Location: Invasive Insect Biocontrol & Behavior Laboratory
2017 Annual Report
Objectives
Objective 1: Design and synthesize novel chemicals such as toxicants, repellents, and attractants that can be used to mitigate the impact of blood-feeding arthropods.
Objective 2: Determine physiological and molecular mechanisms involved in the detection of attractants, repellents, and feeding deterrents by mosquitoes in order to facilitate discovery of novel behavior-modifying chemicals.
Sub-objective 2.A: Characterize gustatory receptors (GRs) and other chemosensory genes in the major gustatory appendages of Aedes aegypti, localize their expression and relative abundance, and determine their function through heterologous expression studies.
Sub-objective 2.B: Determine the specificity of gustatory receptor neurons (GRNs) expressing identified GRs with emphasis on detection of feeding stimulants and repellents, and their role in Ae. aegypti feeding and avoidance behavior.
Objective 3: Develop improved surveillance and control techniques for bed bugs.
Sub-objective 3.A: Identify and elucidate the role of chemicals involved in the behaviors of dispersal (repellency) and aggregation (attractancy), and develop new detection techniques.
Sub-objective 3.B: Develop new chemical or biological control agents to reduce or eliminate bed bug infestations.
Objective 4: Discover and develop new tools for the control of ticks affecting humans, and evaluate their effectiveness at a range of conditions associated with climate change.
Sub-objective 4.A: Develop new tick repellents/formulations and characterize the physiological mechanisms involved in repellent detection by ticks.
Sub-objective 4.B: Determine if certain abiotic and biotic factors affect the responses of deer ticks to repellents.
Approach
New toxicants, repellents and attractants will be synthesized using quantitative structure-activity relationship analyses. This component will also focus on the development of novel inhibitors of detoxifying enzymes that are found in insects. Candidate compounds obtained from existing chemical libraries and commercial sources will be screened for bioactivity against blood-sucking arthropods.
Gustatory receptors and genes in the appendages of the yellow fever mosquito Aedes aegypti will be characterized. Molecular studies will also determine the specificity of gustatory receptor neurons with emphasis on feeding stimulants and repellents.
Chemicals that attract and repel bed bugs will be identified, and their role elucidated. To develop new monitoring devices, behavioral studies will use a photographic tracking system to monitor bed bug responses to behavior-altering compounds. New chemical and biological control agents will also be developed under this objective to mitigate the impact of this blood-sucking pest.
New tick repellents and formulations will be developed and the mechanism of repellent detection by ticks characterized. This will involve the optimization of an in vitro feeding system for ticks, as well as the use of electrophysiological techniques to characterize tick responses to repellents and antifeedants. The effect of pathogen infection status, temperature, humidity, and geographic origin of ticks will also be investigated with regard to repellents.
Progress Report
In 2017, progress was made on all four objectives and their subobjectives in the Project Plan “Prevention of Arthropod Bites.” The objectives and subobjectives in this Project - to mitigate the impact of biting arthropods - support National Program 104 (Veterinary, Medical, and Urban Entomology) and fall within Component 1 (Medical Entomology for the Public and the Military) of this National Program. Specifically, the objectives and subobjectives will provide important scientific information to protect animals, humans, and property from the negative effects of pests and infectious diseases. In mosquito control research (Objective 1), ARS scientists in Beltsville, Maryland, identified novel chemical toxicants which can act as either stand-alone insecticides or in combination with other insecticides. These chemical toxicants are in a different chemical class than existing chemicals used for mosquito control, and exhibit superior activity against both insecticide-susceptible and insecticide-resistant mosquitoes. An ARS scientist in Beltsville, Maryland, also identified a commercial carbon dioxide generator that can be used to attract mosquitoes, and is superior to generators that rely upon dry ice to generate carbon dioxide. In translational mosquito research (Objective 2), ARS scientists in Beltsville, Maryland, demonstrated the presence of taste organs on the wings of mosquitoes that are known to transmit Zika virus and other debilitating disease agents. A model for host acceptance to biting by a mosquito was surmised, which involved sequential taste organs on found on the mosquito. In bed bug research (Objective 3), ARS scientists in Beltsville, Maryland, demonstrated that several potential products provided by other ARS laboratories were ineffective in controlling all stages of bed bugs, including their eggs. Products included several dust formulations and cloths impregnated with certain “nanoparticles.” In tick research (Objective 4), ARS scientists in Beltsville, Maryland successfully developed and used a silicone-based membrane to feed adult lone star ticks in the laboratory, and to assess the toxicity of a several commercial tick control formulations. These ticks are widely distributed across the eastern, southeastern, and midwestern areas of the United States, and are known to transmit many human and animal pathogens. Another type of tick, the deer tick (also known as the black-legged tick) is considered important because it transmits Lyme Disease, and ARS scientists from Beltsville, Maryland, in conjunction with Centers for Disease Control and Prevention (CDC), US Army Public Health Center, and University of Massachusetts researchers, determined the disease status of deer ticks collected from mice and deer, as well as from wooded areas at study sites in Maryland. A high infection rate (greater than 40%) was found in adult deer ticks. In further research, ARS scientists in Beltsville, Maryland, determined if there was a correlation between infection with the Lyme pathogen and the deer tick’s response to a common tick repellent. In laboratory experiments, no difference was observed in the repellency of disease-infected ticks compared to non-infected ticks.
Accomplishments
1. Development of a carbon dioxide generator. Development of new ways to monitor and attract mosquitoes and other arthropods that can transmit the agents of disease are needed to effectively assess disease potential, and control problematic arthropods. Most blood-sucking arthropods utilize carbon dioxide to find their host(s). A new lightweight carbon dioxide generator that does not rely upon dry ice was developed that is field stable and can be used in mosquito traps. This information will be used by personnel involved in surveillance and control of mosquitoes and other blood-sucking arthropods that transmit the causative agents of disease.
2. Development of new strategies to control bed bugs. New strategies to control bed bugs are always in demand for both the general public and companies involved in controlling these blood-sucking insect pests. ARS scientists in Beltsville, Maryland, in collaboration with University of Maryland scientists showed that the fumigation actions of certain essential oils are only marginally useful in controlling bed bugs. Of nine essential oils tested, only rosemary oil proved to be an effective fumigant when compared to a commercially-available fumigant. This information will be useful to industry personnel that are attempting to develop new control methods for bed bugs.
3. Artificial feeding system for ticks. Lone star ticks transmit several human pathogens as well as pathogens that affect livestock and other animals. ARS scientists in Beltsville, Maryland, developed an artificial feeding system for lone star ticks that was used successfully to feed adult lone star ticks in the laboratory. This artificial feeding system allowed ARS personnel test several tick control products, without the need for human or animal hosts. This information, as well as the feeding system, can be used by federal, university and pharmaceutical scientists that are interested in developing new tick control formulations.
Review Publications
Sparks, J.T., Dickens, J.C. 2016. Gustatory reception of chemicals affecting feeding in aedine mosquitoes. Pesticide Biochemistry and Physiology. doi: 10.1016/j.pestbp.2016.12.009.
Costa-Junior, L.M., Miller, R., Alves, P.B., Blank, A.F., Li, A.Y., Perez De Leon, A.A. 2016. Acaricidal efficacies of Lippia gracilis essential oil and its phytochemicals against organophosphate-resistant and susceptible strains of Rhipicephalus (Boophilus) microplus. Veterinary Parasitology. 228:60-64.
Denlinger, D.S., Durham, S., Li, A.Y., Lawyer, P.G., Andersen, J.L., Bernhardt, S.A. 2016. Comparison of in vivo and in vitro methods for blood feeding of Phlebotomus papatasi (Diptera: Psychodidae) in the laboratory. Journal of Medical Entomology. 53(5):1112-1116.
Borges, L.M., Li, A.Y., Olafson, P.U., Renthal, R., Bauchan, G.R., Lohmeyer, K.H., Perez De Leon, A.A. 2016. Neuronal projections from the Haller's organ and palp sensilla to the synganglion of Amblyomma americanum. Revista Brasileira de Parasitologia Veterinaria. 25(2):217-224.
Carroll, J., Babish, J.G., Pacioretty, L.M., Kramer, M.H. 2016. Repellency to ticks (Acari: Ixodidae) of extracts of nigella sativa L.(Ranunculaceae) and the anti-inflammatory DogsBestFriend™. Experimental and Applied Acarology. 70:89-97.
Tabanca, N., Dermici, B., Nalbantsoy, A., Bernier, U.R., Agramonte, N.M., Ali, A., Li, A.Y., Yalcin, H.T., Gucel, S. 2016. Essential oil composition of Pimpinella cypria and its insecticidal, cytotoxic, and antimicrobial activity. Natural Product Communications. 11(10):1531-1534.
Sparks, J.T., Bohbot, J.D., Ristic, M., Misic, D., Skoric, M., Mattoo, A.K., Dickens, J.C. 2017. Chemosensory responses to the repellent nepeta essential oil and its major component nepetalactone by the yellow fever mosquito, aedes aegypti, a vector of zika virus. Journal of Medical Entomology. doi: 10.1093/jme/tjx059.
Mcphatter, L., Mischler, P., Webb, M.Z., Chauhan, K.R., Lindroth, E. 2017. Laboratory and semi-field evaluations of two (Transfluthrin) spatial repellent devices against Aedes aegypti (L.) (Diptera: Culicidae). Army Medical Department Journal. Jan-Jun;(1-17):13-22.
