We can eliminate some mosquito species, but not all; understand

Given this diversity, there are many ecological cycles — in other words, the relationships between species and their environment — to consider.

Healy, who is also president of the American Mosquito Control Association, cited Louisiana as an example, which is home to many swamps where mosquitoes thrive.

“These mosquitoes can serve an excellent purpose, you know, in the ecology of wetland life cycles and feeding fish and other small invertebrates in the aquatic system. And perhaps there are other small animals that can feed on the adults (mosquitoes).”

Other mosquitoes may play similar roles in their native habitats, so complete eradication could end up having some adverse effects. Furthermore, experts say it’s unlikely we’ll be able to completely exterminate all mosquitoes, given their enormous (think hundreds of billions) and widespread population.

But we don’t necessarily need to get rid of all the mosquitoes.

It turns out that the species we’re most familiar with—the ones that cause all those itchy, red bumps, as well as the most notorious illnesses—are few in number.

And as Laura Harrington, professor of entomology at Cornell University, states: “Eradicating all mosquitoes would likely have an impact on the food chain. Eradicating one or two species would probably have no impact.”

Okay, so who’s the problem?

The genera Aedes, Anopheles and Culex, to be exact. Each species within these genera can transmit multiple viruses or parasites. Anopheles transmits malaria, Culex transmits West Nile, and only the Aedes genus includes mosquitoes that can transmit yellow fever, chikungunya, dengue fever and Zika, among others.

And we may not need them in our ecosystems.

“Disease-carrying mosquito species, such as Aedes aegypti and Aedes albopictus, are invasive species in many parts of the world. (…) We were fine without them,” John Marshall, resident professor of biostatistics and epidemiology at the University of California, Berkeley, told CNN.

“There are thousands of mosquito species, only a few of which transmit human pathogens, so if disease-carrying species were eliminated, non-disease-carrying species would often be available to fill their ecological niches.”

Marshall added: “Disease-carrying mosquitoes have been eliminated from many parts of the world throughout history, so local elimination is certainly possible.”

Healy noted that these species also have “a very close relationship” with the viruses or parasites they carry. This means that while sister species could theoretically mutate and become capable of transmitting the same diseases, we are unlikely to see completely unrelated species suddenly become carriers if we eliminated the problematic ones.

Looking more specifically at the US, Culex mosquitoes — namely, the common house mosquito — are a big target for control efforts.

These mosquitoes prefer to feed on birds, where they contract West Nile virus, and humans are “accidental hosts,” Healy said. But as larvae and pupae, these mosquitoes love to live in highly polluted environments, such as septic water, retention and detention ponds, and anywhere with sewage runoff.

The other type of mosquito targeted in the U.S. are the ones that live in your backyard, like the Asian tiger mosquito (part of the Aedes genus). Early in their life cycle, “they live in backyard containers like tires, watering cans, bird baths.”

Importantly, these ecosystems don’t have much going on through other species that could be affected — so eliminating these specific mosquito species wouldn’t upset the natural balance, Healy said.

As for Anopheles mosquitoes, which transmit malaria, the situation is a little different. They prefer swamps, Healy said, which are a much more diverse ecosystem.

“If you were going to attack the larvae of this species, you would have to really think about what types of products you would use in those environments,” she said.

But while some recent cases of malaria have made headlines, it’s still rare in the US.

What are we trying?

Gone are the days of problematic chemicals having unintended effects on ecosystems—control strategies are becoming increasingly specialized, experts say.

“For example, some success has been achieved with Wolbachia (a bacterial infection of mosquitoes) as a tool to ‘sterilize’ the Aedes aegypti mosquito (an important vector of dengue, Zika and yellow fever viruses),” said Harrington.

Wolbachia, for example, has been used to sterilize male mosquitoes. The bacteria also prevents the viruses that cause zika, dengue, yellow fever and chikungunya from replicating inside the Aedes aegypti mosquito.

Gene editing offers other promising strategies, including additional ways to make mosquito populations sterile. Other avenues include using non-chemical options to kill immature mosquitoes — such as bringing in fish to eat the larvae — installing sugar traps and using drones to find stagnant water for removal, Healy said.

But there is no denying that we have not yet won the war.

“It’s been a challenge,” Harrington said. “Mosquitoes have short generation times, can mutate, adapt and change very quickly in response to some strategies. Furthermore, there is still much we don’t know about their basic biology and behavior that is critical to developing effective means to eliminate them.”

She added: “Much research needs to be done to develop and evaluate tools that are accessible and acceptable, especially for those living in resource-poor settings who suffer the highest burden of disease.”

Education about mosquito control is also essential — incorrect use of sprays, for example, can harm other insects, such as bees. “But fortunately, these misapplications are not the norm,” said Healy, who has conducted research into these practices alongside the beekeeping industry.

“We have been organizing mosquito control for more than a century. And our research with the USDA Bee Laboratory continues to emphasize that there are more important stressors for honey bee health. (…) We are constantly educating mosquito control workers to follow these practices. And when followed, we anticipate no harm to these insects.”

What can we do now?

Is it possible to eliminate the worst of the mosquitoes that torment us? Yes. But this will take time.

For now, here’s what experts recommend to stay safe:

• Check your local health department website to be aware of mosquito-borne risks;
• Use repellents registered with Anvisa;
• When outdoors, wear light, loose clothing; long sleeves and long pants if possible;
• Make sure your doors, windows and screens are protected to prevent mosquitoes from entering through cracks or tears;
• o visiting areas with disease-carrying mosquitoes, invest in a mosquito net;
• Check your yard for standing water once a week; empty any buckets or trash cans after raining or watering.