mouse hosts and associated tick-borne pathogens in order to target their populations more efficiently. Acarological risk will be assessed at representative public use areas in urban or suburban settings through field studies. New host-targeted tick control will be developed and evaluated through semi-field and field studies. This includes nestboxes for delivery of mouse baits containing novel pesticides and anti-microbial agents. Various natural products and associated chemical compounds will be evaluated for the development of new acaricides and more effective tick repellent products. Existing pesticides for control of agricultural and veterinary pests will be evaluated against ticks for public health applications, including development of new pesticide formulations for tick control. A demonstration tick control project that utilizes commercially available tick control products will be implemented to promote Integrated Tick Management (ITM). This includes a public outreach component to engage with residents and pest/vector control service providers. Innovative research will be conducted to uncover new molecular and physiological targets for novel tick control technologies. This includes molecular studies of the core microbiome for human-biting ticks and mode-of-action investigation of new acaricidal compounds using a novel tick membrane feeding system.
Progress Report
Objective 1: Expand the current repertoire of tools for surveillance of human-biting ticks to target their populations more efficiently. Researchers at Beltsville, Maryland have developed a Material Transfer and Research Agreement (MTRA)with scientists at the Rutgers University Center for Vector Biology in New Brunswick, New Jersey, to test the utility of the mouse nest box as a new surveillance tool for ticks and tick-borne pathogens. However,the work experienced a major delay due to the retirement of a researcher. On the other hand, significant progress was made in the design of the multimodal tick trap. Required materials will be acquired for the construction of the device. Several field locations have been also identified for tick and tick-borne pathogen surveillance in the coming years.
Objective 2: Develop and evaluate new control technologies like natural products and integrated pest management approaches to control ticks of medical importance. Researchers at Beltsville, Maryland, have acquired several novel chemical compounds to be tested as new tick repellents and/or acaricides. Various bioassay techniques, including the vertical filter paper assay, EthoVision behavioral tracking system, topical treatment and capillary feeding, are being considered. Two new pesticide products that are currently marketed for agricultural insect pests have been tested in the laboratory to assess their effectiveness against ticks. A new cooperative research agreement with a private company has been established to develop and validate a novel mouse bait product targeting white-tooted mice infested with the pathogen that causes Lyme disease.
Objective 3: Discover innovative tick control strategies by utilizing technology for fundamental research on vector-host-pathogen interactions. Researchers at Beltsville, Maryland, are investigating the mechanisms that control blood-feeding in ticks to find new ways to block blood feeding and/or pathogen transmission by ticks. An electric tick feeding monitor has been successfully integrated with a silicone membrane-based tick blood-feeding system to investigate the processes of blood ingestion and salivation of ticks during the entire blood feeding period (days). This combined use of the electric tick feeding monitor and the artificial tick feeding system would help us understand the physiological mechanisms of tick feeding and the modes of action of existing and novel compounds.
Accomplishments
1. A vertebrate-derived semiochemical is a promising new tick repellent. The blacklegged tick is the vector of the pathogens that cause Lyme disease. Over 400,000 Americans contract Lyme disease through tick bites each year. Chemical repellents play an important role in reducing the risk of tick bite and disease transmission. ARS researchers in Beltsville, Maryland, in collaboration with university researchers discovered superior tick repellency of a donkey sebum-derived semiochemical compound, (E)-oct-2-enal, against adult blacklegged ticks, the vector responsible for transmission of Lyme disease to humans in the United States. Responses of ticks to this novel compound were tested with a filter paper bioassay technique in combination with EthoVision, a behavior tracking and analysis system. Results were compared with those of DEET, the active ingredient of most used commercial repellent products on the market. The new compound, (E)-oct-2-enal, was found to be more effective against male ticks than DEET while being equally effective as DEET against female ticks. This study highlights the potential of natural compound (E)-oct-2-enal to be developed as a new active ingredient in new repellent products to protect humans from tick bites and tick-borne diseases.
2. New organic spatial repellents are identified to prevent sand fly bites. Leishmaniasis, a parasitic disease transmitted by sand flies, is endemic in more than 90 countries and territories across four continents, posing a significant global health threat. With over 80 reported human cases since 2017, leishmaniasis is an emerging vector-borne disease in the United States. ARS scientists in Beltsville, Maryland and colleagues at European Biological Control Laboratory in Thessaloniki, Greece joined forces to search for better spatial repellents against sand flies. Cumin essential oil was extracted from Cumin seeds obtained locally in Greece. Gas chromatography–mass spectrometry (GC-MS) analysis of cumin essential oil led to the identification of five major chemical constituents, including cumin aldehyde, ß-pinene, and y-terpinene. A bioassay technique was used to measure responses of female sand flies to cumin essential oil and its major constituents in comparison to two conventional insect repellents, DEET and transfluthrin, and octanol, which can either repel or attract other insects. Cumin seed essential oil, cumin aldehyde, and octanol demonstrated strong spatial and contact repellency against female sand flies at a level comparable to transfluthrin and the repellency can last up to 3 hours. This study established cumin seed essential oil and cumin aldehyde as potential alternatives to conventional chemical repellents against sand fly bites. Further research, including formulation development and field trials, is needed to explore their applicability in vector control strategies.
Review Publications
Tietjen, M., Esteve-Gasent, M.D., Castro-Arellano, I., Li, A.Y., Medina, R. 2024. Lack of host-associated differentiation in Ixodes scapularis using population genetics. Entomologia Experimentalis et Applicata. https://doi.org/10.1111/eea.13533.
Busch, J.D., Stone, N.E., Pemberton, G., Roberts, M.L., Turner, R.E., Thornton, N., Sahl, J.W., Lemmer, D., Buckmeier, B.G., Davis, S.K., Karim, S., Klafke, G., Thomas, D.B., Olafson, P.U., Ueti, M.W., Mosqueda, J., Scoles, G.A., Wagner, D.M. 2025. Fourteen anti-tick vaccine targets are variably conserved in cattle fever ticks. Parasites & Vectors. 18. Article e140. https://doi.org/10.1186/s13071-025-06683-5.
Siegel, E.L., Goodnow, S., Thompson, L., Nicolson, S., Macleod, E., Li, A.Y., Xu, G., Rich, S.M. 2025. Exploiting a natural instance of vertebrate-posed chemical aposematism for tick bite prevention: Repellency of Ixodes scapularis with (E)-Oct-2-enal. PLOS ONE. 20(3). Article e0317975. https://doi.org/10.1371/journal.pone.0317975.
Tskikolia, M., Tsafrakidou, P., Miaoulis, M., Li, A.Y., Chaskopoulou, A., Gundersen, D.E. 2025. Investigation of Essential Oil from Cumin (Cuminum cyminum) Seeds and Selected Terpenes as Repellents Against Adult Female Phlebotomus papatasi (Scopoli) (Diptera: Psychodidae) Sand Flies. Insects. 16:599. https://doi.org/10.3390/insects16060599.