An Intergeneric Comparison of Cephalic Structure in Tabanids (Diptera) in Relation to Feeding Habits

Putative Sensory Structures Associated with the Food Canal of Hybomitra difficilis (Diptera: Tabanidae).

“…In general, the type, number, and position of sensilla lining the food canal of tabanids remains poorly described. Lall and Davies (1971), working with Chrysops vittatus, Hybomitra lasiophthalma, and Tabanus lineola (their samples being a "…total of 5 -6 flies of each species…"), noted only that; "…small, thin-walled trichoid hairs are found in pairs along the food groove." Faucheux (1975) also noted that the alimentary canal of T. bovinus, comparable to the food canal of H. difficilis, contained other, regularly spaced, sensilla along its length.…”

“…Faucheux (1975) also noted that the alimentary canal of T. bovinus, comparable to the food canal of H. difficilis, contained other, regularly spaced, sensilla along its length. Neither Lall and Davies (1971), nor Faucheux (1975) provided information on the number, category, or position, of sensilla in the food canal of the tabanid species they studied, nor did they mention the presence of basiconic sensilla in the food canal proper of any flies in their samples. So, contrary to the pairing described by Lall and Davies (1971), and the regular spacing reported by Faucheux (1975), sensilla in H. difficilis exhibited little evidence of occurring in pairs, and they were significantly aggregated in the distal region of the food canal rather than being "regularly spaced."…”

“…Neither Lall and Davies (1971), nor Faucheux (1975) provided information on the number, category, or position, of sensilla in the food canal of the tabanid species they studied, nor did they mention the presence of basiconic sensilla in the food canal proper of any flies in their samples. So, contrary to the pairing described by Lall and Davies (1971), and the regular spacing reported by Faucheux (1975), sensilla in H. difficilis exhibited little evidence of occurring in pairs, and they were significantly aggregated in the distal region of the food canal rather than being "regularly spaced." Moreover, basiconic sensilla in the food canal of H. difficilis exhibited little evidence of pairing, and were, with but two exceptions, aggregated in the distal-most distal region of the food canal.…”

“…Our observation of putative chemoreceptors aggregated in the distal-most region of the H. difficilis food canal (Table 2) is not unique, since Scudder (1953) mentioned, somewhat ambiguously, the presence of "occasional basicones" among "Group A Trichodes" (his Group A Trichodes being sensilla lining the food canal walls). Other investigators (Buerger 1967;Lall and Davies 1971;Faucheux 1975), however, failed to mention the presence of such chemoreceptors outside the area of the vestibule.…”

“…With their mouthparts adapted for piercing the host's skin and blood feeding, females are most responsible for nuisance activity and the capacity to transmit pathogenic agents, and yet few published reports on the form and function of North American tabanid mouthparts are available (Lall and Davies 1971). Indeed, Muzari et al (2010) note that tabanid flies remain the least studied of arthropod vectors.…”