Keep that bug spray by the door — as climate change causes hotter and longer summer seasons, entomologists say mosquitoes are going to thrive.
That’s especially true in Texas, where it can be warm enough for the pesky pests to flourish almost year-round.
“Shifting weather patterns and increasing temperatures are creating increasingly habitable environments for mosquitoes to migrate, thrive and live longer,” said Ian Cheeseman, an associate professor at Texas Biomedical Research Institute.
“We’re going to have more sustained periods of warm temperatures here in Texas and around the world. The mosquito will live longer or reproduce more quickly, and the diseases that develop within mosquitoes will also develop much more efficiently.”
Their prevalence makes studying the insects and their disease-carrying bites particularly important, he said.
Cheeseman’s studies focus on malaria infections, the malaria parasite genome and the evolution of drug resistance. Malaria is rare in the United States, but he said climate conditions are changing in a way that could allow the mosquito-borne disease to make a comeback despite currently effective treatments.
Cheeseman noted that while the United States hadn’t documented a stateside-acquired case of malaria in 20 years, five cases have been reported this year — one of which was in South Texas.
“We used to have malaria in a lot of the U.S. — definitely in South Texas,” Cheeseman said. “We have all the mosquitoes that can spread malaria here.”
While they don’t seem like a serious concern to many, mosquitoes are referred to as “the most dangerous animal on Earth,” said Renee Holmes, a San Antonio entomologist. Mosquitoes are responsible for more human deaths per year than any other animal species around the world because they spread disease, she added.
Climate change will allow mosquitoes to populate areas where they’ve never lived before, said Molly Keck, a Texas A&M University AgriLife Extension integrated pest management program specialist. As these areas get warmer overall, mosquitoes will find them more habitable and spread, she said.
“We think all insect populations will actually increase from climate change,” Keck said. “Warmer temperatures speed up their reproductive cycle and speed up their metabolism. This will mean they’ll be able to increase where they are found.”
Holmes said as the mosquito population increases, so will the number of mosquito bites, which means we can expect the cases of diseases they spread to also increase.
Earlier this summer WHO shared the results of a study on how dengue, another disease transmitted by mosquitoes, has been affected by warming global temperatures, finding that cases of dengue increased from just over half a million globally in 2000 to 5.2 million in 2019.
Climate change could also cause new mosquito-borne diseases to pop up, Keck said, pointing to the Zika virus as an example of a disease that is more recently transmitted to humans from mosquitoes.
Holmes said people shouldn’t panic, though — there are precautions they can take to protect themselves and their loved ones from mosquitoes.
“There are a lot of things folks at home can do to reduce mosquito populations,” Holmes said. “Minimize dense vegetation and keep your property plants maintained to reduce habitat.”
Mosquitoes love standing water, she added, because they need wet conditions to lay eggs. It’s best to make sure to either limit how much standing water is open to the elements in your yard or to have mosquito dunks on hand, she said. Mosquito dunks are small, donut-shaped disks that dissolve in water and kill mosquito larvae.
Cheeseman agreed, adding that San Antonians concerned about mosquitoes can also put on mosquito repellant bug spray — Holmes suggested sprays that include DEET or citronella, which are especially effective against mosquitoes — before going outdoors, or plant natural repellents in their yard such as lemon grass or rosemary.
“This is a reminder that a lot of diseases that we work on in Texas Biomed are global diseases that are still in need of lots of intense research efforts,” Cheeseman said. “Tuberculosis, HIV, malaria — diseases that we don’t necessarily instantly think of affecting the U.S. are ones that maybe should be a little bit higher up our agenda.”
