Ag­gres­sive type of mosquito takes area by swarm — but ex­perts say it won’t last

Edmonton Journal - - CITY + REGION - JAMIE SARKONAK

A par­tic­u­larly ag­gres­sive species of mosquito has taken to Ed­mon­ton’s skies just be­fore the Vic­to­ria Day long week­end.

Known to bi­ol­o­gists as Och­lero­ta­tus spencerii, the mos­qui­toes that emerged this week tol­er­ate the dry heat of the day and are very ac­tive in seek­ing prey.

Their ag­gres­sion might make them more no­tice­able to Ed­mon­to­ni­ans, said Peter Daly, a bi­o­log­i­cal tech­nol­o­gist with the City of Ed­mon­ton.

“It’s not that the num­bers (of mos­qui­toes) are par­tic­u­larly high,” he said Wed­nes­day. “It’s just that the ones we have right now are very ac­tive ... We no­tice them a lot more.”

More than 30 mosquito species live in the Ed­mon­ton area. Daly said they thrive in warm en­vi­ron­ments with stand­ing wa­ter, such as the river val­ley. While all mos­qui­toes like hu­mid­ity, different weather helps different types of mos­qui­toes thrive.

“(The mos­qui­toes we have now are) still ac­tive at dawn and dusk as nor­mal, but tol­er­ate the heat and dry­ness of the day a lot more,” Daly said.

He added that Ed­mon­ton ex­pe­ri­enced a sim­i­lar trend of ag­gres­sive mos­qui­toes in 2011.

On the pos­i­tive side, Daly said it’s likely the ag­gres­sive mos­qui­toes of this week won’t be a prob­lem for long — they have quicker me­tab­o­lisms, which makes them die more quickly.

“Like ev­ery­thing else in life, this too shall pass,” he said.

The City of Ed­mon­ton con­trols mos­qui­toes by spray­ing tem­po­rary pools of wa­ter with an in­sec­ti­cide con­tain­ing the bac­te­ria Bt, or Bacil­lus thuringien­sis.

The Bt pes­ti­cide tar­gets mosquito lar­vae and doesn’t af­fect other in­sects such as drag­on­flies, Daly said.

The city sprays Bt pes­ti­cide three to four times per sum­mer.

In the past, the city used the neu­ro­toxin Durs­ban to kill mos­qui­toes, but stopped two years ago. Re­searchers ex­pressed con­cerns to city coun­cil’s au­dit com­mit­tee in Jan­uary that the ac­tive in­gre­di­ent in Durs­ban, chlor­pyri­fos, lasts a long time in the en­vi­ron­ment and threat­ens bees, drag­on­flies and other ben­e­fi­cial in­sects.

In the same meet­ing, city of­fi­cials said they used four kilo­grams of the in­sec­ti­cide Pyrate — which also con­tains chlor­pyri­fos.

This year, Daly said the city has not used Pyrate.

Weather con­di­tions can also help to con­trol mos­qui­toes.

Dry weather dis­cour­ages mos­qui­toes, but en­cour­ages the growth of other pests such as ants, yel­low jack­ets, cater­pil­lars and grasshop­pers.

Ed­mon­to­ni­ans can pre­pare for mosquito sea­son by keep­ing lawns trimmed, en­sur­ing win­dows are sealed and clos­ing their doors.

Daly, the bi­o­log­i­cal tech­nol­o­gist with the City of Ed­mon­ton, warned home­own­ers that some mos­qui­toes that emerge later in the sea­son are small enough to squeeze through screen doors.

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