Mosquito population in Conn. jumps 60 percent over 20 years

The state’s mosquito population has increased by 60 percent over the past 20 years, according to the Connecticut Agricultural Experiment Station.

In a study, published Nov. 6 in the journal Scientific Reports, researchers from the stations analyzed yearly changes to mosquito species diversity, abundance and distribution at 87 trapping sites statewide. Not only did they find that mosquito abundance jumped 60 percent, they also found there have been numerous introductions of mosquito species into the state over the past 20 years.

The species showing population growth in the state had some similar characteristics, including a reliance on permanent (or

semi-permanent) bodies of water and a preference for the blood of mammals. Researchers also found indications that many mosquito species are heading north, possibly responding to shifting environmental factors.

“Changes to land and climate create unique chances for opportunistic insects — such as mosquitoes — to take advantage of the many habitats we create for them,” said Dr. Joseph McMillan, a lead coauthor of the study in a news release. “As humans continue to alter the environment, mosquitoes are poised to benefit from these changes.”

McMillan is also a postdoctoral scientist at the agricultural experiment station.

The station traps mosquitoes at 87 municipalities throughout Connecticut as a part of the statewide mosquito surveillance program. Mosquitoes between June and October, and tested for West Nile virus and other mosquitoborne viruses.

This year, at least 143 mosquitoes tested positive for West Nile Virus and two tested positive for Eastern Equine Encephalitis. There were also at least four human cases of West Nile Virus in Connecticut this year.

“This study shows the value of long-term surveillance data,” said Dr. Philip Armstrong, study co-author and a medical entomologist at the experiment station in the news release. “It clearly shows that mosquitoes are on the rise in Connecticut and provides a baseline for monitoring future population changes and range expansions that are anticipated under climate change.”