Utilization of lipid for flight and reproduction in Spodoptera litura (Lepidoptera: Noctuidae)

Research of the physiological traits of a long-distance migratory insect, the common cutworm Spodoptera litura, in relation to flight and reproduction, was focused on triacylglycerol (TG) levels and their fatty acid composition. The TG concentrations of non-flown males were the same as those of males after 12 h of flight, but the ratios of unsaturated fatty acids (UFA) in TG remained nearly unchanged, while four UFA out of eight identified fatty acids in TG (palmitoleic, oleic, linoleic and linolenic acids) gradually declined with longer flight duration. In females, ovarian development was completed within three days after adult emergence. During this three day period TG concentration increased in the ovary, accompanied by increasing ratios of UFA, in spite of a nearly constant TG concentration in the abdomen and unchanged ratio of its UFA. These facts suggest that the mature females utilize the TG deposited in the ovaries as a flight energy source. Then if they migrate a long distance, they use residual TG after flight for egg production.