Mr Jinyeong Choi1, Mr Pradeep Palanichamy1, Ms Yumiko Masukagami1, Mr Filip Husnik1

1Okinawa Institute of Science and Technology Graduate School, 1919-1 Tancha, Onna, Kunigami District, Okinawa, Japan

Biography:

Jinyeong Choi is a postdoctoral researcher in the Evolution, Cell Biology and Symbiosis Unit, at OIST. He is interested in insect-beneficial microbial symbionts to understand how microbes contribute to the adaptation and diversification of insects. Currently, He is focusing on plant-feeding insects and their nutritional symbionts with genomics, phylogenetic and microscopic approaches.

Abstract:

Species diversification of scale insects (>8,500 species) is largely explained by their host shifts to angiosperms when these flowing plants underwent massive radiation. This niche expansion of plant-feeding insects is highly associated with the acquisition of microbial symbionts that supplement deficient nutrients in plant sap. However, the evolution of scale insects with their endosymbiotic microorganisms has not been studied systematically within a phylogenetic framework. How are diverse endosymbionts associated across different scale insect clades? When were these microbial symbioses established, and how have they shaped the diversification of scale insects? In this study, we metagenome-sequenced 120 species of scale insects to obtain genetic information from both hosts and endosymbionts. Using these genome-scale data, we identified their microbial endosymbionts and reconstructed a time-estimated phylogenomic tree of scale insects. Additionally, we employed micro-CT scanning, fluorescent in situ hybridization (FISH), and transmission electron microscopy (TEM) to examine the localization of endosymbiotic microbes within the host insects. We found that the major strains of core obligate endosymbionts across scale insect lineages belong to the bacterial classes Flavobacteriia, Betaproteobacteria and Gammaproteobacteria, as well as the fungus Ascomycota. These microbial endosymbioses are estimated to have originated before or during the angiosperm radiation, coinciding with the lineage diversification of scale insects. Furthermore, we confirmed that the endosymbionts of scale insects are localized intracellularly or extracellularly within hosts, some of which have specialized symbiotic organs. This study provides fundamental insight into how symbiotic associations with microbes have contributed to the current high diversity of herbivorous insects.