six mile lake 2011 summary. weevil biology native to north america and long lake original host...
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Six Mile Lake2011 Summary
Weevil Biology
Native to North America and Long Lake
Original host plant is native Northern watermilfoil
Entirely aquatic, except for shoreline hibernation in
winter
Larvae and Pupae stages have highest impact
Tunnel through stem, emerge as adults
Eggs
Larvae
Pupa
Adult
Weevil-Induced Damage
Nutrient flow disrupted Loss of buoyancy = collapse Reduced biomass & plant
height Secondary infections
EnviroScience Stocking Strategy Stock multiple
years More weevils in first
year Concentrate weevil
populations in a few locations
Annual surveys: evaluate progress
Seasonal variation
YearSites
Stocked Total
Weevils
2009 S1 6,000
2010 S1, S2, S3 12,000
2011 S1, S2, S3 16,000
Survey ComponentsWeevil population density
Milfoil densityNative plant species and relative abundance
Weevil activityOverall health of milfoil
Long term data
2011 Positive Results
• Weevil life stages and damage found at all stocking sites•2011 results indicate an increase in weevil population• Found weevils at S2 which was previously undetected in 2010• Milfoil density at S2 and S3 decreased by 75% and 50% post-stocking 2011• Milfoil is well-below surface of water (1-3 feet) in stocking sites• S1 had a 50/50 mix of milfoil and native plants
Native Plant Species Seven native aquatic plant species were recorded in 2011: Clasping leaf pondweed (Potamogeton
perfoliatus), Chara (Chara sp.), Coontail (Ceratophyllum demersum), Eelgrass/Water Celery (Valisneria americana), Elodea (Elodea canadensis), Flat-stem pondweed (P. zosteriformis), Large leaf pondweed (P. amplifolius), Northern watermilfoil (Myriophyllum sibiricum), Sago pondweed (P. pectinatus), Thin pondweed (P. pusilus), White water-buttercup (Ranunculus aquatilus), and White water lily (Nymphaea spp.).
Slow start to stocking 2011 Seasonal Variability
Expected Results Milfoil growing below surface Decrease in milfoil density and
health Increase in native plant species
density
Six Mile LakeProject Considerations
2012 Proposal
Association contract for 15,000 weevils
EnviroScience will match (30,000 total) for a more aggressive plan
Address additional areas of infestation Comprehensive milfoil assessment
What you can do to help
(800)940-4025(330)688-1111
3781 Darrow RdStow, OH 44224
www.enviroscienceinc.com
Contact EnviroScience
