Pea aphids -- a serious agricultural pest -- have the ability to see and avoid a common, aphid-killing bacteria on plant leaves, according to a new Cornell University study published in Current Biology.
Pea aphids lack immune-response genes, making them highly susceptible to infection. In the lab, pea aphids that became infected with virulent strains of the bacteria all died. They make up for their immune deficiency by reproducing in large numbers but can still die from bacterial infection at a high rate.
It turns out, the bacteria (Pseudomonas syringae), and all members of the genus Pseudomonas, contain compounds called pyoverdine, which bind iron, but also fluoresce in ultraviolet (UV) light -- wavelengths that exist in sunlight. Furthermore, pea aphids can distinguish the unique blue-green light that virulent strains of P. syringae emit.