It used to be thought that the only means of protection for aphids was superfast reproduction, which made it possible to compensate for the death of a part of insects. In a new study by Cornell University, it was found that pea three are able to avoid accumulations of dangerous bacteria, noticing them on the leaves. In laboratory experiments, they consistently preferred to feed on the leaves, where there were no bacteria. Vision helps to make the choice of pea plants. The fact is that Pseudomonas syringae cells, like other representatives of this type of bacteria, contain pyoverdins - substances that promote iron transport through the cell membrane. Pyoverdins fluoresce under the action of ultraviolet solar radiation, while pea aphids are able to distinguish the fluorescence of virulent and safe strains of bacteria.
In a test experiment, the feeding of pea aphids was carried out in a plastic container that does not transmit the ultraviolet part of the spectrum. Accordingly, the bacterial pioverdin in this case did not fluoresce. In such conditions, the pea aphid lost its ability to avoid danger and fed both on clean leaves and on those where a solution with bacteria was applied. A similar result was obtained when a mutated bacterial strain that did not produce pyoverdine was used. The authors of the work believe that this ability of pea aphids can be used to protect plants.