Changes in the Carbohydrate and Fat Content of the Japanese Beetle (Popillia japonica Newman) during Metamorphosis

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Abstract
The glucose content of the Japanese beetle changed in the following manner during metamorphosis. In the early prepupal period, it decreased from 0.52% to 0.42%. Pupation was accompanied by an increase to 0.79%. It dropped to 0.68% in the 2-day pupa, and then began to rise slowly, reaching a high value of 0.86% on the last day of the pupal stage. Emergence was associated with a loss of glucose, but because of the loss of weight which occurs at that time, the percentage value increased. The glycogen content increased from 1.43% in the larva to 2.07% in the early pupa. There was a rapid loss during the first 4 days, an increase on the 5th day, and a decrease throughout the remainder of pupal life. Fat content remained at a constant value during the prepupal and first 4 days of the pupal stage. It decreased sharply on the 5th and 6th days and remained relatively constant throught the remainder of the pupal stage. These results suggest the utilization of glycogen for energy during the pupal stage. When the glycogen reaches a low value, it is replenished at the expense of stored fat.
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