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Things that go ZZZ in the night

"The job is fairly simple – mainly stumbling down steep embankments and crashing through bushes to pockets of standing water to collect mosquito larvae..." Andrew Mitchell joins mosquito-tracker Billy Regan on the hunt for West Nile.
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"The experts have looked at it, and they say there’s no reason why it shouldn’t be here." Billy Regan on West Nile, photo by Andrew Mitchell

Billy Regan dips a coffee cup-sized mosquito collector into a pool of brackish water that has collected in a roadside drainage ditch and draws out a wriggling mass of brown gunk. Small, stick-like creatures, just a few millimetres in length, dart back and forth in the muck.

"There’s probably well over a hundred mosquito larvae in there," he says, carefully transferring the mass into a small plastic container that will be sent to the lab for testing.

"We always check this spot because it has the type of Class 3-plus mosquitoes that are most likely to spread the West Nile virus."

The ditch in question is on the side of Alta Lake Road outside of the Tamarisk parking lot. Just up the road is a staff accommodation building housing hundreds of Whistler-Blackcomb employees.

We approached the ditch from the parking lot side with the sun in our faces, as the mosquito larvae often retreat to the bottom of the pond when they detect shadows and movement.

Regan says this particular ditch and culvert system was cleared recently, but it has become blocked again. Water doesn’t drain well and a film develops over the water that slows evaporation. It’s exactly the kind of breeding environment that certain types of mosquitoes prefer. As well, because it’s a man-made body of water there are no natural predators to feed on the larvae and keep the mosquito population down.

Regan estimates that there are hundreds of man-made mosquito-breeding areas in the Whistler area, most of which are a byproduct of development. These areas need to be identified and mitigated, he said, in case the West Nile virus is discovered.

This is the third year that Whistler’s mosquitoes have been captured and tested for West Nile virus. So far the virus has not been discovered, but Regan and others believe that it’s only a matter of time.

"The experts have looked at it, and they say there’s no reason why it shouldn’t be here," he said.

"It was supposed to be here in 2004, then in 2005, then 2006, but there’s no doubt it will eventually get here. There’s no characteristic that would prevent (West Nile) from getting to Whistler. It’s anyone’s guess why it isn’t here already."

West Nile has already been confirmed in Alberta, and south of the border in Oregon and Idaho. Washington state and B.C., along with Alaska and the Canadian territories, are among the last jurisdictions in North America not to find proof of the virus, which typically travels through migratory birds.

It is believed that the first cases of West Nile in B.C. will be found in the Interior, carried across the border by migratory birds.

Regan is an engineering student at UBC who works summers with his uncle’s company, DG Regan and Associates. Although the job is fairly simple – mainly stumbling down steep embankments and crashing through bushes to pockets of standing water to collect mosquito larvae – he has taken an active interest in the subject, and always reads through his company’s field reports and lab test results.

He travels all over the southern part of the province, collecting mosquitoes in natural and manmade water bodies as far away as Penticton. In Whistler he checks 26 sites every week, which are scattered from one end of the municipality to the other. He also has test sites on both Whistler and Blackcomb mountains.

The type of trap he uses depends on the habitat and type of mosquito he’s looking for. Sometimes he uses a net, sometimes a cup, and other times a type of light trap with a fan that sucks mosquitoes into a filter – moths and other captured bugs are set free, and mosquito larvae are preserved in alcohol and water until they can be tested in the lab.

There’s a lot of data to collect, and his company has come up with a program that lets him record information in the field on his PDA then export it directly to a spreadsheet. Those spreadsheets, over time, will provide an overview of where different mosquitoes can be found at different times of the year and the conditions that are optimal for breeding.

There are approximately 50 different species of mosquito in B.C., about 27 of which have been shown to carry the West Nile virus in other regions of North America, according to an SFU study.

Regan’s study is looking for specific breeds of mosquitoes, rated as either Class 2 or Class 3, which have feeding habits that enable the spread of diseases like West Nile.

Class 3 and 3-plus species, such as Culex tarsalis and Culex pipiens, are the most worrisome, because they bite both birds and mammals and are always hungry. They also breed in man-made pools like catch basins and storm sewers, close to populated areas.

According to Regan, two species rated Class 3 are found within Whistler’s municipal boundaries, as well as several common species of Class 2 mosquitoes.

Class 2 mosquitoes are also considered a risk, generally moving from mammal to mammal and sometimes from bird to mammal.

Both Class 2 and Class 3 species are of specific concern to ranchers and farmers, as horses, cattle and other farm animals are particularly susceptible to West Nile.

Many B.C. ranchers have already started vaccinating their animals against the disease, even though no cases have been found.

All of the mosquito information collected by Regan and others around the province is sent on to the B.C. Centre for Disease Control, which is responsible for managing the province’s response to the disease. The BCCDC also wants to examine any corvids (crows, ravens, magpies, nutcrackers and blue jays) that are found dead where the cause of death isn’t obvious.

Crow populations in eastern Canada and parts of the U.S. have been decimated by the virus – likely through exposure to mosquitoes feeding on infected migratory birds.

As well as searching for West Nile, Regan’s work will help determine what species of mosquitoes are in Whistler and where, the habitats various species prefer, and what weather conditions and seasons are optimal for breeding – some species prefer wet, spring conditions, while others thrive in the hottest summer months.

If some form of mosquito control is ever required to prevent the spread of West Nile, Regan’s information will be used to guide local mitigation efforts.

Currently the municipality has no mosquito control regimen, although other towns in the province use a variety of new biological larvicides that are not harmful to birds or mammals but react to the specific pH balance within a mosquito’s stomach.

For example, after extensive flooding this past spring the Grand Forks area required extensive treatment with larvicide. Water levels rose high enough along riverbanks that they revived eggs that had lain dormant in the soil for up to 20 years.

"You couldn’t live there if they didn’t do anything to control the mosquitoes," said Regan.

As well, some municipalities like Delta are taking steps to reduce areas of standing water in public parks that encourage breeding.

Whistler has also been restoring natural waterways to some extent, and has been successful in reducing mosquito populations in some areas.

For example, Regan points to the recent restoration of the wetland complex on Blackcomb Way (opposite the Montebello townhomes), which was implemented to better filter meltwater from the day skier lots. That water used to be filled with mosquito larvae, says Regan, but now even mosquito pupae are a rare sighting and he has yet to find any larvae.

"That’s because it functions more like a natural ecosystem," he explained. "There are now predators like frogs and insects in the water that eat the larvae that weren’t there before. In the last few years I haven’t found anything in there, and I’m testing every week.

"I found a few mosquito pupae today, but that was a first. The fact that there’s no larvae might mean that the pupae aren’t going to live very long. That’s an ideal situation for this area. There’s still some standing water in this neighbourhood but it’s probably a lot more tolerable to be outside."

In fact, Regan says the best way individuals and governments can reduce mosquitoes is to get rid of standing water deposits where they breed – many of which are man-made and either disrupt the natural flow of water or create new areas for water to pool and stagnate.

The RMOW has created a section on the municipal website encouraging people to take efforts to mitigate standing water around their homes.

"This is the third year that we’ve monitored for West Nile, and we’re monitoring all kinds of different areas and habitats," said Heather Beresford, RMOW stewardship coordinator. "In the first year the exercise was to locate all the storm drain basins, ponds, and obstructions to identify suspect spots, and we’ve been monitoring since then.

"Last year there was a case of West Nile in Washington state (later found to be contracted out of state), so we’ve been on high alert. We’re following a provincially mandated survey and inventory program so we’re ready when West Nile does come into B.C. We’re also working under advisement from the B.C. Centre for Disease Control and with our local health authority."

Beresford said that it is extremely rare for people to become sick if exposed to West Nile, but for some people it can cause a serious illness or be fatal. Children and seniors are also more likely to be affected by the virus.

"It can be serious stuff, but the municipality is prepared," she said. "When (West Nile) does come around we will be able to implement any program the medical health officers ask us to do.

"So at this point we’re really talking about mosquito management, not West Nile. If you want to reduce mosquitoes around your house, you need to empty standing water out of wheelbarrows, flower pots, tires, or, in my case, a broken hot tub in the backyard. That’s just standard advice to eliminate locations for mosquitoes to breed, which we all should be doing anyway.

"It’s also good to try to avoid being bitten. Some of the suggestions include wearing light clothing at sunset, avoiding perfumes, using bug spray with DEET, that kind of thing."

The complete list of BCCDC recommendations, as well as an explanation of what the province will do in the event West Nile is discovered, is on the RMOW website at www.whistler.ca/Community/Social_Services/West_Nile_Virus.php . If you discover a dead bird, such as a crow, contact the B.C. Centre for Disease Control at www.bccdc.org .

Currently 126 communities in B.C. have applied for provincial grants to test for West Nile through a 2004 program established by the provincial government.



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