As part of a larger investigation into what is killing moose in Minnesota, researchers have been trapping mosquitoes in northern Minnesota this summer to see if they are carrying diseases that could be helping to cause the high mortality rate in moose and may potentially be carrying diseases that could affect people.
“To date we have trapped over 3,500 ‘skeets’ and have identified 19 species,” said Erika Butler, D.V.M. Wildlife Veterinarian, Minnesota Department of Natural Resources.
“We won’t be submitting any samples for viral testing until we have completed collecting the mosquitoes for the year. They will be submitted all at once,” Butler added.
Trapping began in June and will continue until the first frost.
So far, Butler said, “Four of our six most abundant species have been identified as possible vectors for eastern equine encephalitis (EEE).”
In the past Butler has described EEE as “West Nile Virus evil sister.”
Moose in northeastern Minnesota have declined from about 8,500 in 2006 to less than 4,500 in 2012. There are now less than 20 moose in northwestern Minnesota, down from a population of over 4,000 in the 1990s.
There are many theories about what is causing the deaths, from global warming to predators to a host of diseases, but Butler said, “As for other theories, I’m going to guess that the most likely culprit is brain worm, but we can’t say for sure. Our big moose mortality project [which begins in January 2013], where we will be capturing 100 moose and collaring them with GPS units that will text message us when they die, will hopefully identify the driving factors behind our moose decline.
“All indications are that the decline of the adult moose population is health related and not due to predators due to the seasonality of the deaths, the fact that the prime age animals are dying, the fact that most carcasses are intact and haven’t even been scavenged yet, etc.
“We also did some horsefly trapping last year to see if we can identify a worm that is present in western US [arterial worm] that has been implicated in the decline of Wyoming’s moose. We are just sending those samples in for PCR testing to see f we can identify that worm.”
When asked about the effects of this summer’s above-average heat and humidity on moose, Butler replied, “So far, we have had little to no reports of sick/ dead moose in this heat. I’d bet they are spending plenty of time in the water though .”
Researchers are cataloguing which species of mosquito are caught in areas that are broken down into grids or what they call vectors. Butler said it has been decades since this was last done and scientists are excited to once again work on a project like this.
Paying the bill for this study is a collection of agencies, Butler said. “The Minnesota DNR Wildlife Health Program is covering reimbursement costs for the volunteers and fleet costs for the DNR employees and the DNR is paying for any DNR employee trapping. The University Department of Entomology and the College of veterinary medicine, the Minnesota Department of Health and the Metro Mosquito Control District are all assisting with trap allocations.”
Because of the size and importance of the study, the DNR has teamed up with the University of Minnesota College of Veterinary Medicine, the University of Minnesota Department of Entomology, the Minnesota Department of Health, the Metropolitan Mosquito Control District and the 1854 Fon du Lac Natural Resources Council to get all of the work done.
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