Diversity of host plant relationships and leaf galling behaviours within a small genus of thrips - Gynaikothrips and Ficus in south east Queensland, Australia

Abstract

Thrips are well known as gall inducers, yet no field studies have been published on phlaeothripids in the genus Gynaikothrips, which gall Ficus leaves in Australia. A detailed field study was conducted in suburban Brisbane, Australia, on thrips species that induce leaf galls on fig trees. Gynaikothrips ficorum is evidently host specific as it induced leaf galls only on Ficus microcarpa, and did so almost continuously throughout the spring and summer growing season. By contrast, G. australis induced leaf galls on F. macrophylla, F. rubingosa and F. obliqua but only when flushes of new leaves appeared, and this occurred at intervals during spring and summer. Gynaikothrips ficorum feeds on the upper surface of new leaves and this causes the leaf to fold and/or twist into a gall. The life of the gall is about 4 weeks, with the thrips pupating within it. Sometimes, the galls are invaded by a kleptoparasite thrips, Mesothrips jordani. Gynaikothrips australis feeds on the underside of the new leaves and this causes the margins to curl under. The life of the gall is about 6 weeks, with the thrips pupating under the bark of the fig tree branches, and sometimes the galls are shared with an inquiline, G. additamentus.