Lifecycle of the Zika-transmitting Mosquito
Mosquito borne illnesses have played a significant role the course of human history and continue to have repercussions on human health. The World Health Organization (WHO) calls the mosquito the “greatest menace” of all disease-transmitting insects, responsible for several million deaths and hundreds of millions of cases every year. Malaria alone, transmitted by Anopheles mosquitoes, caused 438,000 deaths in 2015 and sickened 214 million people globally, according to the World Malaria Report (2015). Historically, it was “a leading obstacle to Africa’s colonization,” note the authors of a National Academies Press book on the
economics of malaria drugs.1 “It struck US presidents from Washington to Lincoln, weakened Civil War soldiers by the hundreds of thousands…traveled to California with the Gold Rush and claimed Native American lives across the continent.”2
The Aedes aegypti mosquito transmits a host of illnesses, from Zika virus and yellow fever to dengue and chikungunya. The YouTube video and photo above clearly illustrate the four life stages of the Aedes aegypti mosquito, from eggs to adults. Understanding the Aedes aegypti mosquito life cycle is key to understanding how to control it.
The “Container-breeding Mosquito”
Standing water is the perfect environment for mosquito breeding because it is where the larvae develop. As summer approaches and Zika virus transmission risk rises, health officials are asking the public to remove even small amounts of standing water. According to a US Centers for Disease Control and Prevention (CDC) blog, the Aedes aegypti mosquito “likes to lay eggs in water that collects or is stored in manmade containers.”
We recommend dumping standing water after no more than two days from 3:
- Vases
- Pet Water Bowls
- Flowerpots/Saucers
- Buckets
- Pool and Boat Covers
- Birdbaths
- Uncovered Trash Cans/Indented Lids
- Rain Barrels
- Toys
- Garden Ornaments that Collect Water
Other Mosquito Control Strategies
The Mosquito Control Association recommends changing the water in birdbaths and wading pools at least once per week, and stocking ornamental pools with “top feeding predacious minnows,” which eat mosquito larvae. Alternatively, ornamental pools may be treated with biorational larvicides (active against a given target, but relatively innocuous to non-target organisms), or S-methoprene-containing (insect growth regulators) products. Chlorine solutions are also known to inhibit mosquito larvae development, probably through an insect growth regulator mechanism. Research is being conducted to determine effective solution concentrations.
Discarded tires can be a mosquito breeding paradise. Avoid storing these outdoors, but if no other options are available, these can be treated with a larvicide.
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Additional Tips for backyard swimming pool owners:
- Empty the water from small inflatable and molded plastic kiddie pools immediately after use.
- Keep larger pools properly chlorinated to inhibit mosquito breeding. Leaving to go on vacation? See to it that the pool is treated while you are away, or cover the pool.
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1 Institute of Medicine (US) Committee on the Economics of Antimalarial Drugs; Arrow KJ, Panosian C, Gelband H, editors. Washington (DC): National Academies Press (US); 2004. On line, available: http://www.ncbi.nlm.nih.gov/books/NBK215638/
2 Ibid.
3 Based on the CDC blog, “Zika Virus: Zika, Mosquitoes, and Standing Water,” posted March 22, 2016. Online, available: http://blogs.cdc.gov/publichealthmatters/2016/03/zikaandwater/