Host Plant Specialization Governed by Facultative Symbiont

Tsuchida et al generate aphid strains that are genetically identical and differ only in pea aphid U-type symbiont (PAUS) infection by injecting adult aphids of naturally PAUS-infected strain, TUt, with ampicillin. The results indicate that PAUS infection improves the fitness of the host aphid specifically on white clover. They further assert that the finding does not necessarily contradict the notion that nuclear genes of the insect play a major role in determining its ecological traits, including plant specialization.