Mosquitoes and Mosquito Control In Hawaii

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The mosquitoes are a family of small, midge-like flies: the Culicidae. Although a few species are harmless or even useful to humanity, most are a nuisance because they consume blood from living vertebrates, including humans. The females of many species of mosquitoes are blood eating pests. In feeding on blood, some of them transmit extremely harmful human and livestock diseases . . . Some authorities argue accordingly that mosquitoes are the most dangerous animals on Earth.

In the bloodsucking species, only the females suck blood. Furthermore, even among mosquitoes that do carry important diseases, neither all species of mosquitoes, nor or all strains of a given species transmit the same kinds of diseases, nor do they all transmit the diseases under the same circumstances; their habits differ. For example, some species attack people in houses, and others prefer to attack people walking in forests. Accordingly, in managing public health, knowing which species, even which strains, of mosquitoes with which one is dealing is important . . . Several scientists have suggested complete eradication of mosquitoes would not have serious ecological consequences.

Some species of mosquitoes prefer to breed in natural reservoirs on plants such as rainwater accumulated in holes in tree trunks, or in the leaf-axils of bromeliads. . . Such species typically take readily to breeding in artificial water containers, such as the odd plastic bucket, flowerpot "saucer", or discarded bottle or tire. Such casual puddles are important breeding places for some of the most serious disease vectors, such as species of Aedes that transmit dengue and yellow fever [or Anopheles which transmit malaria]. Some with such breeding habits are disproportionately important vectors because they are well placed to pick up pathogens from humans and pass them on. In contrast, no matter how voracious, mosquitoes that breed and feed mainly in remote wetlands and salt marshes may well remain uninfected, and if they do happen to become infected with a relevant pathogen, might seldom encounter humans to infect in turn.

The period of development from egg to adult varies among species and is strongly influenced by ambient temperature. Some species of mosquitoes can develop from egg to adult in as little as five days, but a more typical period of development in tropical conditions would be some 40 days or more for most species. The variation of the body size in adult mosquitoes depends on the density of the larval population and food supply within the breeding water.

Adult mosquitoes usually mate within a few days after emerging from the pupal stage. In most species, the males form large swarms, usually around dusk, and the females fly into the swarms to mate.

Males typically live for about a week, feeding on nectar and other sources of sugar. After obtaining a full blood meal, the female will rest for a few days while the blood is digested and eggs are developed. This process depends on the temperature, but usually takes two to three days in tropical conditions. Once the eggs are fully developed, the female lays them and resumes host-seeking.

The cycle repeats itself until the female dies. While females can live longer than a month in captivity, most do not live longer than one to two weeks in nature. Their lifespans depend on temperature, humidity, and their ability to successfully obtain a blood meal while avoiding host defenses and predators.

Disease

Mosquitoes can act as a vector for many disease-causing viruses and parasites. Infected mosquitoes carry these organisms from person to person without exhibiting symptoms themselves. Mosquito-borne diseases include:

  • Viral diseases such as . . . dengue fever . . . transmitted mostly by Aedes aegypti. Dengue fever is the most common cause of fever in travelers returning from the Caribbean, Central America, and South Central Asia. This disease is spread through the bites of infected mosquitoes and cannot be spread person to person. Severe dengue can be fatal, but with good treatment, less than 1% of patients die from dengue.
West Nile virus is a concern in the United States, but there are no reliable statistics on worldwide cases.
  • The parasitic diseases collectively called malaria, caused by various species of Plasmodium, carried by mosquitoes of the genus Anopheles.

Control

Source reduction

Source reduction means elimination of breeding places of mosquitoes. It includes engineering measures such as filling, leveling and drainage of breeding places, and water management (such as intermittent irrigation). Source reduction can also be done by making water unsuitable for mosquitoes to breed, for example, by changing salinity of water. Some specific measures are:

  • Abolition of domestic and peridomestic sources of water suitable for breeding, for example removal and disposal of sewage and other waste water
  • Eliminating incidental containers such as discarded tins, crockery, pots, broken bottles, and coconut shells
  • Abolish breeding places by filling or drainage
  • A thin layer of oil on top of the water prevents mosquito breeding in two ways: mosquito larvae in the water cannot penetrate the oil film with their breathing tube, and so drown and die; also adult mosquitoes do not lay eggs on the oiled water.

Details of the biology of different species of mosquitoes differ too widely for any limited set of rules to be sufficient in all circumstances. However, the foregoing are the most economical and practical measures for most purposes. The importance of peridomestic control arises largely because most species of mosquitoes rarely travel more than a few hundred metres unless the wind is favorable.

Natural predators

Dragonfly and damselfly nymphs and various other aquatic insect predators eat mosquitoes at all stages of development and dense populations can be useful in reducing mosquito problems.

Various small fishes . . ., such as mosquitofish and guppies, eat mosquito larvae and sometimes may be worth introducing into ponds to assist in control. Many other types of fish are also known to consume mosquito larvae...

Although bats can be prodigious consumers of insects, many of which are pests, less than 1% of their diet typically consists of mosquitoes. Bats aren't known to control or even significantly reduce mosquito populations.

Other natural predators and parasitoids include fungi and nematodes. Though important at times, their effectiveness varies with circumstances.

Bacillus thuringiensis israelensis has also been used to control them as a biological agent.

Summit B.t.i. Briquets--Biological Insecticide

Archer® Insect Growth Regulator

Talstar Professional Insecticide

References

122-person outbreak in Hawaii in 2001, the first time the virus had been seen in the islands since 1944.
"Slate"

Battle begins to prevent dengue fever
"Maui News"

Dengue Fever Maui
"Maui Now"

Mosquitoes
"U.S. Army Garrison, Hawaii"

Mosquitoes
"Wikipedia"

Dragon Flies vs. Mosquitoes
Can the Mosquito Pest be Mitigated?

"Google Books"

BEST MANAGEMENT PRACTICES--Mosquitoes
"FMC"

Oahu Location
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Maui Location
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Hawaii 96732
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Big Island Location
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