Wyeomyia smithii is a model organism for photoperiodism and "hourglass" regulation studies. This species uses photoperiodism, the physiological regulation and reaction to changes in the length of day and night, as well as an internal clock to determine the time of year and development rate.
Northern populations rely heavily on photoperiodism as there are more drastic changes through the year in day length. Southern populations lose sensitivity to light as day lengths change less drastically so the larvae use an internal clock, often referred to as an hourglass in studies, to determine appropriate times for diapause and eclosion.
Adults also rely heavily on visual cues to determine prime locations for oviposition. Wyeomyia smithii will chose the youngest leaves. This is most likely due to nutrient availability as studies of the purple pitcher plant have shown that after 2-4 weeks, the capture rate of leaves drops exponentially. Selection may be signalled by the color of the leaves since other species of Wyeomyia prefer colors of younger leaves for oviposition.
While there is little research on W. smithii, mosquitoes in general find a mate based upon sounds produced by wing vibrations. The tactile receptors on male antennae detect the frequencies of female sounds, which helps species such as Aedes aegypti find mates.
Communication Channels: visual ; acoustic ; chemical
Perception Channels: visual ; infrared/heat ; polarized light ; acoustic
This species has no special conservation status but is used as an example to defend mosquitoes across the globe as it has a great impact within its ecosystem.
US Federal List: no special status
CITES: no special status
State of Michigan List: no special status
Wyeomyia smithii eggs hatch within the leafy pool communities of the purple pitcher plant and hatch most quickly after periods of dryness or freezing. In captivity eggs hatch within five days of oviposition. The larval form undergoes five instar stages over the course of about 22 days. Females remain in the fifth instar stage for an average of 2.1 days longer than the males as they develop ova and build fat stores. The instars of males are determined by the rotation of their terminalia (caudal segments). Males experience the final rotation between 9 and 12 hours after eclosion (hatching). Completion of this rotation is critical for successful copulation. Females emerge sexually mature.
The purple pitcher plant mosquito undergoes larval diapause depending on seasonal day length or moisture levels. This species uses the length of daylight, or photoperiodism, to determine the optimal time to enter hibernal diapause. Hibernal diapause occurs yearly in northern populations where their aqueous habitat freezes. All populations undergo diapause when water is removed from their environment. The effects of diapause were shown to significantly decrease the fitness of individuals by as much as sixty percent.
Development - Life Cycle: metamorphosis ; diapause
This species is not known to be of any negative importance to humans.
There is little evidence to suggest any positive interactions between this species and humans.
The larval forms of this species live commensally within the phytotelma of the purple pitcher plant, Sarracenia purpurea. The commensalistic relationship benefits Wyeomyia smithii by providing a habitat for eggs and developing young, as well as a food source from the microbial populations and detritus it eats. The mosquito provides no direct measurable benefit to the plant, although this relationship is being continuously studied.
The larvae increase microbial biodiversity. Rotifer, midge, and colpodan abundances drop with the introduction of this predator, however bacterial abundance and richness increases greatly.
The direct predatory actions of Wyeomyia smithii impact the population size of its prey, and also play a key role in the evolution and population size of the ciliated protozoan Colpodea colpodida. Wyeomyia smithii will feed upon the colpopods, decreasing their population sizes. However, when populations of some other ciliated protozoans such as Pseudocrytolophosis alpestris are present, Wyeomyia smithii preferentially feed on P. alpestris since these are more free swimming. This preferential feeding indirectly affects the evolution of C. colpodida as it develops traits opposite to those expressed when W. smithii feeds only on these colpopods.
The purple pitcher plant mosquito can be considered a keystone predatory species since it impacts its community directly and indirectly at almost every level of the ecosystem. Wyeomyia smithii may reduce rotifer, midge, and colpodan populations, thus increasing bacterial diversity and abundance. This abundance may drastically increase decomposition rates of insect prey and nutrient availability for the plant, although this effect hasn't been fully studied or quantified. Without this species, protozoan populations limit prokaryotic biodiversity. Because of these indirect effects, the relationship between the purple pitcher plant mosquito and the purple pitcher plant is being further studied. Removing this species in natural populations may affect plant growth, but removal has not been extensively studied.
Ecosystem Impact: creates habitat; keystone species
Mutualist Species:
Wyeomyia smithii resides inside micro-communities in the phytotelmata (leaf contained pools) of the purple pitcher plant. Prior to eclosion, W. smithii feeds on bacteria, rotifers, protozoans, and midges as well as pieces of deteriorating insects caught by the pitcher plant's leaves. While it can eat these insect pieces, this species does not seek out insects and is not truly insectivorous. This mosquito is considered a detritovore and microbial filter feeder in its larval stages.
Adults, like with other mosquitoes, feed primarily on nectar and the fat stores from larval development. While they have can be sanguineous, this only happens after the first oviposition in southern populations and is generally considered rare.
Animal Foods: blood; body fluids; insects
Plant Foods: nectar
Other Foods: detritus ; microbes
Foraging Behavior: filter-feeding
Primary Diet: carnivore (Sanguivore ); herbivore (Nectarivore ); detritivore
The purple pitcher-plant mosquito, Wyeomyia smithii, is found in the Nearctic Region from the northeastern coast of the Gulf of Mexico to northeastern Saskatchewan. The distribution is determined by the range of the purple pitcher plant, which is found from 30° N to 50° N in North America.
Biogeographic Regions: nearctic (Native )
This species' larval stages live submerged in the aqueous reservoirs (inquiline habitat) of their hosts, the purple pitcher plants. Airborne adults may travel, but generally remain near the plants where they hatched. Purple pitcher plants are found in wet areas in North American forests, usually in clusters near streams. Although normally found in moist climates, they are sometimes found in grassland areas.
Habitat Regions: temperate
Terrestrial Biomes: savanna or grassland ; forest
Wetlands: swamp ; bog
Other Habitat Features: riparian
After hatching, Wyeomyia smithii develop for approximately 22 days prior to eclosion depending on resource availability and sex. Since individual wild mosquitoes are difficult to track, determining the average age of wild mosquitoes is impractical. Captive individuals are usually reared in environments to mimic natural conditions and live an average of 38-42 days.
Range lifespan
Status: wild: Unknown to Unknown hours.
Average lifespan
Status: wild: Unknown hours.
Range lifespan
Status: captivity: Unknown to Unknown days.
Average lifespan
Status: captivity: Unknown days.
Typical lifespan
Status: wild: 34 to 50 days.
Average lifespan
Status: wild: 38-42 days.
Typical lifespan
Status: captivity: 34 to 50 days.
Average lifespan
Status: captivity: 38-42 days.
In its larval stages Wyeomyia smithii is extremely small with white or clear skin. This insect has only two anal gills, compared to other Wyeomyia that normally have four. Depending on the larval stage, Wyeomyia smithii can weigh anywhere from .4 mg to 2.5 mg upon eclosion, or the shedding of pupal casing by a new adult.
The adult forms are dark brown to black and are approximately two centimeters in length with a wingspan of similar size. They have six legs and a pair of wings attached to the thorax. Adults rest with their legs bend forward, above their heads.
More research is needed on the other sensory organs of this species, however other mosquitoes develop several stages of eyes. Initial larval forms possess only a pit-eye ocellus, or simple eye, and more eyes develop as the larvae grow. The compound eyes of the adults are large and hexagonal.
This species is sexually dimorphic. Males undergo their final metamorphosis about two days earlier than females. Because of this extra time developing, females tend to be larger. Males also undergo a predictable rotation of their terminalia, the terminal grouping of body segments, that females do not. Males have two highly segmented antennae that are used to detect the vibrations of females' wings.
Range mass: .0004 to .0025 g.
Average mass: .0015 g.
Other Physical Features: ectothermic ; heterothermic ; bilateral symmetry
Sexual Dimorphism: female larger; sexes shaped differently
Wyeomyia smithi has no known predators of its own mainly because of its use of the purple pitcher plant.
Wyeomyia smithii are polygynous. Males deposit sperm into the spermathecae of multiple females if able. Males of similar mosquito species can identify and locate females by using their antennae to detect the vibrations of the female's wings. After copulation, females store sperm in their spermathecae to be utilized upon ovulation, which begins on average on day 24 of the females' life, or shortly after emerging from the pupal casing.
Mating System: polygynous
Wyeomyia smithii eggs hatch during two seasons, late spring and early fall. This species exhibits protandry--males will develop an average of 2.1 (20 days old) days before females (22.1 days old). Male reproductive organs are found on the last segments of the body (terminalia) and undergo a 180° rotation from birth to reproductive maturity. Females emerge from their pupal shells sexually mature and are generally fertilized within two days.
The first oviposition of female is autogenous, meaning the species does not require a blood meal to deposit eggs. Northern populations are non-biting and thus obligatorily autogenous. Southern populations, however, are facultatively autogenous. After their first oviposition, females may consume blood to be able to lay more eggs.
There has been difficulty categorizing the oviposition patterns exhibited by W. smithii. Although W. smithii oviposits only a few times and dies before the next breeding season, females do not die after oviposition and are therefore not truly semelparous; many populations may lay several clutches within a breeding season and are therefore described as quasi-iteroparous.
Wyeomyia smithii are polygynous. Females store the sperm of males within their spermathecae which can be used for fertilization of multiple clutches. Females lay an average of 38 eggs per season with an average number of two clutches.
Breeding interval: Male purple pitcher plant mosquitoes will breed as frequently per season as possible. Females will only successfully breed with one mate as only one is required to full the spermathecae.
Breeding season: Purple pitcher plant mosquitoes breed twice yearly, in the late spring and early fall.
Range eggs per season: 1 to 66.
Average eggs per season: 38.
Range gestation period: 1 to 8 days.
Average gestation period: 2 days.
Range time to independence: 0 to 0 minutes.
Range age at sexual or reproductive maturity (female): 20 to 25 days.
Average age at sexual or reproductive maturity (female): 22.1 days.
Range age at sexual or reproductive maturity (male): 19 to 25 days.
Average age at sexual or reproductive maturity (male): 20 days.
Key Reproductive Features: seasonal breeding ; gonochoric/gonochoristic/dioecious (sexes separate); sexual ; fertilization (Internal ); oviparous ; sperm-storing ; delayed fertilization
Parental investment by females of this species is made largely during the fifth instar of larval development. Females remain in this instar on average two days longer than males while the unfertilized eggs develop. After completing metamorphosis and the subsequent copulation, females utilize sperm from their spermathecae to fertilize the eggs and deposit them within the pools of young purple pitcher plant leaves. After the first oviposition, southern populations may seek blood meals to produce more clutches. Northern populations do not seek blood meals and often do not lay more than one set of eggs. After deposition there is no known parental care.
Parental Investment: female parental care ; pre-fertilization (Provisioning, Protecting: Female); pre-hatching/birth (Provisioning: Female)
Wyeomyia smithii, the pitcher plant mosquito, is an inquiline mosquito that completes its pre-adult life cycle in the phytotelma of—that is, the water contained by—the purple pitcher plant, Sarracenia purpurea. In this microcommunity of bacteria, rotifers, protozoa, and midges, W. smithii is the top-level predator; its presence determines the bacterial species diversity within the pitcher.[1]
W. smithii is not a pest mosquito in general. The northern US population does not consume blood at all, while the southern US populations only consume blood after laying an initial egg batch;[2][3] even then they appear disinterested in feeding. In fact, it is the only known mosquito to have both obligatory biting and non-biting populations in the same species.[4]
The life cycle of Wyeomyia smithii begins in either late spring or early fall when the adult female lays her eggs in the phytolema of a purple pitcher plant. The eggs then gestate in the pitcher plant anywhere from 1–8 days before they hatch as larvae. The larvae remain in the phytolema feeding on bacteria, micro-animals, and decaying insects. The mosquito larvae will live in the pitcher plant until it goes through its fifth instar about 20 to 22 days after hatching. They then emerge as adult mosquitoes ready to mate. Wyeomyia smithii females will produce a clutch of fertilized eggs generally within two days of sexual maturity. Some populations in the southern United States have also been known to drink blood after producing their first clutch to help produce a second clutch; there are no reports of northern populations displaying this behavior, however.[5]
Wyeomyia smithii is a model organism for the study of photoperiodism, the biotic process of controlling seasonal life history events by measuring day length as a reliable predictor of the seasons. W. smithii enters a state of developmental arrest, larval diapause, that is initiated and maintained by short day lengths and averted or terminated by long day lengths.[6] There is speculation that hypothetical global warming and the shortening of winters, W. smithii has been observed to now require shorter days before going dormant, this led to the theory that this is an example of microevolutionary selection; mosquitoes that waited longer to go dormant and which had a greater fitness have been favored.[7]
Photoperiodism in Wyeomyia smithii is believed in nature to examine the startling finding that proposed, but not proven, recent climate change can force genetic change in plants and animals. Wyeomyia smithii lives through the winter as diapausing larvae in the leaves of the pitcher plant. The pitcher-plant mosquito enters a hibernal diapause as larvae. Which means, short days initiate and maintain diapause, and long days promote continuous development in diapausing larvae. The day length promotes 50% development and 50% diapause (the critical photoperiod) as the same for the initiation and termination of not developing in unchilled larvae. For the initiation of not developing, insects pass through a "sensitive period" during which day length is interpreted as long or short, which results in a diapause/no-diapause response. Wyeomyia smithii is photoperiodic while in diapause. The sensitive period is indefinitely long, and the effect of manipulating different light. Dark cycles can be assessed over weeks or months, instead of a few days. Wyeomyia smithii oviposits into and completes their entire preadult development only within the water-filled leaves of the carnivorous pitcher plant Sarracenia purpurea. Throughout this range, W. smithii occupies a uniform microhabitat whose community composition remains highly consistent. The photoperiodic response has been exposed to various seasonal changes, both in situ and during postglacial dispersal.[8]
The purple pitcher plant (Sarracenia purpurea), which houses W. smithii, is known to be the most habitable pitcher plant for many different inquilines. At least 165 various species of insects, protozoa, algae, and other organisms can live within the purple pitcher plant. The plant has adapted to have fluid with a higher pH than other, more acidic, carnivorous pitcher plants. There is little fluid secreted by this plant in comparison to the rainwater it collects in its pitcher, which dilutes the solution and creates a more habitable environment for outside organisms. The plant's adaptation allowing it to host diverse life is an advantage to the mosquito because its larvae prey upon those organisms. The mosquitos also prey on the food that the pitcher plant catches, giving them a steady food source.[9]
The pitcher plant mosquito, Wyeomyia smithii, has been featured in scientific studies because of its co-evolution with the purple pitcher plant. The relationship between the two species highlights a genetic response to climate change, which details how a population can evolve at a quicker pace in order to make accommodations due to the changes in climate. The water-filled pitcher plant proved to be a suitable home for the mosquito in its habitat range. It is because both species can endure a temperate climate. This idea makes the pitcher plant the next option for this mosquito species to stay in its current domain.[10]
The relationship is beneficial for both species and allows them to continue to evolve together. The purple pitcher plant uses the mosquito for nutrients once the mosquitoes die off. And, these mosquitoes are no different than any other subspecies, in terms of attraction, they are drawn to water. The pitcher plant is filled with water and this is a type of environment that is used as a location for female mosquitoes to lay their eggs. Most pitcher plant mosquitoes tend to frequent a pitcher plant younger in age. Not only does the plant provide a steady source of food, it is a protective place for larvae to develop.[11]
Wyeomyia smithii, the pitcher plant mosquito, is an inquiline mosquito that completes its pre-adult life cycle in the phytotelma of—that is, the water contained by—the purple pitcher plant, Sarracenia purpurea. In this microcommunity of bacteria, rotifers, protozoa, and midges, W. smithii is the top-level predator; its presence determines the bacterial species diversity within the pitcher.
W. smithii is not a pest mosquito in general. The northern US population does not consume blood at all, while the southern US populations only consume blood after laying an initial egg batch; even then they appear disinterested in feeding. In fact, it is the only known mosquito to have both obligatory biting and non-biting populations in the same species.
