Biting Midges: Ceratopogonidae

• Biting midges, belonging to the family Ceratopogonidae, are tiny bloodsucking flies represented by a few genera.
• They are often called "no-see-ums" because of their small size.
• In the northeastern United States, they are known as "punkies".
• Biting midges are vectors for viruses, protozoans, and nematodes and can be annoying pests to humans, domestic and wild animals.
• There are approximately 123 genera and 6,267 extant species worldwide within the Ceratopogonidae family.
• Ceratopogonids are divided into four subfamilies: Leptoconopinae, Forcipomyiinae, Dasyheleinae, and Ceratopogoninae.

Vector-borne Diseases

• Biting midges can transmit Oropouche fever in humans.
• They transmit bluetongue disease (BT) and epizootic hemorrhagic disease in ruminants.
• They also transmit African horse sickness (AHS) in equids.
• Blood protozoans transmitted by biting midges cause diseases in poultry.
• Certain nematodes carried by biting midges can cause Mansonellosis in humans.
• They also transmit onchocerciasis in various domestic and wild animals.
• A table lists viruses transmitted by biting midges, including Akabane, Sabo, Tinaroo, Lokern, Main Drain, Buttonwillow, Oropouche, Utive, Utinga, and Rift Valley Fever.
• The same table identifies the vertebrate hosts and geographic areas for each virus.

Morphology

• Ceratopogonid larvae are long and slender, typically 2 to 5 mm long when mature.
• Larvae have a white, translucent body, in contrast to a yellow-to-brown head capsule.
• Larvae are often marked with subcutaneous pigmentation on their thorax.
• Pupae are typically brownish and have prothoracic respiratory horns at the anterior end.
• Adult Culicoides midges are tiny, usually 1.0-2.5 mm in body length, with mouthparts adapted for biting or piercing tissues.
• Female mouthparts are surrounded by a relatively short proboscis, about as long as the head.

Life History

• Adult females typically need a blood meal to develop their eggs.
• Some species exhibit autogeny. They carry over enough nutrients from the larval stage to develop eggs during the first gonotrophic cycle without feeding on blood.
• Egg development usually takes 7-10 days, but can be as short as 2-3 days.
• Eggs are deposited in batches on moist substrates, ranging from 30 to 450 or more per female, depending on the species and size of the blood meal.
• Autogenous females tend to produce fewer eggs.
• Eggs are small and elongate, measuring 250-500 mm in length, commonly banana-shaped, with minute projections for plastron respiration.
• Eggs are initially white, gradually turning brown, and hatch in 2-7 days.
• Larvae develop through four instars with a development time varying from 2 weeks to over a year. It reflects species, latitudes, and seasons.
• Some species overwinter as larvae, spending 7 or 8 months in this stage.
• In other cases, larvae become dormant during summer, prolonging larval development.
• Larval development of some arctic species can last up to 2 years.
• Pupation usually occurs near the surface of the substrate, where the pupae's prothoracic horns can penetrate the water film.
• Pupae of Culicoides species in water-filled tree holes may remain afloat.
• Overwintering larvae pupate in the spring or early summer. This produces the first generation of adults.
• Autogenous females oviposit a week after emergence. They must obtain a blood meal each time before forming another batch of eggs.
• Newly emerged, anautogenous females oviposit after their initial blood meal.
• A small percentage of females can produce a second batch of eggs after a second blood meal, but rarely a third.
• In the laboratory, C. variipennis is capable of completing up to seven gonotrophic cycles.
• Longevity of captive adults ranges from 2 to 7 weeks, but most survive only a few weeks under natural conditions.
• Generation time varies from 2 weeks for members of the C. variipennis complex and 6 weeks or longer for most species.