Laboratory efficacy and performance of several type of chitin synthesis inhibitors (CSIs) towards three species of subterranean termite (Blattodea:Rhinotermitidae, Termitdae)

The lower group of subterranean termites, Coptotermes gestroi (C. gestroi), and the higher groups, Globitermes sulphureus (G. sulphureus) and Macrotermes gilvus (M. gilvus), were bait treated in a no-choice laboratory bioassay using multiple active ingredients (chlorfluazuron, hexaflumuron, and bistrifluron) in Chitin Synthesis Inhibitor (CSI) baits in individual separated petri dishes. The mortality rate for each sample group was observed daily for four weeks. After one week of bait introduction, the record showed the acceleration of mortality rate in M. gilvus, followed by C. gestroi and G. sulphureus. Within four treatment weeks, C. gestroi and M. gilvus reached the complete mortality. The Tukey’s post-hoc test revealed the significant differences between the mortality rate of G. sulphureus and those of C. gestroi and M. gilvus in response to chlorfluazuron and bistrifluron (p < 0.01). No significant differences in the mortality rate were observed among these three termite species when hexaflumuron was used. Additionally, the observation of the feeding activity indicated significant differences among all species in response to hexaflumuron and bistrifluron (p < 0.01). As for the case of chlorfluazuron, the feeding activity of G. sulphureus and M. gilvus under the treatment of this substance did not show any significant difference. The correlation analysis further revealed that both the study variables were distantly related. In conclusion, the mortality rates of the three termite species tested in this study were recorded after four weeks of CSI-bait bioassay.