( A group of scientists from Oregon have ...)Butterflies lose body fat during metamorphosis

"The transformation of a caterpillar to a butterfly is one on nature's great mysteries," says William E. Connor of the Oregon Health and Science University in Portland. "Powerful chemical mediators are necessary to produce this transformation. We hypothesized that considerable energy would be necessary for metamorphosis to occur. It appears as though the larva is sleeping, and one might think that very little energy would be required in hibernation, but the reverse must be true since a great deal of metabolic activity is occurring in the butterfly chrysalis."

Because of this energy expenditure, Connor and his colleagues surmised that butterflies experience a great loss in body fat during metamorphosis. Using the Blue Morpho butterfly from the Butterfly Farm in Belize, the scientists analyzed the fatty acid composition and content of the butterflies, their diet, and their larva. They were able to do this easily because the larva feed solely on the leaves of the rain forest tree Pterocarpus, on which the butterfly lays its eggs.

On a daily basis, they measured the food consumption of the larva and then analyzed the fatty acid composition and content of the diet as well as the larva. Once the larva had transformed into butterflies, the researchers examined the fatty acid composition and content of the butterfly.

They found that both the diet and the tissues of the larva and butterfly had a high concentration of polyunsaturated fatty acids. However, the larva had a much higher total fatty acid content than the butterfly, indicating that the transformation from larva to butterfly drastically reduced the total fatty acid content.

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Source:American Society for Biochemistry and Molecular Biology