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Gasterophilus spp. (view source)

Revision as of 09:58, 9 July 2010

1,385 bytes removed ,  09:58, 9 July 2010
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[[Image:Horse Bot Fly.jpg|thumb|right|150px|Horse Bot Fly - Dennis Ray - Wikimedia Commons]]
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[[Image:Horse Bot Fly.jpg|thumb|right|150px|Horse Bot Fly - Dennis Ray - Wikimedia Commons]
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*Also known as the horse bot fly
      
===Introduction===
 
===Introduction===
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L1 are extremely small and motile, and begin devlopment in the mouth, tongue and gums of the host.  The development of L1 into L2 occurs on the pharynx.  L2 then attaches to the base of the tongue ad slowly migrates to the stomach.
 
L1 are extremely small and motile, and begin devlopment in the mouth, tongue and gums of the host.  The development of L1 into L2 occurs on the pharynx.  L2 then attaches to the base of the tongue ad slowly migrates to the stomach.
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L3 attaches to the squamous gastric mucosa along the margo pliacatus, in the case of '''G. intestinalis'''. '''G. nasalis''' attaches to the dorsoproximal part of the duodenum, and '''G. haemorrhoidalis''' attaches to the gastric epithelium within the stomach.
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L3 attaches to the squamous gastric mucosa along the margo pliacatus, in the case of ''G. intestinalis''. ''G. nasalis'' attaches to the dorsoproximal part of the duodenum, and ''G. haemorrhoidalis'' attaches to the gastric epithelium within the stomach.
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The larvae then remain and develop within the stomach for around 10-12 months.  They mature in the following spring or early summer (generally between May and September), detach from their surface and are passed out in the host faeces. The larvae then penetrate the soil, where they transform into pupae and the flies hatch 30 to 40 days later.
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The larvae then remain and develop within the stomach for around 10-12 months.  They mature in the following spring or early summer (generally between May and September), detach from their surface and are passed out in the host faeces. ''G. haemorrhoidalis'' also attaches to the rectal mucosa before being passed out.
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They are only found on pasture, as they do not survive well on stable bedding.  The pupae are known to be sensitive to frost, moisture and flooding, so the environmental conditions present play a significant role in the success of the parasite.
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The larvae then penetrate the soil, where they transform into pupae and the flies hatch 30 to 40 days later.
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Eggs are laid on the bodyof the host and either 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;
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''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
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They are only found on pasture, as they do not survive well on stable bedding.  The pupae are known to be sensitive to frost, moisture and flooding, so the environmental conditions present play a significant role in the success of the parasite.
    
[[Image:Gasterophilus.jpg|200px|thumb|right|'''Fasciola hepatica (Copyright Notafly, Wikimedia Commons) ''']]
 
[[Image:Gasterophilus.jpg|200px|thumb|right|'''Fasciola hepatica (Copyright Notafly, Wikimedia Commons) ''']]
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===Identification===
 
===Identification===
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*Medium to large flies at 10-20mm long
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Gasterophilus are medium to large flies at 10-20mm long, and are thought to look similar to drone bumble bees.
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*Look similar to drone bumble bees
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**Body covered with dense yellow hair
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**Dark coloured hairs produce a banding pattern
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*Clear wings with brown patches
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'''Life cycle'''
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*Adults are most active in '''late summer'''
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*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
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**''G. intestinalis'' eggs are laid in the hair of the shoulders and fore legs
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**''G. nasalis'' eggs are laid in the intermandibular area
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**''G. haemorrhoidalis'' eggs are laid around the lips
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*Creamy-white eggs
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*1-2mm in length
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*Larvae crawl into the mouth and penetrate the tissues of the tongue and buccal mucosa
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*Larvae then emerge after a couple of weeks and are swallowed
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*Larvae pass into the [[Forestomach - Anatomy & Physiology|stomach]] and attach to the gastric mucosa
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**Larvae are now known as '''bots'''
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*Each species attaches to a specific part of the stomach
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**''G. intestinalis'' attaches to the cardiac region
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**''G. nasalis'' attaches to the pylorus
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*After 10-12 months in the stomach, the larvae detach and are passed out in the faeces
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**''G. haemorrhoidalis'' attaches to the rectal mucosa before being passed out
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*Larvae pupate on the ground
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*Adults hatch after 1-2 months and survive from a few days to 2 weeks
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**Adults have non-functional mouthparts so cannot feed
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*There is only '''1 generation per year''' in temperate regions of the world
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'''Pathogenesis'''
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*Adults cause annoyance when egg laying
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**Disturbance and panic can ensue
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*Larvae cause a marked inflammatory reaction when attached to the gastric mucosa
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**Ring like thickening around the base of each attached larvae
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*Large numbers of larvae may interfere with the passage of food and action of gastric sphincters
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*''G. haemorrhoidalis'' can cause mild irritation to the rectal wall
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*Host reaction to larvae in the mouth is minimal
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They have clear wings with brown patches, and produce creamy-white eggs, around 1-2mm in length
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'''Control'''
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Adults have non-functional mouthparts so cannot feed.
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*Treatment of horses with [[Ectoparasiticides|insecticides]] over winter
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**Breaks the life cycle as all the population are present as bots in the [[Forestomach - Anatomy & Physiology|stomach]]
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*If eggs are present in late summer, the horse's coat can be sponged with an [[Ectoparasiticides|insecticide]]
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Both ''G. haemorrhoidalis'' and ''G. nasalis'' have spikes on the ventral surface of the larval segments arranged in two rows. ''G. intestinalis'' have mouth parts that are not uniformlu curved dorsally and the body spikes present have blunt ended tips.
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**Stimulates hatching
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**Kills larvae
         
[[Category:Oestridae]]
 
[[Category:Oestridae]]
 
[[Category:To_Do_-_Max]]
 
[[Category:To_Do_-_Max]]
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