Source: UNIVERSITY OF CALIFORNIA, RIVERSIDE submitted to
MANAGEMENT AND ECOLOGY OF MOSQUITOES INHABITING WATER RECLAMATION WETLANDS AND PERIURBAN ENVIRONS
Sponsoring Institution
National Institute of Food and Agriculture
Project Status
TERMINATED
Funding Source
HATCH
Reporting Frequency
Annual
Accession No.
0223420
Grant No.
(N/A)
Project No.
CA-R-ENT-5029-H
Proposal No.
(N/A)
Multistate No.
(N/A)
Program Code
(N/A)
Project Start Date
Oct 1, 2010
Project End Date
Sep 30, 2015
Grant Year
(N/A)
Project Director
Walton, W.
Recipient Organization
UNIVERSITY OF CALIFORNIA, RIVERSIDE
(N/A)
RIVERSIDE,CA 92521
Performing Department
Entomology, Riverside
Non Technical Summary
Mosquitoes emanating from constructed wetlands may pose serious threats to the health and comfort of humans, companion animals and wildlife. Despite favorable uses for agriculture, constructed treatment wetlands in the southwestern U.S. have often suffered from a lack of sustainability of water treatment and high levels of mosquito production. This project will develop wetland management protocols, enhance mosquito control and advance resistance management practices that are economically sound and effective. As water becomes a scarcer commodity and water costs increase, reclaimed water will be an attractive supplement to the water supply, particularly in arid regions of the U.S. Multipurpose constructed wetlands have the potential to provide a cost-effective means of water reclamation, while also providing benefits such as wildlife habitat, recreation, and a venue for public education on issues related to water resources and wildlife conservation. Man-made wetlands provide potential benefits to agriculture, such as a comparatively inexpensive source of irrigation water and a cost-effective means of reducing nutrient concentrations in wastewater and storm water runoff. However, constructed treatment wetlands also create several drawbacks including a potential lack of sustainability and the production of mosquitoes that vector pathogens causing diseases. There is a need to understand the ecological interactions among the fauna of these wetlands, especially if these wetlands are situated near human development and are intended to replace wetlands lost to or degraded by human activities. A greater understanding of the factors contributing to high levels of mosquito production in constructed treatment wetlands is needed. New ways of controlling mosquitoes that take advantage of the native mosquito eating organisms and replace potentially invasive species are needed. Lastly, strategies that optimize the long-term success of vector control programs (e.g., resistance management) at wetlands and in suburban/urban neighborhoods are also needed. This research will provide a basis for the development of strategies to forestall the evolution of resistance in mosquitoes to mosquito-specific bacterial toxins, to broaden the range of mosquito species susceptible to environmentally-friendly vector control strategies using bacterial-based mosquito larvicides, and to develop transgenic bacteria exhibiting toxin characteristics that provide long-term effective vector control in California as well as in the tropics where mosquito-borne pathogens cause significant levels of human morbidity and mortality.
Animal Health Component
(N/A)
Research Effort Categories
Basic
(N/A)
Applied
(N/A)
Developmental
(N/A)
Classification

Knowledge Area (KA)Subject of Investigation (SOI)Field of Science (FOS)Percent
1110330107010%
1110330113010%
1110899107010%
1113110107010%
1113110113010%
1114010115010%
1115370107010%
1120330107010%
1125370107010%
1350330113010%
Knowledge Area
135 - Aquatic and Terrestrial Wildlife; 112 - Watershed Protection and Management; 111 - Conservation and Efficient Use of Water;

Subject Of Investigation
0899 - Wildlife and natural fisheries, general/other; 4010 - Bacteria; 5370 - Sewage and waste disposal facilities and systems; 3110 - Insects; 0330 - Wetland and riparian systems;

Field Of Science
1130 - Entomology and acarology; 1070 - Ecology; 1150 - Toxicology;
Goals / Objectives
The objectives of the studies carried out in this project are (1) investigate wetland macroinvertebrate food webs and mosquito production across a gradient of nitrogen enrichment that reflects the range of nitrogen concentration found across natural and treatment wetlands in southern California; (2) determine the effectiveness of an alternative species of emergent macrophyte (SCHOENOPLECTUS MARITIMUS) to the large bulrush (S. CALIFORNICUS) for reducing mosquito production and the costs of vector control and vegetation management in constructed treatment wetlands used to reclaim water and to improve the quality of water destined to recharge aquifers used for human consumption; (3) carry out a GIS-based assessment of the potential sites for use of native fishes as a replacement biological control agent for mosquitoes for the mosquitofish, GAMBUSIA AFFINIS, in southern California and develop rearing methods and production costs for three native fishes; (4) analyze the potential synergy between Mtx toxins with toxins from BACILLUS THURINGIENSIS (Bti) and B. SPHAERICUS for the enhancement of activity and extension of the host range of environmentally friendly mosquito control agents; and (5) study the patterns of inheritance of resistance and cross-resistance to BACILLUS THURINGIENSIS Cry-toxins in the malaria vector ANOPHELES GAMBIAE and in Bti-resistant colonies of the southern house mosquito, CULEX QUINQUEFASCIATUS, by Mendelian analysis and extend our investigations into the possible roles of linkage and toxin binding in Cry-resistance.
Project Methods
The effects of nutrient enrichment on aquatic insect community composition and food web interactions will be studied using 12 replicate wetland mesocosms. Nitrogen and phosphorus concentrations will bracket the range of nutrient concentrations across the gradient observed in riverine and man-made wetlands in southern California. Three nitrogen concentrations will be used. Phosphorus concentrations will be elevated to 1 mg P per liter in all nitrogen treatments. Physicochemical parameters will be measured by electronic sensor arrays and by standard colorimetric analyses. The invertebrate community will be sampled using two methods. Mortality rates of immature mosqiutoes will be estimated using a vertical life table approach and the trophic interactions within the wetlands will be assessed using stable isotope analysis of carbon and nitrogen. Insect community structure will be analyzed by multivariate statistical methods and the significance of enrichment effects assessed by parametric statistical analyses. The growth characteristics and survival of alkali bulrush and nutrient uptake by the plants will be studied in a wetland in Indio, CA and in mesocosms at the U.C. Riverside AES. Ambient nutrient levels in the treatment wetland will be measured. Four ammonium nitrogen treatments will be used in the mesocosm studies. Physiochemical variables within representative stands of bulrush will be monitored using electronic sensors coupled to data loggers and by standard chemical analyses. Nutrient uptake by the above- and below-ground components of the plants will be analyzed in summer, autumn and spring. The elemental ratios of carbon, nitrogen and phosphorus within plants will be analyzed. The effectiveness of mosquito abatement will be assessed by measuring mosquito production. ANOVA and MANOVA will be used the test the statistical significance of findings. A GIS-based assessment of the potential sites for use of native fishes as a replacement biological control agent for mosquitoes for the mosquitofish in southern California will be used to estimate the number of native fish that might be stocked into appropriate habitats, and to evaluate the potential interactions of integrated mosquito management activities, such as source reduction using vegetation management, on native fish populations. A publication describing rearing methods and production costs for native fishes also will be developed. The potential synergy among accessory toxins and the predominant mosquitocidal toxins in BACILLUS will be analyzed by standard bioassay for the enhancement of activity and extension of the host range of environmentally friendly mosquito control agents. The patterns of inheritance of resistance and cross-resistance to BACILLUS toxins in ANOPHELES GAMBIAE and CULEX QUINQUEFASCIATUS will be analyzed by Mendelian analysis to extend our investigations into the possible roles of linkage and toxin binding in Cry-resistance. Mortality data will be analyzed by Probit analysis and synergy ratios will be calculated. Publication of research results and direct interaction with natural resources and vector control agencies will cause change in the knowledge base.

Progress 10/01/10 to 09/30/15

Outputs
Target Audience:The target audience includes wetlands practitioners, natural resource managers, vector control and public health personnel and other individuals involved in water reclamation activities that utilize constructed treatment wetland to improve water quality. Efforts included training of graduate and undergraduate students through the delivery of science-base knowledge by classroom and laboratory instruction, and outreach activities. Changes/Problems: Nothing Reported What opportunities for training and professional development has the project provided?Dr. Walton and Dr. Wirth worked one-on-one with the graduate students and undergraduate students who participated in the activities supported by this project. Five graduate students and ten undergraduate students participated in research related activities. Walton, Wirth and Why participated in continuing education activities for vector control personnel sponsored by the Mosquito and Vector Control Association of California. Thirty-five presentations were made by persons associated with this project during the current project period. How have the results been disseminated to communities of interest?Research findings were presented and disseminated at the annual meetings of the Entomological Society of America, the Society for Vector Ecology, the American Mosquito Control Association, and the Mosquito and Vector Control Association of California, as well as the biennial meeting of the Mosquito Control Association of Australia and the quadrennial INTECOL Wetlands Conference. Publications on the design and management of constructed treatment wetlands for enhanced mosquito control (invited contribution), evolution of resistance to the mosquitocidal proteins of BACILLUS THURINGIENSIS subsp. ISRAELENSIS, the influence of vegetation planting designs for constructed wetlands on mosquito production, the efficacy of botanical extracts for control of AEDES AEGYPTI and the role of wetlands as environmental determinants of infectious disease transmission were published. Other outreach activities included participation as an invited member of the Southern California Vector Control Environmental Taskforce which promoted dialog and exchange of information among natural resource management agencies, permitting agencies, and vector control and public health agencies; participation in the Southern California Native Freshwater Fauna Working Group which is a consortium of representatives from natural resources agencies, academia, consulting firms, Cooperative Extension and other agencies that meets regularly to discuss ongoing activities related to conservation, assessment, public policy and regulations and other topics related to riparian wetlands and other aquatic habitats of southern California; and as liaison between the University of California and the Mosquito and Vector Control Association of California. What do you plan to do during the next reporting period to accomplish the goals? Nothing Reported

Impacts
What was accomplished under these goals? All goals of the project were accomplished. A multi-year experiment to investigate the effectiveness of an alternative species of emergent macrophyte (SCHOENOPLECTUS MARITIMUS) for reducing mosquito production was carried out in replicate wetland mesocosms. The use of hydrological regime for the management of senescent plant biomass and reduction of mosquito harborage was investigated by measuring plant density and height, wetland nutrient removal and mosquito production prior to raising water levels in one half of the replicate wetlands during late winter. Mosquito production, emergent macrophyte develpment and wetland performance did not differ significantly between the two treatments during the second growing season. Genomic analyses of the microbial populations growing epiphytically on bulrush, in the water column and symbiotically inside mosquito larvae were completed. Using data from amplified 16S rRNA gene hypervariable regions, the alpha diversity of mosquito gut microbiomes from different mesocosms containing monotypic plots of the two bulrush species did not differ significantly. Proteobacteria, dominated by THORSELLIA (Enterobacteriaceae), was the most abundant phylum recovered from CULEX TARSALIS larvae. Bacterial community diversity was greatest in young mosquito larvae and declined during immature development. Bacterial communities inside mosquito larvae were largely distinct from the water column and epiphytic habitat communities and were comparatively constant across the experiment. A GIS-based assessment of potential sites for use of native fishes as a biological control agent for mosquitoes identified sites for supplementation of native fishes was completed for Orange County. Important gaps in our knowledge about native fish populations and their potential use in vector control programs were identified. Rearing methods and differences in the costs of rearing native fishes versus mosquitofish were determined. CULEX QUINQUEFASCIATUS that had evolved high levels of Cry-toxin resistance after laboratory selection were studied for changes in multiple fitness traits. There were no statistically significant differences for fecundity, egg viability, immature development time, emergence success and sex ratio traits among the three colonies tested. This result suggests that high levels of resistance to Cry-toxins that evolved over a long period of time are not associated with a significant gain or loss in biological fitness in these mosquitoes. ANOPHELES GAMBIAE was examined to determine whether exposure of susceptible larvae to a recombinant biopesticide expressing the mosquitocidal toxins from both BACILLUS THURINGIENSIS subsp. ISRAELENSIS and LYSINIBACILLUS SPHAERICUS affected adult female longevity. No statistically significant differences in adult longevity, male or female, were detected between the treated and untreated groups.

Publications

  • Type: Conference Papers and Presentations Status: Published Year Published: 2014 Citation: Walton, W.E., N. McConnell, A. M. Why, S. Merkley, M. Saba, A. Semrow, R. Cummings, K. Nguyen, and J. Newton. 2014. Assessment of native fishes for vector control in Orange County, California. Proceedings and Papers of the Mosquito and Vector Control Association of California 82: 70-79.
  • Type: Conference Papers and Presentations Status: Published Year Published: 2014 Citation: Why, A.M., B. Johnson, S. Nygren, R. Zembal, J. Thieme, and W. E. Walton. 2014. Suitability of the arroyo chub (Gila orcutti) for the biological control of mosquitoes in a southern California treatment wetland. Proceedings and Papers of the Mosquito and Vector Control Association of California 82: 80-88.
  • Type: Journal Articles Status: Published Year Published: 2014 Citation: Duguma, D., and W. E. Walton. 2014. Effects of nutrients on mosquitoes and an emergent macrophyte, Schoenoplectus maritimus, for use in treatment wetlands. Journal of Vector Ecology. Vol. 39: 1-13.
  • Type: Journal Articles Status: Published Year Published: 2015 Citation: Duguma, D., M. Hall, P. Rugman-Jones, R. Stouthamer, J. D. Neufield, and W. E. Walton. Microbial communities and nutrient dynamics in experimental microcosms are altered after application of a high dose of Bti. Journal of Applied Ecology. doi: 10.1111/1365-2664.12422.
  • Type: Journal Articles Status: Published Year Published: 2015 Citation: Duguma, D., M. Hall, P. Rugman-Jones, R. Stouthamer, J. D. Neufield, and W. E. Walton. Developmental succession of the gut microbiome of Culex mosquitoes. BMC Microbiology. vol.15: p. 140-152.
  • Type: Journal Articles Status: Published Year Published: 2015 Citation: Wirth, M.C., Walton, W.E., Federici, B.A. 2015. Evolution of resistance in Culex quinquefasciatus Say (Diptera: Culicidae) Selected with a recombinant Bacillus thuringiensis strain producing Cyt1Aa and Cry11Ba and the binary toxin, Bin, from Lysinibacillus sphaericus. Journal of Medical Entomology. Vol. 52. p.1028-1035.
  • Type: Journal Articles Status: Awaiting Publication Year Published: 2016 Citation: Pennington, M.J., Prager, S.M., Walton, W.E., Trumble, J.T. 2016. Culex quinquefasciatus larval microbiomes vary with instar and exposure to common wastewater contaminants. Scientific Reports (Nature). In press.
  • Type: Journal Articles Status: Awaiting Publication Year Published: 2016 Citation: Popko, D.A., Walton, W.E. 2016. Large-volume gravid traps enhance collection of Culex vectors. Journal of the American Mosquito Control Association. Vol. 32. In press.


Progress 10/01/13 to 09/30/14

Outputs
Target Audience: The target audience includes wetlands practitioners, natural resource managers, vector control and public health personnel and other individuals involved in water reclamation activities that utilize constructed treatment wetland to improve water quality. Efforts included training of graduate and undergraduate students through the delivery of science-base knowledge by classroom and laboratory instruction, and outreach activities. Changes/Problems: Nothing Reported What opportunities for training and professional development has the project provided? Dr. Walton, Dr. Wirth and Mr. Popko worked one-on-one with the graduate and undergraduate students who worked on the project. Eleven presentations were made at scientific conferences and three presentations were made as part of continuing education programs for vector control personnel. How have the results been disseminated to communities of interest? Research findings were presented and disseminated at the annual meetings of the Entomological Society of America, the Pacific Branch of the Entomological Society of America, the Society for Vector Ecology, the American Mosquito Control Association, and the Mosquito and Vector Control Association of California. Publications on the design and management of constructed treatment wetlands for enhanced mosquito control, evolution of resistance to the mosquitocidal proteins of Bacillus thuringiensis subsp. israelensis, the influence of native fish and vegetation planting designs for constructed wetlands on mosquito production, the potential use of native fish in vector control programswere published. Other outreach activities included participation as an invited member of the Southern California Vector Control Environmental Taskforce which promoted dialog and exchange of information among natural resource management agencies, permitting agencies, and vector control and public health agencies; participation in the Southern California Native Freshwater Fauna Working Group which is a consortium of representatives from natural resources agencies, academia, consulting firms, Cooperative Extension and other agencies that meets regularly to discuss ongoing activities related to conservation, assessment, public policy and regulations and other topics related to riparian wetlands and other aquatic habitats of southern California. What do you plan to do during the next reporting period to accomplish the goals? Nothing Reported

Impacts
What was accomplished under these goals? A multi-year experiment to investigate the effectiveness of an alternative species of emergent macrophyte (Schoenoplectus maritimus) for reducing mosquito production was carried out in replicate wetland mesocosms. The use of hydrological regime for the management of senescent plant biomass and reduction of mosquito harborage was investigated by measuring plant density and height, wetland nutrient removal and mosquito production prior to raising water levels in one half of the replicate wetlands during late winter. Mosquito production, emergent macrophyte develpment and wetland performance did not differ significantly between the two treatments during the second growing season. Implementation of these procedures has the potential to save about $150,000 in annual costs for vegetation maintenance for small wetlands (<20 acres) that are used to improve water qualtiy and reduce pollution. Genomic analyses of the microbial populations growing epiphytically on bulrush, in the water column and symbiotically inside mosquito larvae were completed. Using data from amplified 16S rRNA gene hypervariable regions, the alpha diversity of mosquito gut microbiomes from different mesocosms containing monotypic plots of the two bulrush species did not differ significantly. Proteobacteria, dominated by Thorsellia (Enterobacteriaceae), was the most abundant phylum recovered from Culex tarsalis larvae. Bacterial community diversity was greatest in young mosquito larvae and declined during immature development. Bacterial communities inside mosquito larvae were largely distinct from the water column and epiphytic habitat communities and were comparatively constant across the experiment. A GIS-based assessment of potential sites for use of native fishes as a biological control agent for mosquitoes was completed for Orange County. Culex quinquefasciatus that had evolved high levels of Cry-toxin resistance after laboratory selection were studied for changes in multiple fitness traits. There were no statistically significant differences for fecundity, egg viability, immature development time, emergence success and sex ratio traits among the three colonies tested. This result suggests that high levels of resistance to Cry-toxins that evolved over a long period of time are not associated with a significant gain or loss in biological fitness in these mosquitoes. Culex quinquefasciatus rapidly evolved resistance to a recombinant bacterial strain expressing mosquitocidal toxins for Bacillus thuringiensis subsp. israelensis and Lysinibacillus sphaericus, but resistance declined and was maintained low levels thereafter. Poor activity in the mid-range concentrations and lower than expected synergistic interactions were identified as potential sources of early resistance in the mosquitoes.

Publications

  • Type: Journal Articles Status: Under Review Year Published: 2015 Citation: Pennington, M.J., N. G. Rivas, S. M. Prager, W. E. Walton, and J. T. Trumble. 2015. Pharmaceuticals and personal care products alter the holobiome and development of a medically important mosquito. Environmental Pollution.


Progress 01/01/13 to 09/30/13

Outputs
Target Audience: The target audience includes wetlands practitioners, natural resource managers, vector control and public health personnel and other individuals involved in water reclamation activities that utilize constructed treatment wetland to improve water quality. Efforts included training of graduate and undergraduate students through the delivery of science-base knowledge by classroom and laboratory instruction, and outreach activities. Changes/Problems: Nothing Reported What opportunities for training and professional development has the project provided? Three graduate students and three undergraduate students participated in research related activities. Research findings were presented and disseminated at the annual meetings of the Entomological Society of America, the Society for Vector Ecology, the American Mosquito Control Association, and the Mosquito and Vector Control Association of California. How have the results been disseminated to communities of interest? Publications on the design and management of constructed treatment wetlands, evolution of resistance to Mtx proteins of LYSINIBACILLUS SPHAERICUS, and the influence of emergent vegetation species for constructed wetlands on mosquito production were published. Other outreach activities included participation as an invited member of the Southern California Vector Control Environmental Taskforce which promoted dialog and exchange of information among natural resource management agencies, permitting agencies, and vector control and public health agencies; participation in the Southern California Native Freshwater Fauna Working Group which is a consortium of representatives from natural resources agencies, academia, consulting firms, Cooperative Extension and other agencies that meets regularly to discuss ongoing activities related to conservation, assessment, public policy and regulations and other topics related to riparian wetlands and other aquatic habitats of southern California. Several lab members gave presentations in continuing education programs sponsored by the Mosquito and Vector Control Association of California. What do you plan to do during the next reporting period to accomplish the goals? We plan to complete studies that will allow us to fulfill all of the major goals of this porject.

Impacts
What was accomplished under these goals? A multi-year experiment to investigate the effectiveness of an alternative species of emergent macrophyte (SCHOENOPLECTUS MARITIMUS) for reducing mosquito production was completed in replicate wetland mesocosms. The use of hydrological regime for the management of senescent plant biomass and reduction of mosquito harborage was investigated by measuring plant density and height, wetland nutrient removal and mosquito production prior to raising water levels in one half of the replicate wetlands during late winter. Mosquito production, emergent macrophyte development and wetland performance were measured during the second growing season. Immature mosquito abundance was significantly greater in wetlands where water levels were raised during late winter. Hydrological regime did not significantly affect wetland performance during spring and summer following changes in water levels during winter. A GIS-based assessment of potential sites for use of native fishes as a biological control agent for mosquitoes identified sites for supplementation of native fishes in Orange County. Efforts were directed to maximizing resistance levels in CULEX QUINQUEFASCIATUS colonies identified for Mendelian crosses in order to facilitate determination of the phenotypic inheritance of resistance and cross-resistance in a BACILLUS THURINGIENSIS subsp. JEGATHESAN Cry11Ba-selected colony, as well as it’s pattern of inheritance of BACILLUS THURINGIENSIS subsp. ISRAELENSIS Cry-toxin cross-resistance. Methods were developed to visualize patterns of binding of fluorescent-labeled Cry-toxins from BACILLUS THURINGIENSIS subsp. ISRAELENSIS in the adult midgut and studies using two toxins were performed. Significantly different binding patterns were observed between adult and larval midguts, suggesting that the receptors, whose presence was indicated by fluorescence, have a very different distribution and concentration in the adult versus the larval midgut. ANOPHELES GAMBIAE was selected with an engineered bacterium expressing the mosquitocidal toxins from both BACILLUS THURINGIENSIS subsp. ISRAELENSIS and LYSINIBACILLUS SPHAERICUS. The selected colony is undergoing evaluation of its resistance levels to that recombinant, as well as its components, to determine the response of this mosquito species to intensive treatment with such materials.

Publications

  • Type: Journal Articles Status: Published Year Published: 2014 Citation: Wirth, M. C., C. Berry, W. E. Walton, and B. A. Federici. 2014. Mtx Toxins from Lysinibacillus sphaericus Enhance Mosquitocidal Cry Activity and Suppress Cry-resistance in Culex quinquefasciatus (Diptera: Culicidae). Journal of Insect Pathology 115: 62-67.
  • Type: Journal Articles Status: Published Year Published: 2013 Citation: Popko, D. A., and W. E. Walton. 2013. Small-stature Emergent Macrophytes and Crepuscular Sprinkler Disturbance Reduce Mosquito Abundance in Wetland Mesocosms. Journal of Vector Ecology 38(2): 379-389.
  • Type: Journal Articles Status: Published Year Published: 2013 Citation: Duguma, D., P. Rugman-Jones, M. G. Kaufman, M. Hall, J. D. Neufield, R. Stouthamer, and W. E. Walton. 2013. Bacterial Communities Associated with Culex Mosquito Larvae and Two Emergent Aquatic Plants of Bioremediation Importance. PLoS ONE 8(8): e72522.
  • Type: Journal Articles Status: Published Year Published: 2013 Citation: Walton, W. E., D. A. Popko, A. R. Van Dam, and A. Merrill. 2013. Distribution of Culex Species in Vegetation Bands of a Constructed Wetland Undergoing Integrated Mosquito Management. Journal of the American Mosquito Control Association 29: 6973.
  • Type: Book Chapters Status: Published Year Published: 2014 Citation: Walton, W. E., and W. K. Reisen. 2014. Influence of Climate Change on Mosquito Development and Blood Feeding Patterns. Chap. 3. Pp. 35-56. In: S. K. Singh (ed.), Viral Infections and Climate Change. John Wiley and Sons.
  • Type: Journal Articles Status: Published Year Published: 2013 Citation: Bideshi, D. K., G. Waldrop, M. T. Fernandez-Luna, M. Diaz-Mendoza, M. C. Wirth, J. J. Johnson, and B. A Federici. 2013. Intermolecular interactions between Cry2Aa and Cyt1Aa and its effect on larvicidal activity against Culex quinquefasciatus. J. Microbiol. Biotechnol. 23(8): 1107  1115.


Progress 01/01/12 to 12/31/12

Outputs
OUTPUTS: Experiments were conducted and analyzed. Three graduate students and three undergraduate students participated in research related activities. Research findings were presented and disseminated at the annual meetings of the Entomological Society of America, the Society for Vector Ecology, the American Mosquito Control Association, and the Mosquito and Vector Control Association of California, as well as the biennial meeting of the Mosquito Control Association of Australia and the quadrennial INTECOL Wetlands Conference. Publications on the design and management of constructed treatment wetlands for enhanced mosquito control (invited contribution), evolution of resistance to the mosquitocidal proteins of BACILLUS THURINGIENSIS subsp. ISRAELENSIS, the influence of vegetation planting designs for constructed wetlands on mosquito production, the efficacy of botanical extracts for control of AEDES AEGYPTI and the role of wetlands as environmental determinants of infectious disease transmission were published. Other outreach activities included participation as an invited member of the Southern California Vector Control Environmental Taskforce which promoted dialog and exchange of information among natural resource management agencies, permitting agencies, and vector control and public health agencies; participation in the Southern California Native Freshwater Fauna Working Group which is a consortium of representatives from natural resources agencies, academia, consulting firms, Cooperative Extension and other agencies that meets regularly to discuss ongoing activities related to conservation, assessment, public policy and regulations and other topics related to riparian wetlands and other aquatic habitats of southern California; and as liaison between the University of California and the Mosquito and Vector Control Association of California. PARTICIPANTS: PI: Dr. William Walton, Dept. of Entomology, Univ. California, Riverside, CA Staff: Dr. Margaret Wirth, SRA IV, Dept. of Entomology, Univ. California, Riverside, CA; David Popko, Lab. Asst., Dept. Entomology, Univ. California, Riverside, CA; Jennifer Thieme, Lab. Asst., Dept. Entomology, Univ. California, Riverside, CA Graduate Students: Dagne Duguma, Adena Why, Steven Merkley, Dept. of Entomology, Univ. of California, Riverside, CA; Undergraduate Assistants: Jordan Greer, Tristan Hallum, Jia Sun; Cooperators: Dr. Brian Federici, Dept. of Entomology, Univ. California, Riverside, CA; The California Dept. of Fish and Wildlife, the Freshwater Native Fauna Working Group (a consortium of southern California scientists), Coachella Valley Mosquito and Vector Control District (Indio, CA), Orange County Vector Control District (Garden Grove, CA), Orange County Water District (Fountain Valley, CA) and Mosquito Research Foundation (Sacramento, CA) are contacts on the project. Training opportunities were provided for three graduate students and three undergraduate assistants. Dr. Brian Federici collaborated with Drs. Walton and Wirth on studies of bacterial larvicides and provided the BACILLUS strains used in the selection experiments focused on the evolution of resistance in mosquitoes. TARGET AUDIENCES: The target audience includes wetlands practitioners, natural resource managers, vector control and public health personnel and other individuals involved in water reclamation activities that utilize constructed treatment wetland to improve water quality. Efforts included training of graduate and undergraduate students through the delivery of science-base knowledge by classroom and laboratory instruction, and outreach activities. PROJECT MODIFICATIONS: Nothing significant to report during this reporting period.

Impacts
A multi-year experiment to investigate the effectiveness of an alternative species of emergent macrophyte (SCHOENOPLECTUS MARITIMUS) for reducing mosquito production was initiated in replicate wetland mesocosms. The use of hydrological regime for the management of senescent plant biomass and reduction of mosquito harborage was investigated by measuring plant density and height, wetland nutrient removal and mosquito production prior to raising water levels in one half of the replicate wetlands during late winter. Mosquito production, emergent macrophyte develpment and wetland performance will be measured during the second growing season. Immature mosquito abundance was very low in the wetlands during the first growing season when plants were establishing. Genomic analyses of the microbial populations growing epiphytically on bulrush, in the water column and symbiotically inside mosquito larvae were completed. Using data from amplified 16S rRNA gene hypervariable regions, the alpha diversity of mosquito gut microbiomes from different mesocosms containing monotypic plots of the two bulrush species did not differ significantly. Proteobacteria, dominated by THORSELLIA (Enterobacteriaceae), was the most abundant phylum recovered from CULEX TARSALIS larvae. Bacterial communities inside mosquito larvae were largely distinct from the water column and epiphytic habitat communities and were comparatively constant across the experiment. A GIS-based assessment of potential sites for use of native fishes as a biological control agent for mosquitoes identified sites for supplementation of native fishes in Orange County. CULEX QUINQUEFASCIATUS that had evolved high levels of Cry-toxin resistance after laboratory selection were studied for changes in multiple fitness traits. There were no statistically significant differences for fecundity, egg viability, immature development time, emergence success and sex ratio among the three colonies tested. This result suggests that high levels of resistance to Cry-toxins that evolved over a long period of time are not associated with a significant gain or loss in biological fitness in these mosquitoes. ANOPHELES GAMBIAE was examined to determine whether exposure of susceptible larvae to a recombinant biopesticide expressing the mosquitocidal toxins from both BACILLUS THURINGIENSIS subsp. ISRAELENSIS and LYSINIBACILLUS SPHAERICUS affected adult female longevity. No statistically significant differences in adult longevity, male or female, were detected between the treated and untreated groups.

Publications

  • Wirth, M.C., Walton, W.E., and Federici, B.A. 2012. Inheritance, Stability, and Dominance of Cry Resistance in CULEX QUINQUEFASCIATUS (Diptera: Culicidae) Selected with the Three Cry Toxins of BACILLUS THURINGIENSIS subsp. ISRAELENSIS. Journal of Medical Entomology 49: 886-894.
  • Walton, W.E., Popko, D.A., Van Dam, A.R., Merrill, A., Lythgoe, J. and Hess, B. 2012. Width of Planting Beds for Emergent Vegetation Influences Mosquito Production from a Constructed Wetland in California (USA). Ecological Engineering 42: 150-159.
  • Rey, J.R., Walton, W.E., Wolfe, R.J., Connelly, C.R., O Connell, S.M., Berg, J.A., Sakolsky-Hoopes, G.E., and Laderman, A.D. 2012. North American Wetlands and Mosquito Control. International Journal of Environmental Research and Public Health 9(12): 4537-4605.


Progress 01/01/11 to 12/31/11

Outputs
OUTPUTS: Experiments were conducted and analyzed. Three graduate students and three undergraduate students participated in research related activities. Research findings were presented and disseminated at the annual meetings of the Entomological Society of America, the Society for Vector Ecology, the American Mosquito Control Association and the Mosquito and Vector Control Association of California. A publication on the impact of fish aquaculture on the nutrient concentrations and pestiferous blackflies was published. An invited chapter in a book on aquatic invasive species was published. Other outreach activities included participation as an invited member of the Southern California Vector Control Environmental Taskforce which promoted dialog and exchange of information among natural resource management agencies, permitting agencies, and vector control and public health agencies; participation in the Southern California Native Freshwater Fauna Working Group which is a consortium of representatives from natural resources agencies, academia, consulting firms, Cooperative Extension and other agencies that meets regularly to discuss ongoing activities related to conservation, assessment, public policy and regulations and other topics related to riparian wetlands and other aquatic habitats of southern California; and as liaison between the University of California and the Mosquito and Vector Control Association of California. PARTICIPANTS: PI: Dr. William Walton, Dept. of Entomology, Univ. California, Riverside, CA Staff: Dr. Margaret Wirth, SRA IV, Dept. of Entomology, Univ. California, Riverside, CA; David Popko, Lab. Asst., Dept. Entomology, Univ. California, Riverside, CA; Jennifer Thieme, Lab. Asst., Dept. Entomology, Univ. California, Riverside, CA Graduate Students: Dagne Duguma, Jennifer Henke, Adena Why, Dept. of Entomology, Univ. of California, Riverside, CA Undergraduate Assistants: Rex Tse, Tristan Hallum, Samantha Wong; Cooperators: Dr. Brian Federici, Dept. of Entomology, Univ. California, Riverside, CA; The California Dept. of Fish and Game, the Freshwater Native Fauna Working Group (a consortium of southern California scientists), Coachella Valley Mosquito and Vector Control District (Indio, CA), and Valley Sanitary District (Indio, CA) are contacts on the project. Training opportunities were provided for three graduate students and three undergraduate assistants. Dr. Brian Federici collaborated with Drs. Walton and Wirth on studies of bacterial larvicides and provided the Bacillus strains used in the selection experiments focused on the evolution of resistance in mosquitoes. TARGET AUDIENCES: TARGET AUDIENCES: The target audience includes wetlands practitioners, natural resource managers, vector control and public health personnel and other individuals involved in water reclamation activities that utilize constructed treatment wetland to improve water quality. Efforts included training of graduate and undergraduate students through the delivery of science-base knowledge by classroom and laboratory instruction, and outreach activities. PROJECT MODIFICATIONS: Nothing significant to report during this reporting period.

Impacts
A multi-year replicated block experiment to investigate the growth of and mosquito production from two species of bulrush was carried out in a local constructed treatment wetland receiving secondary-treated municipal effluent. Carbon and nitrogen concentrations, plant density and height of SCHOENOPLECTUS MARITIMUS and S. CALIFORNICUS in experimental plots were measured. Immature mosquito abundance and adult mosquito production also were measured. An ongoing integrated mosquito management program was very effective and kept immature mosquito populations at low levels. Mosquito production did not differ significantly between the two bulrush species. Nitrogen content per unit dry mass was similar in both bulrush species. Genomic analyses of the microbial populations growing epiphytically on bulrush, in the water column and symbiotically inside mosquito larvae were initiated for an experiment of bulrush growing in replicate microcosms containing a single species of the two bulrush species. Microbial DNA was successfully extracted from each of the three foci; genomic analyses are currently underway. Mtx toxins from BACILLUS SPHAERICUS (Bs) were tested for potential interactions with various toxins from two mosquitocidal bacterial strains, Bs and BACILLUS THURINGIENSIS subsp ISRAELENSIS (Bti). Dose response assays of mixtures of the Bs and Bti toxins with Mtx-1 or Mtx-2 revealed positive synergy with Bs, and positive synergy with the individual Bti toxins against CULEX QUINQUEFASCIATUS. However no synergy was detected with a smaller subset of Mtx+Cry toxins against AEDES AEGYPTI. In the cases where synergy was detected, improvements in activity were also measured against laboratory mosquitoes with Cry-toxin resistance. These data suggest that Mtx toxins have potential to enhance activity against susceptible and resistant C. QUINQUEFASCIATUS when engineered for expression in current mosquitocidal bacterial strains.

Publications

  • Walton, W.E., Henke, J. A, and Why, A. M. 2011. GAMBUSIA AFFINIS (Baird and Girard) and GAMBUSIA HOLBROOKI Girard (Mosquitofish). Chap. 22. In: R. Francis (ed.) A Handbook of Global Freshwater Invasive Species. Earthscan. London, U.K. p. 261-273.
  • Pachon, R.T., and Walton, W. E. 2011. Seasonal Occurrence of Black Flies (Diptera: Simuliidae) in a Desert Stream Receiving Trout Farm Effluent. Journal of Vector Ecology 36:187-196.
  • Walton, W.E. 2011. Design and Management of Free Water Surface Constructed Wetlands to Minimize Mosquito Production. Wetlands Ecology and Management (Special Issue on Wetlands and Human Health edited by P. Dale and C. R. Connelly). DOI: 10.1007/s11273-011-9243-1


Progress 01/01/10 to 12/31/10

Outputs
OUTPUTS: Experiments were conducted and analyzed. Four graduate students and nine undergraduate students participated in research related activities. Research findings were presented and disseminated at the annual meetings of the Entomological Society of America, the Pacific Branch of the Entomlogical Society of America and the Mosquito and Vector Control Association of California. A publication on current practices in wetland management for mosquito control was developed with wetlands scientists and mosquito control practitioners for the Society of Wetland Scientists newsletter. Our research findings were included in an invited chapter in a book on aquatic invasive species. Other outreach activities included participation as an invited member of the Southern California Vector Control Environmental Taskforce which promoted dialog and exchange of information among natural resource management agencies, permitting agencies such as the Army Corps of Engineers, vector control and public health agencies; participation in the Southern California Native Freshwater Fauna Working Group which is a consortium of representatives from natural resources agencies, academia, consulting firms, Cooperative Extension and other agencies that meets regularly to discuss ongoing activities related to conservation, assessment, public policy and regulations and other topics related to riparian wetlands and other aquatic habitats of southern California; participation as a technical advisor for the Vector Habitat Remediation Program in San Diego County; and as liaison between the University of California and the Mosquito and Vector Control Association of California. PARTICIPANTS: PI: Dr. William Walton, Dept. of Entomology, Univ. California, Riverside, CA Staff: Dr. Margaret Wirth, SRA IV, Dept. of Entomology, Univ. California, Riverside, CA; David Popko, Lab. Asst., Dept. Entomology, Univ. California, Riverside, CA; Peter Brabant, Lab. Asst., Dept. Entomology, Univ. California, Riverside, CA; Jennifer Thieme, Lab. Asst., Dept. Entomology, Univ. California, Riverside, CA Graduate Students: Donald Beasley, Dagne Duguma, Jennifer Henke, Adena Why, Dept. of Entomology, Univ. of California, Riverside, CA Undergraduate Assistants: Henrique Chan, Christina Handayan, Kevin Mai, Ngoc Nguyen, Justin Richardson, Rex Tse, Andrew Nguyen, Tristan Hallum, Samantha Wong; Cooperators: Dr. Brian Federici, Dept. of Entomology, Univ. California, Riverside, CA; Jeffrey Johnson, SRA IV, Dept. of Entomology, Univ. California, Riverside, CA; Bonnie Nash, Orange County Water District, Fountain Valley, CA; Richard Zembal, Orange County Water District, Fountain Valley, CA; Training opportunities were provided for four graduate students and nine undergraduate assistants. Dr. Brian Federici and Mr. Johnson collaborated with Drs. Walton and Wirth on studies of bacterial larvicides and provided the Bacillus strains used in the selection experiments focused on the evolution of resistance in mosquitoes. Richard Zembal and Bonnie Nash collaborated on studies of the arroyo chub as a replacement for mosquitofish in integrated mosquito management programs in sensitive wetlands and watersheds of southern California. The California Dept. of Fish and Game, the Freshwater Native Fauna Working Group (a consortium of southern California scientists), Coachella Valley Mosquito and Vector Control District (Indio, CA), and Valley Sanitary District (Indio, CA) are contacts on the project. TARGET AUDIENCES: The target audience includes wetlands practitioners, natural resource managers, vector control and public health personnel and other individuals involved in water reclamation activities that utilize constructed treatment wetland to improve water quality. Efforts included training of graduate and undergraduate students through the delivery of science-base knowledge by classroom and laboratory instruction, and outreach activities. PROJECT MODIFICATIONS: Nothing significant to report during this reporting period.

Impacts
Outcomes included the generation of new knowledge that was included in five publications. Topics of new knowledge included improved management techniques for mosquito populations associated with man-made and natural wetlands; an improvement of environmentally friendly methods for controlling vectors of disease-causing pathogens of humans, companion animals and wildlife; and a greater understanding of the evolutionary mechanisms underlying resistance in insects. Information was provided to assist the general public for the prevention of production of mosquitoes and adoption of safe preventative measures against biting insects. Changes of conditions that resulted from this project included reduced use of chemical pesticides, improved water quality of wastewaters and stormwaters, improved methods for reducing the production of pest and vector insects during water reclamation, and improvement in the quality of life for citizens of California.

Publications

  • Berg, J. A., M. G. Felton, J. L. Gecy, A. D. Laderman, C. R. Mayhew, J. L. Mengler, W. H. Meredith, N. R. Read, J. R. Rey, C. Roberts, G. E. Sakolsky-Hoopes, W. E. Walton, R. J. Wolfe. 2010. Mosquito Control and Wetlands. Wetland Science and Practice 27(2): 24-34.
  • Wirth, M. C., W. E. Walton, and B. A. Federici. 2010. Inheritance Patterns, Dominance, Stability and Allelism of Insecticide Resistance and Cross-resistance in Two Colonies of CULEX QUINQUEFASCIATUS (Diptera: Culicidae) Selected with Cry-toxins from BACILLUS THURINGIENSIS subsp.ISRAELENSIS. Journal of Medical Entomology 47: 814-822.
  • Wirth, M. C. 2010. Mosquito Resistance to Bacterial Larvicidal Toxins. The Open Toxicology Journal (3): 110-115.
  • Wirth, M. C., W. E. Walton and B. A. Federici. 2010. Evolution of Resistance to the BACILLUS SPHAERICUS Bin toxin is Phenotypically Masked by Combination with the Mosquitocidal Proteins of BACILLUS THURINGIENSIS subspecies ISRAELENSIS. Environmental Microbiology: 47: 814-822.
  • Gordillo, A. R., and W. E. Walton. 2010. Effects of Larval Diet on Life History Traits of CULEX Mosquitoes. Proc. Papers Mosq. Vector Control Assoc. Calif. 78: 16-18.