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.
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.
In 2018, progress was made on most 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, conducted mosquito surveillance using five traps designed to collect egg-laying female mosquitoes. Four locations in Maryland were used, including the Patuxent Wildlife Research Center. In translational mosquito research (Objective 2), the ARS scientist in Beltsville, Maryland, retired, effectively ending this thrust. In bed bug research (Objective 3), ARS scientists in Beltsville, Maryland demonstrated that several potential fumigants were effective in controlling both susceptible and chemically-resistant bed bug strains. These fumigants were considered “green insecticides” and controlled other, agriculturally-important insect pest species. In tick research (Objective 4), ARS scientists in Beltsville, Maryland, collected blacklegged ticks, the vector of Lyme disease, in three States (Maryland, Massachusetts, and Texas) and tested their responses to DEET and other repellent compounds. ARS scientists in Beltsville, Maryland also successfully evaluated four commercial natural products for their utility in tick control. Their repellency and toxicity against lone star ticks (vectors of other tick diseases such as Erlichiosis) were compared with those of DEET and permethrin, the standard technical repellent and acaricide compounds. Results indicate these products offer a natural way to repel ticks. ARS scientists in Beltsville, Maryland, in conjunction with ARS scientists in Stoneville, Mississippi, also completed a study to test five novel ant-derived compounds for repellency and toxicity against ticks. These ant-derived compounds were more effective in repelling ticks than DEET, but much less toxic than DEET. These ant-derived natural compounds may have utility as personal protection repellents and/or as chemical barrier at landscape scale.
1. Developing new strategies to control bed bugs. New strategies to control bed bugs are always in demand for both the public and companies involved in controlling these blood-sucking insect pests. ARS scientists in Beltsville, Maryland, in conjunction with university scientists in Towson, Maryland showed that fumigation with a naturally-occurring chemical was useful in controlling both chemically-susceptible and chemically-resistant bed bug strains. This information will help industry personnel develop new bed bug control methods.
2. Superior tick repellency of ant-derived compounds. Tick-borne diseases, such as Lyme disease, are the most important vector-borne diseases affecting Americans in the northeastern United States. ARS scientists in Beltsville, Maryland, and Stoneville, Mississippi, discovered superior repellency of several ant-derived compounds against lone star ticks that transmit pathogens to humans, livestock, and other animals. This information will help federal, university and pharmaceutical scientists to develop new natural repellent formulations for personal protection, thereby reducing the risk of tick bites and therefore, disease transmission.
Zha, C., Wang, C., Li, A.Y. 2017. Toxicity of selected essential oils, silicone oils, and paraffino oil against the common bed bug, cimex lectularius L. (Hemiptera: Cimicidae). Journal of Economic Entomology. 111(1):170-177.
Tisgratog, R., Sukkanon, C., Chauhan, K.R., Chareonviriyaphap, T. 2017. Evaluation of the constituents of vetiver oil against Anopheles minimus (Diptera: Culicidae), a malaria vector in Thailand. Journal of Medical Entomology. 55(1):193-199.
Chauhan, K.R., Le, T.C., Chintakunta, P., Lakshman, D.K. 2017. Phyto-fungicides: Structure activity relationships of the thymol derivatives against Rhizoctonia solani. Journal of Agricultural Chemistry and Environment. 6:175-185.
Machtinger, E.T., Li, A.Y. 2017. Evaluation of four commercial natural products for repellency and toxicity against the lone star tick, Amblyomma americanum (Acari: Ixodidae). Experimental and Applied Acarology. 73:451-460.
Choo, Y., Xu, P., Tan, K., Bhagavathy, G., Chauhan, K.R., Leal, W. 2018. Reverse chemical ecology approach for the identification of a mosquito oviposition attractant. Proceedings of the National Academy of Sciences. https://doi.org/10.1073/pnas.1718284115.
Welzell, K.F., Lee, S., Chauhan, K.R., Dossey, A.T., Choe, D. 2018. Verification of Argentine ant defensive compounds and their behavioral effects on heterospecific competitors and conspecific nestmates. Scientific Reports. 8:1477.
Chauhan, K.R., Webb, M.Z., Natarajan, S.S. 2018. Novel repellent and antifeedents properties lead us to investigate cultivation of the cat thyme T. Marum. African Journal of Biotechnology. 17(4):91-95.
Lakshman, D.K., Chauhan, K.R., Pandey, R., Choudhury, B. 2017. Evaluation of plant-based antifungal chemicals and control of damping-off caused by Rhizoctonia solani. Biopesticides International. 13(1):21-34.
Paez-Rondon, O., Aldana, E., Dickens, J.C., Otalora-Luna, F. 2018. Fixed action pattern in a kissing bug (Triatominae): vision, gustation, proboscis extension and drinking of water and guava. Journal of Ethology. https://doi.org/10.1007/s10164-018-0547-y.
Feldlaufer, M.F., O'Connor, L.L., Ulrich, K.R. 2018. Bed Bug Laboratory Maintenance. In: Doggett, S.L., Miller, D.M., Lee, C., editors. Advances in the Biology and Management of Modern Bed Bugs. Indianapolis, IN: John Wiley & Sons Ltd. p. 199-208.
Doggett, S.L., Feldlaufer, M.F. 2018. Limitations in bed bug management technologies. Advances in the Biology and Management of Modern Bed Bugs. 311-321. https://doi.org/10.1002/9781119171539.ch31.
Machtinger, E.T., Yang, X., Chen, J., Li, A.Y. 2018. Repellency and toxicity of five ant defensive compounds against the lone star tick, Amblyomma americanum (Acari: Ixodidae). Applied Entomology and Zoology. https://doi.org/10.1007/s13355-018-0559-7.