Generality
The tiger mosquito ( Aedes albopictus ) is a particular type of mosquito, which owes its name to the elegant white streaks on its black body.
Quick to act and responsible for itchy and often painful stings, the tiger mosquito has a preference for cool and shady environments, lays eggs where there is stagnant water (eg: pots, gutters etc.) and comes out during the cooler daylight hours.
In the fight against the tiger mosquito, the actions carried out by health institutions and municipalities are crucial, as is the contribution of individual citizens, who, with simple preventive measures, can make the proliferation of the insect in question extremely difficult.
As can be seen, therefore, in order for it to be effective, the intervention against the tiger mosquito must be collective, that is to say concerning several components.
What is the tiger mosquito?
The tiger mosquito, or Aedes albopictus, is a type of mosquito originating in the Tropical and Subtropical area of South-East Asia, which has some peculiar white streaks on the body and on the black legs.
Surely, many readers will have noticed this very particular insect, especially in the summer months or in some newspapers in which the marked aggressiveness was described.
The tiger mosquito is characterized by inflicting bites (or stings, if you prefer) really annoying, more acute than the traditional mosquitoes that have long been populating Italy.
| Scientific classification of the tiger mosquito |
Kingdom: Animal Phylum: Arthropods Class: Insects Order: Diptera Family: Culicide Genus: Aedes Species: Aedes albopictus |
When and how did it come to Europe and the so-called Western world?
According to the most reliable sources, the tiger mosquito came to Europe at the end of the 70s of the 20th century. The first discovery took place in Albania, in 1979, after the importation of some goods from China; after which, the subsequent finds interested in the order:
- Italy (two-year period 1990-1991, after the importation of rubbers used from US Georgia, a state in which the tiger mosquito was already widespread for some time);
- France (1999, in particular southern France);
- Belgium (2000);
- Montenegro (2001);
- The Canton Ticino of Switzerland and Greece (2003);
- Spain and Croatia (2004);
- Holland and Slovenia (2005);
- Bosnia and Herzegovina (2006).
Moving outside of Europe, in the United States the spread of the tiger mosquito could be dated, according to experts, around 1983-1984; the place of discovery was Memphis, in the State of Tennessee. From here, in a short time, the insect in question spread to many other regions of the US nation, especially in the North-East. According to the chronicles of those years, a decisive event in the spread of the tiger mosquito in the United States was an import of used tires from China, which landed in Houston in 1985 .
In South America, the first findings of the tiger mosquito took place in Brazil (1986) and Argentina (1988); in Central America, they took place in Mexico (1988); in Africa, they occurred in South-Africa (1990) and then in Cameroon and Nigeria (between 1990 and 1991); in the Middle East, finally, they were based in Libya and Israel (2003).
Features
Equipped with 6 legs and a single pair of wings, the adult tiger mosquito can measure, in terms of length, from 2 to 10 millimeters; its body size depends on two factors: the density of the larval population and the feeding within the so-called reproduction water. Since these two factors are rarely optimal, it is also infrequent to encounter 10 millimeter tiger mosquitoes.
According to experts, the average measurements of the tiger mosquito are:
- Average length of the abdomen: 2.63 mm;
- Average wing length: 2.7 mm;
- Proboscis average length: 1.88 mm.
The males of the tiger mosquito are about 20% smaller than the females; however, morphologically, the two genera are very similar.
As in all mosquito species, the male antennae are feathered and contain a sort of auditory receptors, which serve to detect the presence of females.
The tiger mosquito is a vector of diseases
The tiger mosquito is a potential vector (ie carrier ) of several viral pathogens; the latter include: the dengue virus, the Chikungunya virus, the yellow fever virus, the La Crosse encephalitis virus, the so-called Zika virus and the filaria virus, a disease that affects some animals (eg : dogs).
It should be noted that all these viral pathogens (apart from the heartworm virus) are practically absent in our country and in general in the developed world, therefore the risk of contracting the aforementioned diseases, through the tiger mosquito, is only theoretical (NB: vice versa, the danger exists where the aforementioned viruses are endemic, or rooted).
- Dengue and Chikungunya . The symptoms of these two viral diseases reflect the symptoms of severe influenza, namely: fever, muscle pain, arthralgia, headache, nausea, vomiting, rash and pain around the eyes.
- Yellow fever . In a first phase, it causes: fever with chills, headache, bradycardia, back pain, nausea and conjunctival hyperaemia; subsequently, it produces fever accompanied by jaundice, acidosis, oliguria, hemorrhages and proteinuria.
- La Crosse encephalitis . In less severe cases, it causes nausea, headache and vomiting; in the most serious cases, on the other hand, in addition to the previous symptoms, it is also responsible for: attacks of epilepsy, coma, paralysis and brain damage.
- Zika virus disease . Like Dengue and Chikungunya, cause: fever, skin rash, headache, nausea, vomiting, arthralgia, muscle pain and pain around the eyes. In addition, it is responsible for: widespread itching (all over the body), conjunctivitis and back pain.
What is a carrier?
Vectors are organisms capable of transmitting pathogens from an infected animal to humans or another animal.
By pathogen, we mean a microorganism (eg: virus, bacterium, fungus or parasite) capable of triggering a disease.
Therefore, to say that the tiger mosquito is, with respect to the human being, a potential vector of viral pathogenic agents means to say that, where this insect has the possibility of combining with these viruses, it can transmit them to the human being, after a prick .
Behavior
The tiger mosquito is very aggressive . Unlike other types of mosquitoes, it carries out its annoying activity during daylight hours, especially in the cooler ones (so early in the morning and at sunset); during the night, he is at rest.
The tiger mosquito has a tendency to nest in cool and shady environments . His favorite places are tall grass, hedges, flowers and shrubs; however he also appreciates the interiors of the houses, to be precise the cooler rooms.
As a rule, the tiger mosquito flies at low altitudes and it is for this reason that, in general, it "attacks" the human being in the legs and ankles.
Able to puncture even through the fabric of light clothing, it has a good ability to adapt to various environments, which makes it difficult to suppress or keep under control.
Life cycle and reproduction
All types of mosquitoes, including the tiger mosquito, present a phased life cycle, which includes:
- Spawning by the adult female . The eggs need water to grow and move on to the next phase, therefore the deposition takes place in containers of stagnant water, such as, for example, the flower pots, the bowls in which the animals drink, the manholes, the garden watering cans and the buckets;
- Egg hatching and passage to larval life . The larvae live just below the surface of the stagnant water, where the eggs used to reside, and feed on microscopic organisms (eg bacteria) and organic material (eg: leaves).
In specialized jargon, the larvae are also called wigglers ;
- The passage from larva to pupa . It is a phase that generally takes a week. Pupae are comma-shaped and do not normally feed.
In specialized jargon, pupae are also called tumblers ;
- The transformation of the pupa into an adult insect . Usually, this transformation occurs within 3 days.
Unlike other types of mosquito - which lay their eggs directly in stagnant water - the tiger mosquito prefers to lay its eggs in the dry parts of stagnant water containers, which it chooses as a "home" for its future progeny.
To allow this is the fact that a little water is enough for her eggs and her larvae to move on to the next phase of the life cycle (just to get an idea of the amount of water needed, just the simple condensation that forms in response to the daily temperature changes).
When the temperature conditions are optimal (generally, in the hottest months of the year), the tiger mosquito is able to complete its life cycle over 10 days .
Is it the female or male that stings the human being?
Similarly to all other types of mosquitoes, even in the case of the tiger mosquito it is the female that bites the human being; the male specimen, in fact, deals only with taking the nectar from the flowers, thus being harmless.
Curiosity: why does the female tiger mosquito bite the human being?
The tiger mosquito stings the human being, in order to steal his blood and use the latter to feed his eggs.
According to reliable scientific studies, the amount of blood stolen is really small: 2 microliters.
Symptoms of tiger mosquito bite and any complications
The tiger mosquito bites are very annoying. In fact, they are responsible for: swelling, irritation, intense itching (which can lead to bleeding), redness and often even pain .
In performing the puncture, the tiger mosquito is very fast, so that it is difficult to catch it or crush it while it is doing the above action.
If they have the possibility and the necessity, tiger mosquitoes tend to prick the same human subject several times.
In particularly sensitive individuals, a large number of tiger mosquito bites can trigger an allergic reaction that requires medical attention.
Which season of the year is it active?
During the year, the tiger mosquito can be present as an adult insect from late March until the last days of November - beginning of December . The duration of its activity is obviously influenced by the environmental and climatic conditions: the more favorable it is, the more the aforementioned timing is respected; otherwise, the activity season is reduced.
In the time window in which the tiger mosquito is active, its maximum density is recorded between August and September .
Flight and displacement capacity
The tiger mosquito can travel great distances and this allows it to migrate, without particular problems, from one city to another, provided it is bordering.
According to experts, the migration capacity of tiger mosquitoes is strictly dependent on the winds: the stronger the winds, the greater this capacity.
However, most tiger mosquitoes prefer to stay within 1-2 kilometers of their place of origin.
Countermeasures
The fight against the tiger mosquito and its spread is the responsibility of health institutions, municipalities and individual citizens .
In this struggle, the task of health institutions and municipalities is to identify and destroy larval outbreaks, and to carry out an information campaign for the citizen, in order to prevent the possibility of spawning; the role of individual citizens, on the other hand, is to follow carefully the indications that the aforementioned campaign proposes, in such a way as to simplify the amount of work that weighs on health institutions and municipalities.
In essence, therefore, synergy between the parts considered is necessary: the work of one part depends on the work of the other.
Role of health institutions and municipalities
Healthcare institutions and municipalities must:
- Monitor all areas where there is the possibility of water stagnation, as these are the areas most sought after by tiger mosquitoes for laying eggs;
- Remove the containers of stagnant water (eg containers of unused vases, old tires, gutters of public buildings no longer functional, etc.) and, if this is not possible, drain and clean them (this is the case, for example, with public swimming pools) ;
- Perform specific larvicidal treatments, at least fortnightly, of manholes and all urban drainage areas, where there is the possibility of water stagnation; before the larvicidal treatments on the manholes a careful cleaning is provided;
- Perform adulticide treatments (ie against adult tiger mosquitoes), using synthetic insecticides, only in case of particularly intense infestations. Among the insecticides used in these circumstances, the so-called pyrethroids stand out. Pyrethroids have immediate action in the sense that they kill tiger mosquitoes instantly. Since the pyrethroids are potentially harmful both for the environment and for the health of the human being, their use requires extreme caution and foresees the alert of the resident population in the urban area of use.
- Invest, as far as possible, in the installation of tiger mosquito trays. The ovitraps represent an economic and ecological solution;
- Carry out information campaigns in the fight against tiger mosquitoes that involve citizens of all ages. Any citizen, in fact, can do his part, even the elderly who frequently go to cemeteries, places among the most infested with tiger mosquitoes (think of the enormous number of saucers present).
Role of citizens
According to information campaigns carried out by health institutions and municipalities, it is up to the citizens:
- Avoid the outdoor abandonment of material in which rainwater can accumulate (eg: old tires, flower pots, watering cans for flowers, cans, etc.);
- Empty the manholes, the saucers and the other containers, present in their homes, from rain or stagnant water;
- Empty any inflatable pools and other garden toys where water can accumulate;
- Watering allotments and gardens with pumps, rather than withdrawing water from open-air reserves. If this is not possible, cover these reserves with special mosquito nets;
- Perform larvicidal treatments in the manholes and in the drainage areas of their homes every 7-10 days. Larvicidal products can be purchased in pharmacies; among these, one of the most common is the so-called Bacillus thuringiensis israelensis, a bacterium that produces a specifically effective toxin against tiger mosquito larvae and practically harmless to humans and the environment.
- Introducing goldfish, excellent predators of the tiger mosquito larvae, in tanks and garden fountains used for ornamental purposes;
- Avoid stagnation of rainwater on sheets used for covering material, such as wood;
- Periodically clean the flower vases of the cemeteries, on the occasion of visits to loved ones.
Health institutions and municipalities are keen to point out that the contribution of citizens to the fight against the tiger mosquito is fundamental.
How to protect yourself from tiger mosquito bites
To protect yourself from tiger mosquito bites, there are special repellents . Among these repellents, deserve a special mention: DEET (an acronym that stands for dietiltoluamide ), picaridin / icaridine and citrodiol .
Picaridin / icaridine has repellent properties similar to DEET, but lasts less (4 hours). Some of its variants are also suitable for children; does not stain fabrics.
Finally, citrodiol is a mild repellent, with a duration of action that does not exceed 3 hours; it is irritating to the eyes. Its use in children requires caution.
Treatments in domestic environments
In the domestic environment, electric burner plates and electric vaporizers / electric emitters for the supply of insecticides are an excellent resource in the fight against tiger mosquitoes.
