Aphids are known to cause great losses to agriculture worldwide, and are devastating insect pests. These sap-feeding plant pests harbor in their body cavity bacteria, which are essential for the aphids' fecundity and survival. Buchnera, the bacterium, benefits also because it cannot grow outside the aphid. This mutually beneficial relationship is sabotaged, however, by the bacterium which proceeds to betray the aphid, a research team led by scientists at the University of California, Riverside has found.
"Although this betrayal is unintentional, it nevertheless alerts the plant about the aphid's presence and the aphids are unable to reproduce in large numbers," said Isgouhi Kaloshian, a professor of nematology, who led the research project. "A protein from the bacterium, found in the aphid saliva and likely delivered inside the plant host by the aphid, triggers plant immune responses against the aphid. It seems that the plant immune system targets the bacterium and exploits the strict mutual dependency between the plant and aphid to recognize the aphid as the intruder."
Study results appear online this week in the Proceedings of the National Academy of Sciences.