Lipid and carbohydrate utilization during flight of the migratory moth, Agrotis ipsilon (Lepidoptera: Noctuidae)

Abstract

AbstractMale black cutworm, Agrotis ipsilon (Hufnagel) moths, were attached to laboratory flight mills on the third night after emergence. Individuals were classified according to their longest uninterrupted flight during the night. There were not enough non‐fliers or trivial fliers (flight < 1 h) to make meaningful comparisons, so only short‐fliers (flight ≥ 1 h but ≤ 5 h) and long‐fliers (flights ≥ 5 h) were further tested. After a day of rest, short‐ and long‐fliers were tethered to a stationary pin and forced to fly 0, 10, 20, 30, 60, 120, or 180 min, after which hemolymph was sampled and lipid and carbohydrate concentrations determined. Concentrations in samples taken at intervals after cessation of a 60‐min flight indicated that both energy sources were being utilized during flight. Neck‐ligation experiments indicated that a handling‐induced hyperlipemic response occurs 15 min after the beginning of the sampling procedure, and that the hormone triggering does not come from the head. Resting concentration of lipid in long‐fliers is about half that of short‐fliers, but it increases threefold in the first 20 min of flight, whereas that of short‐fliers remains unchanged. In‐flight lipid concentration in controls, which experienced their first and only flight on day 5, was greater than the concentration in both short‐ and long‐fliers. Between 10 and 20 min, carbohydrate concentrations decrease about twofold in long‐fliers but drop only slightly in short‐fliers. These data suggest that long‐fliers may have a lower basal metabolic rate and depend more on carbohydrate when at rest than short‐fliers and that long‐fliers may utilize more carbohydrate than lipid during the initial period of flight. In addition, previous flight on the flight mills has a greater influence on lipid mobilization and usage in short‐fliers than it does on long‐fliers. Patterns of lipid mobilization during flight seem to differ between migrant and non‐migrant species and to vary among migrants depending on the flight strategy used, but there are no major differences in patterns of carbohydrate usgaeg. © 1995 Wiley‐Liss, Inc.