Aphids Control Sun’s Energy With Internal Photosynthesis
Aphids might not be much to look at. Small, pear-shaped insects that travel from plant to plant, chewing leaves and extracting sugars. But aphids, like people, have some special things on the inside. Most recently, Entomologist Alain Robichon at the Sophia Agrobiotech Institute in Sophia Antipolis, France, discovered that aphids may be using sunlight to create energy. Photosynthesis is common in plants and fungi, but until now, has never been seen in an animal species.
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The discovery is based on chemical pigments called carotenoids. Carotenoids are used by many species of animals for a variety of biological functions, such as maintaining an immune system or making vitamins. The aphid is unique in that it creates its own carotenoids; all other animals obtain carotenoids through their diets. Robichon became curious as to why the insect would expend so much energy on producing the pigments. His team examined three different colors of aphids; green, orange and white.
The green aphids produced significantly higher levels of ATP, the chemical responsible for energy transfer in all living things, than the other two colors. Orange aphids generated more ATP when exposed to light, supporting Robichon's claim that the insect is converting light energy into food energy. Carotenoids are likely the vehicle for this process, as they are also a critical part of the photosynthesis process in plants as well. The carotenoids gather in areas on the aphid body that are exposed to the most sunlight, adding more weight to the theory. The researchers admit that these findings are far from solid proof that aphids photosynthesize, but the possibility exists and this should encourage other researchers to begin examining the aphid for photosynthetic properties.
What remains for researchers to unravel, beyond finding more evidence of photosynthesis in aphids, is the evolutionary reason for the process. The obvious answer is that it the sunlight provides another fuel source for the aphid, but Nancy Moran, an insect geneticist at Yale University, isn't so sure.
"Energy production seems to be the least of an aphid's problems - their diet is loaded with excessive sugar, most of which they cannot use," she told the journal Nature.
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