Changes over time in activity patterns of Reticulitermes speratus (Blattodea: Rhinotermitidae) fed fast- or slow-acting termiticides

Abstract

This study aimed to determine the insecticidal effectiveness of commercial fast- and slow-acting termiticides against Reticulitermes speratus by observing the changes in its activity patterns over time. Both the Petri dish and planar arena methods were used to evaluate colony mortality and activity changes over time associated with each termiticide, and the evaluation methods were compared. A colony elimination pattern was observed weekly in R. speratus colonies that ingested fast- or slow-acting termiticides using the planar arena method; however, the results showed that the Petri dish method was not suitable for evaluating slow-acting termiticides with an insecticidal effect that appeared after 3 weeks or more. In the colony-level evaluation, using the planar arena method, termites that ingested fipronil bait became sublethal within 1 week and died inside the 2 m plastic tube connected to the bait feeding site. The dead termites accumulated in the plastic tube and blocked access to the bait feeding site. In contrast, termites that ingested bait treated with bistrifluron or hexaflumuron during the first 3 weeks of the experiment spread throughout the colony. Decreased colony activity and immune mechanism collapse were observed in all screens and subnests, and more than 95% of termites in the colony had died after 10 weeks.