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Funded Project

Funding Program: Regional IPM Competitive Grants - Northeastern

Project Title: Development of Novel Application Technology for the Control of the Asian Tiger Mosquito in Urban Environments

Project Directors (PDs): George C. Hamilton [1] Gregory Williams [2]

Lead State: NJ Lead Organization: Rutgers University

Extension Funding: $11,900

Research Funding: $48,100

Start Date: Jun-01-2008 End Date: May-31-2011

Pests Involved: mosquitos, mosquitoes

Site/Commodity: urban, residential

Area of Emphasis: biocontrol, biological control, public health

Summary: This is a Community IPM, Joint Research-Extension project to address the control of the invasive vector mosquito Aedes albopictus (the Asian tiger mosquito) in urban residential environments. The Asian tiger mosquito is responsible for most complaints to mosquito control programs. These programs rely on controversial and ineffective area-wide applications of broad-spectrum adulticides to combat this mosquito. While larvicides work effectively, it is impractical if not impossible to identify and treat all sources by hand. Without any efficient means of control, many mosquito control programs ignore this pest. The area-wide application of larvicides would solve the problem, but the technology has not been developed sufficiently for use in urban residential environments. This project will develop novel technologies for the area-wide low volume application of the bacterial larvicide Bacillus thuringiensis ssp. israelensis to control Ae. albopictus. We will develop this new biocontrol strategy by adapting low-volume truck-mounted adulticide equipment commonly in use by mosquito control programs to apply liquid Bti in an outdoor urban residential setting. After application the larvicide will drift and settle in containers of water where the larvae reside, providing quick, efficient, cost effective control. This IPM approach will reduce the abundance of this pest, the dependence on broad-spectrum adulticides, non-target impacts, and the development of resistance through the use of novel application technology, host-targeted applications of biological larvicides, and training programs for stakeholders. Efficacy of the program will be evaluated by monitoring larval mortality, adult presence, droplet size and distribution, and pesticide persistence. We will also prepare workshops and materials to train mosquito control personnel throughout the northeast and beyond in the use of this technology. The proposed project addresses the priorities of the Northeastern Integrated Pest Management Center's Public Health IPM Working Group, which include evaluation of novel IPM methodologies for vector-borne diseases, and the dissemination of IPM guidelines and educational programs for the control of insect vectors and vector-borne diseases. Objectives: The research component of the proposed study will develop and test the efficacy of LV applications of Bti to rapidly control Ae. albopictus in urban residential environments. First, we will conduct staged field trials where equipment is tested and optimized to deliver the Bti to containers of larvae at various distances. Then, we will test the method in actual mosquito control programs under real world conditions. We will demonstrate reductions in larval and adult populations of Ae. albopictus, a reduction in the amount of chemical adulticides applied, and an overall reduction in the cost of area-wide control of Ae. albopictus. The extension component of the proposed study will develop training workshops as well as printed and web-based materials to disseminate the knowledge generated in this study to the stakeholders. The extension component will begin with the training of local mosquito control agencies in NJ. These training sessions will be used to develop a formal workshop and training materials that will be made available to mosquito control agencies throughout the northeast. All of the impacts listed below will be compounded across the northeast and beyond as various stakeholders adopt this technology. Proposal USDA CRIS research data USDA CRIS extension data

Interim Report: Sep-14-2009

Outcomes Staged field trials have been very successful (Fig 1 & 2). Essentially, larvae are killed in any containers that droplets land. Mortality data are supported by analysis of spray cards. It was found that spray cards are closely correlated to mortality data enabling rapid evaluation of spray equipment using spray cards only; no bioassays of larvae are needed. Anecdotal evidence from another mosquito control program suggested a swath width of at least 300 feet was attainable. We have had difficulty achieving such distances. Upon comparing our data with data from the other program, we determined that humidity was likely the limiting factor. This theory will be tested once environmental conditions are favorable. As a result of our workshop it was determined that backpack mist applications of WDG would be an effective alternative to truck mounted equipment. Because these applications are made directly on site and do not depend upon droplet drift, humidity does not matter. We have trained several mosquito control programs in this technique late this season and they have tried the method operationally. Preliminary results suggest that the method is very effective in killing larvae and is viewed favorably by applicators and homeowners alike. Dose-mortality tests have demonstrated the high toxicity of WDG to Ae. albopictus larvae. The LC50 values were 3 ppb (Fig. 2). This helps to explain why mortality is observed in containers of larvae even when spray cards did not detect any droplets. Droplets too small to detect with the spray cards are sufficient to deliver a lethal does of Bti. These data suggest that the mix ratio of the product can be reduced thereby reducing the amount of material applied and the cost of applications. However, a reduction of product may also result in a reduction of residual activity. We will work to determine the optimal mix ratio to provide lasting control while limiting cost. Presentations and workshops were given as outlined in the Progress section. In addition, the Rutgers Center for Vector Biology has become extremely interested in the area wide application of mosquito larvicides. They have used our project to help develop and submit a proposal for a Deployed War Fighter Protection grant in the amount of $750,000 to look at the area wide application of insect growth regulators for Ae. albopictus control.

Impacts Safeguarding human health and the environment: The new IPM practices that will be adopted as a result of this project are that mosquito control agencies will implement area wide larval control of Ae. albopictus in place of repeated ULV applications of mosquito adulticides. The total number of acres or homes on which these practices could be implemented is difficult to quantify. Any home with an active Ae. albopictus problem could be treated with these methods. Currently, this mosquito is a problem in 30 states including all of the east coast south of New Hampshire. These practices could be implemented in all of those states. Current methods of Ae. albopictus control rely on the repeated application of adulticides like pyrethroids and malathion. These broad spectrum pesticides can have an impact on non-target organisms and have led to the development of resistance. This project will reduce risk by replacing the repeated application of these adulticides with applications of Bti which has a lower mammalian toxicity, fewer non-target impacts, and less chance of resistance. Additionally, many mosquito control programs have begun to look at applications of residual pesticides as a barrier treatment for Ae. albopictus out of frustration due to the lack of efficacy of adulticides. These types of applications would undoubtedly have non-target impacts. With the availability of an effective alternative for Ae. albopictus control, these programs may abandon the pursuit of barrier treatments. Other impacts on human health include a potential increase in personal comfort and outdoor activities as a result of the reduction in the adult population of Ae. albopictus. Economic Benefits: The application of WDG is actually more expensive per acre than adulticiding, but well within the budget of any mosquito control program. However, adulticiding provides very temporary relief and must be repeated. It is also, largely ineffective for Ae. albopictus. Larviciding can have a residual effect and therefore can be conducted less frequently than adulticiding. Reapplication intervals will be determined as part of this study. Area wide application of larvicides is much less expensive than traditional methods of hand larviciding or trash remediation for Ae. albopictus control. Preliminary calculations estimate greater than $100 per acre saved over current methods of Ae. albopictus control due to the extreme reduction in labor involved. Because this project utilizes existing equipment and materials, we do not envision any potential for commercialization. This project is not likely to create new IPM employment. However, it will cause current mosquito control personnel to increase their use of IPM techniques. The actual number of personnel that will be affected will not be known until the conclusion of the project. Personal communications with other mosquito control directors that have instituted the backpack version of this technique have expressed great satisfaction with the method. They report excellent efficacy, ease of implementation, and residual results. Mosquito control personnel have reported a preference for this type of application over hand larviciding and habitat removal. Homeowners have also reported a reduction in biting activity following these treatments. Implementation of IPM: Three IPM strategies have been validated through this project including 1) the use of truck mounted ULV equipment, 2) the use of truck mounted mist sprayers, and 3) the use of backpack mist sprayers for the control of Ae. albopictus larvae in urban residential settings. Truck mounted equipment was validated though open field trials. Mock urban trials are forthcoming. Backpack equipment has been validated through large plot tests. Real world operational trials will commence next season. Educational materials consisted of oral presentations, posters, and a workshop. Oral presentations were delivered at the annual conferences of the New Jersey and American Mosquito Control Associations. These conferences were attended by mosquito control personnel as well as university and government researchers and health professionals. Each audience consisted of approximately 100-150 people. Posters were presented at the annual conferences of the New Jersey Mosquito Control Association and the International Symposium on the Asian Tiger Mosquito. The symposium was comprised of 170 people from fifteen countries and 30 states including the top researchers on Ae. albopictus. A presentation was also given at a workshop we hosted including mosquito control personnel from five states, three countries, the US Navy, and industry researches and representatives to encourage information sharing to help develop and promote this methodology. Three county mosquito control programs in NJ have been trained in the area wide control of Ae. albopictus larvae with the backpack version of this methodology. More training events will take place next year. Dozens of other people have expressed an interest in this method as a result of our presentations and have begun their own investigations. A website will be developed next year. Three NJ mosquito control programs including dozens of mosquito control personnel have adopted the backpack version of this technology as a direct result of this project. Many more are anxious to try the truck mounted version as soon as the environmental conditions are worked out. The Rutgers Center for Vector Biology has begun submitting grant applications to conduct research on the area-wide application of other larvicides such as insect growth regulators as a result of this project.

Report Appendices Progress Report 2009 [PDF]

Interim Report: Sep-03-2010

Outcomes The aforementioned work has resulted in a wealth of information regarding the area-wide application of Bti for the control of container mosquitoes. Environmental Conditions: Data from last year illustrated the importance of humidity during applications to minimize droplet evaporation. This year, all truck mounted applications were made in the late evening during conditions of high humidity and during a temperature inversion to maximize droplet travel at ground level. However, the two truck mounted trials resulted in poor efficacy (Fig 2). We believe that the poor mortality was due to a small swath width resulting from a lack of wind during the trials. Both pieces of equipment functioned perfectly and appeared to make large clouds of WDG that hung in the air but did not disperse. In response to the sensitivity of these applications to environmental conditions, Valent BioSciences has assisted us in modeling optimal droplet sizes based on ambient humidity and wind conditions (Fig 3 & 4, Table 2). These data will be used for future trials to optimize swath width. The backpack applications (Fig 1) were not sensitive to environmental conditions because the applications are made directly to the target areas and do not depend on drift. Larvicide: We experienced difficulty in mixing the WDG at the required ratio to obtain the recommended application rates. If the flow rate of the equipment is too low, the product must be mixed at a very high ratio which creates a thick material that is difficult to mix and deliver through the machines. We have experimented with several mix ratios, application speeds, flow rates, and application rates to establish a set of recommendations. Based on our work we recommend an application rate of 400 gm/ha, a maximum mix ratio of 120 gm/l, a minimum equipment flow rate of 7.5 l/min, and application speeds of 5-10 mph depending on the equipment flow rate. We have a spreadsheet to calculate the correct mix ratio for various conditions that will be provided on a website to simplify calculations for stakeholders. Equipment: The original intent of this grant was to utilize traditional ULV equipment to apply the mosquito larvicide VectoBac WDG. However, we have discovered that most ULV machines have maximum flow rates that are too low to permit the application of this product at the recommended rates. In order to mix the product at a manageable ratio, flow rates need to be at least 7.5 l/min. Most ULV equipment delivers around 0.5 l/min. Even with an optional high volume pump on the Clarke Cougar which can flow 2.3 l/min, the mix ratio is still too high. Low volume mist sprayers can deliver the required flow rates however significant wind is required to move the material. Backpack mist sprayers work well (Fig 1) because the applications are made directly to target areas and wind is not required for delivery. However, this method is much more labor intensive than truck-mounted equipment. It is a viable option for small areas less than 10 acres. Larger areas will require some type of truck mounted mist sprayer. Last March a meeting was held to discuss recent developments and future directions of area-wide larviciding technology. The group consisted of representatives from Valent BioSciences, equipment manufacturers, the US Navy, and several mosquito control programs. At this meeting everyone shared information and a strategy was established to further develop the concept. The group determined that the area-wide application of WDG from truck-mounted equipment is a viable strategy once all of the required conditions are worked out. Another meeting is planned for March 2011.

Impacts Safeguarding human health and the environment: The new IPM practices that will be adopted as a result of this project are that mosquito control agencies will implement area wide larval control of Ae. albopictus in place of repeated ULV applications of mosquito adulticides. The total number of acres or homes on which these practices could be implemented is difficult to quantify. Any home with an active Ae. albopictu problem could be treated with these methods. Currently, this mosquito is a problem in 30 states including all of the east coast south of New Hampshire. These practices could be implemented in all of those states. Current methods of Ae. albopictus control rely on the repeated application of adulticides like pyrethroids and malathion. These broad spectrum pesticides can have an impact on non-target organisms and have led to the development of resistance. This project will reduce risk by replacing the repeated application of these adulticides with applications of Bti which has a lower mammalian toxicity, fewer non-target impacts, and less chance of resistance. Additionally, many mosquito control programs have begun to look at applications of residual pesticides as a barrier treatment for Ae. albopictus out of frustration due to the lack of efficacy of adulticides. These types of applications would undoubtedly have non-target impacts. With the availability of an effective alternative for Ae. albopictus control, these programs may abandon the pursuit of barrier treatments. Other impacts on human health include a potential increase in personal comfort and outdoor activities as a result of the reduction in the adult population of Ae. albopictus. Economic Benefits: The application of WDG is actually more expensive per acre than adulticiding, but well within the budget of any mosquito control program. However, adulticiding provides very temporary relief and must be repeated. It is also, largely ineffective for Ae. albopictus. Larviciding can have a residual effect and therefore could be conducted less frequently than adulticiding. Reapplication intervals will be determined as part of this study. Area wide application of larvicides is much less expensive than traditional methods of hand larviciding or trash remediation for Ae. albopictus control. Preliminary calculations estimate greater than $100 per acre saved over current methods of Ae. albopictus control due to the extreme reduction in labor involved. Because this project utilizes existing equipment and materials, we do not envision any potential for commercialization. This project is not likely to create new IPM employment. However, it will cause current mosquito control personnel to increase their use of IPM techniques. The actual number of personnel that will be affected will not be known until the conclusion of the project. Personal communications with other mosquito control directors that have instituted the backpack version of this technique have expressed great satisfaction with the method. They report excellent efficacy, ease of implementation, and residual results. Mosquito control personnel have reported a preference for this type of application over hand larviciding and source reduction. Homeowners have also reported a reduction in biting activity following these treatments. Implementation of IPM: Three IPM strategies have been validated through this project including 1) the use of truck mounted ULV equipment, 2) the use of truck mounted mist sprayers, and 3) the use of backpack mist sprayers for the control of Ae. albopictus larvae in urban residential settings. Truck mounted equipment was validated though large scale operational tests. More field experiments and operational tests are forthcoming with the new equipment. Backpack equipment has been validated through large plot tests. Educational materials consisted of oral presentations, posters, and a workshop. Oral presentations were delivered at the annual conferences of the New Jersey and American Mosquito Control Associations. These conferences were attended by mosquito control personnel as well as university and government researchers and health professionals. Each audience consisted of approximately 100-150 people. Three county mosquito control programs in NJ have been trained and are using the backpack version of this methodology. Two county mosquito control programs have used the truck mounted technology operationally. A third county inspired by this work has begun applying a different larvicide by truck. More training events will take place next year. The Rutgers Center for Vector Biology has integrated some of our techniques into their USDA grant work on the area wide management of Ae. albopictus. Based on our work they submitted, and were awarded, a Deployed War Fighters Protection grant to explore the area wide application of another larvicide pyriproxyfen. Dozens of other people have expressed an interest in this method as a result of our presentations and have begun their own investigations.

Report Appendices Progress Report 2010 [PDF]

Final Report:

Impacts This project has increased the awareness of the concept of area-wide larviciding for the control of Ae. albopictus. Previously most area-wide control efforts for this mosquito focused on labor intensive source reduction or largely ineffective adulticide applications. Our project has increased the realization that area-wide larviciding can achieve greater control than source reduction with the ease and cost similar to adulticide operations. Several local mosquito control agencies have begun adopting the technology we have developed and promoted. At least five programs in New Jersey have incorporated area-wide larviciding into their control programs. Since the start of the project we have witnessed a change in philosophy from reactive mosquito control in the form of adulticiding to the more proactive measures developed with this project. In fact, several mosquito control programs have begun to expand upon our work to look at the area-wide application of other classes of larvicides such as methoprene. Based on this project, the Rutgers University Center for Vector Biology has incorporated our techniques into a multi million dollar Deployed War Fighter Protection grant project exploring the area-wide suppression of Ae. albopictus. To increase the products available for area-wide larviciding, the Center has also obtained an experimental-use permit to explore the application of pyriproxyfen with truck mounted equipment on an area-wide basis. In the short three years since this project began, area-wide larviciding has been transformed from an abstract concept to viable mosquito control strategy. The decreased labor requirements of these methods compared to source reduction will result in financial savings for publicly funded mosquito control programs. We also expect a reduction in the use of broad spectrum mosquito adulticides resulting in fewer non-target impacts and a cleaner environment. We have witnessed an increase in industry support as a result of this project. Valent BioSciences is now marketing VectoBac WDG in much larger quantities making it more convenient for area-wide use. Equipment manufacturers such as Buffalo Turbine and Curtis-Dyna Fog have modified and now market some of their machines for area-wide larviciding. Bayer Environmental Science has developed a new Bti product specifically designed for area-wide larviciding. The product was specifically developed to address some of the problems that our research has identified such as droplet evaporation.

Outcomes Trials were conducted to test spray equipment. We ran open-field trials with several different sprayers under a variety of conditions. Each trial consisted of a grid of bioassay cups for mortality tests and spray cards to measure droplet deposition, swath width, and droplet sizes. Dose-mortality tests were conducted against Aedes albopictus following WHO guidelines for larval assays to determine the LC50 values for VectoBac WDG and extrapolate deposition rates in bioassay cups. We ran droplet analyses of spray equipment with the Navy Entomology Center of Excellence (NECE) on a 2D Phase Doppler Particle Analyzer. Tests were performed under various equipment settings and mix ratios to determine effects on droplet size. This allowed us to rule out ineffective equipment and set equipment for optimal droplet sizes. Trials were conducted to determine the operational efficacy of this program in urban residential areas (70-125 acres) with high Ae. albopictus populations. Bioassays measured larvicide penetration, the direct impact on larvae and residual efficacy. Traps were used to measure the impact on adult mosquito populations. Events: Presentations were given at the annual conferences of the New Jersey and the American Mosquito Control Associations in 2008-2010. Each field trial was also open to local mosquito control personnel to teach equipment calibration, larvicide application, and bioassay techniques. This enabled many local programs to begin developing their own area-wide larviciding programs. Services: Consulting services to several mosquito control programs consisted of assistance with equipment settings, droplet sizes, mix ratios and application rates. Products: We will host a regional workshop with field demonstrations, deliver printed training materials, and launch a website. All products will outline environmental and equipment requirements, methods for setting up equipment, and techniques for measuring efficacy. Dissemination: In 2009 we hosted a meeting with Valent BioSciences to discuss the current status and future direction of this technology. In attendance were mosquito control representatives from 3 countries, 4 states, 2 universities, the US Navy and several corporate representatives. We presented the goals and progress of this project to date. Seven other groups also gave related talks. The workshop stimulated interest in this project, engaged industry support, and formed collaborations with others mosquito programs. In March 2010 we held a session at the annual meeting of the American Mosquito Control Association with Valent BioSciences. The group consisted of representatives from the US Navy, several mosquito control programs and equipment manufacturers. Everyone shared information and a strategy was established to further develop the project. Industry partners offered their assistance with equipment and material needs. In May 2011 we presented this research at the 2nd International Forum for Surveillance and Control of Mosquitoes and Mosquito-Borne Diseases in Beijing, China to over 100 mosquito control representatives from around the globe. Our presentation sparked international interest and partnerships.

Report Appendices Final Report 2011 [PDF]

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