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Anopheles Mosquito

The mosquito family (Culicidae) can be divided to three sub families: Culicinae, Toxorhynchitinae, and Anophelinae – better known as the Anopheles mosquito.

In its adult stage of his life cycle, the Anopheles mosquito can be easily identified while resting even to the unprofessional eye. The adult rests with its body, head and proboscis (the sting) in an almost straight line. Furthermore, the straight line is positioned at an angle to the substrate, with some Anopheles mosquito species appear to be standing on their heads… This adult resting manner is typical only to the Anopheles mosquito.

The Anopheles mosquito’s larvae is also distinct. Like all mosquito larvae they are aquatic and occur in various types of pools (from very slow running water to stagnant water). Mosquito larvae breathe atmospheric air at the water surface. However, while most mosquito species have breathing siphon, Anopheles mosquito larvae do not. They spend most of their time parallel to the water surface, breathing through opening located on the 8th abdominal segment.

Single small eggs (no more than 200) are laid on the water surface by the Anopheles mosquito female. About two to three days later the egg hatches. On cold weather, hatching maybe delayed for more than a week.

Anopheles mosquitoes are famous as some of the Anopheles species can transfer Malaria. There are nearly 500 Anopheles mosquito species known to science, but only about 50 can actually transfer Malaria. When an Anopheles mosquito bites an infected person, it gets infected with Malaria itself and then bites a healthy person – infecting him/her too. Studies have demonstrated that most Anopheles mosquitoes prefer human for blood meal, bite mostly indoors and prefer the night with peak biting between 11 pm and 2 am.

The Malaria parasites are Protist called Plasmodium. Four species of Plasmodium can infect and be transmitted to humans by the Anopheles mosquito. They have 3 cycles during the development of the disease: one cycle in the infected mosquito and two cycles in the infected person. During these cycles the parasites transform through 3 phases:

When an Anopheles mosquito bites an infected person, it sucks the parasite along with the blood. The parasites enter the mosquito blood meal as phase 1 in its life cycle (gametocytes). Then it develops to the 2nd phase within the mosquito gut (sporozoites). This 2nd phase fills the salivary glands of the infested mosquito.

When this female Anopheles mosquito bites another person for a blood meal, phase 2 (sporozoites) are injected into the blood stream of the fresh victim, and Malaria have been transferred. The sporozoites migrate in the bloodstream to the liver and infect liver cells (hepatocytes), where they multiply into a 3rd phase (merozoites). After a while they rupture the liver cells, and escape back into the infected victim’s bloodstream.

The merozoites in the bloodstream infect red blood cells, where they develop into ring forms, trophozoites and schizonts which in turn produce further merozoites. Sexual forms (gametocytes – back to phase 1) are also produced, which, if taken up by a mosquito, will infect the Anopheles mosquito female and continue the life cycle!

To summarize, the anopheles mosquito also known as the Malaria mosquito should be carefully controlled to avoid his global distribution and his ability to easily transfer the Malaria desease and infect us humans. Different mosquito control methods are available and are well established. For personal mosquito bites protection read more on our best mosquito repellent recommendation.

Natural Mosquito Repellent

The natural/organic fashion penetrates quickly into our lives as many people prefer to eat organic food, use natural deodorants, natural tooth paste and so on. The insect repellents market was not excluded: natural mosquito repellent products are gaining much more popularity and are available from several vendors in the market.

Add to this the recognition that the most popular mosquito repellent Diethyl-meta-Toluamide (known as DEET) is not that good for our health, and no wonder you see the natural mosquito repellent alternative being more popular than ever.

But is the popularity of natural mosquito repellents justified? For start, DEET is a highly effective repellent that, according to the US Environmental Protection Agency (EPA) stays active for up to 8 hours. Can a natural mosquito repellent achieve that? Well, few studies demonstrated for some of the natural mosquito repellents even longer effectiveness than DEET. Still, other studies showed that the same repellents do not even come near the DEET active duration.

The EPA publishes a list of substances they accept as mosquito repellent. Though authorities in countries around the world are not obliged to accept the American ruling regarding mosquito repellents, in many countries the EPA decisions are respected. As for today, the EPA recognizes the following natural mosquito repellents, but according to the American agency none of them is approved for 8 hours as DEET:

Catnip Oil – also known as catmint (7 hours duration!)
Oil of Lemon Eucalyptus – (6 hours duration)
2-undecanone – which is derived from wild tomato (4.5 hours)
P-Menthane-3,8-Diol – also known as PMD, made of oil of lemon eucalyptus (2 hours)
Citronella – (1 hour)

Other natural mosquito repellent compounds that are commonly mentioned (but not by the EPA) are neem oil, garlic extract, thyme essential oil, celery seed oil, mint oil, spearmint oil, rosemary oil, lavender oil and geranium oil. Furtheremore, people from many parts of the world use natural mosquito repellents from other plants that are unfamiliar to most western society.

Most studies with the aforementioned natural repellents showed the mosquito repelling efficiency close to 100% but others showed less than that. Furthermore, many of the natural mosquito repellents are highly efficient at the beginning (sometimes even less than an hour) but their efficiency degrades quickly over time.

Out of the natural mosquito repellents I reviewed, the ones recognized by the EPA (see above) are the most promising ones and also Neem, Rosemary, Lavender and Geranium oils. Since some studies on these natural mosquito repellents demonstrated higher efficiency than others, it appears the natural repellents have different efficiency for different mosquito species, at different parts of the world and under different personal conditions (running/resting, before/after shower, etc.).

To summarize, using natural mosquito repellents is a very wise decision how to avoid mosquito bites and should be selected per its effeciveness and durability over time. Catnip oil is currently the most long lasting one, but Lemon Eucalipus oil is a very good choice too. One best consider his odor preferences too before purchasing his personal repellent.

Mosquito Traps

Get Rid Of Mosquitoes Mosquito

In contrast to repellents, mosquito traps base their protection on attracting mosquitoes instead of repelling them. Most trappers are pleased to watch how many mosquitoes they catched but overlook the number of mosquitoes that were attracted but managed to escape…

Furthermore, we humans will always be more attractive to mosquitoes than any mosquito trap, as they have evolved to detect and be attracted mainly to us! As good as mosquito traps will be, they will never be more than a mimic of us… For this reason, many entomologists reject the idea of using mosquito traps (and other nuisance insects trapping) as a mean to locally reduce mosquito population.

Nevertheless, mosquito traps can be quite useful as a complementary measure together with a more efficient local control method. For example, use of mosquito repellents in the target area and a mosquito trap somewhat far-off, as an attractant away from the target area.

The most common mosquito trap is a light trap, based on the fact that Nocturnal (night active) insects are attracted to light. Many mosquito traps are using ultraviolet light as it can be detected by insects, but does not disturb our darkness. These mosquito traps are almost useless for day-biting mosquitoes like the Asian tiger mosquito. Furthermore, they will normally kill other nocturnal insects like many species of moth, more efficiently than the mosquitoes themselves. Such light traps for home use are normally surrounded with an electric coil to zap the insects to death.

Carbon-dioxide (CO2) is a major attractant for the biting mosquito females, a fact that did not elude mosquito trap designers. With the addition of dry-ice, CO2 gas tank or a device that generates CO2, such advanced light traps will increase the catch of mosquitoes, sometimes even 100 times more. Some mosquito traps with CO2 generation even skip the usage of light completely.

The optimal CO2 concentration around a mosquito trap should be similar to the concentration of CO2 around a breathing person. The more sophisticated mosquito traps also mimic our body temperature, generating temperature of 37ºc (99ºf) around the trapping point. Modern mosquito traps even add additional odors that attract mosquito females, in their search for making the mosquito trap even more attractive. Such odors can be of lactic acid and even human sweat…

We focused here on mosquito traps for the adult biting mosquitoes. Other kinds are aimed to attract the mosquito females when searching for a place to oviposit (lay eggs). Since the mosquito oviposits only after getting her blood meal (i.e. biting us), the oviposition mosquito traps are of no real interest to the private consumer and are used mainly by researchers or as part of a large mosquito control campaigns.

To summarize, the best domestic mosquito traps should include as many attractants as possible and should be located only in the surrounding area. Such a trap will be fairly effective as it will attract and catch as many mosquitoes as possible away from us. Putting the mosquito trap too close to us can actually have negative impact, since it will summon mosquitoes to our vicinity that had no intention to be there in the first place…

Mosquito Control

Get Rid Of Mosquitoes Mosquito

The main target of mosquito control is to minimize the mosquito population in a given area to control their nuisance and risk for public health.

There are few pratical methods to obtain mosquito control. Still, the general recommendation for effective control is to operate in several types of action. In most cases, only a combination of few methods will significantly reduce the mosquito population size. Here is a review of the most common methods, divided according to the mosquito life cycle stage affected:

1) Adult mosquito control

Controlling adult (flying) mosquitoes is done by spraying insecticides. Most of the sprays commercially available are chemical agents; however more and more insecticides of vegetal extracts appear in the market lately. The control agent should be replaced from time to time to avoid resistance to appear among the treated mosquito population.

Generally speaking, adult mosquito control is not sufficient to obtain efficient results in the long run. It helps with the immediate relief only. For longer and sustainable impact, the efforts should target the younger stages too: eggs, larvae and pupae.

2) Eggs prevention mosquito control

The possible oviposition (eggs laying) sites should be identified and treated so they would not suit for mosquito larvae. This mosquito control type of action relies on the mosquito female’s high sensitivity to correct oviposition habitat selection. First, dry any possible water source of ponds, etc. to minimize the available larvae locations. If drying is not an option: Clean the water area from local vegetation, exposing the water source to a direct sunlight.

The direct sunlight will overheat the water, making them unsuitable for the larvae. It will also help the natural predators to prey the larvae which will become more detectable to them in the clear (plant free) water. Finally, make sure to seal any opening of water tanks to prevent the mosquitoes to reach the water.

3) Larvae and Pupae mosquito control

This type is covered by three different methods in general: chemical control, physical control and biological control:

Chemical mosquito control uses chemical pesticides in the water, which are toxin to the mosquito larvae and pupae (and usually other organism as well). In big water bodies it should be sprayed mostly near the shores. The most common pesticides are: Carbon-chlorides, Pyrethroids, Carbamates and organic Phosphorous.
Physical mosquito control is also called MLO (Mosquito Larvicide Oil). This special oil easily spreads all over the water surface and prevents from the larvae and pupae to come up and breathe air, which is essential for their existence.
Biological mosquito control is based on using the mosquito natural enemies. A bacteria called BTI is an example of a parasite that kills mosquitoes larvae and do not harm any vertebrate. Predation of the larvae is another example for biological control: Such predator can be invertebrates like back-swimmers, dragonfly nymphs, diving beetles and others. Vertabrate predators can be different species of fish (Gambusia – the mosquito fish is the most famous) and tadpoles of salamanders and newts.

To summarize, remember that the best mosquito control results shall be obtained when using a mixture of the above methods. West Nile Virus and other mosquito transferred diseases can be avoided by consistent control plan in your area!

How to Get rid of Mosquito Bites

Get Rid Of Mosquitoes Mosquito Mosquito Bite

How to get rid of mosquito bites is a repeated question I hear again and again. Since this question bothered the American military, a chemical formula by the name of N,N-Diethyl-meta-Toluamide was developed during previous century 40′s, commonly known as the nick name DEET.

DEET is a highly effective mosquito repellent that stays active up to 8 hours. Many people fighting how to get rid of mosquito bites end up using DEET mosquito repellent, making it one of the most commonly used mosquito repellents, if not the most common one.

During the last 2 decades or so, several scientific studies raised the suspicion that DEET is a highly unhealthy mean how to get rid of mosquito bites. Once spread on our skin, DEET penetrates into our blood system and is suspected to be carcinogenic, harmful for our fertility, harmful for our nerve system and more. Nevertheless, it would be only fair to mention that many other studies claim the exact opposite.

So how to get rid of mosquito bites? There is DEET and there are currently numerous other alternative products. Autan and Cutter, for instance, are examples of mosquito repellents that contain synthetic compound called Picaridine (also named Icaridin or Bayrepel), which is synthesized from black pepper and has similar long lasting effect as DEET. Other products use pure organic compounds as natural mosquito repellent.

While not all organic compounds are necessarily harmless, to the best of my knowledge those that are commonly used in natural mosquito repellents are safe. The downside of organic products is usually their price, which is higher than the synthetic repellents. In addition, many organic repellents get rid of mosquito bites as well as DEET, but their effect is limited to only a couple of hours and they carry strong odors which some people like and others do not.

So what’s the best way to get rid of mosquito bites? Lemon Eucalyptus essential oil and the organic compound Citradiol that can be produced out of it, proved to have long lasting impact with reasonable odor. Repel and Mosi-guard offer very good natural mosquito repellents with these organic active ingredients, that provide a long lasting solution like DEET, yet without any known health impact.

Catnip is another organic long lasting active ingredient one should consider for how to get rid of mosquito bites. Refined Oil of Nepata Cataria is such a natural mosquito repellent. Other essential oils are also effective as natural mosquito repellents but for relatively short times, like citronella, lavender and geranium.

Finally, how to get rid of mosquito bites is not the only nuisance bothering people around the globe. Many of the mosquito repellents may be effective against bed bug bites, flea bites, tick bites and others biting insects. There are some exceptions, where the product is a good mosquito repellent but not affecting another biter. Still, in many cases mosquito repellents will reduce flea bites on humans, bed bugs bites and others.

To learn more on mosquito bites, read more interesting facts in The secret behind Mosquito Bites.

Mosquito Larvae

Mosquito

The mosquito larval stage is the second stage in the mosquito life cycle. This mosquito life cycle has 4 instars (developmental stages). They emerge from the eggs as very small first instar larvae. As time goes by, they feed and grow till their skin (cuticle) is too small to obtain them. They emerge larger as a second instar, and going on doing so until the forth mosquito larval instar. After the larval life cycle stage the mosquito larvae pupates.

Under optimal condition each mosquito larval stage may last about one day. However, in the wild the conditions are rarely optimal. The amount of available food and the water temperature are of the leading factors that determine the time between the instars and thus the entire mosquito larval stage duration.

Mosquito Larvae - Habitat characteristics

The mosquito larvae have long and narrow body, which fit for life in the water. In fact, they can be found only in standing or very slow running water. Mosquito larvae are definitely not terrestrial. Though usually associated with fresh water, the larvae of different mosquito species can be found in all type of (standing) water. Mosquito larvae are found in water salinity from very low salinity (e.g. Aedes albopictus, also known as the Asian tiger mosquito) to salinity level that may be as twice as sea water (e.g. Aedes mariae and Aedes caspius).

Some mosquito larvae can be found in water with high organic matter density (e.g. Culex pepiens) while other species do better in water with low organic matter density (e.g. Aedes albopictus, Anopheles sacharovi). They also spread from small water bodies (e.g. Aedes triseriatus, Aedes aegypti) to very large water bodies (e.g. Anopheles sacharovi).

Numerous factors, such as water temperature, shade, vegetation, acidity, other organism in the water – were associated with the presence of mosquito larvae in many studies throughout the years. As expected, different species prefer different levels of the measured factors. The only common factor to all mosquito larvae of the different species was the water being standing or slow running.

Nutrition

Some mosquito larvae filter micro-organisms and other organic matter from the water column. Many of the Culex and Anopheles species are like that. Other mosquito larvae species scrape algae on pond edges, like Culiseta longiareolata or Aedes caspius. Fewer mosquito larvae species are predators, like the different Toxorhynchites species. Of course some species are not so specialist and may use more than one feeding strategy. Culiseta longiareolata larvae were observed scraping algae, filter feeding and preying on other mosquito larvae as well…

Breathing under water

Like all mosquito life cycles, the mosquito larvae breathe atmospheric oxygen and have to swim up to the surface for that. Most species have a siphon at their abdominal edge with which they cling into the water surface tension as they breathe. Species of Anopheles do not have this siphon and attach the surface with all body length. Species of Mansonia have saw-like teeth in the siphon edge. They cut and stick the siphon into water plant to still their oxygen.

Mosquito Life Cycle

Mosquito

Like all insects with a complete life cycle (HOLOMETABOLA), the mosquito life cycle has 4 stages: egg, larvae, pupae and finally the flying (and biting) adult.

Mosquito Life Cycle - 1

The first stage in the mosquito life cycle is the egg. Under optimal conditions, normally two days after being blood fed – the mosquito female finds water source for oviposition (laying eggs in insects). Mosquito females have complex set of attractants and repellents when they are selecting a site to oviposit. Water salinity, acidity, and temperature affect the oviposition site selection as well as the presence of mosquito larval food and larva predators.

This mosquito life cycle stage starts for some species as a single egg on the water surface (e.g. Anopheles), single egg at the water pond edges (e.g. Aedes) or a group of eggs on the water surface, known as egg rafts (e.g. Culex). Normally under optimal conditions, the eggs will hatch after two days. Some mosquitoes (e.g. Aedes) have aestivation eggs, which can stay dormant if conditions are not right (drying pond, low temperatures) and hatch in the next appropriate (e.g. rainy) season.

Mosquito Life Cycle - 2

The second stage of mosquito life cycle is the larvae. Mosquito larvae have long and narrow body which fits for life in the water. Some filters micro-organisms and other organic matter from the water column, other scrape algae on pond edges and few are predators. Like in all mosquito life stages, the mosquito at its larvae phase breathe atmospheric oxygen and has to swim up to the surface for that.

Most species have a siphon at their abdominal edge with which they cling into the water surface tension as they breathe. Species of Anopheles do not have this siphon and attach the surface with all their body length. Species of Mansonia have saw-like teeth in the siphon edge. They cut and stick the siphon into water plant to steall their oxygen!

Mosquito Life Cycle - 3

The third stage of the mosquito is the pupae. Mosquito pupae would normally float immobile just below the water surface. However, they are capable to dive or swim aside in a case of danger. This phase in the mosquito life cycle last usually 2-3 days, after which the adult emerges.

Mosquito Life Cycle - 4

The last stage of the life cycle is the adult. On the first day after emergence the adults feed on sugar from sources like nectar or fruits. During this day they can mate and the males will die shortly after mating. Females, however, may live for few weeks and that first mating provide them with enough sperm to last throughout their lifetime.

Being fed and mated the mosquito female will look for a host to blood-feed during its adult mosquito life cycle. Few mosquito species do not bite at all and thus oviposit only a small number of eggs. The mosquito finds the right host by the typical concentration of CO2 around its body, body temperature and other typical odors.

Some species will look after a wide range of hosts during their adult mosquito life cycle, while other will have more specific attraction. Some will prefer mammals, some will look for birds and some will even specialize on biting reptiles or amphibians. Normally, two days after biting the mosquito will oviposit and starts the mosquito life cycle all over again…