“Bubbling” or Droplet Regurgitation in Both Sexes of Adult <I>Phormia regina</I> (Diptera: Calliphoridae) Fed Various Concentrations of Sugar and Protein Solutions

Abstract

Bubbling behavior or regurgitation is defined as the production of a droplet on the tip of the proboscis. No behavioral differences were observed in the components of the bubbling behavior between the two sexes of adult Phormia regina Meigen (Diptera: Calliphoridae). One of the most interesting behaviors, from a functional standpoint, is the proboscis shaking and proboscis pumping that is always associated with droplet extrusion. Droplets were usually reingested and not dropped on the substrate as reported in some fly species. On a sucrose meal, the average total time the fly spent on bubbling, regardless of sex, was 9.4 min, whereas the average time the droplet was present on the proboscis was 7 min. The number of droplets produced per fly for both sexes was 19.8 for sucrose and 24.6 for liver. The average time to initiate droplet extrusion after a meal by both sexes was 69 min for sucrose and 102 min for the liver meal. Bubbling flies had a statistically significant greater crop volume (7.9 μl on liver and 6.2 μl on sucrose) than nonbubbling flies (4.1 μl on liver and 2.3 μl on sucrose). The latter results place the important functional significance of bubbling or regurgitation on crop volume and the need of flies to eliminate crop water load, thus concentrating crop solute.