2008 Annual Report
1a.Objectives (from AD-416)
1) Identify, and evaluate chemical attractants to augment trap selectivity and efficacy under laboratory and field conditions.
2) Design, develop, and evaluate innovative, robust, automated and economically feasible traps capable of selective sampling of mosquitoes, biting and filth-breeding flies.
3) Investigate relationships between mosquito and fly biology, physiology, and behavior and disease transmission and surveillance.
4) Design and validate automated, remote surveillance systems that incorporate selective trapping and global information technology to direct control efforts.
1b.Approach (from AD-416)
Conduct basic laboratory and field research to determine the relationship(s) between mosquito biology, physiology, and behavior and disease transmission, surveillance, and control. Design, develop, and evaluate innovative, robust and inexpensive traps capable of selective sampling of biting and filth-breeding flies. Isolate, identify, and adapt chemical attractants to augment trap selectivity. Devise accurate biological assays to evaluate attractant activity for biting and filth-breeding flies under laboratory and field conditions. Design and validate surveillance systems based on an understanding of the quantitative relationship between mosquito activity in time and space and the presence/absence of biotic and abiotic factors with GIS technology to predict disease transmission patterns and to direct control efforts.
This research supports National Program 104 Veterinary Medical and Urban Entomology, Component 1 Ecology and Epidemiology, Component 2 Detection and Surveillance Technology and Component 3 Biology and Physiology. A thorough understanding of the habits of these insects is essential to the development and implementation of control strategies for the protection of livestock and people from mosquitoes and flies that may transmit pathogens. Among the pathogens that they transmit are viruses (e.g., West Nile and Rift Valley fever), bacteria and parasites that cause diseases in animals and humans. One objective of a field research project is to determine which mosquito species are responsible for transmission of West Nile virus to horses and humans. Information is being obtained on many aspects of the target species’ life cycles, such as temporal and spatial information on their breeding, feeding and dispersal patterns. Cues (visual, physical and chemical) that mosquitoes use to locate their hosts and subsequently oviposition sites are under investigation in laboratory, semi-field and field studies. Trap design, placement, various attractant combinations and delivery systems are being evaluated. Trapping, as a means to monitor mosquito populations, is an integral component of surveillance efforts; yet standard techniques for interpreting the results are lacking. Thus, another ongoing project is being conducted to determine trap biases. Knowledge of these biases is essential when deciding what traps to use, where and when to deploy them, and how to interpret the results that they produce. Efforts are being directed toward the use of spatial models to identify high risk areas for mosquito-borne diseases. These models will be used to guide intervention efforts. Understanding the limitations of mosquito surveillance data is necessary to improve the accuracy of these spatial models. Electrophysiological methods (GC-EAD, EAG and single-sensillum recordings) were initiated this year for identification of new compounds as host-associated (human and avian) and oviposition attractants for Culex and Aedes mosquitoes. Additionally, the characterization of the impact of known and new repellents and inhibitors on the electrophysiological responses of mosquitoes to host odors is on-going. New lures for Culex mosquitoes containing new compounds and mixtures of compounds developed under laboratory and field conditions are being evaluated. Laboratory, screen cage and field evaluations of different infusions determined optimal concentration and source material for attraction of gravid Aedes albopictus. Mixtures of compounds identified from bovine and avian blood that enhance the attraction and landing responses of Aedes aegypti and Culex quinquefasciatus were also developed. Precision methodology for in-flight analysis of orientation of mosquitoes to individual or combinations of chemicals was developed and used to characterize flight paths of Aedes aegypti to avian and human host odors that differ in volatility.
Efficacy of new oviposition lures for Culex. Trapping of gravid Culex mosquitoes, often used for arbovirus surveillance, relies on a hay infusion as an attractant. Instability, variation and inconvenience of the infusion are limiting factors in trapping. Mixtures of compounds identified by GC/MS and olfactometer assays were effective in attracting gravid mosquitoes in the laboratory and field. These mixtures form the basis for development of controlled-release lures for gravid Culex traps. This addresses National Program 104, Veterinary, Medical and Urban Entomology; Component 1: Ecology and Epidemiology, Problem Statement - Understanding of the habits of harmful arthropods.
Effectiveness of “field-expedient” fly traps. In response to a request by U.S. Navy personnel, the effectiveness of bottle traps constructed from ready-to-hand materials (empty water bottles) was evaluated following guidelines in the military manual on fly control. Molasses was superior to honey, maple syrup, and jaggery for baiting the traps. None of the traps performed as well as a commercial product, but the simple expedient of painting the top halves of the traps black resulted in a 6-fold improvement in trap catch. This addresses National Program 104 Veterinary, Medical and Urban Entomology, Component 2 Detection and Surveillance Technology, Problem Statement - Harm caused by arthropods.
Develop sampling procedures for adult mosquito populations. New and improved methods are needed to obtain accurate estimates of adult mosquito population density for purposes of vector abatement and to prevent disease epidemics. In this study, the capture rate responses of five mosquito species to CDC-type light trap (LT) and human landing (HL) collection methods were evaluated using HL responses as a comparison baseline. The efficiency of LT compared to HL varied significantly for each species but was generally <10%. For four of the mosquito species studied, fitted regression models of the relationship between LT and HL indicated that mosquito landing rates on human subject could be accurately approximated from capture rate responses to LT. LT collections between sunset and sunrise were most precise in this regard for Anopheles quadrimaculatus and Culex nigripalpus as were those between sunrise and sunset for Cx. quinquefasciatus and Ocherotatus triseriatus. There was no significant relationship between LT and HL responses for Aedes albopictus. This addresses National Program 104 Veterinary, Medical and Urban Entomology, Component 2 Detection and Surveillance Technology, Problem Statement - Harm caused by arthropods.
Develop strategies for the deployment of mosquito traps in vector surveillance systems. Use environmental predictors of mosquito activity in a GIS to identify ideal locations for the placement of mosquito traps in a vector surveillance system. In this study, historical vector surveillance data (from Chatham County Mosquito Control, Savannah, GA) have been organized into a geodatabase. Land use was classified and NDVI calculated from a 15m Landsat image. Other ecological elements such as urbanization, proximity to storm sewers, and the age of associated structures in the study region were obtained, quantified, and/or derived and selected locations characterized on the basis of these parameters and vector density. Several of the predictor variables thus identified are correlated with vector activity and comprise terms in a predictive model that will be used to identify locations in the environment for the placement of mosquito traps. This addresses National Program 104 Veterinary, Medical and Urban Entomology, Component 2 Detection and Surveillance Technology, Problem Statement - Harm caused by arthropods.
Effectiveness of commercial fly traps in selected climates. In response to a request by the Armed Forces Pest Management Board, a comparison was made between the Farnam Captivator Fly Trap and the Bayer liquid Quickbayt under the dry environmental conditions in Cairo, Egypt. The Bayer bait is applied in a liquid form but becomes dry after application. The Farnam trap, which captured significantly more flies in our previous evaluations in Cairo than any other commercial trap or dry bait, captured significantly more flies than the Bayer Quickbayt. As a result of our evaluations in Cairo in 2006 and 2007, the Farnam Captivator Trap was given a national stock number (NSN) and is now available for purchase by US government agencies. This addresses National Program 104 Veterinary, Medical and Urban Entomology, Component 2 Detection and Surveillance Technology, Problem Statement - Harm caused by arthropods.
Attractants for sand flies. Lures and placement location were tested in studies with MMX mosquito traps to improve capture of sand flies. A human odor sample, octenol, and carbon dioxide were tested in a Latin square design in Aswan, Egypt. Extracts of human odors in combination with carbon dioxide did attract larger number of flies, however the difference was not statistically significant compared to the use of carbon dioxide alone as the lure. The Phlebotomus papatasi captured were impacted numerically by the placement of the trap, but again, the differences were not significant. Future efforts are underway to explore the use of repellents in this system and the use of other odors from preferred hosts of sand flies. This addresses National Program 104 Veterinary, Medical and Urban Entomology, Component 2 Detection and Surveillance Technology, Problem Statement - Harm caused by arthropods.
Detection of resting sites of adult sand flies. Potential resting sites of adult phlebotomine sand flies were sampled in a village in Aswan, Egypt. Adults were captured in low piles of mud bricks with a suction device and trapped on sheets of adhesive paper. Most of the flies collected were Phlebotomus papatasi, a vector of leishmaniasis in the Middle East. A better understanding of the resting sites of adult sand flies will lead to more effective adult sand fly control. This addresses National Program 104 Veterinary, Medical and Urban Entomology, Component 2 Detection and Surveillance Technology, Problem Statement - Harm caused by arthropods.
Commercial mosquito traps were tested for their ability to capture Phlebotomus sand flies. Four commercial adult mosquito traps (Mosquito Magnet Pro, Sentinel 360, Mega-Catch ULTRA and BG-Sentinel) against the standard Centers for Disease Control and Prevention (CDC) light trap. The Mosquito Magnet Pro produced its own carbon dioxide, the CDC light trap and BG-Sentinel traps were provided with dry ice, while the Sentinel 360 and Mega-Catch ULTRA were not baited with a carbon dioxide source. Traps were operated in a small farming village in the Nile River Valley located 10 km north of Aswan, Egypt. Phlebotomus papatasi constituted 93.7% of the 6,440 sand flies collected. Trap means were BG-Sentinel (142.1)>Mosquito Magnet Pro (56.8)>CDC light trap (52.3)>Mega-Catch ULTRA (38.2)>Sentinel 360 (12.6). This addresses National Program 104 Veterinary, Medical and Urban Entomology, Component 2 Detection and Surveillance Technology, Problem Statement - Harm caused by arthropods.
Continued work creating strategic inter-agency partnerships and synthesizing research programs to protect the US against Rift Valley fever, a potential emerging mosquito-borne viral threat. Rift Valley fever virus (RVFV) is a potential emerging mosquito-borne viral threat that could have severe economic and public and veterinary health impacts should it emerge in the US. Although US agencies and universities are actively creating response/surveillance plans for RVFV and researching critical technological advances such as diagnostics and vaccines, we risk confusion and delay due to lack of communication and/or integrated response efforts should RVFV unexpectedly arrive in the US. MFRU staff continued to organize key researchers and administrators from several federal and state agencies and universities into a Working Group to formulate synthesized response plans, avoid duplicating research efforts, and set a future trajectory that will significantly strengthen and protect the US against the possible arrival of RVFV. MFRU staff co-organized the Fourth RVF Working Group meeting in July 2008, bringing in several new key members, compiling new information for a second draft of a comprehensive RVFWG White Paper, and confirming through in-depth discussions among key members that the three previous meetings continue to have a tangible positive impact on RVF research direction and outcomes. A latent but high-value impact of this Working Group is that its products and partnerships will be laterally transferable to other mosquito-borne viruses currently or potentially impacting the US economy and public and veterinary health. This addresses National Program 104 Veterinary, Medical and Urban Entomology, Component 2 Detection and Surveillance Technology, Problem Statement - Harm caused by arthropods.
Continued synthesis and analysis of temporal and spatial dynamics of US mosquito population surveillance data at the national level. Population dynamics of medically-important species of mosquitoes in the US are poorly understood at regional and national levels. Particularly lacking are GIS models of climate-population associations that could predict the temporal and spatial dynamics and abundance of important mosquito species, thus serving as key elements of mosquito borne disease risk maps. To resolve this problem, mosquito population surveillance data and climate data from across the US have been accumulated. Focusing on potential US mosquito vectors of Rift Valley fever (RVF) virus, results of pilot studies showing that US satellite-based climate data are a powerful tool in forecasting high densities of mosquitoes at local, regional, and national levels have been published. The techniques developed in these pilot studies, and new techniques developed with NASA collaborators, have been used in the analysis of long-term mosquito population surveillance data from the Chatham County Mosquito Control Program in Savannah, Georgia. This analysis demonstrated that patterns derived from the combination of satellite and ground-based environmental data are strong predictors of unusually high densities of medically important mosquitoes. Integrating these products with the remote-sensing RVF virus prediction model for Africa, also developed by scientists at CMAVE, will lead to development of an RVF virus early-warning GIS for the US which will target key areas such as ports for heightened disease surveillance, prevention and response efforts; potentially reducing severity of future exotic mosquito-borne disease outbreaks in this country. This addresses National Program 104 Veterinary, Medical and Urban Entomology, Component 2 Detection and Surveillance Technology, Problem Statement - Harm caused by arthropods.
Enhanced mosquito attraction and membrane feeding with volatile attractants from blood. Blends of volatile compounds chemically identified from bovine and avian blood were evaluated for their role in enhancing orientated flight and landing responses to membranes. These attractant chemicals from blood can form the basis for enhanced trap attractants for mosquito surveillance and control programs and for enhanced membrane feeding methods for mosquito colony maintenance. This addresses National Program 104 Veterinary, Medical and Urban Entomology, Component 1 Ecology and Epidemiology, Problem Statement - Understanding of the habits of harmful arthropods.
5.Significant Activities that Support Special Target Populations
|Number of Non-Peer Reviewed Presentations and Proceedings||5|
Xue, R.-D., Ali, A., Barnard, D. R. 2008. Host species diversity and post-blood fedding carbohydrate availability enhance survival of females and fecundity in Aedes albopictus (Diptera: Culicidae). Experimental Parasitology. 119(2008):225-228.
Britch, S.C., Linthicum, K. 2007. Gis early-warning system for vectors of rift valley fever: anomaly analysis of climate-population associations. California Mosquito and Vector Control Association Proceedings.
Linthicum, K., Allan, S.A., Barnard, D.R., Becnel, J.J., Bernier, U.R., Britch, S.C., Clark, G.G., Cooperband, M.F., Geden, C.J., Hogsette, Jr, J.A., Kline, D.L., Pereira, R.M., Wei Pridgeon, Y., Quinn, B.P., Reinert, J.F., Welch, C.H., Zhao, L. 2007. Mosquito and Fly Control Research by the USDA-ARS Center for Medical, Agriculture and Veterinary Entomology (CMAVE) in the Deployed War-Fighter Protection (DWFP) Program. California Mosquito and Vector Control Association Proceedings. 75:131-133.
Brown, H. E., Paladini, M., Cook, R. A., Kline, D. L., Barnard, D. R., Fish, D. 2008. Effectivness of mosquito traps in measuring species abundance and composition. Journal Medical Entomology. 45(3):517-521.
Kobylinski, K.C., Allan, S.A., Connelly, R. 2007. Aspirator modification for the removal of mosquitoes from tight spaces. Journal of the Mosquito Control Association. 23(4):492-495
Linthicum, K., Allan, S.A., Barnard, D.R., Becnel, J.J., Bernier, U.R., Carlson, D.A., Geden, C.J., Clark, G.G., Hogsette, Jr, J.A., Kline, D.L. 2008. Overview of Mosquito Research Programs at the United States Department of Agriculture - Agricultural Research Service, Center for Medical, Agricultural & Veterinary Entomology. Wing Beats of the American Mosquito Control Association. 19(1):31-34.
Chretien, J., Linthicum, K. 2007. Chikungunya in Europe: What’s next? Lancet. 370(9602):1805-6.
Hogsette, J.A., Nalli, A., Foil, L.D. 2008. Evaluation of different insecticides and fabric types for development of treated targets for stable fly (Diptera: Muscidae) control. Journal of Economic Entomology. 101(3):1034-1038.
Vavra, J., Becnel, J.J. 2007. Vavraia culicis (Weiser, 1947) Weiser, 1977 revisited: cytological characterisation of a Vavraia culicis-like microsporidium isolated from mosquitoes in Florida and the establishment of Vavraia culicis floridensis subsp. n. Folia Parasitologica. 54:259-271.