Scanning electron microscope observations on the anterior thoracic and post-abdominal spiracles of Gasterophilus larvae (Diptera: Gasterophilidae)
Principato, M.; Tosti, M.
International Journal for Parasitology 18(2): 191-196
Comparative scanning electron microscope photographs and drawings of the anterior thoracic spiracles of 3rd-instar larvae of the 6 Italian Gasterophilus species (G. intestinalis, G. pecorum, G. nasalis, G. haemorrhoidalis, G. meridionalis and G. inermis) are presented. Differences in size and shape of the spiracles and in number and distribution of their papillae are described. The trabecular tissue observed in the anterior thoracic spiracles becomes thicker towards the bottom of the spiracle felt-chamber, forming a plug that makes the anterior thoracic spiracles in larvae non-functional. The post-abdominal spiracles, that are functional, contain serrate-sided openings through which is visible some trabecular tissue very similar to that observed in the anterior thoracic spiracles. The protective systems of the respiratory apparatus, permitting larvae to survive in the horse's digestive apparatus, are discussed.