LIPID, CARBOHYDRATE AND NITROGEN-CONTENT OF LONG-WINGED AND SHORT-WINGED GRYLLUS-FIRMUS - IMPLICATIONS FOR THE PHYSIOLOGICAL COST OF FLIGHTCAPABILITY

Concentrations of a total lipid, triglyceride, soluble carbohydrate, t otal nitrogen and water were measured in the long-winged (LW) and shor t-winged (SW) morphs of the cricket, Gryllus firmus. In addition, the weights and composition of wings and oviposited eggs were compared bet ween morphs. This was don to obtain information on the energetic cost of flight capability in the LW morph. Whole-cricket content (% dry mas s) of triglyceride was significantly higher in LW vs SW individuals of both sexes. Since triglyceride is a likely flight fuel in G. firmus, the biosynthesis of elevated levels of this high energy substance in t he LW morph may represent an important energetic cost of flight capabi lity. The existence of such a cost is consistent with the elevated res piratory metabolism previously observed in LW vs SW G. firmus. A highl y significant negative correlation was observed between triglycerides and non-triglycerides in LW but not SW crickets. This suggests that li pid biosynthesis may be operating under some constraint in the LW morp h. Increased triglyceride biosynthesis may require a concomitant decre ased biosynthesis of non-triglycerides. In contrast to the elevated tr iglyceride level in the LW morph, carbohydrate concentration was highe r in the Sw morph during early adulthood. Carbohydrate content also de creased with age in the Sw but not in the LW adults. No differences we e observed between morphs in (1) the total nitrogen or water contents of whole crickets, (2) the nitrogen content of wings or (3) the wt wei ght, dry weight, lipid content, or total nitrogen content of oviposite d eggs.