Adapting to Climate Change: Issues for the Metropolitan Mosquito Control District

Transcription

1 Adapting to Climate Change: Issues for the Metropolitan Mosquito Control District Nancy Read MMCD Technical Coordinator Oct. 28, 2010 aq-ppt2-05

2 Metro Mosquito Control District 7-county metro agency 3,000 sq. miles 70,000 wetlands 2.8 million residents 1958

3 Services Regional and local reduction of Mosquitoes Biting gnats (black flies, Simuliidae) Monitoring and public information for Deer ticks

4 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

5 Biology: 2 egg-laying strategies Eggs on water surface (Culex, Anopheles) OR Eggs on moist soil or container, last up to 5 yrs (Aedes)

6 Biology Basics Larvae develop in standing water 14+ days in early spring 5-7 days

7 Floodwater Mosquitoes - Aedes Eggs laid in moist, exposed wetland soil Eggs hatch when water level rises after rain, flooding Larval stage in water 5-7 days in summer Ae. vexans common summer pest Water Eggs

8 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

9 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

10 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

11 Aedes japonicus Japanese Rock Pool Mosquito Capable of transmitting Japanese encephalitis St. Louis encephalitis West Nile virus La Crosse virus Eastern equine virus Others?

12 Aedes japonicus Japanese Rock Pool Mosquito Larval habitat Rock pools Tree holes Tires, Containers Concrete

13

14

15 Aedes japonicus,

16 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

17 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

18 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

19 Standing water species: Culex Main vectors of West Nile Virus Feed on birds more than mammals, or both

20 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

21 Culex pipiens, Cx. quinquefasciatus, Cx. restuans Stormwater catch basins, other structures Small shallow ponded areas

22 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??

23 West Nile Virus in U.S.A., Cx. pipiens US 2002: 4156 cases, focus in MI, OH, Chicago, Toronto (400) 284 human deaths First Minn. occurrence

24 West Nile Virus in U.S.A. Cx. tarsalis Cx. pipiens US 2003: 8694 cases, 206 deaths Canada: 1481 cases Minnesota: 145 cases, 4 deaths Virus mutation

25 West Nile Virus in U.S.A. Cx. tarsalis Cx. pipiens US 2010 (to Oct. 26) 832 cases, 33 deaths MN: 5 cases, 0 deaths Why fewer illnesses? Cx. tarsalis population Low to moderate in MMCD Herd immunity birds? Cx. quinquefasciatus

26 MMCD s Control Approach Which mosquito species in which locations? Basis of Integrated Pest Management Focus on larvae in water

27 Map

28 Bti Bacillus thuringiensis var israelensis Soil bacterium On corn cob granule Applied by helicopter or by hand Dose 5 to 8 lbs/acre

29 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

30 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

31 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

32 Interactions with Weather / Climate Precipitation Temperature Different by species group, habitat Implications for control, resources

33 2009

34 Avg. mosquitoes / CO2 trap night Rainfall (in.) 2010 Spring Aedes Summer Aedes (Floodwater) Cattail (Cq. perturbans) Culex (Standing Water)

35 La Crosse Encephalitis vectors MMCD Aspirator Collections of Ae. triseriatus Average Cool, dry fewer mosquitoes /18 6/1 6/15 6/29 7/13 7/27 8/10 8/24 9/7 9/21 Mean Capture Week

36

37 WICCI - Wisconsin

38

39

40 Avg. mosquitoes / CO2 trap night Rainfall (in.) 2010 Spring Aedes Summer Aedes (Floodwater) Cattail (Cq. perturbans) Culex (Standing Water)

41

42

43 Avg. mosquitoes / CO2 trap night Rainfall (in.) 2010 Spring Aedes Summer Aedes (Floodwater) Cattail (Cq. perturbans) Culex (Standing Water)

44

45

46

47 Avg. mosquitoes / CO2 trap night Rainfall (in.) 2010 Spring Aedes Summer Aedes (Floodwater) Cattail (Cq. perturbans) Culex (Standing Water)

48 Climate issues for MMCD Extended season Variability and resource use New species, range expansion? Ae. albopictus