NE1443: Biology, Ecology & Management of Emerging Disease Vectors
(Multistate Research Project)
NE1443: Biology, Ecology & Management of Emerging Disease Vectors
Duration: 10/01/2014 to 09/30/2019
Statement of Issues and Justification
The need. Despite ongoing extraordinary medical advances infectious diseases are on the rise worldwide and account for a quarter of all human mortality and morbidity. Diseases once thought to menace only remote tropical inhabitants are now spreading everywhere, fueled by international travel. Of particular concern are arthropod-borne diseases. After the recent West Nile virus epidemic that swept through the US within 5 years impacting thousands and killing many, there has been a recent confirmed case of locally-transmitted dengue fever in New York, as well ongoing epidemics in Texas and Florida. Additionally, for the first time in the Western Hemisphere, local transmission of chikungunya has been detected in the Caribbean with over 5,000 confirmed cases of chikungunya since the fall of 2013 (Anon. 2014a). Experts predict local epidemics of chikungunya in the USA within two years. Dengue, chikungunya virus and other mosquito-borne pathogens can be deadly to humans and there are no vaccines or therapeutic drugs. Vector avoidance and control remain our only means against disease spread. In addition to pathogen spread, medically important arthropods are establishing and spreading in the USA, with recent examples that include the Yellow Fever mosquito (Aedes aegypti) and the Asian Tiger mosquito Ae. albopictus (Rochlin et al. 2013), both reported in California within the last two years. Furthermore, new mosquitoes are also arriving, such as Ae. j. japonicus, a cold weather adapted mosquito that is becoming increasingly common in the urban and suburban USA (Kaufman & Fonseca 2014).
While outbreaks of mosquito-borne arboviruses pose serious risks to the public, tick-borne diseases are the most common vector-borne diseases in the USA. Blacklegged ticks (Ixodes scapularis) are the primary vectors of most of these pathogens, including Lyme Disease. Every year, there are over 20,000 confirmed cases of Lyme disease, and CDC has recently noted that this is likely a 10 fold underestimate. In addition, many new tick borne pathogens have emerged in the past 20 years. Confirmed cases of human anaplasmosis (first described in the 1990’s) now exceed 1000/year in the Upper Midwest, with an additional focus on the east coast. Other pathogens, while still rare, are also associated with rising incidence of human disease. These include human babesiosis and new bacterial pathogens such as an agent closely related to Ehrlichia muris (Pritt et al. 2011) and an undescribed species of Borrelia. Tick-borne viruses are also a concern. Human infections with Powassan/deer tick virus have been steadily increasing, frequently causing mortality and serious disability (Khoury et al. 2013). In, 2012 a tick borne virus (Heartland virus) was first described in Missouri (McMullan et al. 2012). The suspected vector is the Lone star tick, Amblyomma americanum. This virus, new to the Western Hemisphere has caused illness in 8 humans and one death as of March 2014. The changing patterns of tick-borne disease reflect the fact that tick species (such as Ixodes scapularis and Amblyomma americanum) are expanding their range, and tick population sizes are increasing. Ecological changes, including increases in the populations of wildlife reservoirs, altered climate, and changes in forest and landscape features are clearly important contributing factors. In the near term, these changes will likely lead to an even greater burden on human health with continuing increases in Lyme disease as well as other tick borne infections.
Encouragingly, important advances are being made in areas that include new methods and tools for monitoring and controlling mosquitoes and ticks. However, the budgets for research and abatement programs have been substantially reduced. Thus, improved information sharing and coordination will result in better decisions in applying the limited resources, standardization of monitoring and control tools and teams able to better compete for limited funding resources.
The availability of vector resources (laboratory colonies, cell cultures, pathogen strains) are critical components for investigations to prevent the spread of pathogens by vectors. The aim of this project area is to support and promote available resources such as the BEI Resources established by the National Institute of Allergy and Infectious Diseases (NIAID) for human pathogens and to identify alternative sources for vector resources beyond those found in BEI.
The importance of the work and consequences if not done. Arboviruses are the most significant cause of mosquito-borne disease in the U.S. Arboviral infections often result in encephalitis, a brain inflammation which can result in death or severe neurologic after-effects. U.S. mosquitoes transmit several serious endemic encephalitic viruses including St. Louis, LaCrosse, Venezuelan, and eastern and western equine encephalitis. There are no vaccines, antibiotics, or treatments for viral encephalitis. Mitigation centers on controlling the mosquito vectors.
The introduction and rapid dispersal of mosquito-borne West Nile virus (WNV) has effectively demonstrated the infectious threat posed by arboviruses. WNV is merely the latest in a series of infectious viruses of national public health significance to be introduced into the United States. This virus swept across the country following its appearance in New York in 1999, and the disease is now endemic in the continental 48 states. The outbreak constituted the largest documented epidemic of mosquito-borne meningoencephalitis in the history of the western hemisphere. Although principally a disease of birds (explaining its swift dispersal), nearly 40,000 people in the U.S. have become infected with WNV with 1,610 deaths recorded to date. The elderly and children are at particular risk of developing serious illness. In addition to human cases, WNV has had an important impact on livestock also. For example, 26,918 equine cases have been reported in the USA, between 1999 and November 13, 2013 (Anon. 2014b).
The U.S. will continue to experience the arrival of new arboviral diseases. Consider chikungunya virus, a deadly infectious disease that causes crippling arthritic damage to survivors. The virus has infected more than 10 million people in the Indian Ocean region in a massive eruption since 2001. Closer to home, ten cases were reported in December 2013 in St. Martin in the Caribbean, the first time chikungunya was reported in the western hemisphere. By early May 2014, over 5,000 confirmed cases in the Caribbean have been reported (Anon. 2014a). Even before this new threat, nearly a dozen U.S. states have reported cases of travelers infected with chikungunya virus that returned from Asia and East Africa. Ultimately, infectious patient will meet competent vector and the disease will undergo establishment, amplification, and dispersal. The U.S. not only is a travel and immigrant destination but also has highly competent vectors. Or consider dengue, currently the predominant worldwide mosquito-borne viral disease in humans. Dengue is endemic in >100 countries and infects 100 million persons each year with 2.5 billion at risk. The World Health Organization has reported a 30-fold incidence increase in dengue over the past 50 years. Finally, Rift Valley fever virus (RVFV) (Pepin et al. 2010), is an arbovirus currently epidemic in Africa that due to its high morbidity and mortality if introduced into the US would have a tremendous impact on livestock and man. Again, mosquito vectors are already abundant in the USA (Xue et al. 2013).
The economic impact of mosquito-borne illness is devastating. The cost of treating WNV infections has been immense, with Louisiana estimating $70 million for 2002 alone. The estimated cost per human case of eastern equine encephalitis (EEE) is $3 million. EEE and WNV both threaten the nation’s multi-billion dollar equine industry. The mortality rate of horses infected with WNV is 34 percent; the rate for those with EEE approaches 100 percent. In 2000, the estimated loss in New Jersey due to equine cases of WNV was $6 million. Tourism, which increases human exposure to mosquitoes, is similarly impacted by outbreaks of mosquito-borne disease. This was effectively demonstrated in 1959 in New Jersey, when 21 out of 32 infected people died during an EEE outbreak, resulting in tourism coming to a near standstill. Since the discovery of EEE virus in the 1930s, outbreaks in temperate regions have been sporadic, both temporally and spatially, highly focal, and largely unpredictable. However, over the last decade, we have witnessed a sustained resurgence of EEE virus activity within long-standing foci in the northeastern US and unprecedented northward expansion into new regions where the virus had been historically rare or previously unknown, including northern New England and eastern Canada. This has resulted in severe disease in humans (46 cases with 16 fatalities) and domestic animals (173 cases). The factors responsible for reemergence of EEE are largely unknown but are likely complex reflecting ongoing changes in the ecology and epidemiology of this virus that may be exasperated with global climate change.
The lessons learned from WNV and the threat posed by additional new and emerging arboviruses serve as an impetus for bolstering U.S. vigilance against insect-borne diseases (Anyamba et al. 2014), particularly when we consider their potential to be used by terrorists (Tabachnick et al. 2011). The U.S. requires research and outreach capabilities that provide answers to preventing and controlling outbreaks of arboviruses and other pathogens transmitted by mosquitoes.
We are proposing 5 key emphasis areas for this Multistate project: (1) development of parasitic arthropod catalogue/resources; (2) integrated tick management and community-centered approaches, including understanding the biology and ecology of novel and emerging tick-borne pathogens; (3) Ae. albopictus and Ae. aegypti, with a focus on surveillance, invasion ecology, genetics; (4) new control tools, including socio-ecological approaches; and (5) new training and training tools. Each of these areas is important and can be most effectively and efficiently addressed in a larger multistate context.
The technical feasibility of the research. Our research will focus on genetic and ecological studies of mosquitoes and ticks. The targeted vectors include Ae. aegypti, Ae. albopictus and Cx. pipiens, which are three of the most important mosquito vectors nationally and Ae. j. japonicus, the newest arrival to the US and a model of rapid evolution and changing vectorial capacity in an exotic disease vector. Our tick projects will focus on I. scapularis and A. americanum. Research will also evaluate new monitoring and control tools and methods, targeting the identification, treatment and elimination of vectors within different locations and ecological contexts. The proposed research is technically feasible, but only if done by a coordinated team. Our committee is composed of top entomologists in the US who study vector and pathogen biology, with the required experience and facilities. Thus, we are confident we can succeed with the proposed research.
The advantages for doing the work as a multistate effort. This work cannot be completed without a multistate effort. In a rapidly-changing landscape, the experience and guidance of one region is critical to others. As a specific example, both Ae. aegypti and Ae. albopictus have recently established in California, and California abatement districts have benefited from the experience of those in the east coast states where these species are often common. Ae. albopictus has also only become entrenched and abundant in New York and Connecticut in the last 5 years. Both states have unique ecology, geography, and socioeconomic settings that will require customization of surveillance, education and control strategies developed in other regions. Conversely, other researchers bring to the table experience working with populations afflicted with dengue, a set of skills that will likely be needed more broadly across the USA. Research on ticks and tick-borne pathogens is lagging behind efforts directed towards mosquitoes, likely a reflection of their much more recent emergence.
Participants in this project represent a diverse group of scientists from Universities as well as federal and state government institutions conducting a broad range of research on vectors of human and animal pathogens. The institutional knowledge of this group as both users and holders of vector resources will be essential for achieving the stated objectives.
What the likely impacts will be from successfully completing the work. The project seeks to build an interactive and interdependent network of scientific expertise to deal with expanding/invasive tick and mosquito species and mosquito-borne disease outbreaks. The project will affect all U.S. residents by understanding, assessing, and mitigating the threat posed by mosquitoes of public health importance. Further, we anticipate enhanced ability to detect and predict outbreaks of vectors and associated diseases. The project further provides for and encourages environmentally sound, scientifically based, and professional control by mosquito control agencies. We are requesting an extension of the project for another 5 years. Since 2010, we have met and exchanged published and unpublished results and have vetted ideas from group participants. We are now ready to start developing collaborative proposals for federal funds. In addition, some of our activities, such as the development of an arthropod catalogue, will result in enhanced visibility on the availability of vector resources for human and animal pathogens.
Related, Current and Previous Work
Some of the key outcomes of the prior NE-1043 project include:
• Public health studies indicating that ‘nuisance’ Ae. albopictus negatively impacted public health by reducing outdoor physical activity (including children’s).
• Improved understanding into the mechanisms that regulate host-parasite life cycle synchrony in mosquito parasitic mermithids. Host penetration and emergence patterns and behaviors are described.
• Studies to improve the use of native fish and copepod species for biological control of Culex pipiens/restuans.
• Analysis of early season blooded Cx. restuans reveal the importance of nesting birds as sources of blood.
• Analysis of the effects of forced-egg retention on the blood-feeding behavior and reproductive potential of Culex pipiens suggest that during droughts populations of Cx. pipiens have time to locate the remaining water holes, which are associated with human populations and WNV-competent bird species.
• Development of innovative rapid assays to detect human blood in mosquitoes.
• Host feeding studies demonstrated that Ae. albopictus feeds predominately on mammals, which matches the new evidence they are seldom infected with WNV.
• Oviposition studies have revealed that female Ae. albopictus shifts from density dependent skip-oviposition in the summer to egg accumulation in the fall. These findings affect the interpretation of surveillance approaches that use ovicups and allow for the development of new control approaches.
• Modeling and laboratory vector competence studies highlighted the risk of introduction and establishment of Chikungunya virus in the US through Ae. albopictus mediated transmission
• New information on the mating biology and behavior of Ae. albopictus
• New understanding of the role of community ecology in the invasion of Ae. japonicus japonicus.
• Population genetic studies of Ae. j. japonicus in Hawaii reveal effects of temperature/elevation on this expanding species that deny expectations of mathematical models.
• Ecological studies illustrating the effect of elevated CO2 on Aedes through changes in litter resources
• Design and construction of new control devices, including unmanned aircraft capable of applying larvicides
• Design, construction and testing of an autodissemination station for the transfer of an insect growth regulator to container mosquitoes. The latest prototype provided up to 89% reduction in Ae. albopictus field populations. Option to License agreement signed for the station technology.
• Improved definition of (1) the urban Ae. albopictus larval habitat and (2) optimal trap placement for adult surveillance.
• Mark release recapture trials and improved methods for measuring mosquito dispersal and survival.
• Contained trials of a microbial pesticide approach against mosquitoes, in which sterility is caused by Wolbachia bacteria.
• Study demonstrating that dsRNA constructs targeting mosquito genes can be delivered in a sugar meal as part of an attractive toxic sugar bait strategy (Coy et al. 2012).
Related Multistate Projects: A search of the national multistate website reveals no other project involving mosquitoes or ticks.
Development of parasitic arthropod catalogue/resources
Integrated tick management and community-centered approaches, including understanding the biology and ecology of novel and emerging tick-borne pathogens
Ae. albopictus and Ae. aegypti, with a focus on surveillance, invasion ecology, genetics
New Control Tools, including socio-ecological approaches
Training and training tools
Objective 1: Development of parasitic arthropod catalogue/resources
The availability of vector resources (such as laboratory colonies, cell cultures, pathogen strains) is often a critical component of investigations to prevent the spread of pathogens by vectors. The aim of this project area is to support and promote available resources such as the BEI Resources established by the National Institute of Allergy and Infectious Diseases (NIAID) for human pathogens and to identify alternative sources for vector resources beyond those found in BEI. The main objective is to support, promote, and enlarge the BEI resource for pathogens and vectors of human disease to include the identification and development of alternative resources that can be used to facilitate the study of arthropod vectors and arthropod-borne zoonotic disease agents of human and animal health importance
The BEI Resources established by NIAID is a comprehensive catalogue of publicly accessible arthropod resources related to human pathogens. According to Dr. Timothy Stedman, Principal Investigator BEI Resources, NIAID is selective with the vector strains and reagents accepted and maintained due to limitations on resources and maintenance capacity. Less common strains, lower demand (low research use), genetic variants or difficult to maintain vectors may not receive support for deposit in BEI. Also, there are occasional researchers that may be unwilling to deposit items in NIAID’s collection but are willing to distribute to investigators, and there is value in identifying alternative sources and lineages of potentially fragile colonies even if held in BEI, to circumvent issues of loss or genetic drift/contamination. In addition, agriculturally important vector resources are not accepted by BEI and are currently held by individual researchers and laboratories. Identifying and making available information on agriculturally important vector resources and others not available through BEI will enhance investigations on human and animal pathogens conducted by project participants as well as the larger research community.
The project will work in conjunction with the established BEI Resources (tentative support for this effort given by Dr. Timothy Stedman, Principal Investigator BEI Resources, Dr. Adriana Costero, Vector Biology Program manager, NIAID and Dr. Susan Luckhart, School of Medicine, U.C Davis). Project participants will compile a database of vector resources and availability held by members of the group and their institutions and subsequently expand this to include resources held by non-participants and institutions. In collaboration with BEI, the project would identify and recommend vector resources for consideration to be added to the BEI collection. In addition, the group would identify vector resources important for research on animal diseases and agricultural importance and compile into a database. Best methods for distribution of this database and a role for the group to support, promote and expand vector resources will be pursued.
Objective 2: Integrated tick management and community-centered approaches, including understanding the biology and ecology of novel and emerging tick-borne pathogens
The rapid increase in the incidence of human illness due to tick-borne pathogens requires better integration of available management options as well as development of new approaches. The aim of Objective 2 will be to improve methods for assessment of infection status of ticks and reservoirs, to assess ecological features that regulate tick density, and to test and develop methods for suppression of ticks or pathogens in urban and suburban environments. The specific objectives are:
1) Develop and validate a multiplex PCR for identification of Borrelia burgdorferi sensu stricto, Anaplasma phagocytophilum (human-infectious), the Ehrlichia muris-like agent. andPowassan virus in ticks and reservoirs using a single assay.
Currently, there is no 1-step assay to detect and distinguish the multiple well-known tick-borne pathogens B. burgdorferi s.l. and the human-infectious A. phagocytophilum (i.e., Ap-ha) from newly emerging pathogenic species (e.g., Borrelia myiamotoi, the Ehrlichia muris-like agent or EMLA) or from closely related non-human pathogenic genotypes (e.g., A. phagocytophilum Ap-var1 infecting deer). This clouds the epidemiology of important tick-borne illnesses such as Lyme disease and anaplasmosis, and causes related emerging pathogens to go undetected. Current PCR-based methods require sequence verification to distinguish novel species, which is cumbersome, expensive, and not usually done. A multiplex assay has great potential to facilitate rapid assessment of infection status of animal reservoirs and vector-status of ticks, and will provide data on geographic distribution that will guide risk assessment and control efforts.
This aim will further be facilitated by advances achieved by the collaborators and their colleagues, i.e., 1) in vitro culture of Ap-ha and Ap-var1 and identification of a marker to distinguish Ap-var1 from Ap-ha using genomic sequences of multiple Ap isolates (Al-Khedery and Barbet 2014; available in GenBank); 2) in vitro establishment of two different isolates of EMLA (Pritt et al. 2011; Lynn et al. 2012), and whole-genome sequencing of one of these. We will use bioinformatics including BLASTN to identify diagnostic sequences of the EMLA genome that can be targeted to differentiate it from Ehrlichia chaffeensis for which multiple genome sequences are available in GenBank already. Targets specific for B. burgdorferi s.s and s.s have previously been identified (Marconi et al.), and we will initially design our assay using those. To identify sequences that are unique to B. myiamotoi found in ticks in an area of Wisconsin identified by Dr. Paskewitz, we will compare its chromosome (sequence available; Hue et al. 2013) to sequences of B. burgdorferi s.l. Alternatively, we can target the flagellin gene (Krause et al. 2013). If we have difficulties with targets identified in silico, we will initially use broad-range primers (Weissburg et al.) for amplification, and sequence the product.
We will additionally include primers that amplify sequences of the deer tick virus lineage (DTV) of Powassan virus, the lineage found in Wisconsin. Multiple complete of partial sequences have been determined and are available in GenBank (Pesko et al. 2010). This will allow us to evaluate the spatial distribution and environmental risk of Powassan virus infection by estimating the prevalence of virus infection in field-collected I. scapularis ticks. Powassan encephalitis is a relatively rare but serious viral infection that has been documented in Canada, the U. S. A., and eastern Russia. Powassan virus comprises two genotypes: POW (lineage 1) and Deer tick virus (DTV) (lineage 2), each with a distinct natural history. The POW lineage is maintained in an enzootic cycle involving mainly Ixodes cookei and I. marxi and medium-sized mammals, such as red squirrels, groundhogs, and skunks, whereas the DTV lineage has been isolated primarily from Ixodes scapularis. Episodes of human disease have become increasingly prevalent in Lyme disease endemic regions of the northeastern and northcentral US suggesting that these cases were caused by DTV and I. scapularis ticks. Accordingly, I. scapularis nymphs and adults will be sampled and tested for Powassan virus (DTV) to derive acarological estimates of risk in newly emergent regions. Phylogenetic studies of isolates will be conducted to determine viral genotype and strain variability.
2) Determine how A. phagocytophilum variants that are infectious for humans (Ap-ha) or not (Ap-var1) compete in natural transmission cycles with each other and possibly with E. muris.
Closely related bacteria co-infecting ticks compete with each other in a phenomenon described as interference, and this can affect disease epidemiology as has been shown for Rocky Mountain spotted fever caused by Rickettsia rickettsii and non-pathogenic Rickettsia peacockii. Nothing is known about HOW or IF Ap-var1 (which only infects deer) interferes with maintenance and transmission of Ap-ha (which infects humans and small animal reservoirs) or the closely related EMLAin nature. Epidemiologic data and analysis of ticks and wild mammals suggest that Ap-ha and Ap-var1 are maintained in separate transmission cycles in the field. This hypothesis is supported by several findings: 1) an area in central Minnesota that is highly endemic for Ap-var1 (Johnson et al. 2011) does not have a significantly higher incidence of human anaplasmosis than surrounding areas (MN Department of Health data); 2) ticks collected from deer only carry Ap-var1; 3) small mammals sampled in the area are never infected with Ap-var1. This separation of variants may be maintained by outcompetition of Ap-ha by Ap-var1, or by feeding behavior of ticks that favor deer as immatures. The fact that immature I. scapularis readily feed on deer is well-known (Kirby Stafford III, pers. comm.). Concerning the prevalence of EMLA in ticks, there is as yet no satisfactory explanation for why it is so much less common than Ap with which it shares the same vector, since it was already present in Wisconsin over two decades ago (Telford et al. 2011). This work will also be facilitated by the development of the multiplex PCR assay above, but can be initiated and carried out using single-plex PCR methods. Results would provide a first analysis of the ecology of human anaplasmosis and ehrlichiosis in the upper Midwest, and guide human disease risk estimates.
3) Quantify tick abundance across forest types and assess the role of biotic and abiotic factors in regulating tick populations. A key aspect of this work will focus on determining how the abundance and activity of white-tailed deer affect tick populations and spatial distribution and whether a threshold density is required to maintain Lyme disease transmission.
Whereas much information has been accumulated on the ecology of Lyme disease and the life history of the vector tick in the Northeast, much less information is available for the upper Midwest (Munderloh and Kurtti 2011). Notably, the 1.5-year life cycle of I. scapularis is not upheld here, and activity of adults extends well into July, overlapping with nymphal activity (our unpublished observations). Therefore, models developed for other regions are not applicable to the upper Midwest without substantial modificatons, and a reassessment of factors regulating tick populations in Wisconsin and Minnesota is reasonable. We envision that programs aimed at regulating deer densities will most benefit suburban areas and new housing developments that favor natural settings in which deer thrive. Exclusion/reduction of deer may also be desirable in areas where cattle are grazed on pastures to reduce the incidence of tuberculosis (e.g., in Northwestern Minnesota)
4) Integrate host-targeted and area-wide methods for suppression of tick populations in newly emerging foci in urban/suburban areas. This work will focus on development of a community-based approach similar to abatement districts used to control mosquitoes.
Several methods targeting small and large animal hosts of ticks have been developed, such as baited boxes to attract small rodents to enter a box in a manner that results in application of an acaricide to the animal, containers offering acaricide-impregnated nesting material for mice, and the 4-poster developed by the USDA to control Lone star ticks on deer. These are easily adaptable to Midwestern settings, and may have the advantage that only one seasonal application may be needed due to the different phenology of black-legged ticks in that region. Additionally, salt licks or corn impregnated with ivermectins may provide an alternative that has proven successful on an island in Maine, and could lend itself well to an integrated control program (Rand et al. 2000).
Objective 3: Ae. albopictus and Ae. aegypti, with a focus on surveillance, range expansion, ecology, genetics, climate change and disease risk
The key outcome will be improved knowledge of the biology of two of the most important disease vectors in the USA, the Asian tiger mosquito (Ae. albopictus) and the yellow fever mosquito (Ae. aegypti). While much work has been conducted already on these species, not enough is known about their recent biology, especially in areas where Ae. albopictus has recently invaded (Northeastern States), or where a resurgence in population abundance is occurring for Ae. aegypti (Florida) where it overlaps with Ae. albopictus but appears to have a competitive advantage in hot dry areas due to increased resistance to egg dessication (Juliano et al 2002). This objective will involve investigations of climate change, invasion biology and the impact these factors will have on risk for vector borne disease transmission. Specifically, we will conduct experiments to investigate biological traits and conditions that allow the Asian tiger mosquito to spread and for Ae. aegypti to dominate and develop models for predicting the limits of range expansion shifts in population abundance, and temporal targets for vector control. We will begin by examining the thermal overwintering constraints for Ae. albopictus in the Northeast region using natural and manipulated overwintering field experiments. In addition, we will examine conditional limits for egg desiccation tolerance in Ae. albopictus and Ae. aegypti. We will then take the data generated from our experiments in year 1 and 2 to develop models that will allow us to predict the range expansion and distribution of these two important disease vectors with predicted climate change. We will estimate population sizes using data generated through our existing network of surveillance programs. Models will be expanded in years 3 and 5 to incorporate estimates of disease transmission risk (Brady et al 2013, Brown et al 2012, Wang et al 2014, Ruiz-Moreno et al 2012). A key component of project will be development of simulations to understand the most effective timing and type of vector control to use in the face of an outbreak threat. In addition, we will gather environmental predictors of biological optimals for each species that could aid surveillance efforts.
This collaboration will lead to the development of new and innovative projects.
This objective will produce the following: (1) development of new data on overwintering survival of the Asian tiger mosquito (2) development of predictive models for vector range expansion and disease transmission, and (3) recommendations best practices for vector control and disease intervention in the face of an outbreak. Future work, which is beyond the scope and resources of this grant proposal, would involve validation and feasibility studies for interventions in concert with outcomes from Objective 4.
Objective 4: New Control Tools, including socio-ecological approaches
The key outcome of our research on mosquito control and management tools will be development of effective strategies for maintaining mosquito populations below nuisance levels and/or below epidemic levels for disease transmission. This objective will involve development of a variety of surveillance, control, economic tools and analyses. These products will complement and expand the comprehensive scientific literature regarding operational technologies for mosquito surveillance and control that is already in existence. We will focus on further development of the autodissemination approach, wherein mosquitoes contaminated with an insect growth regulator transport lethal concentrations to subsequently visited larval habitats. Our efforts will focus on development of improved delivery tools, including unmanned aerial aircraft (UAV) to highly target applications, thereby minimizing environmental impact. Additional effort will focus on biological and chemical pesticides, including recombinant Bacillus thuringiensis strains, mermithid nematodes, Metarhizium and Coelomomyces lativittatus fungi, Wolbachia and RNAi technology (gene silencing) to suppress expression of specific critical proteins in the target vector species such as Ae. aegypti, Ae. albopictus, Cx. quinquefasciatus, An. albimanus and An. gambiae. Double stranded RNA molecules targeting different critical genes/proteins will be synthesized and evaluated in vivo against mosquitoes through topical application and per os in attractive toxic sugar bait traps (ATSB). High throughput larval screens will be used to identify new toxicants for adult and immature mosquitoes.
Importantly, although the current paradigm is that three bites in rapid succession drive residents indoors, there are few detailed studies that correlate passive trap catches with putative bites. This information is critical to determine the level which mosquito populations need to be reduced in order to prevent disease transmission. We will develop experiments specifically to address these questions, involving the public when possible, a strategy members of this coalition have been championing. We will also bring in or extend our research on vector blood feeding patterns and infection rates for specific pathogens, information that is critical for improving delivery systems for emergency/rapid intervention.
The results of our efforts will aid, in part, in the development of effective implementation practices for vector control/management, especially with urban vectors. In order to fully develop best control practices, we will refine strategies to inform the public, public officials and other scientists of the need to address each mosquito species as a unique Public Health problem with its own customized solutions. We will also develop strategies using GIS, surveillance and population genetics and dynamic models to predict hot-spots of activity for different nuisance and vector species. This information is needed so surveillance and control can be developed with area-wide effects without having to be applied everywhere. Our research also will decrease costs and impacts on the environment and non-target species. A final critical aim is to catalyze contacts between academic researchers and local /state mosquito control professionals – where they exist. We will become advocates of their establishment, so we can directly evaluate the locale- and species-specific efficacy of our approaches and fine-tune (i.e., evaluate and enhance control effectiveness under local conditions) traditional control technologies, as well as implement new classes of interventions.
This multistate group is uniquely endowed to fulfill these aims since it includes university and federal research professionals with multiple levels of experience in extension responsibilities.
Objective 5: Training and training tools
The key outcome will be training delivered to developing scientists within the field of Medical and Veterinary Entomology. Tools will be (1) a training course in conjunction with one or more Multistate meetings and (2) Publication of a position paper regarding the development of the next generation of scientists within our field.
Measurement of Progress and Results
Database of availability and location of resources (laboratory colonies, cell cultures, pathogen strains, DNA samples) for vectors of animal diseases of agricultural and human health importance (Obj.1)
Document that identifies/supports/promotes vector resources for investigations on human and animal diseases. (Obj.1)
Improved surveillance of tick-borne pathogens through development of a multiplex PCR-assay
Mapping new areas of expansion of vector tick species
Accurate assessment of the risks from emerging tick-borne pathogens (Anaplasma and Ehrlichia spp.) through improved understanding of the distribution of pathogen strains in reservoirs and vectors
Improved management of tick populations through community-based involvement and host-targeting
Data on thermal and dessication tolerance limits for the yellow fever and Asian tiger mosquito (Obj.3)
models that will allow us to predict the range expansion and distribution of this two important disease vectors with predicted climate change (Obj.3)
Recommendations for effective timing and type of vector control to be utilized in the face of an outbreak threat (Obj.3)
Database of activity of natural products, microbes and dsRNA constructs against mosquitoes. (Obj.4)
Discovery of novel classes of mosquito toxicants and microbes with new modes of action effective against resistant mosquitoes. (Obj.4)
New control tools that are effective and environmentally benign. (Obj.4)
Better understanding and testing of surveillance and control strategies. (Obj.4)
Evaluated the use of community peer educators in a source reduction program, using AmeriCorps volunteers. We showed a significant reduction in container habitats in the sites where the volunteers actively engaged the community compared to untreated control areas. (Obj. 4)
Development of collaborative proposals for external funding that make use of the multistate nature of the group to address strong environmental effects on vector-borne disease transmission (Obj.4)
Increased translational results by building collaboration with local and state mosquito (and pest) control professionals. (Obj.4)
Student and Postdoctoral participants in courses, who have received training relevant to Medical and Veterinary Entomology. (Obj. 5)
Multiple training courses, held in conjunction with topically-important conferences (Obj. 5)
A course structure and materials, which can be used beyond the grant period. (Obj. 5)
Position paper regarding the development of the next generation of scientists within our field. (Obj. 5)
Outcomes or Projected Impacts
- An interactive and interdependent network of scientific expertise to deal with new mosquito-borne disease outbreaks.
- Impact on the general public by understanding, assessing, and mitigating the threat posed by mosquitoes of public health importance.
- Enhanced capacity to detect, predict and respond to outbreaks of vectors and associated human and livestock diseases.
- Provide for and encourage environmentally sound, scientifically based, and professional control by mosquito control agencies.
- New, marketable, vector control tools and products for public health.
- Establish contacts within BEI resources to determine areas of collaboration and identify agriculturally important resources not supported by BEI. (Obj. 1)
- Work with local DNR and MDH contacts to determine areas to sample for surveillance of A. phagocytophilum and Ehrlichia muris strains. (Obj. 2)
- Establish contacts with local mosquito control districts to formulate host-targeting and habitat management approach to tick control (Obj. 2)
- Initiation of thermal tolerance studies with the Asian tiger mosquito (Obj. 3)
- Population size estimates for Ae. albopictus and Ae. aegypti from our coordinated network of researchers conducting surveillance (Obj. 3)
- White paper on problem species across the US. (Obj. 4)
- Screen compounds from natural products and microbes and establish database of activity for mosquitoes. B.) Investigate and identify genes critical to mosquito survival and design dsRNA constructs. (Obj. 4)
- Development of draft course materials, for consideration by Multistate participants; Identification of volunteer instructors to lead course(s); Decision from Meeting organizers as to their support of the course (financial or otherwise); Decision at the Annual Multistate meeting about proceeding with course development for the Annual Meeting in Year 2; Decision about where the Year 2 Multistate meeting will be held (i.e., if held in conjunction with AMCA, greater participation may occur). (Obj. 5)
- Prepare working document on priority list of agriculturally important resources and initiate contacts to determine availability and locations. (Obj. 1)
- Validate primers and probes for multiplex PCR to detect tick-borne pathogens (Obj. 2)
- Obtain samples of reservoir hosts through trapping, to be tested for infection with Anaplasma and Ehrlichia (Obj. 2)
- Select and test available host targeting methods (bait stations, treated nesting material) (Obj. 2)
- Build collaborations and identify critical research needs that will be the foundation to build proposals to pursue additional funding. (Obj. 4)
- Logistical arrangements defined; Course materials defined; Course promoted/advertised; Recruitment of any financial support; Multistate Course #1, held in conjunction with the Annual Multistate meeting. (Obj. 5)
- Continue validation of multiplex PCR using field-collected samples (Obj. 2)
- Evaluate efficacy of host targeting for tick control (Obj. 2)
- Incorporation of estimates disease transmission risk in mosquito models and validation of vector transmission rates if time and funds allow(Obj. 3)
- Exchange and testing of Standard Operating Procedures (SOPs). We will develop and curate a webpage to synergize exchanges of protocols and procedures and obtain updates on successes and failures of different approaches. (Obj. 4)
- Evaluate dsRNA constructs against mosquitoes for addition to database on effectiveness for various physiological pathways. Select best dsRNA constructs for scale-up production and evaluate for msquitocidal activity in ATSB traps. (Obj. 4)
- Review of the Year 2 course; Decision of whether to hold a Course #2; Revision of course materials. Logistical arrangements made for Course #2 (Obj. 5)
- Finalize and distribute document on availability of agriculturally important resources that compliments the BEI resources. (Obj. 1)
- Establish genotypic identity of Anaplasm and Ehrlichia strains in the field by sequencing of target genes, and map distribution to mammal species and region (Obj. 2)
- Conduct simulations to understand the most effective timing and type of vector control to be utilized in the face of an outbreak threat (Obj. 3)
- Exchange and testing of predictive models of the occurrence and spread of nuisance and vector species. We will develop a centralized website where we can share information during model development and after publication for guidance of users. (Obj. 4)
- Optimize parameters (e.g. dose response, mortality, specificity) of dsRNA constructs. (Obj. 4)
- Multistate Course #2, held in conjunction with the Annual Multistate meeting. (Obj. 5)
- Assemble data and prepare summary documents, publications, including position papers. Begin writing grant proposals to expand projects and funding. (All Objectives)
- Evaluate candidate compounds in laboratory and semi-field tests for activity against resistant mosquitoes. (Obj. 4)
Projected ParticipationView Appendix E: Participation
Several of the universities represented in this multistate group of researchers have formal extension programs while some do not. However, most researchers and all institutions interact closely with health officers, mosquito and tick professionals or the public at large (Table 1). Many of us conduct a variety of outreach activities and create documents or web based information. In order to summarize a large amount of information in the limited space available in this proposal, we are providing in Table 1 links to the webpages where descriptions of the outreach programs as well as PDFs of fact sheets, publications, lecture summaries and curricula, standard operating procedures, etc. can be found and downloaded.
Additionally we will hold an annual meeting to promote cooperation among participants, which can lead to enhance research opportunities. Results of our meetings and activities will be available to all interested parties via the NIMSS website. All publications, both refereed and non-refereed, will be listed on NIMSS. Informational meetings will be held to brief appropriate state and county mosquito control personnel on our progress, particularly via oral presentations at national (e.g., American Mosquito Control Association), regional (Northeastern Mosquito Control Association) and local (e.g., New Jersey Mosquito Control Association) meetings that are designed to bring together scientists and mosquito control practitioners.
Table 1. Critical outreach activities provided by researchers at the institutions participating in this multistate collaboration. Click on the webpages to access and download materials and obtain lists of publications and course curricula.
Name of Institution
Serve as a consulting resource to state and local Officers
Provide non-University outreach
Provide cooperative Research outreach
Provide Services and Standard Operating Procedures (SOPS)
Develop fact sheets and other education materials
Serve as a resource for media (examples provided)
Rotary Club; landscape professionals; k-12
Rutgers U. (State U. NJ)
Health, Mosq Control, Agriculture, Veterinary
Citizen Science: "Enlightened Mosquito Control"
Yes (30 publications to date)
Yes (8 SOPs available from website)
Efforts targeting state public health employees and the general public
Educational posters and extension bulletins
Tick identification and parasite screening
Rotary Club; K-12; Youth sum. camps; citizen sci. workshops
Ohio State U.
A Bug's World'; Insect Night Walk
Connecticut Experiment Station
Support for local boards of health and county extension.
Tick identification and pathogen testing for individual citizen; various local and state health agenices
Texas A&M University
services. Virus testing in mosquitoes
Multistate research project will be established in accordance with the format suggested in the “Manual for Cooperative Regional Research”. One person at each participating institution or agency will be designated, with approval of the institution’s or agency’s director, as the voting member of the Technical Committee. Other individuals and interested parties are encouraged to participate as non-voting members of the committee. There will be elections of a Chair, Chair-elect, and a Secretary. All officers are to be elected for two-year terms to provide continuity. Administrative guidance will be provided by an assigned Administrative Advisor and a CSREES Representative.
Note: This proposal has purposefully been written to define the project in broad research terms. This is intended to best position the Multistate Project to cast a broad net to secure an expanded membership, and therefore expanded opportunities for community building and collaboration. First, an expansion of membership will be sought geographically so that the Multistate Project can become a truly national project. Second, the intended expansion will be aimed at securing participants beyond the traditional agricultural experiment station and ARS-UDSA mosquito biologists to involve mathematical modelers, community ecologists and others with special skills regardless of whether or not they study mosquitoes and/or ticks.
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