Adapting to Climate Change: Issues for the Metropolitan Mosquito Control District Nancy Read MMCD Technical Coordinator Oct. 28, 2010 aq-ppt2-05 Metro Mosquito Control District 7-county metro agency 3,000 sq. miles 70,000 wetlands 2.8 million residents 1958 Services Regional and local reduction of Mosquitoes Biting gnats (black flies, Simuliidae) Monitoring and public information for Deer ticks Mosquitoes and Habitats Over 150 native species in US (50 just in Minn.) Well-adapted to many conditions Photos from The Nature Conservancy and Canisius Ambassadors for Conservation Biology: 2 egg-laying strategies Eggs on water surface (Culex, Anopheles) OR Eggs on moist soil or container, last up to 5 yrs (Aedes) Biology Basics Larvae develop in standing water Å 14+ days in early spring Æ 5-7 days Floodwater Mosquitoes - Aedes Eggs laid in moist, exposed wetland soil Eggs hatch when water level Eggs rises after rain, flooding Larval stage in water Water 5-7 days in summer Ae. vexans common summer pest Floodwater Mosquitoes - Aedes Adults will fly far to find hosts; 5 to 50 miles Prefer large bovines Vector of heartworm, possibly other viruses Many generations per year, if rainfall; eggs last up to 5 years Floodwater Mosquitoes – “Spring” Spring species common in wooded areas Temporary water, vernal pools Eggs hatch in snow melt, larvae may take 3 wks One generation per year, but adults live 2-3 mo. Short dispersal distance Floodwater Mosquitoes – “Treehole” Aedes triseriatus Floodwater-type, eggs can stay dormant in dry conditions LaCrosse encephalits Other container-users: Ae. aegypti, Ae. albopictus Yellow fever, Dengue Aedes japonicus Japanese Rock Pool Mosquito Capable of transmitting – Japanese encephalitis – St. Louis encephalitis – West Nile virus – La Crosse virus – Eastern equine virus – Others ? Aedes japonicus Japanese Rock Pool Mosquito Larval habitat – Rock pools – Tree holes – Tires, Containers – Concrete Aedes japonicus, 2007-2010 Floodwater Habitats – Recap Dormant eggs - changing water level triggers hatch - large wetlands: Aedes vexans, #1 pest - woodland pools: Spring species - containers, tires, treeholes: Ae. triseriatus and Ae. japonicus Standing water species Lay eggs in rafts on water Hatch to larvae in 1-3 days, adult emergence 5-8 days Overwinter as adults or larvae Includes Anopheles, potential malaria vectors Culiseta melanura, Eastern encephalitis vector Cattail mosquitoes Larvae attach to roots underwater to breathe Overwinter under ice Adults emerge around July 4th Major annoyance, may be a vector Adults travel up to 5 miles, usually less Standing water species: Culex Main vectors of West Nile Virus Feed on birds more than mammals, or both Culex pipiens, Cx. quinquefasciatus, Cx. restuans Likely WNV vector in Eastern and Southern U.S., urban areas May occur in containers, tires, gutters, rain barrels Culex pipiens, Cx. quinquefasciatus, Cx. restuans Stormwater catch basins, other structures Small shallow ponded areas Culex tarsalis Probable vector of West Nile Virus west of Miss. River, historical vector of Western Encephalitis Found in standing water 5+ days after rain or flood, usually with grass infusion Irrigation runoff ?? West Nile Virus in U.S.A., 1999+ US 2002: Cx. pipiens 4156 cases, focus in MI, OH, Chicago, Toronto (400) 284 human deaths First Minn. occurrence West Nile Virus in U.S.A. US 2003: Cx. tarsalis Cx. pipiens 8694 cases, 206 deaths Canada: 1481 cases Minnesota: 145 cases, 4 deaths Virus mutation West Nile Virus in U.S.A. Cx. tarsalis US 2010 (to Oct. 26) Cx. pipiens 832 cases, 33 deaths MN: 5 cases, 0 deaths Why fewer illnesses? Cx. tarsalis population ¾ Low to moderate in MMCD Herd immunity – birds? Cx. quinquefasciatus MMCD’s Control Approach Which mosquito species in which locations? Basis of Integrated Pest Management Focus on larvae in water Map Bti Bacillus thuringiensis var israelensis Soil bacterium On corn cob granule Applied by helicopter or by hand Dose 5 to 8 lbs/acre Material sinks through water column Larvae feed on spores and crystals Control activity for ca. 24 h Inactivated by UV light Must reapply for subsequent larval hatch Methoprene JH mimic, inhibits adult emergence Breaks down rapidly in sunlight, soil Extended release formulations Active period 150 days for briquet, 30 days for pellet in water, longer if dry Efficacy of control Larvae reduced in treated sites: Bti – typically 85 to 95% Methoprene – 75 to 95% Many mosquito species migrate over 5 miles from larval habitat Regional control most effective to reduce overall populations Interactions with Weather / Climate Precipitation Temperature Different by species group, habitat Implications for control, resources 2009 Spring Aedes 2010 Summer Aedes (Floodwater) Cattail (Cq. perturbans) Rainfall (in.) Culex (Standing Water) Avg. mosquitoes / CO2 night mosquitoes trap Avg. La Crosse Encephalitis vectors MMCD Aspirator Collections of Ae. triseriatus 2008 1.8 2000 - 2007 Average 1.6 Cool, dry – fewer mosquitoes 2008 1.4 1.2 1 0.8 Mean Capture 0.6 0.4 0.2 0 6/1 9/7 5/18 6/15 6/29 7/13 7/27 8/10 8/24 9/21 Week WICCI - Wisconsin Spring Aedes 2010 Summer Aedes (Floodwater) Cattail (Cq. perturbans) Rainfall (in.) Culex (Standing Water) Avg. mosquitoes / CO2 night mosquitoes trap Avg. Spring Aedes 2010 Summer Aedes (Floodwater) Cattail (Cq. perturbans) Rainfall (in.) Culex (Standing Water) Avg. mosquitoes / CO2 night mosquitoes trap Avg. Spring Aedes 2010 Summer Aedes (Floodwater) Cattail (Cq. perturbans) Rainfall (in.) Culex (Standing Water) Avg. mosquitoes / CO2 night mosquitoes trap Avg. Climate issues for MMCD Extended season Variability and resource use New species, range expansion? – Ae. albopictus.