Mosquito biology and control suggestions

Habitat · Biological Cycle · Suggestions

The life of the mosquito is very closely linked to water since both larvae and pupae live in an aquatic environment and the adult females have return to this environment to lay their eggs.

Provided it is shallow and calm, almost every water body can be a breeding place for at least one mosquito species. This water body need not even to be permanent, as a new mosquito generation is complete within a week or ten days.

While certain species prefer dirty waters, many others colonize clean water only. Similarly, some mosquito species are resistant to a very wide range of temperatures whereas many others are much less resistant. Most species, however, favour high temperatures.

Culex pipiens is the most common species in the Baix Llobregat. The larvae appear when water temperatures rise above 15 degrees C, although they can tolerate lower temperatures. In our latitude, this means that the breeding season lasts from April to October. Although Culex pipiens is a highly adaptable species which can be found in virtually all environments, it prefers organically polluted water in which to breed.

The second most common species in this region is Ochlerotatus caspius. As other species in the genus Ochlerotatus , eggs are laid in floodable areas when they are still dry, and remain inactive for months waiting for the floods to arrive. This usually happens in spring or fall and can lead to large-scale hatching. In the Llobregat delta, this species is found in several coastal marshes in the districts of El Prat de Llobregat and Viladecans.

The mosquito Aedes albopictus was first found in el Baix Llobregat in 2005. Larvae of Aedes albopictus develop in small containers such as jugs, cans, pots, buckets and ashtrays.

Two typical larval habitats are to be found in hilly areas: rock pools in creeks, and tree hollows. Both of these can fill up with rain water and contain larval populations of certain mosquito species such as Anopheles claviger, Ochlerotatus vexans and Ochlerotatus geniculatus.

Mosquitoes have many natural enemies. In their larval stage they are attacked by predators, mostly fish (such as the mosquitofish Gambusia holbrooki), adult insects (Dytiscidae, Notonectidae) and dragonfly larvae (Odonata). The mosquitofish is a North American species which was introduced in Spain at the beginning of the century by the Comisión Antipalúdica (the Spanish Malaria control and eradication team), as part of mosquito program. It is such a voracious species that usually no mosquito larvae at all can be found in waters containing mosquitofish. Adult mosquitoes are a common prey for spiders, dragonflies, bats, amphibians and birds.

Mosquitoes belong to the Order Diptera, Family Culicidae. They undergo a complete metamorphosis, that is, the eggs give rise to mobile aquatic larvae which turn into nymphs from which adults are produced. More than 3,000 mosquito species are known throughout the world; 19 of them are regularly found in the Baix Llobregat belonging to 6 genera: Culex (4), Ochlerotatus (3), Aedes (3), Culiseta (3), Coquillettidia (2), Anopheles (3), Uranotaenia (1).