Ppt1

Wetlands Restoration and Mosquito Management: 

Wetlands Restoration and Mosquito Management Sabrina Drill UC Cooperative Extension Los Angeles and Ventura Counties Sldrill@ucdavis.edu 323-260-3404

Why Restore Wetlands?: 

Why Restore Wetlands? Wetland loss reduces environmental health. Wetlands are“ the sponges, kidneys, and supermarkets of the natural landscape. As sponges, they provide natural flood protection…As kidneys, they filter sediments, nutrients, and contaminants from inflowing waters…As supermarkets, they provide the foods for a wide variety of local and migratory animals.”Zedler, in Meffe and Carroll, 1994

Why Mosquitoes? : 

Why Mosquitoes? If you produce mosquitoes on your property, you can be held financially liable Mosquitoes can spread diseases among humans and other animals by acting as vectors Viral vector-borne diseases spread by mosquitoes are also known arboviruses (arthropod-borne viruses Malaria Several kinds of encephalitis West Nile Virus

WNV in North America: 

WNV in North America Human and equine outbreaks in Africa and Eurasia since 1930’s First appeared in the U.S. in 1999 in New York NY strain unusual in: Speed of spread Pathogenicity Rate of neuroinvasive disease Broad host range 2004 spread to 47 states, Puerto Rico, No. and Central America 9862 human cases, 264 deaths in US

WNV in California: 

WNV in California 1st detected in mosquito pool in Imperial Valley, July 2003 In 2004, found throughout state, most activity in southern California 1136 positive pools 3232 dead birds 830 human cases , 25 fatalities

WNV in Wildlife: 

WNV in Wildlife Evidence of infection of 328 bird, 33 mammal, and 2+ reptile sps. in N. America 84+ SoCal resident species, 66+ migrants Infection and mortality rates vary Corvids have very high mortality Owls, raptors, several other songbirds species May lead to extirpation of Greater sage grouse Others, like American Coot and pigeons, do not develop viral loads or illness

Slide7: 

Species reported in DHS dead bird data 2004:

WNV in California 2005: 

WNV in California 2005 45 counties 31 human cases, 2 deaths 619 positive birds in state lab so far Most from Central Valley and Southern California Orange, Riverside, San Bernardino Only 2 from San Diego

Wetlands Restoration and WNV: 

Wetlands Restoration and WNV If “restoration” leads to aquatic habitat existing where it did not before, could increase mosquito production In most cases, restoration means improving the ecological function of existing wetlands. This reduces mosquito production.

Mosquito biology: 

Mosquito biology 53 species in CA, at least 12 could vector WNV Eggs laid in or near water Differ in: Way they lay eggs Length of larval stage Preferred prey Time of day of activity Ability to transmit disease Larvae breathe air through a tube Prefer slow, shallow water

Implications for Mosquito management: 

Implications for Mosquito management Constructed wetlands Inherently nutrient rich water favors mosquito production Designed to attract birds, provide needed habitat but increase avian disease risk Can be carefully manipulated/managed “Natural” or restored wetlands May function well, control mosquitoes ecologically, monitoring required May be in very poor condition, great mosquito habitat, really need restoration

Treatment Wetlands: 

Treatment Wetlands High nutrients, low flow, may or may not include a habitat component Prado wetlands, Orange County Water District

Coastal Saltmarsh: 

Coastal Saltmarsh Higher, but variable, salinity changing water levels Malibu Lagoon, Cathy Jacobs Pt. Mugu, Sean Anderson

Perennial Freshwater Wetlands: 

Perennial Freshwater Wetlands May have seasonally inundated areas San Joaquin Freshwater Marsh, UCI

Riparian Ecosystems: 

Riparian Ecosystems Moderate to high flow, may have seasonally inundated areas in floodplain Santa Clara River, FSCR Malibu Creek, S. Drill

Vernal Pools: 

Vernal Pools Seasonally inundated, drying may result in deep soil fissures Vernal Pool NWR in San Diego, USFWS

Approaches to Mosquito Control in Wetlands: 

Approaches to Mosquito Control in Wetlands It is far more effective to control breeding and larvae than adults Ecological management Water flow, depth, period of inundation Vegetation management Biological control Natural or introduced predators Larval or adult Chemical control Synthetic or natural origin

Ecological Management: 

Ecological Management Seeks to eliminate mosquito habitat Improve water quality elements Hydrologic elements Keep water flowing, aerated Keep retention time under 72 hours Maintain depth, keep slopes steep Vegetation Management Reduce dense stands of vegetation

Ecological Management: 

Ecological Management Management of both hydrodynamics and vegetation may run counter to intended wetland functions for water quality improvement and habitat Source: Metzger et al., 2002

Biological Control: 

Biological Control Increase predation by natural or introduced predators Pros: May be self-sustaining Reduce use of chemicals Native species might be used: research ongoing Cons Usually, involves introduction of non-natives Can compete with or predate on native, non-target species

Chemical Control: 

Chemical Control Bacterial larvicides Effective and safe but expensive Chemical larvicides Surface oils or films suffocate larvae Toxicology to wildlife not well known Growth regulators inhibit development of larvae Toxicology to humans and wildlife very low Adulticides Most have higher toxicity to wildlife Pros: Allows for very rapid specific treatment in area and time Cons: Can harm fish, wildlife species Requires repeated application

Cultural Management: 

Cultural Management Reduce conflict with human population centers Appropriate site selection Buffer zones Establish guidelines for acceptable levels of nuisance vs. risk Restore watershed to re-establish natural hydrology, ecology, reduce mosquito production Cons: May be impossible (can’t re-plan the civic environment) Pros: Reduces need for costlier control down the road

Integrated Vector Management: 

Integrated Vector Management Develop monitoring plan to determine sources of mosquitoes Modify sources to reduce mosquito breeding Maintain equipment/infrastructure to function properly Monitor mosquito production Use minimum necessary response Control larvae when necessary Monitor to check effectiveness of control

Factors in Designing IVM for Restored Wetlands: 

Factors in Designing IVM for Restored Wetlands Mosquito species and habitat Goals for wetland If nutrient reduction, may need to practice ecological and biological control EVEN IF it reduces habitat quality For habitat wetland, spot chemical control may have least impact Establish long term management and funding mechanism 5 year restoration grants not sufficient On-going monitoring and management necessary Coordinate with vector control Allow access for control activities Develop plan for on-going maintenance Coordinate with neighboring communities

For more information about wetlands and mosquitoes: 

For more information about wetlands and mosquitoes General information about Mosquitoes and West Nile http://celosangeles.ucdavis.edu/natural_resources/West-Nile-Virus.pdf Vector management Guides from UC DANR Press: Managing Mosquitoes in Surface Flow Constructed Treatment Wetlands by Willam Walton, UCR, can be downloaded at http://anrcatalog.ucdavis.edu/merchant.ihtml?pid=5595&step=4 Managing Mosquitoes in Stormwater Treatment Devices by Marco Metzger, CA DHS, can be downloaded at http://anrcatalog.ucdavis.edu/merchant.ihtml?pid=5601&step=4   Guides for vector control in wetlands around California: Guidelines for Ecological Control of Mosquitoes on Non-Tidal Wetlands of the San Francisco Bay Area. Collins, Joshua N., and Resh, Vincent. 1989. Mosquito and Vector Control Association of California, www.mvcac.org. Other publications of interested can be identified at the San Francisco Estuary Institute web site at http://www.sfei.org/staff_pubs/JCpubs2000.html Best Management Practices for Mosquitoes on Managed Wetland Environments (focusing on the Central Valley) should be available soon from the Central Valley Habitat Joint Venture, http://www.usbr.gov/mp/cvhjv/ Information on controlling mosquitoes with minimal use of pesticides can be found at the website of the Northwest Coalition for Alternatives to Pesticides at http://www.pesticide.org/factsheets.html

For more information about wetlands and mosquitoes: 

For more information about wetlands and mosquitoes Information about WNV and Wildlife: Potential Impacts of West Nile Virus on Wildlife in California can be downloaded at http://www.vetmed.ucdavis.edu/whc/pdfs/wnvreport.pdf National information about WNV and wildlife can be found at the website for National Audubon, http://www.audubon.org/bird/wnv/ National Wildlife Health Center at http://www.nwhc.usgs.gov/ Data and data reporting: Surveillance information about the spread of WNV can be found at the UC Davis Center for Vector Borne Diseases at http://vector.ucdavis.edu/arbo.html General West Nile information can be found at the state Dept. of Health Services web site at http://www.westnile.ca.gov/. You can also report a dead bird at this site, or call 1-877-WNV-BIRD UCR West Nile Data Collection: http://www.westnilevirus.ucr.edu/