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

ƒ 7-county metro agency ƒ 3,000 sq. miles ƒ 70,000 wetlands ƒ 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 ƒ Over 150 native species in US (50 just in Minn.) ƒ Well-adapted to many conditions

Photos from The Nature Conservancy and Canisius Ambassadors for Conservation Biology: 2 egg-laying strategies ƒ Eggs on water surface (Culex, Anopheles) OR ƒ Eggs on moist soil or container, last up to 5 yrs (Aedes) Biology Basics ƒ Larvae develop in standing water

Å 14+ days in early spring Æ 5-7 days Floodwater Mosquitoes - Aedes

ƒ Eggs laid in moist, exposed wetland soil ƒ Eggs hatch when water level Eggs rises after rain, flooding

ƒ Larval stage in water Water 5-7 days in summer ƒ Ae. vexans common summer pest Floodwater Mosquitoes - Aedes

ƒ Adults will fly far to find hosts; 5 to 50 miles ƒ Prefer large bovines ƒ Vector of heartworm, possibly other viruses ƒ Many generations per year, if rainfall; eggs last up to 5 years Floodwater Mosquitoes – “Spring”

ƒ Spring species common in wooded areas ƒ Temporary water, vernal pools ƒ Eggs hatch in snow melt, larvae may take 3 wks ƒ One generation per year, but adults live 2-3 mo. ƒ Short dispersal distance Floodwater Mosquitoes – “Treehole”

ƒ Aedes triseriatus ƒ Floodwater-type, eggs can stay dormant in dry conditions ƒ LaCrosse encephalits Other container-users: ƒ Ae. aegypti, Ae. albopictus ƒ 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 ƒ 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

ƒ Lay eggs in rafts on water ƒ Hatch to larvae in 1-3 days, adult emergence 5-8 days ƒ Overwinter as adults or larvae ƒ Includes Anopheles, potential malaria vectors ƒ Culiseta melanura, Eastern encephalitis vector Cattail mosquitoes

ƒ Larvae attach to roots underwater to breathe ƒ Overwinter under ice ƒ Adults emerge around July 4th ƒ Major annoyance, may be a vector ƒ Adults travel up to 5 miles, usually less Standing water species: Culex ƒ Main vectors of West Nile Virus ƒ Feed on birds more than mammals, or both Culex pipiens, Cx. quinquefasciatus, Cx. restuans ƒ Likely WNV vector in Eastern and Southern U.S., urban areas ƒ May occur in containers, tires, gutters, rain barrels Culex pipiens, Cx. quinquefasciatus, Cx. restuans

ƒ Stormwater catch basins, other structures ƒ Small shallow ponded areas Culex tarsalis ƒ Probable vector of West Nile Virus west of Miss. River, historical vector of Western Encephalitis ƒ Found in standing water 5+ days after rain or flood, usually with grass infusion ƒ Irrigation runoff ƒ ?? West Nile Virus in U.S.A., 1999+

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

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

Cx. tarsalis ƒ US 2010 (to Oct. 26) Cx. pipiens 832 cases, 33 deaths ƒ 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?

ƒ Basis of Integrated Pest Management ƒ Focus on larvae in water Map Bti

ƒ Bacillus thuringiensis var israelensis ƒ Soil bacterium ƒ On corn cob granule ƒ Applied by helicopter or by hand ƒ Dose 5 to 8 lbs/acre ƒ Material sinks through water column ƒ Larvae feed on spores and crystals ƒ Control activity for ca. 24 h ƒ Inactivated by UV light ƒ Must reapply for subsequent larval hatch Methoprene

ƒ JH mimic, inhibits adult emergence ƒ Breaks down rapidly in sunlight, soil ƒ Extended release formulations ƒ Active period 150 days for briquet, 30 days for pellet in water, longer if dry Efficacy of control

Larvae reduced in treated sites: ƒ Bti – typically 85 to 95% ƒ Methoprene – 75 to 95%

Many mosquito species migrate over 5 miles from larval habitat ƒ 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