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First report of insect galls on Ficus microcarpa in Penghu Islands, Taiwan
Authors: YOU-TING HSIEH, SHENG-FENG LIN, YI-CHANG LIAO
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The morphology of insect galls often has a species-specific relation to gall-inducers. Therefore, using gall morphotypes as a surrogate of insect species, researchers can preliminarily investigate the gall-inducing insect fauna of an area. The Penghu Islands are the largest offshore islands of Taiwan, but the gall-inducing insect fauna is poorly known. In this study, we selected the widespread Chinese banyan (Ficus microcarpa L.) as the target of our faunistic survey focused on gall-inducing insects. We collected insect galls on F. microcarpa in Magong island, Baisha island and Xiyu island from September 2020 to February 2021. A total of 4 gall morphotypes were newly recorded in the islands. These gall morphotypes were induced by Horidiplosis sp. and an unidentified gall midge (Diptera: Cecidomyiidae, 2 morphotypes), Macrohomotoma gladiata Kuwayama (Hemiptera: Carsidaridae), and Gynaikothrips sp. (Thysanoptera: Phlaeothripidae, 1 morphotype). We infer and discuss the potential taxonomic position of each gall-inducing insect based on given specimens and gall morphotypes. Gall-inducing insects on F. microcarpa in Penghu Islands might naturally disperse from neighboring regions, such as mainland China or Taiwan Island, but there is a possibility that gall-inducing insects were introduced from the southern part of Taiwan Island due to the import of nursery trees for the afforestation project in the 1910s. Further molecular work could help clarify the origin of the gall-inducing insects on F. microcarpa in Penghu Islands.