2. Establishment and Current Distribution Fig. 1 W. auropunctata colony nesting under a stone (a), and a close-up view of an ant brood (b). Fig. 2 Map showing survey locations for the little fire ant, W. auropunctata in Taichung City, Taiwan. Red circles indicate locations with confirm, established little fire ant colonies. C.C. LEE et al. the early detection and rapid response action, we conducted surveillance to assess the extent of the little fire ant infestation in Taiwan. Based on public reports gathered from a social media platform (Facebook), where the public could share cases involving suspected sightings of W. auropunctata, a total of eight locations were selected for little fire ant surveillance (Fig. 2). These locations included two sites where W. auropunctata alates had previously been photographed. A food lure method using potato chips was adopted to detect the presence of W. auropunctata at all survey locations (see Section 4.1 below). The surveillance results indicated that W. auropunctata was confined to two locations: Wuri and Heping Districts in central Taiwan, which are separated by approximately 30 km. In Wuri District, W. auropunctata was primarily detected in semi-disturbed secondary forest and along roadsides (Fig. 3a), covering an area of approximately four hectares. On the other hand, in Heping District, W. auropunctata was primarily detected in orchards (Fig. 3b) and along street trees in the commercial district (Fig. 3c), covering an area of approximately two hectares. In both locations, nesting sites of W. auropunctata were located in tree bark, under or within dead wood, under stones or in leaf litter. In addition, genetic analyses were performed later to structure of W. auropunctata assess populations in Taiwan to infer their putative introduction source and reproduction mode (Hsu et al., 2022). Our results showed that queens from the two locations (i.e., Wuri and Heping Districts) shared a single mtDNA haplotype. Coupled with evidence from an intraspecific aggression assay (i.e., W. auropunctata workers from Wuri District behaved amicably towards workers from Heping District and vice versa), we determined that the two populations were most probably derived from a common source population, and formed a unicolonial the genetic The little fire ant, Wasmannia auropunctata, was first officially recorded in Taiwan in 2021 (Hsu et al., 2022; Lee et al., 2021). In June 2021, a citizen myrmecologist photographed female alates of W. auropunctata and posted the photos in a Facebook group. Based on the specific location provided by the citizen myrmecologist, we discovered many active ant nests in a secondary forest in Wuri District, Taichung City through visual hand searching (e.g., flipping stones, breaking open dead wood) (Fig. 1). Further searches through the Facebook group revealed the earliest photo evidence of W. auropunctata dated back to June 2019, when another citizen myrmecologist photographed female alates of W. auropunctata in Heping District, Taichung City. As part of that 152
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