Fig. 1

Morphology, bacteriomes and symbiotic bacteria of R. dominica. a An adult feeding on a rice grain. b A teneral adult inside a rice grain (arrowhead). c An artificial nutriment piece, approximately 3 cm × 3 cm × 1 cm in size, with holes tunneled by the insects (arrowheads). d A larva (arrowhead) in a broken diet piece. e A teneral adult (arrowhead) in a broken nutriment piece. f A dissected adult insect, in which the gut-associated paired bacteriomes are highlighted (arrowheads). g-j Microscopic images of symbiotic bacteria released from dissected bacteriomes and stained with SYTOX Green. g An epifluorescence microscopic image, in which rosette-like symbiotic bacteria can be seen. h A close-up of rosettes in g. i An enlarged epifluorescence microscopic image, highlighting the thread-like structures connecting the symbiotic bacteria (arrowheads). j A differential interference microscopic image corresponding to i