Ethyl Formate-Based Quarantine Treatment for Exotic Ants and Termites in Imported Rubber Plants and Stone Products

Exotic ants and termites, including Solenopsis invicta, are frequent hitchhikers intercepted from miscellaneous nonfood commodities. In particular, S. invicta has been intercepted in Korea in imported nursery plants, stone, and lumber products, which increases the potential for establishment of this destructive invasive pest in Korea. In this study, we conducted commercial-scale fumigation trials to evaluate ethyl formate (EF) as a potential alternative of methyl bromide using two species of imported rubber plants and pieces of marble as representative good and workers of Reticulitermes speratus as an EF-resistant surrogate for S. invicta. An EF treatment at 35 g/m³ for 4 h at >15^◦ C, the dose required for LCt_99% (lethal concentration × time product required for 99% mortality of R. speratus), resulted in the complete control of R. speratus workers tested with rubber plants (Ficus benghalensis and F. retusa) and marble, 9% (w/v) and 60% (v/v) loading ratios, respectively. EF treatment did not adversely affect the leaf chlorophyll content, leaf color, and overall health of rubber plants or the visual appearance of the marble. Our results suggest that EF fumigation is a potential alternative to methyl bromide for the disinfestation of hitchhiking invasive termites and ants, including S. invicta, on imported rubber plants and stone products.