Field performance of a biodegradable cellulose nanofiber hydrogel bait containing pyriprole for control of the Argentine ant, Linepithema humile (Hymenoptera: Formicidae)
摘要
The Argentine ant, Linepithema humile (Mayr) (Hymenoptera: Formicidae), is a globally invasive species that forms dense supercolonies and remains difficult to control, especially in complex environments, such as riverbanks and urban facilities. Hydrogel baits have emerged as cost-effective resources for managing invasive ants; however, most formulations depend on synthetic polymers. This study assessed the field efficacy of a biodegradable hydrogel bait composed of cellulose nanofiber (microfibrillated cellulose) with pyriprole as the active ingredient. Field trials were conducted at riverbank habitats and around urban facilities in Japan. At riverbank sites, area-wide application of hydrogel bait at 15 g/m2 reduced mean trap catches to < 1% of pretreatment levels within 2 weeks, including in a plot lacking vegetation removal, demonstrating rapid, high-level suppression. At urban sites, hydrogel bait was applied mainly along linear perimeters with a liquid formulation, suppressing seasonal population increases relative to untreated controls. Unlike riverbank sites, monitoring at urban locations occurred at approximately 1-month intervals between successive hydrogel treatments. These differences in application strategy and monitoring frequency likely influenced the observed temporal suppression patterns. Overall, these findings indicate that a cellulose nanofiber-based biodegradable hydrogel bait can effectively suppress L. humile under field conditions and offers a practical, environmentally compatible option for management in sensitive or operationally challenging habitats.