Conclusions
This study revealed that a host specialized aphid successfully achieved
feeding on a new host plant when the new host plant was pre-infected
with a phytopathogen. The feeding experience enabled the
host-specialized aphid to fully adapt to the new host plant that was
healthy. This is a new pathway of insect adapting to host plant, which
may be widespread in other polyphagous aphids with host specialization.
The results were of great significance for the management of polyphagous
aphids. For instance, plant pathogen control should be effective to
prevent A. gossypii on overwintering hosts from infesting
cucurbit crops. In order to further understand the host adaptation
pathway of aphid mediated by phytopathogen, we suggest to compare
aphid-derived and biotrophic phytopathogen-derived molecules (effectors)
in overcoming plant defenses, and to find and analyze differentially
expressed genes during the rapid adaptation process mediated by
phytopathogen.