Diversity, Biology, and Nutritional Adaptation of Psyllids and their Galls in Taiwan

Summary

Psyllids, or jumping plant lice, are a group of sternorrhynchous Hemiptera. They are highly host specific sucking insects, and many of them form galls. In Taiwan, a revision and some supplemental works of psyllid taxonomy were done in the 1980s. In these publications, 18 species of psyllids were noted as being gall formers. Our survey, as of 1996 found a total of 98 types/species of psyllid galls, and many of them are new species/records. The host range of these gall forming psyllids belongs to a wide spectrum of vascular plants, consisting of 28 families, 45 genera, and 89 species. Galls are most abundant on Lauraceae and Myrtaceae. The psyllid galls as a whole are highly diverse in both gall shape and galling position, but they are mainly species specific. Life histories and the differentiation between gall tissue of several galling psyllids on Machilus, Cinnamomum (Lauraceae) and Ficus (Moraceae) are studied and compared. In these psyllid galls, different from normal plant tissue, phloem in the vesicular bundles is oriented closer to the larval chamber than the xylem in the enclosed type of galls. The psyllid species Trioza shuiliensis which induce globular galls on the leaves of Machilus japonica var. kusanoi were used as a model system for testing the nutritional hypothesis of gall adaptation. The results of this investigation support the nutritional sink hypothesis.