Wasabi versus red imported fire ants: preliminary test of repellency of microencapsulated allyl isothiocyanate against Solenopsis invicta (Hymenoptera: Formicidae) using bait traps in Taiwan

Sea container has been identified as a major pathway for the unintended entry and spread of alien ant species. In Japan, red imported fire ants, Solenopsis invicta Buren (Hymenoptera: Formicidae), which are among the most harmful alien ants, were first detected in a shipping container from China in May 2017, and the invasion into Japan via the trade pathway is still continuing. To prevent containers contaminated with S. invicta and its establishment in Japan, control measures, such as repellents, are urgently required. The present study is the first to evaluate repellency of microencapsulated allyl isothiocyanate (AITC) against S. invicta, as a preliminary step to use the innovative equipment for invasive species management in sea containers. In a field in Taiwan heavily infested with S. invicta, a repellent test of microencapsulated AITC using bait traps showed that the equipment completely prevents S. invicta from accessing the bait. Due to its volatility and irritancy, AITC, a safe natural repellant in wasabi (Eutrema japonicum (Miq.) Kiudz), has not been used for pest management in containerized cargo. However, the encapsulation of AITC solves this problem by allowing controlled vapor release. Microencapsulated AITC has considerable potential as an effective measure to stop the spread of S. invicta through global trade.