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Title: MORPHOLOGY AND DIAGNOSIS OF FOURTH-STAGE LARVAE OF TRIDENTOINFUNDIBULUM GOBI (NEMATODA, STRONGYLOIDEA) PARASITIZING HORSES, EQUUS CABALLUS

Author
item KHARCHENKO, VITALIY - NATL ACAD SCIENCES
item Lichtenfels, James
item KUZMINA, TATIANA - NATL ACAD SCIENCES

Submitted to: Comparative Parasitology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 4/3/2003
Publication Date: 1/15/2004
Citation: KHARCHENKO, V.A., LICHTENFELS, J.R., KUZMINA, T.A. MORPHOLOGY AND DIAGNOSIS OF FOURTH-STAGE LARVAE OF TRIDENTOINFUNDIBULUM GOBI (NEMATODA, STRONGYLOIDEA) PARASITIZING HORSES, EQUUS CABALLUS. COMPARATIVE PARASITOLOGY. 71: 73-77. 2004.

Interpretive Summary: Strongyloid nematodes are a major cause of morbidity and mortality in equines in the United States. Resistance to antiparasitic drugs is common and alternative control methods for these parasites are needed. The 65 species in horses can be identified by a few authorities using comparative anatomy of adult stages, but larval stages are exceptionally difficult to identify and eggs are impossible to identify to even subfamily level. This study describes the parasitic fourth-stage larval stage of Tridentoinfundibulum gobi, a nematode parasite of the large intestine and caecum of horses. The results will be used by researchers worldwide working to control these economically important nematodes of horses, especially in the pharmaceutical industry, the Food and Drug Administration, and scientists evaluating biological control agents. The information will assist in efforts developing diagnostic probes, biological control agents and antiparasitic drugs for larval cyathostominosis, an emerging disease of horses worldwide.

Technical Abstract: The fourth-stage larva (4) of Tridentoinfundibulum gobi, one of the rare species of Cyathostominae, is identified and described. The larva was identified as T. gobi as a result of finding molting forms showing characteristics of both larvae and adults. The buccal capsule is large and spherical; its width exceedds its depth. The buccal capsule walls are thick, gradually narrowed to the apical edge and abruptly narrowed to the posterior edge. The esophageal funnel has 3 large, triangular teeth projecting into the buccal cavity similar to those of Triodontophorus spp. and Gyalocephalus capitatus. The L4 of T. gobi can be distinguished by its buccal capsule being of a smaller diameter than the esophagus. In addition, the buccal capsule of T. gobi L4 is wider than deep, but is as deep or deeper than wide in L4 of Triodontophorus spp., and, the buccal teeth of T. gobi L4 are much more steeply pointed and have smoother anterior edges than those of G. capitatus.