Turning the sun’s rays into usable energy is a skill thought to be limited to plants, algae, and solar panels. But a new study suggests that aphids may be also possess this ability. Aphids

already stand out from other animals for their production of carotenoids

, pigments that also help out the immune system---most organisms get carotenoids from food, rather than making them themselves. A group of French and Israeli researchers now suggests

that the reason aphids expend energy making these pigments is because they play an additional role in aphid life: Carotenoids, which plants use in photosynthesis, could be helping aphids do some of the same tricks. There are three colors of pea aphids: green, orange, and white. Greens have the most carotenoids and white ones the least. Intriguingly, the researchers found that the green aphids contain the most ATP

---a molecular battery that carries energy throughout the body---and white aphids the least. This suggested to the researchers that perhaps the carotenoids were helping the little bugs capture light energy. To test this hypothesis, they placed some aphids in the dark and let others experience light-dark cycles. They found that at least in the case of orange aphids, those exposed to light manufactured more ATP than those that lived in darkness. These results are certainly suggestive, but they do not prove that carotenoids help aphids turn sunlight into usable energy. For their next step, researchers may want to engineer aphids with no carotenoids at all and compare them to their pigmented brethren, to find out if these little bugs are really imitating plants.

Image courtesy of Luc Viatour / Wikimedia Commons