A new species of the genus Megischus Brullé, 1846, Megischus kuafu Ge & Tan, sp. nov., is described and illustrated from Guizhou Province, China. The key to all four species from China is included. A distribution map of the Chinese species is added.

The taxonomic status of the Pieris napi-complex and similar species which occur in China are revised. Relevant species distributed in the adjacent regions were included to clarify the status of Chinese species and were briefly revised. All those species are described and illustrated and new synonyms are established. A molecular phylogenetic analysis is also performed on the species group including similar species, to investigate the phylogenetic relationships between taxa. Species of the Pieris napi-complex that occur in China and adjacent regions are redefined, with four similar species excluded (P. melaina, P. extensa, P. chumbiensis gyantsensis and P. melete). A distribution map and keys of the complex including similar species are provided. The taxon P. mihon Yakovlev, 2006 stat. nov. is raised from subspecies to species status; P. narina Verity, 1908 stat. rev. is confirmed as a distinct species rather than a subspecies of P. ochsenheimeri; Pieris euorientis Verity, 1908 stat. rev. is recovered as a distinct species sister to P. dulcinea. Two taxa, ssp. sauron and ssp. bryonides are moved from subspecies of P. euorientis and P. bryoniae, respectively, to P. napi, i.e. P. napi sauron Yakovlev, 2004 comb. nov and P. napi bryonides Sheljuzhko, 1910 comb. rev. A new synonym is proposed: Pieris ochsenheimeri tianshansis Tadokoro, Shinkawa & Wang, 2014, new synonym of P. mihon Yakovlev, 2006. A new mistaken identification is proposed: Pieris dulcinea kneitzi is a misidentification of Pieris erutae kneitzi Eitschberger, 1983 comb. rev. Five Chinese species belonging to the Pieris napi-complex were confirmed, namely P. narina, P. mihon, P. latouchei, P. dulcinea, and P. erutae. Among them, two species, P. mihon Yakovlev, 2006 and Pieris narina Verity, 1908, are newly recorded from China. The taxonomic status of Pieris steinigeri Eitschberger, 1983 and Pieris bryoniae sifanica Grum-Grshimailo, 1895 is also discussed.

Adaptation to host plants is of great significance in the ecology of xylophagous insects. The specific adaptation to woody tissues is made possible through microbial symbionts. We investigated the potential roles of detoxification, lignocellulose degradation, and nutrient supplementation of Monochamus saltuarius and its gut symbionts in host plant adaptation using metatranscriptome. The gut microbial community structure of M. saltuarius that fed on the two plant species were found to be different. Plant compound detoxification and lignocellulose degradation genes have been identified in both beetles and gut symbionts. Most differentially expressed genes associated with host plant adaptations were up-regulated in larvae fed on the less suitable host (Pinus tabuliformis) compared to larvae fed on the suitable host (Pinus koraiensis). Our findings indicated that M. saltuarius and its gut microbes respond to plant secondary substances through systematic transcriptome responses, allowing them to adapt to unsuitable host plants.

Foenatopus meridionalis Ge & Tan, sp. nov., as the first species of the genus Foenatopus Smith, 1861 discovered from southern Vietnam, is reported and illustrated in detail. The key to the species of Foenatopus from Vietnam is compiled. A distribution map of the Vietnamese species is provided.

The first discovery of the genus Megischus Brullé, 1846 (Hymenoptera: Stephanidae) from Ryukyu Islands is reported and Megischus baogong Ge & Tan, sp. nov., is described and illustrated.