| 1. |
Takahiro Hosokawa, Takema Fukatsu, Relevance of microbial symbiosis to insect behavior, Current Opinion in Insect Science, 10.1016/j.cois.2020.03.004, 39, 91-100, 2020.06, Microbial symbiosis is widespread among insects. This article reviews our understanding of insect behaviors relevant to commensalistic and mutualistic microbial symbiosis, which has received relatively less attention compared to insect behaviors in parasitic symbiosis. First, we review our knowledge of symbiont transmission behaviors by which the host insects maintain associations with beneficial microorganisms over generations. Some insects that extracellularly harbor mutualistic symbionts exhibit particularly sophisticated behaviors for vertical symbiont transmission. Next, we highlight notable studies on behavioral changes induced by symbiont infection. In the last decade, a number of studies have demonstrated or suggested that mutualistic or commensalistic symbiont infections affect their host behaviors. Finally, future directions regarding these research topics are discussed.. |
| 2. |
Takahiro Hosokawa, Yoshiko Ishii, Naruo Nikoh, Manabu Fujie, Nori Satoh, Takema Fukatsu, Obligate bacterial mutualists evolving from environmental bacteria in natural insect populations, Nature Microbiology, 10.1038/nmicrobiol.2015.11, 1, 1, 2016.01, Diverse organisms are associated with obligate microbial mutualists. How such essential symbionts have originated from free-living ancestors is of evolutionary interest. Here we report that, in natural populations of the stinkbug Plautia stali, obligate bacterial mutualists are evolving from environmental bacteria. Of six distinct bacterial lineages associated with insect populations, two are uncultivable with reduced genomes, four are cultivable with non-reduced genomes, one uncultivable symbiont is fixed in temperate populations, and the other uncultivable symbiont coexists with four cultivable symbionts in subtropical populations. Symbiont elimination resulted in host mortality for all symbionts, while re-infection with any of the symbionts restored normal host growth, indicating that all the symbionts are indispensable and almost equivalent functionally. Some aseptic newborns incubated with environmental soils acquired the cultivable symbionts and normal growth was restored, identifying them as environmental Pantoea spp. Our finding uncovers an evolutionary transition from a free-living lifestyle to obligate mutualism that is currently ongoing in nature.. |
