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*The larvae of ''Oestridae spp.'' are '''obligatory''' parasites
 
  
*The three important species of veterinary interest
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#REDIRECT[[:Category:Oestridae]]
**''Hypoderma''
 
**''Oestrus''
 
**''Gasterophilus''
 
 
 
<big>
 
'''[[Hypoderma spp.|''Hypoderma spp.'']]
 
 
 
'''[[Oestrus ovis|''Oestrus ovis'']]
 
 
 
</big>
 
 
 
===''Gasterophilus spp.''===
 
[[Image:Horse Bot Fly.jpg|thumb|right|150px|Horse Bot Fly - Dennis Ray - Wikimedia Commons]]
 
*Also known as the horse bot fly
 
 
 
*Obligate parasites of equids
 
 
 
*Spend most of life cycle in the equine stomach
 
**Of little pathogenic significance
 
 
 
*Three important species (in the UK)
 
**''G. intestinalis'' which is the most common
 
**''G. nasalis''
 
**''G. haemorrhoidalis'' which is rare
 
 
 
*Two other important veterinary species
 
**''G. nigricornis''
 
**''G. inermis''
 
 
 
 
 
'''Recognition'''
 
*Medium to large flies at 10-20mm long
 
 
 
*Look similar to drone bumble bees
 
**Body covered with dense yellow hair
 
**Dark coloured hairs produce a banding pattern
 
 
 
*Clear wings with brown patches
 
 
 
 
 
'''Life cycle'''
 
*Adults are most active in '''late summer'''
 
 
 
*Eggs are laid on the body and hatch spontaneously or are stimulated to hatch through an increase in warmth and moisture from the animal self-grooming. They are laid in different areas according to species
 
**''G. intestinalis'' eggs are laid in the hair of the shoulders and fore legs
 
**''G. nasalis'' eggs are laid in the intermandibular area
 
**''G. haemorrhoidalis'' eggs are laid around the lips
 
 
 
*Creamy-white eggs
 
 
 
*1-2mm in length
 
 
 
*Larvae crawl into the mouth and penetrate the tissues of the tongue and buccal mucosa
 
 
 
*Larvae then emerge after a couple of weeks and are swallowed
 
 
 
*Larvae pass into the [[Forestomach - Anatomy & Physiology|stomach]] and attach to the gastric mucosa
 
**Larvae are now known as '''bots'''
 
 
 
*Each species attaches to a specific part of the stomach
 
**''G. intestinalis'' attaches to the cardiac region
 
**''G. nasalis'' attaches to the pylorus
 
 
 
*After 10-12 months in the stomach, the larvae detach and are passed out in the faeces
 
**''G. haemorrhoidalis'' attaches to the rectal mucosa before being passed out
 
 
 
*Larvae pupate on the ground
 
 
 
*Adults hatch after 1-2 months and survive from a few days to 2 weeks
 
**Adults have non-functional mouthparts so cannot feed
 
 
 
*There is only '''1 generation per year''' in temperate regions of the world
 
 
 
 
 
'''Pathogenesis'''
 
*Adults cause annoyance when egg laying
 
**Disturbance and panic can ensue
 
 
 
*Larvae cause a marked inflammatory reaction when attached to the gastric mucosa
 
**Ring like thickening around the base of each attached larvae
 
 
 
*Large numbers of larvae may interfere with the passage of food and action of gastric sphincters
 
 
 
*''G. haemorrhoidalis'' can cause mild irritation to the rectal wall
 
 
 
*Host reaction to larvae in the mouth is minimal
 
 
 
 
 
'''Control'''
 
*Treatment of horses with [[Ectoparasiticides|insecticides]] over winter
 
**Breaks the life cycle as all the population are present as bots in the [[Forestomach - Anatomy & Physiology|stomach]]
 
 
 
*If eggs are present in late summer, the horse's coat can be sponged with an [[Ectoparasiticides|insecticide]]
 
**Stimulates hatching
 
**Kills larvae
 
 
 
[[Category:Parasites]][[Category:Flies]][[Category:Myiasis Producing Flies]]
 

Latest revision as of 13:19, 5 April 2010

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