4.1. Insects and Bacteria

Odontotermes formosanus colonies were obtained from Nanjing Forestry University (Nanjing, China) and kept in a dark environment at 25 ± 1 °C with 75% relative humidity (RH) that was maintained in a feeding device consisted of colony and foraging areas. The larval instars and soldiers from the colonies were utilized for caste- and tissue-specific gene expression analysis. The naïve female and male dealates were collected for caste- and tissue-specific gene expression analysis. The Serratia marcescens (SM1) and the B. thuringiensis (Bt) strains were stored at −80 °C in our laboratory. For experiments, SM1 was cultured in fermentation medium for 30 h in a shaker incubator with a temperature set at 28 ℃ and a rotation set at 180 rpm. Bt was cultured with lysogen broth under the same conditions for 6 days.