Geographic Range
Ochlerotatus dorsalis
is a widespread species of mosquito that occurs in the northern hemisphere including
Europe, Central Asia, China, Northern Russia and North America.
Ochlerotatus dorsalis
is most commonly found in North America and Europe from Scandinavia to Greece.
- Biogeographic Regions
- nearctic
- palearctic
Habitat
Ochlerotatus dorsalis
has a wide range of habitat all over the northern hemisphere. Along with many other
Ochleratatus
species,
O. dorsalis
lives primarily in salt marshes, littoral habitats and inland habitats. Larvae live
in small bodies of water and swamps as well as temporary bodies of water formed by
rainfall, melted snow and floods.
Ochlerotatus dorsalis
occurs near humans because they are the main source of bloodmeal for female mosquitoes.
Ochlerotatus dorsalis
lives in a variety of different habitats including grasslands, coastal areas, forests,
tidal areas, and marshes. These habitats must have a standing water source of some
kind in order for pale marsh mosquitoes to reproduce.
- Habitat Regions
- temperate
- terrestrial
- saltwater or marine
- freshwater
- Terrestrial Biomes
- savanna or grassland
- forest
- Aquatic Biomes
- temporary pools
- coastal
- Other Habitat Features
- suburban
- intertidal or littoral
Physical Description
Ochlerotatus dorsalis is recognizable by its scutal markings and coloration that forms a dark brown median stripe that extends to the prescuttal stripes, which are lighter in color. The female has a proboscis which is covered in dark scales and the wing veins are predominately covered in light scales. The abdominal terga, tergites or sections of the abdomen, of the female have a white stripe running longitudinally and may not be present on all segments. Males are similarly colored but have smaller proboscis with larger setae surrounding it. Setae are bristly, hair-like structures that are used for protection in mosquitoes. Adults usually reach a length of around 16 mm and can weigh as much as 2.0 mg. This species displays sexual dimorphism in that females are typically larger than males.
Larva are distinguished by short antennae, a siphon with 4 to 5 branches and a rounded
anal papillae. The siphon is used for breathing air while the larvae are underwater.
- Other Physical Features
- ectothermic
- Sexual Dimorphism
- female larger
- sexes colored or patterned differently
Development
The eggs of
Ochlerotatus dorsalis
are laid in any small open body of water or swamp. The females lay their eggs individually
in the mud of these habitats before the winter. Females may oviposit in saline or
fresh water bodies but salt water is preferred. The aquatic eggs overwinter and hatch
into larvae at the first signs of warm weather. The larvae remain underwater to grow
and develop. Larvae feed on suspended particles in the water by filter feeding at
the top or bottom of the water column. The larvae then molt into pupae where they
do not eat and stay inactive until completely molted into the adult form. After the
transformation is complete, the adult splits the pupa shell and emerges. Total development
time takes 7 to 10 days under optimal conditions.
- Development - Life Cycle
- metamorphosis
Reproduction
In spring or early summer, males gather to form large swarms which attract females.
It is not known how the males know to swarm or why the females are attracted to them,
but swarming does seem to be the most common mating style exhibited by all
Culicidae
. All species of
Ocherlotatus
are known to swarm while mating.
Ochlerotatus dorsalis
females will most likely mate more than one time, but will only do so after all of
her eggs are laid.
- Mating System
- polygynandrous (promiscuous)
Mosquitoes in general, as well as Ochlerotatus dorsalis , mate seasonally. In the spring or early summer, O. dorsalis males will form large swarms to attract females. Within a swarm, males can sense females by wing beat frequencies and species specific chemicals. Ochlerotatus dorsalis females require only one mating to fertilize her lifetime store of eggs. Fertilization takes place internally and females can hold the sperm until they are ready to lay their eggs. Ochlerotatus dorsalis is capable of long flight paths and can lay its eggs 5 to 15 miles away from breeding or feeding areas. Females must take a blood meal in order for the eggs to develop.
Maturity for male and females occur at different times. Females are able to reproduce
as soon as they emerge from the pupa as adults. Males, on the other hand, have to
wait 24 hours to a few days for their accessory glands to mature and allow for sperm
to transfer. In most cases, males experience a 24 to 48 hour time lapse between emergence
and mating.
- Key Reproductive Features
- semelparous
- seasonal breeding
- gonochoric/gonochoristic/dioecious (sexes separate)
- sexual
- fertilization
- oviparous
- sperm-storing
Parental involvement is nonexistent in
Ochlerotatus dorsalis
. Females lay their eggs singularly in the ground along the sides of standing water
sites. The females leave after ovipositing and the eggs hatch into larvae which make
their way to the water to complete development.
- Parental Investment
- no parental involvement
Lifespan/Longevity
Ochlerotatus dorsalis
have delayed-hatching eggs which do not hatch until the soil conditions have reached
a certain temperature and moisture content. The eggs of
O. dorsalis
have an overwintering period where they stay dormant in the soil until spring arrives.
Larva and pupa stages last 7 to 10 days under optimal conditions. It can take up
to two days to complete the pupal stage.
Ochlerotatus dorsalis
has a typical lifespan of two months in the summer, although some can hibernate and
live up to six months.
Behavior
Ochlerotatus dorsalis has characteristic habitats of open fields, forests and coastal areas. Here female pale marsh mosquitoes search for warm-blooded hosts when the temperature is in the range of 9 to 32 degrees Celsius. Peak biting frequency usually occurs in the late afternoon and early evening, but O. dorsalis can be active into the night also. They are most active on calm or cloudy days. Searching for bloodmeal during the day may also occur in open fields. Females are primarily exophagic (feed outside), but will enter tents and houses to feed.
Female
Ochlerotatus dorsalis
are vicious biters that leave painful bites on the skin of their hosts. The females
feed mostly on mammals including humans, squirrels, chipmunks, deer and livestock,
but will also feed on birds. Males are not parasitic and feed mostly on nectar, pollen
or fruit for nutrition. They have no need for a blood meal because they are not incubating
eggs. Males may follow the females post-mating up to 20 miles away. Larvae live
in stagnant ponds or other small bodies of water. They do not breathe oxygen from
the water, but instead use a siphon to breathe air from above the surface. They will
float just under the surface of the water and filter feed. There are 4 larval stages
that are dependent on the amount of food, crowding and water temperature. Pupae will
also stay in the water and breathe air by coming to the surface.
- Key Behaviors
- flies
- crepuscular
- parasite
- motile
Home Range
Ochlerotatus dorsalis
is a very strong flier which allows it to have a very large home range. Females can
fly up to 20 miles to disperse their eggs. Males will sometimes accompany them on
these flights. Pale marsh mosquitoes usually breed in marshy areas that have been
recently flooded.
Communication and Perception
Ochlerotatus dorsalis
uses visual cues for perception.
Ochlerotatus dorsalis
, like other
Culicidae
, features large compound eyes. In addition to sight,
O. dorsalis
uses chemical cues and auditory signals during mating to communicate. Males can
detect females by their wing beat frequency, which is lower than males'. Females
may detect male chemicals during mating rituals.
- Other Communication Modes
- scent marks
- vibrations
- Perception Channels
- visual
- acoustic
- vibrations
Food Habits
The adult female Ochlerotatus dorsalis is a parasitic sanguivore, meaning it drinks blood as its main food source. Males are nectarivores that drink nectar from plants, plant sap and honeydew produced by aphids. The males do not drink blood at all. Some females may be nectarivorious if there is not a blood meal present. These females can still produce eggs, but the development of the egg will depend on energy stores of the mother. Females who do feed on blood will do so on mammals , including humans , chipmunks , squirrels and livestock, and some will obtain their blood meal from birds .
Larvae feed by filter feeding in the water by using specialized "gills" to trap food
particles. The
Ochlerotatus dorsalis
larvae stay on the surface of the water and breathe oxygen using a siphon, and filter
out the food particles by sending them past the mouthparts where they are eaten.
The food usually consists of algae, small living organisms, and parts of plant or
animal material. Larval development is dependent on the amount of food it consumes.
- Primary Diet
- herbivore
- Animal Foods
- blood
- zooplankton
- Plant Foods
- nectar
- sap or other plant fluids
- algae
- phytoplankton
- Foraging Behavior
- filter-feeding
Predation
General predators of mosquitoes include bats , birds , dragonflies and fish . Fish that live in the water where O. dorsalis larvae are present may feed on them. Mosquitofish are common predators of pale marsh mosquitoes due to their ability to withstand various water conditions.
Ecosystem Roles
Ochlerotatus dorsalis
females are parasitic insects that use many
mammals
including
humans
as hosts.
Birds
may also be parasitized, though not as frequently. Female pale marsh mosquitoes
may cause certain habitats to become uninhabitable if the swarms become too great.
Host species cannot live in these areas due to the painful bites inflicted by the
mosquitoes.
Ochlerotatus dorsalis
males do not take blood meals, but instead feed on plant sap and nectar. Pollination
may occur from feeding on the nectar of flowers, but they are not main pollinators.
- Ecosystem Impact
- parasite
- humans ( Homo sapiens )
- livestock
- chipmunks ( Tamias )
- birds ( Aves )
- squirrels ( Sciuridae )
Economic Importance for Humans: Positive
Ochlerotatus dorsalis
does not provide many positive benefits to humans. Male
O. dorsalis
may occasionally pollinate crops by feeding on nectar and sap.
Economic Importance for Humans: Negative
Ochlerotatus dorsalis
has many negative effects on humans. The largest being painful bites inflicted when
females feed on hosts' blood. These bites are common on other
mammals
and
birds
. Due to their vicious biting, areas where pale marsh mosquitoes are present can
be rendered uninhabitable for humans and other animals. This species can be very
detrimental to livestock, leading to reduced feeding and dangerous behavior from attempting
to escape the attacks. In addition to its extremely painful bites,
Ochlerotatus dorsalis
is a vector of many diseases. These diseases include West Nile virus, Western equine
encephalitis virus, St. Louis encephalitis virus, and California encephalitis virus.
The Japanese encephalitis virus and the bacteria
Francisella tularensis
(causing tuleremia) are also carried by
O. dorsalis
. Some of these diseases affect humans and animals while some only affect animals.
The Western equine encephalitis virus is a disease of livestock that can cause significant
destruction.
- Negative Impacts
-
injures humans
- bites or stings
- carries human disease
- causes or carries domestic animal disease
Conservation Status
Currently, there are no conservation concerns regarding Ochlerotatus dorsalis . If anything, population control methods are in place to reduce numbers, therefore reducing the spread of disease.
Additional Links
Contributors
Eric Dryer (author), University of Michigan-Ann Arbor, Heidi Liere (editor), University of Michigan-Ann Arbor, John Marino (editor), University of Michigan-Ann Arbor, Barry OConnor (editor), University of Michigan-Ann Arbor, Rachelle Sterling (editor), Special Projects.
- Nearctic
-
living in the Nearctic biogeographic province, the northern part of the New World. This includes Greenland, the Canadian Arctic islands, and all of the North American as far south as the highlands of central Mexico.
- native range
-
the area in which the animal is naturally found, the region in which it is endemic.
- Palearctic
-
living in the northern part of the Old World. In otherwords, Europe and Asia and northern Africa.
- native range
-
the area in which the animal is naturally found, the region in which it is endemic.
- temperate
-
that region of the Earth between 23.5 degrees North and 60 degrees North (between the Tropic of Cancer and the Arctic Circle) and between 23.5 degrees South and 60 degrees South (between the Tropic of Capricorn and the Antarctic Circle).
- terrestrial
-
Living on the ground.
- saltwater or marine
-
mainly lives in oceans, seas, or other bodies of salt water.
- freshwater
-
mainly lives in water that is not salty.
- tropical savanna and grassland
-
A terrestrial biome. Savannas are grasslands with scattered individual trees that do not form a closed canopy. Extensive savannas are found in parts of subtropical and tropical Africa and South America, and in Australia.
- savanna
-
A grassland with scattered trees or scattered clumps of trees, a type of community intermediate between grassland and forest. See also Tropical savanna and grassland biome.
- temperate grassland
-
A terrestrial biome found in temperate latitudes (>23.5° N or S latitude). Vegetation is made up mostly of grasses, the height and species diversity of which depend largely on the amount of moisture available. Fire and grazing are important in the long-term maintenance of grasslands.
- forest
-
forest biomes are dominated by trees, otherwise forest biomes can vary widely in amount of precipitation and seasonality.
- coastal
-
the nearshore aquatic habitats near a coast, or shoreline.
- marsh
-
marshes are wetland areas often dominated by grasses and reeds.
- swamp
-
a wetland area that may be permanently or intermittently covered in water, often dominated by woody vegetation.
- suburban
-
living in residential areas on the outskirts of large cities or towns.
- intertidal or littoral
-
the area of shoreline influenced mainly by the tides, between the highest and lowest reaches of the tide. An aquatic habitat.
- ectothermic
-
animals which must use heat acquired from the environment and behavioral adaptations to regulate body temperature
- metamorphosis
-
A large change in the shape or structure of an animal that happens as the animal grows. In insects, "incomplete metamorphosis" is when young animals are similar to adults and change gradually into the adult form, and "complete metamorphosis" is when there is a profound change between larval and adult forms. Butterflies have complete metamorphosis, grasshoppers have incomplete metamorphosis.
- polygynandrous
-
the kind of polygamy in which a female pairs with several males, each of which also pairs with several different females.
- semelparous
-
offspring are all produced in a single group (litter, clutch, etc.), after which the parent usually dies. Semelparous organisms often only live through a single season/year (or other periodic change in conditions) but may live for many seasons. In both cases reproduction occurs as a single investment of energy in offspring, with no future chance for investment in reproduction.
- seasonal breeding
-
breeding is confined to a particular season
- sexual
-
reproduction that includes combining the genetic contribution of two individuals, a male and a female
- fertilization
-
union of egg and spermatozoan
- internal fertilization
-
fertilization takes place within the female's body
- oviparous
-
reproduction in which eggs are released by the female; development of offspring occurs outside the mother's body.
- sperm-storing
-
mature spermatozoa are stored by females following copulation. Male sperm storage also occurs, as sperm are retained in the male epididymes (in mammals) for a period that can, in some cases, extend over several weeks or more, but here we use the term to refer only to sperm storage by females.
- crepuscular
-
active at dawn and dusk
- parasite
-
an organism that obtains nutrients from other organisms in a harmful way that doesn't cause immediate death
- motile
-
having the capacity to move from one place to another.
- acoustic
-
uses sound to communicate
- chemical
-
uses smells or other chemicals to communicate
- scent marks
-
communicates by producing scents from special gland(s) and placing them on a surface whether others can smell or taste them
- vibrations
-
movements of a hard surface that are produced by animals as signals to others
- visual
-
uses sight to communicate
- acoustic
-
uses sound to communicate
- vibrations
-
movements of a hard surface that are produced by animals as signals to others
- zooplankton
-
animal constituent of plankton; mainly small crustaceans and fish larvae. (Compare to phytoplankton.)
- phytoplankton
-
photosynthetic or plant constituent of plankton; mainly unicellular algae. (Compare to zooplankton.)
- filter-feeding
-
a method of feeding where small food particles are filtered from the surrounding water by various mechanisms. Used mainly by aquatic invertebrates, especially plankton, but also by baleen whales.
- parasite
-
an organism that obtains nutrients from other organisms in a harmful way that doesn't cause immediate death
- causes or carries domestic animal disease
-
either directly causes, or indirectly transmits, a disease to a domestic animal
- herbivore
-
An animal that eats mainly plants or parts of plants.
- nectarivore
-
an animal that mainly eats nectar from flowers
References
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Milankov, V., D. Petric, A. Vujic, L. Vapa. 2009. Taxonomy, biology, genetic variability and medical importance of Ochlerotatus caspisu (Pallas, 1771) and O. dorsalis (Meigen, 1830) (Diptera: Culicidae). Acta entomologica serbica , 14/2: 195-207.
Purdue University Medical Entomology, 2010. "Medical Entomology - Mosquitos" (On-line). Accessed April 01, 2010 at http://extension.entm.purdue.edu/publichealth/insects/mosquito.html .
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2008. "Mosquito Notes: A Pale Marsh Mosquito" (On-line). Marin/Sonoma mosquito & vector control district. Accessed March 31, 2010 at http://www.msmosquito.com/pdf/Dorsalis.pdf .
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