Collaborative Response of the Host and Symbiotic Lignocellulytic System to Non-Lethal Toxic Stress in Coptotermes formosanus Skiraki

Simple SummaryCoptotermes formosanusShiraki is a wood feeding lower termite and is widely distributed in many areas. The dynamic adjustment of theC. formosanusdigestive system to unfavorable survival environments was investigated via non-lethal toxic feeding. The toxic stress did not change the dominant role of microbial lignocellulases in cellulose degradation ofC. formosanus. The core symbiotic community was stable in abundance during the tolerance to the toxic treatment. However, a large number of low abundance taxa were significantly enriched by the low toxic feeding. These rare bacterial lineages likely contribute to toxic stress tolerance of termite. Above all, these findings add important new knowledge to our understanding of environmental adaptation of the lignocellulose hydrolysis system in termites.AbstractDisturbing the lignocellulose digestive system of termites is considered to be a promising approach for termite control. The research on the tolerance mechanism of the termite lignocellulose digestive system to harmful environment conditions is limited. In this study, we keepCoptotermes formosanusSkiraki under a non-lethal toxic condition by feeding the termites with filter paper containing the kojic acid (a low toxic insecticide). The effects of low toxic stress on the activities and gene expressions of host/symbiotic originated lignocellulases, and on the symbiotic microbial community structure ofC. formosanuswere explored. Our result showed that the low toxic stress would lead to the synchronous decrease of cellulase and hemicellulase activities, and supplementary increase of corresponding gene expressions. The symbiotic community maintained its role as the main force in the lignocellulolytic system ofC. formosanus. Meanwhile, a large number of rare taxa were significantly enriched by kojic acid treatment. These numerically inconspicuous bacterial populations might be responsible for the functions similar to phenoloxidase or insecticide detoxification and enableC. formosanusto tolerate the harmful environment. Overall, our data suggested that the digestive adaptation ofC. formosanusto physiotoxic feeding is closely related to the triple collaboration of termites–flagellates–bacteria.Keywords:lignocellulolytic system;non-lethal stress;symbiont;termite;toxic tolerance