Culicoides
Author: Dr Gert Venter
Licensed under a Creative Commons Attribution license.
Introduction
Distribution
Biting midges in the genus Culicoides are like mosquitoes
With the exception of Antarctica and New Zealand,
in that the females of nearly all species need a blood meal
Culicoides midges are found virtually worldwide. The
in order to develop eggs. These midges are smaller (1-
most important Culicoides vectors of orbiviruses
3mm) than mosquitoes but can be much more abundant.
include C. imicola in Africa, C. sonorensis in North
Culicoides midges may occur in enormous numbers and
America, C. insignis in South and Central America, C.
are important in the transmission of a number of diseases
wadai, C. brevitarsis and C. actoni in Australia, C.
in livestock. It has been suggested that these midges
fulvus, C. schultzei in Asia and C. imicola, C. ulicaris
were involved in two of the ten biblical plagues of ancient
and C. obsoletus in Europe.
Egypt.
Importance
Systematics/Taxonomy/Identification
Female Culicoides midges feed on a broad spectrum
The genus Culicoides is part of the suborder Nematocera.
of hosts including reptiles, mammals, birds, humans,
Members of the genus tend to be small, fragile insects
and even blood-engorged mosquitoes. Their bites may
with long antennae, from which they derive their name.
be a severe nuisance to humans in certain parts of the
Midges belong to the family Ceratopogonidae and are
world and can cause an acute allergic dermatitis in
distinguished by their 15-segmented antennae, sexual
horses. They are biological vectors of viruses,
dimorphism and distinctive wing venation. The important
protozoa and filarial nematodes in birds, humans, and
bloodsucking species are found in the genera Culicoides
a range of domestic and wild animals. Among the
and Leptoconops. Feeding of Culicoides midges is largely
viruses that are transmitted by Culicoides species are
restricted to the night. Most Culicoides have a wing
those causing bluetongue, African horse sickness,
pattern that is composed of grey and white spots that are
equine encephalosis and epizootic haemorrhagic
unique to each species.
disease which are all of major veterinary importance.
Biology/Ecology
Around livestock, Culicoides can occur in remarkable
All Culicoides species display a typical holometabolous
high numbers especially on warmer nights and during
life cycle and only the females, which need blood for the
periods of excessive rainfall. During these periods
completion of the gonotrophic cycle, are haematophagous
more than 1 000 000 C. imicola can be captured in a
and pool feeders. The bites of these midges are painful.
single light-trap. It is estimated this may represent less
The immature stages are always aquatic or semi-aquatic.
than 0.001% of the number of midges active on a
Both the males and females feed on plant juices.
particular night. This illustrates the intensity of attacks
that may occur on exposed animals.
Control
Most of the Culicoides-transmitted diseases can be
controlled by vaccination, stabling of animals at night,
meshing of stables, and application of insect repellents
both to the animal and its stable environment.
Sampling /Collection methods
Only a limited number of suction light traps, the primary
monitoring
tools
for
the
collection
of
midges,
are
commercially available. These traps make use of a light
source to attract Culicoides midges and a fan to draw them
into a holding cage or container. The variation in the trap
types used by different laboratories/research groups makes
direct comparison between investigations difficult. The
number of Culicoides collected in light traps is not
necessarily comparable to species diversity and host bite
rate.