Mosquito can't survive European winters

Other View vs Mainstream View

There is a non-mainstream point of view that "Mosquitoes can't survive European winters". Let's take a look into pros and cons of this statement:

1. Pros: Many mosquito species dramatically decline in activity and reproduction when temperatures drop below certain thresholds (e.g. 10-17°C). Cold weather significantly slows mosquito life cycles.
   – Cons (Mainstream View): While mosquito activity decreases in winter, many species have adapted strategies to survive the cold. Eggs can be incredibly resilient, some species overwinter as larvae buried in mud, and adults of certain species hibernate in sheltered areas. Even some invasive species like Aedes albopictus have been shown to potentially survive winters in parts of Europe.

2. Pros: Mosquitoes function best around 27°C (80°F) and cannot function below 10°C (50°F). Most mosquito activity ceases during the coldest winter months when temperatures are consistently low.
   – Cons (Mainstream View): Although mosquito activity dramatically decreases in winter, it doesn't completely stop. Some species remain active throughout winter, especially in milder regions or urban microclimates. You may still occasionally encounter mosquitoes on warmer winter days.

3. Pros: Some tropical mosquito species that are important disease vectors, like Aedes aegypti (dengue/Zika vector), have difficulties establishing permanent populations in southern Europe, likely due to winter constraints.
   – Cons (Mainstream View): Studies show Aedes aegypti eggs can actually survive short-term exposure to low and sub-zero temperatures, in some cases even better than more cold-tolerant species. A cold winter alone may not prevent the potential re-establishment of Aedes aegypti in southern Europe.

4. Pros: Mosquito-borne diseases like West Nile virus show distinct seasonality in Europe, with human cases peaking in late summer/early fall then dropping to near zero in winter, suggesting a strong link between mosquito activity and temperature.
   – Cons (Mainstream View): While disease transmission is greatly reduced in winter, it doesn't necessarily drop to absolute zero. Occasional off-season cases may still occur, especially in milder climates. Overwintering mosquitoes could also potentially harbor viruses.

5. Pros: Cold winter temperatures, especially sustained periods below freezing, can directly kill adult mosquitoes and aquatic stages not in diapause. This can significantly reduce mosquito populations compared to areas with milder winters.
   – Cons (Mainstream View): Many mosquito species have evolved diapause strategies to survive cold and freezing temperatures in egg, larval or adult stages. Harsh winters may reduce populations but enough mosquitoes survive to rebuild numbers the following season. Urban areas can also provide microclimates and sheltered spots for mosquitoes to overwinter.

Terms

• Aedes aegypti: The yellow fever mosquito, a major vector of dengue, Zika, chikungunya, and yellow fever viruses. Highly adapted to urban environments and human hosts.

• Aedes albopictus: The Asian tiger mosquito, an invasive species that can transmit dengue, chikungunya, Zika, and other viruses. Increasingly widespread in Europe.

• Dengue: A mosquito-borne viral infection causing flu-like illness and occasionally severe complications. Transmitted primarily by Aedes aegypti mosquitoes.

• Diapause: A period of dormancy and suspended development in insects, usually triggered by environmental cues like shorter days and cooler temperatures. Allows insects to survive unfavorable winter conditions.

• Overwintering: The process by which organisms survive winter, often in a dormant or resistant state. Mosquitoes may overwinter as eggs, larvae, or hibernating adults.

• West Nile Virus: A mosquito-borne virus that can cause febrile illness and neurological disease. Increasingly common in parts of Europe. Birds serve as reservoir hosts, with Culex mosquitoes as primary vectors.

Analogy

Saying mosquitoes can't survive European winters is like saying bears can't survive winter because they hibernate. While mosquito activity and development slows or stops in winter, like a hibernating bear, they have strategies to emerge again when conditions improve. For example, some mosquitoes overwinter as hardy eggs that "sleep" through winter before hatching in spring, similar to how bears hibernate then re-emerge.

History

1. Pre-1900s: Mosquitoes recognized as widespread summer pests in Europe, but winter biology poorly understood.

2. 1920s-1930s: Research begins investigating how mosquitoes survive winter via egg resilience and adult hibernation.

3. 1950s-1980s: More in-depth studies on mosquito diapause and overwintering. Asian tiger mosquito (Aedes albopictus) begins spreading to Europe.

4. 1990s-2000s: Continued research on winter strategies of native and invasive mosquitoes as diseases like West Nile Virus emerge in Europe. Evidence that Aedes albopictus is adapting to colder climates.

5. 2010s-Present: Ongoing studies of mosquito winter survival in light of climate change and emerging disease threats. Increasing evidence that even tropical species may persist in Europe.

How to use it

1. When planning travel to Europe, don't assume there will be zero mosquito risk in winter. While populations are lower, some mosquitoes remain active and could potentially transmit diseases. Continue to use repellent and take precautions, especially in sheltered areas on warmer days.

2. If you store items like tires, buckets, or tarps outside in Europe over winter, check them for mosquito eggs in spring. Eggs laid in fall can survive winter to hatch when water collects and temperatures rise. Regularly dump out any standing water.

3. As a health official, don't become complacent about mosquito surveillance and control in winter. Continue monitoring for overwintering mosquitoes and eggs, especially of invasive species. Larvae control in fall can help reduce spring populations. Communicate that some mosquito risk can persist year-round.

Facts

• Certain mosquitoes in the Arctic can survive temperatures down to -50°C (-58°F) using antifreeze compounds and dehydration techniques.

• The common house mosquito (Culex pipiens) remains active throughout winter in places like Spain.

• Eggs of the yellow fever mosquito (Aedes aegypti) were found to survive over 6 days at -2°C (28°F) in lab studies.

• Mosquitoes like Culex pipiens can overwinter as mated adult females hibernating in places like cellars and sewers.

• Regional climate change may extend mosquito activity seasons and allow more exotic species to persist in Europe.