Viruses

Natural Enemies of Blackflies and Midges

Viruses

Viruses are not commonly found in black flies or midges. The most frequently reported viruses from both groups are the iridescent viruses (or Iridovirus) and the cytoplasmic polyhedrosis viruses (cpv). Most research on these two viruses is reported for economically important insects. A third virus, the Entomopoxvirus, has been reported from many species of chironomid midge. Harkrider and Hall (1979) documented annual epizootics of this virus in Chironomus decorus populations in Southern California. A more complete record of this virus is provided below.

Entomopoxvirus

	These are large, double-stranded DNA viruses. Similar viruses are known from grasshoppers, beetles, and a few other insects. The entomopoxvirus infecting chironomids is classified as an Entomopoxvirus C.
Electron Micrograph of cross-section of a virus particle. The virion is approximately 250 ľ across.	One of the characteristic features of the C group is the hourglass-shaped genomic area (dark-staining central area in the figure).

Entomopoxvirus C Illustrated
Data Bank Summary of Entomopoxvirus C (External Link to National University of Australia)

Iridescent Viruses (Iridovirus)

The Iridovirus is a group of icosahedral viruses with double-stranded DNA. These viruses infect a variety of insects as well as other organisms. The virus often accumulates in the hemocoel and produces a turquoise or blue-indigo iridescence.

Iridovirus Illustrated (External Link to Leicester University, UK)
This site provides an outstanding review of the viruses in this family with excellent illustrations.
Data Bank Summary of Iridoviruses (External Link to International Committee on Taxonomy of Viruses)

Cytoplasmic Polyhedrosis Virus

Cytoplasmic Polyhedrosis Viruses (cpv) are small double-stranded RNA viruses that are members of the Reoviridae family. The insect cpvs are formally grouped with the Cypovirus. In black flies and midges, these viruses usually infect the midgut region and characteristically cause the tissue to appear white. Little is reported on this virus other than their occurrence. Bailey (1977) observed cpvs in black flies with an incidence as high as 54%. Federici, et al. (1973) observed cpvs in chironomids in Florida.

Data Bank Summary of Cypovirus (External Link to International Committee on Taxonomy of Viruses)

Natural Enemies of Blackflies and Midges

Viruses

Entomopoxvirus

Entomopoxvirus C Illustrated

Data Bank Summary of Entomopoxvirus C (External Link to National University of Australia)

Iridescent Viruses (Iridovirus)

Iridovirus Illustrated (External Link to Leicester University, UK)

Data Bank Summary of Iridoviruses (External Link to International Committee on Taxonomy of Viruses)

Cytoplasmic Polyhedrosis Virus

Data Bank Summary of Cypovirus (External Link to International Committee on Taxonomy of Viruses)

Literature References

Natural Enemies Page

Last modified 22 August 2004