The effect of fumigation with microencapsulated allyl isothiocyanate in a gas-barrier bag against Solenopsis invicta (Hymenoptera: Formicidae)

Red imported fire ants, Solenopsis invicta Buren (Hymenoptera: Formicidae), which are among the most harmful alien ants, were first detected in Japan in a shipping container from China in May 2017, and continue to enter Japan via this trade pathway. Fumigation is one of the most effective ways to eliminate S. invicta from goods transported in containers. The present study is the first to evaluate the effect of fumigation with allyl isothiocyanate (AITC) against S. invicta. Fumigation using microencapsulated AITC pellets in a gas-barrier bag for 24 h completely killed S. invicta. Furthermore, our fumigation system was able to maintain a high concentration of AITC vapor for at least 13 days. AITC, a naturally occurring compound in wasabi [Eutrema japonicum (Miq.) Koidz], has been demonstrated to be safe for humans and the environment, but its use as a fumigant is limited by its strong volatility and pungency. However, its encapsulation solves this problem by allowing controlled vapor release. Thus, the use of microencapsulated AITC in combination with a gas-barrier bag has considerable potential to provide an effective and easy-to-use protocol for fumigation of S. invicta.