The effect of diapause and age on the tarsal acceptance threshold of the fly, Musca autumnalis

Abstract

Using proboscis extension as an index of acceptance, cow blood, cow manure, and various molar solutions of glucose were applied to the tarsi of the face fly, Musca autumnalis DeGeer, to determine differences between the tarsal acceptance thresholds of diapausing and non-diapausing adults. The effect of adult age on tarsal acceptance threshold was also investigated. It was demonstrated that non-diapausing face fly adults had a significantly greater percentage response than did diapausing adults to blood, manure, and various molar solutions of glucose. These results suggest an elevation of the tarsal acceptance threshold for diapausing adults. Gravid females produced a response similar to that of diapausing females. Male face flies, over the 5 days tested, exhibited a similar response to the substances tested whereas females responded differently. At the peak of ovary development, females had a significant decrease in the percentage response to blood and glucose. Evidence is presented to support the hypothesis that the mechanism causing elevation of the tarsal acceptance threshold in diapausing and gravid face flies may be similar to that reported for Phormia by Dethier and Gelperin.