Anopheles

Anopheles is a genus of mosquito that was first described by a German entomologist J. W. Meigen in 1818. These mosquitoes are often called nail mosquitoes or marsh mosquitoes. Many of them can carry a tiny organism called Plasmodium, which causes a sickness known as malaria in birds, reptiles, and mammals, including people. One well-known type is the Anopheles gambiae, which spreads a very harmful form of malaria called Plasmodium falciparum.

These mosquitoes have been around for a very long time—about (https://geoltime.github.io/?Ma=100) million years. Like all mosquitoes, they start their lives in water as eggs, then grow into larvae and pupae. The larvae breathe by staying close to the water's surface. Adult mosquitoes emerge from the water and drink flower nectar, but the females also need blood to help them carry and spread parasites to other animals or people. They bite with their heads pointed downward, which looks different from other kinds of mosquitoes.

Anopheles mosquitoes are found nearly everywhere, from tropical to cooler areas of the world. When it gets very hot and dry, they can go into a resting state called aestivate to wait for better conditions. This helps them survive in places such as the Sahel.

Evolution

The genus Anopheles was first described by the German entomologist Johann Wilhelm Meigen in 1818. Fossils of these mosquitoes are rare, with only two found by 2015. One was found in amber from the Dominican Republic dating back between 40.4 and 33.9 million years ago, and another from Germany dating back between 28.4 and 23 million years ago.

All flies, including mosquitoes, first appeared around 260 million years ago. The group of mosquitoes that includes Anopheles split off from other mosquitoes between 120 and 150 million years ago. The different species of Anopheles mosquitoes spread across the Old and New World between 80 and 95 million years ago. The study of their family tree helps scientists understand how these mosquitoes evolved.

Main article: Taxonomy of Anopheles

Life cycle

Like all mosquitoes, Anopheles mosquitoes go through four stages in their life: egg, larva, pupa, and adult. The first three stages happen in water and last between 5 to 14 days, depending on the type of mosquito and the temperature. The adult stage is when female Anopheles mosquitoes can spread malaria.

Adult females lay between 50 and 200 eggs on water. These eggs are very small and have floats on the sides to stay on the surface. The eggs hatch in 2 to 3 days, but may take up to 3 weeks in colder places.

The mosquito larva has a head, thorax, and abdomen. It does not have legs and feeds on tiny plants and microorganisms on the water's surface. The larva goes through four stages before changing into a pupa. The pupa swims to the surface to breathe and, after a few days, turns into an adult mosquito.

Adult Anopheles mosquitoes have a head, thorax, and abdomen. The head has eyes, long antennae for finding hosts, and a proboscis for feeding. The thorax has legs and wings, while the abdomen is used for digesting food and developing eggs. Females need a blood meal to develop their eggs, while males feed on nectar and sugar. Most female mosquitoes live about one to two weeks in the wild.

Ecology

Distribution

Anopheles mosquitoes live in tropical areas where malaria is common, such as sub-Saharan Africa, but they can also be found in colder places. In the past, malaria outbreaks happened in colder climates, like during the building of the Rideau Canal in Canada in the 1820s. Even areas where malaria has been stopped can still get the disease back if these mosquitoes return.

Habitat

Anopheles mosquitoes need small bodies of water for their young to grow. These can be ponds, water tanks, swamps, ditches, or even puddles. The adult mosquitoes can live in dry places like Africa's savanna and Sahel. They can travel far from water and sometimes get blown hundreds of kilometers by the wind. In very hot, dry weather, they can rest for months until conditions improve. They have even been found traveling in luggage on airplanes.

Parasites

Some tiny organisms called Microsporidia live inside Anopheles mosquitoes. These organisms have different ways of spreading and can affect the mosquito's body. Another type of tiny organism, called Wolbachia bacteria, is being studied to help control mosquito populations.

Predators

A type of jumping spider called Evarcha culicivora hunts female Anopheles mosquitoes. Young spiders prefer these mosquitoes over other insects, even if they don't have blood. The spiders recognize mosquitoes by their special resting posture and attack them from below.

Malaria vectors

Anopheles mosquitoes are the only ones that can spread malaria. Scientists study these mosquitoes to find ways to stop malaria. Some Anopheles mosquitoes prefer to bite humans, which makes them more likely to spread malaria from one person to another. In Africa, species like A. gambiae are known for biting humans and are major reasons why malaria is a big problem there.

For malaria to spread, the parasites need time to grow inside the mosquito. This can take between 10 to 21 days. If the mosquito does not live long enough, it cannot spread the disease. Scientists have estimated how long these mosquitoes live in places like Tanzania. They found that most do not live longer than 14 days, which affects how well malaria can spread. Using tools like insecticide-treated bed nets or spraying inside homes can help reduce the number of mosquitoes and slow down malaria.

Control

Insecticide control and resistance

Insecticides have been used to reduce the number of mosquitoes that spread malaria. However, mosquitoes can quickly learn to survive these chemicals, making them less effective over time. This happened during big efforts to stop malaria in the 1950s. Using insecticides in farming has also helped mosquitoes become stronger. So, any plan to control mosquitoes needs to watch for this problem and be ready to change methods if needed.

Eradication

In 2016, scientists suggested a new way to stop a type of mosquito called Anopheles gambiae using a special technology called CRISPR-Cas9. This technology could remove a gene that allows female mosquitoes to have babies, stopping them from making more mosquitoes. Tests showed it could stop an entire group of these mosquitoes in just a few months. But, people worry about how well this works and what it might mean for nature. Because of this, scientists are trying to use this technology to add genes that help mosquitoes fight the malaria parasite instead. Researchers in Burkina Faso made a special kind of fungus that can stop most mosquitoes from surviving.