Can Gallers Expand the Host Range to Alien Plants within a Short Period of Time ?

Abstract

Among 607 alien plant species of Angiospermae that have naturalized in Japan since 185Os, only four species were found in the list of 568 host plant species of Japanese galling insects and mites. The rate of alien Angiospermae used by Japanese gallers to the total number was only 0.7%, which was apparently lower than 13.1% for the domestic gall-bearing species of Angiospermae. Although some of the alien plants are congeneric relatives to the domestic hosts and have been utilized by gallers in the original places. most of Japanese gallers could not expand their host range to alien plants within such a short period of time as 150 years. The galling habit is considered to be one of the main reasons to explain this evidence.