Honeydew and nectar sugars differentially affect flight performance in female black flies

Abstract

In the wild, black flies (Diptera: Simuliidae) feed on both floral nectar and homopteran honeydew. We tested the hypothesis that sugar meal composition affects flight performance using tethered black flies that had been flown to exhaustion. Individuals were then fed distilled water (dH2O), 10% (m/v) artificial nectar (AN), or 20% (m/v) artificial honeydew (AH) sugars, and the distance, speed, and duration of the resultant flights were recorded using a computerized flight mill. Following a dH2O meal, flies were unable to regain flight. There were three different artificial honeydew diets (AHlow, AHmed, AHhigh), each differing in the proportion and composition of simple sugars (glucose, fructose, sucrose) and complex sugars (melezitose, stachyose). Flies flew the farthest and longest on AH meals that contained higher levels of complex sugars (AHmed, AHhigh) compared with flies fed on AN (simple sugars only) or AHlow. On this flight mill, the mean flight speed was 10.6 ± 3.5 m/min and was not affected by the type of sugar meal ingested.