Types of life forms of mosquitoes

In Austria, about 40 gnat types of 6 different genera have been detected. Although they are all different in terms of their biology and their behaviour, they can be characterised in terms of just a few life forms. Knowledge of these types of life forms is important because it makes it easier to understand the various forms of behaviour of the different mosquitoes. This in turn allows people to find their own strategies for protecting themselves and possibly even for preventing uncontrolled multiplication.

Flooding mosquitoes

The group of so-called flooding mosquitoes predominantly lays their eggs in dried-up flooding areas where the clutch can then wait for water for long periods of time. When the water recedes after a flooding event, this is immediately followed by exponential growth of these mosquitoes on a large scale. As adult flying gnats, they only have a relatively short lifespan. However, in this phase, the females need blood to allow maturation of new eggs. For this reason, they are exceptionally active and irritating. They prey on amphibians, game animals, and, given the opportunity, also on humans. On their own, these gnats do not migrate far from their breeding place. However, they can be blown across vast distances by strong winds and thus reach human settlements where, for a short time, they become a major nuisance not only during twilight but even during the day. Of the flooding mosquitoes, only the strongest eggs overwinter. Flooding mosquitoes hardly ever enter buildings. The most important types are Aedes vexans, Aedes (Ochlerotatus) sticticus, Aedes rossicus, etc.

House mosquitoes

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Culex Pipiens
Abbildung einer saugenden Stechmücke

The biology of so-called house mosquitoes is very different. The females survive winter by taking shelter in hollow trees and holes in the ground. In inhabited areas, they may enter houses to overwinter in cellars or frost-free rooms. It is this type of mosquito that makes it difficult for humans to go to sleep in late summer and autumn. The following spring, the mosquito females find small puddles of water in the vicinity of their wintering place to lay their eggs. Apart from the edge of ponds and still water ditches, they use rain barrels, old tyres filled with water, bird baths etc. as their “breeding water”. A female lays about 150 eggs from which several generations can hatch in one year. Depending on the weather conditions, such a female can in theory produce up to one billion new mosquitoes before the end of the season. Although flooding events can boost house mosquito numbers, they have developed into a typical synanthropic species, in that human settlements provide precisely the conditions that they need. Types of house mosquitoes: Culex pipiens, Culex hortensis, Culiseta annulata, etc.

Fever gnats or malaria mosquitoes

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Anopheles_stephensi
Saugenden Stechmücke der Gattung Anopheles stephensi mit Bluttröpfchen am Hinterleib

In terms of their life form type, “fever gnats or malaria mosquitoes”, genus Anopheles, are similar to house mosquitoes, for they too are found in human settlements. Unlike house mosquitoes, however, they tend to live in humid rooms and stables which they not only use to overwinter but even during the summer months, for example as a resting place for pregnant females. In our latitudes, they can also transmit blood plasmodia (malaria pathogens). Transmission occurs when an anopheles mosquito ingests the pathogens in the relevant stage of development from the blood of a person already suffering from malaria. During a long warm period due to good weather, the pathogen cycle is able to continue inside this mosquito, so that the pathogen can complete its development. If this is the case and the carrier mosquito then bites a person again, malaria infection is possible even in Austria. The Anopheles species can also overwinter as eggs or larvae, and large populations can occasionally develop outdoors. This typically takes the form of a late second “plague wave” in the wake of flooding mosquitoes following a flooding event.

Invasive mosquitoes

Over the last few years, so-called “invasive mosquitoes” have become more prevalent in Central Europe. They are types of mosquitoes that previously were found only in southern and tropical areas and in countries in East Asia. More and more details are being revealed about their adaptation to and their life in our temperate latitudes. Thus it is now known, for example, that the ecological tolerance of the Asian bush mosquito (Aedes japonicus) – which has been shown to exist in South Austria – is very high. Due to its robustness, it is even able to live in submontane zone of the Alps. This means that the worldwide spread of tropical types of mosquitoes is not necessarily due to the much-discussed climate change. Rather, it is also attributable to the global trade with goods populated by these mosquitoes in different stages of their development and their transportation to other parts of the world.

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