Equis ISSN 2398-2977

Culicoides spp

Synonym(s): Biting midges, no-see-ums, gnats, punkies

Contributor(s): Sheelagh Lloyd, Sue Paterson

Introduction

Classification

Taxonomy

  • Phylum: Arthropoda.
  • Class: Hexapoda.
  • Order: Diptera.
  • Suborder: Nematocera.
  • Family: Ceratopogonidae.
    • Genus:Culicoides,Leptoconops,Pulicara.
    • Species:austeni,brevitarsis,furens,grahami,nubeculosus,pulicaris,pungens,variipenis.
  • Family: Culicidae.
    • Genus:Anopheles,Culex.
    • Species:pipiens,tarsalis.

Distribution

  • There are over 1,000 species in the genusCulicoides.
  • The distribution of midges in the genusCulicoidesis worldwide:
    • 47 species are known to occur in Florida, USA.
    • Species belonging to the genusLeptoconopsoccur in the tropics, sub-tropics, the Caribbean, and some coastal areas of southeast Florida, USA.

Breeding sites

  • Midges:
    • Water, wet soil, moist decaying vegetation, marshy areas, particularly contaminated with animal effluent.
    • Sandy and clay soil, stream beds.
    • Emerging after rain.
  • Mosquitoes:
    • Aquatic.
    • Permanent water bodies, troughs, ponds, edges of streams, etc.
    • Artificial habitats that may temporarily fill with rain, shallow ground pools, swamps.

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Clinical Effects

Epidemiology

Lifecycle

Adults

  • Progress from egg to larva to pupa, and finally to the adult stage. 
  • Complete cycle can occur in 2-6 weeks, although dependent on species and environmental conditions.

Eggs

  • Culicoidesfeed on nectar, but the female requires blood for her eggs to mature.
  • Females usually blood-feed around dawn and dusk.
  • Numbers of eggs produced varies among species and size of bloodmeal, eg:
    • C. furens- can lay 50-110 eggs per bloodmeal.
    • C. mississippiensis- can lay 25-50 eggs per bloodmeal.

Larvae

  • Require water (they cannot develop without moisture), air and food. 
  • Are present in and around mud, sand, salt-marsh, mangrove swamps, streams/ponds/lakes/springs, muddy substrates, tree holes, etc.
  • The larval stage lasts from 2 weeks to a year, depending on species, temperatures and geographic area.

Pupae

  • This stage lasts approximately 2-3 days.

Control

Control via animal

  • Stabling between 1 h before and 1 h after sunrise and sunset;Culicoidesdont enter buildings.
  • Stabling at night may also be beneficial.
  • Fly protecting blankets and hoods when not stabled.
  • Move horse to a new area at least 0.5 miles fromCulicoidesspp breeding habitats (ponds, marshes) asCulicoidesspp are not capable of flying further than 0.25-0.5 miles from their breeding areas. 
  • Individual animals may be particularly sensitive to individual species ofCulicoidesor mosquito so may improve in a new area.

Control via chemotherapies

Corticosteroids

  • See Therapeutics: skin    Therapeutics: skin  . 
  • May be necessary while insect-control measures are being implemented or if stabling is not feasible due to behavioral problems.
  • Long-term oral prednisolone    Prednisolone  at smallest possible dose during allergy season.
  • Topical corticosteroids.

Insecticides

Insect repellents

  • See Therapeutics: skin    Therapeutics: skin  .
  • Lotions and oily preparations provide a mechanical barrier.
  • Pyrethrins   Pyrethrin  , pyrethroids, diethytoluamide (DEET), dipropylisocinchromeronate, butoxypolypropylene glycol, citronella, Simonsia chinensis.

Antihistamines

Specific immunotherapy

  • Hyposensitization.
  • Injection of increasing concentrations of antigen to induce IgG antibodies.
  • Reported efficacy in some open trials of some >60% may show >50% improvement.
  • Further double blind placebo controlled studies are required.
  • Improvement likely when allergens identified and isolated.

Control via environment

  • Begin before the start of the fly season.
  • Insect-proof stables with fine-mesh screens, may be sprayed with permethrin   Permethrin   insecticide/repellent with residual activity.
  • Ceiling or wall mounted fans to create a breeze.
  • If breeding sites on property, improve pasture drainage, drain ponds etc, regular emptying of troughs, water butts, elimination of unnecessary containers.
  • Prevent breeding areas in water troughs by frequent cleaning.

Further Reading

Publications

Refereed papers

  • Recent references from PubMed and VetMedResource.
  • Robin M et al (2014) Threat of midgeborne equine disease: investigation of Culicoides species on UK equine premises. Vet Rec 174 (12), 301 PubMed.

Other sources of information


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