Correlation between rearing temperature and the dual cellulolytic system of Coptotermes formosanus Shiraki and its intestinal microenvironment

The lower termite, Coptotermes formosanus Shiraki, is an important model species for studying the dual cellulolytic system of termites. The effect of rearing temperature on the interaction between the intestinal symbiont community and the host in lignocelluloses digestion was investigated by assaying the activity and gene expression of cellulase, and monitoring the population size of intestinal protozoan community, which was followed by rearing C. formosanus at a temperature gradient (15-37 degrees C) for 3 d. The results showed that the rearing temperature of C. formosanus had a much greater impact on cellulase activity and gene transcription of the intestinal symbiont than on the host. The transcriptional variations of endogenous and symbiotic cellulase genes presented mutual complement and restrained when C. formosanus living in high temperature environment (32 and 37 degrees C). Additionally, the optimum survival temperature of Pseudotrichonympha grassii Koidzumi (22 degrees C) was found lower than that of Holomastigotoides mirabile Koidzumi (28 degrees C) and Spirotrichonympha leidyi Koidzumi (28 degrees C).The optimum rearing temperature for cellulase activity and protozoan survival of C formosanus was found much lower than its optimum temperature for feeding. These findings provide a novel glimpse into host-symbiotic mutualism in lower termite digestion. (C) 2016 Korean Society of Applied Entomology, Taiwan Entomological Society and Malaysian Plant Protection Society. Published by Elsevier B.V. All rights reserved.