Culicoides variipennis

Culicoides variipennis is a 1 millimetre (0.039 in) long

The C. variipennis is less than 1 millimetre (0.039 in) long, which makes it difficult to keep from livestock.[2] The wings of C. variipennis are spotted and narrow with few veins; the wings fold over the abdomen while the C. variipennis is at rest.^[2] The max flight range for male C. variipennis is 0.8 kilometres (0.50 mi) and for females 4.0 kilometres (2.5 mi), while the mean flight range is 1.89 kilometres (1.17 mi).^[3] Flight activity is dependent on the light intensity and temperature; most flight, and thus most bites, occur around dawn and dusk.^[1] A distinction between male and female C. variipennis is that females have different mouthparts that allow them to blood feed.^[2]

Life cycle

The life cycle of C. variipennis is from half a year to three years.^[2] The larva, found typically near sewage tank outlets or stock tanks where manure is trampled into the soil, is slender, transparent to orange colored, worm-like and lasts 15–23 days in larval stage.^{[citation needed]} The aquatic/sub aquatic larvae feed on dying organisms or other organic material.^[2]

Subspecies

Locations

The C. variipennis and the five subspecies, C. v. variipennis, C. v. sonorensis, C. v. occidentalis, C. v. australis, and C. v. albertensis, are found in various locations of the United States. The C. v. variipennis is found in the north east United States, but is not a vector for Bluetongue virus in this area because of low susceptibility; the C. v. sonorensis is found from Florida to California, north to Virginia and Ohio, and in the west from Washington to British Columbia, but they leave Colorado in the winter; the C. v. occidentalis is found in Arizona to California and from Washington to British Columbia.^[1]

Morphologic distinctions

The C. v. australis and C. v. albertensis have difficulty in defining the subspecies relationship and together make up the C. variipennis complex.^[1] There are more outbreaks for Bluetongue virus in California than New York, as the bite rate of C. v. sonorensis is twice as much as the C. v. variipennis.^[1] Female C. variipennis show slender to slightly swollen third palpal segments with sensory pits that are shallow round and small as opposed to males^[4] Distinction against the subspecies C. v. sonorensis and C. v. occidentalis show that the females are identical morphologically with the enlarged third palpal segment with their sensory pit being a rounded, medium to large size^[4] For the male difference of C. v. variipennis, C. v. occidentalis and C. v. sonorensis, on the ventral surface of aedeagus, C. v. variipennis and C. v. occidentalis lack spicules, while male C. v. sonorensis have many prominent spicules on the aedeagus.^[4]

C. variipennis as a vector

Bluetongue Virus

The C. variipennis attacks in swarms with the