Distribution of sensory sensilla in the labral food canal and cibarium of Chrysops exitans (Diptera: Tabanidae).

Abstract

Sensilla, beginning at the distal-most tip of the labrum and extending proximally through the cibarium to the stomodaeum, were examined in females of Chrysops exitans Walker. Totals of 328 setiform sensilla (range, 14 to 21; mean = 18.2; ±1 SD = 1.67), and 36 basiconic sensilla (mean = 2.0; ±1 SD = 0) were observed in the food canal of n = 18 sample individuals. Both types of sensilla were aggregated distally in the canal. Additionally, a group of five to 10 sensilla was observed in each lateral wall of the epipharynx, with a single median group, consisting of both setiform and basiconic sensilla, positioned immediately distal to the mouth opening into the cibarium. Two pairs of basiconic sensilla were consistently observed in the stomodaeum of every fly.

Aggregation Patterns of Sensory Sensillae in the Food Canal and Cibarium of Glossina morsitans morsitans (Diptera: Glossinidae)

“…Curiously, aggregation patterns of sensory sensillae in the food canal/cibarium complex of tsetse flies are quite different from those found in bloodfeeding tabanids despite both groups of flies being PWVAS housed in the Brachycera clade and sharing similar diets. For example, sensory sensillae are aggregated in the distal regions of the food canals of tabanid flies (Buerger 1967, Joy and Stephens 2016, Joy 2017, Ranavaya and Joy, 2017, Setser and Joy 2017, whereas these sensillae are aggregated in the proximal-most canal region of tsetse flies (Stephens et al 1906, Buerger 1967, Rice, et al 1973. Why aggregations of sensory sensillae in deer flies and horse flies is so different from that of tsetse flies is uncertain, but a plausible explanation may lie in the structure of the distal labrum/food canal complex (Figs.…”

“…Sexes were separated for all subsequent measurements and sensory sensilla counts. The head of each fly was removed from the body and lateral cephalic extremities (i.e., portions of the compound eyes) were cut off to expose the internal head region in sagittal section after a procedure described for Chrysops exitans (Ranavaya and Joy 2017). These sagittal sections were then placed in a 5% KOH solution for 24 to 48 hours on a warming tray at 40 o C to soften and clear sclerotized elements (e.g., the head capsule, rostrum), and to remove muscle tissue surrounding the cibarium.…”