4. Monitoring and Control Fig. 6 Different worker abundance levels of W. auropunctata attracted to the potato chip, from left to right, are abundance scores 1 to 4. C.C. LEE et al. the abundance and distribution of this invasive species, ultimately delaying time-sensitive control actions. Since both W. auropunctata and Solenopsis invicta (red imported fire ant) exhibit relatively similar feeding habits, the standard operating procedure used for monitoring the red imported fire ant in Taiwan (i.e., using potato chips as a food lure; Bao et al., 2011) is being applied to delineate the boundaries of infested areas and monitor the abundance of W. auropunctata as well in this region (Hsu et al., 2022; Lee et al., 2021). Potato chips (original flavor, Pringles®, USA) were placed on the ground in the survey locations, usually every 50 m alongside the roads (i.e., a piece of potato chip at each sampling point). To quantify the worker abundance of W. auropunctata, we measured ant activity by counting the number of foraging workers on the top side of the potato chips 30 minutes after deployment. To facilitate the counting process, the top side of each potato chip was photographed using a digital camera. In the laboratory, worker abundance at each potato chip was counted using the digital images and then scored according to the following categories: 1 = 1–5 ants; 2 = 6–50 ants; 3 = 51–200 ants; 4 = > 200 ants (Fig. 6). To successfully detect an incipient infestation or quantify ant activity when W. auropunctata is at low abundance, field workers may also need to pay attention to the presence of W. auropunctata workers on the underside of the potato chips as well. Compared with conventional methods, potato chips are easier to use and deploy without the need to smear peanut butter on a bait stick. Additionally, unlike a bait stick, it is more feasible to count ants on a potato chip using single digital image due to its flat surface. 4.2 Chemical Control Previously, organochlorine pesticides such as DDT, Aldrin and Chlordane were widely used to control W. auropunctata through contact sprays (Abedrabbo, 1994; Fernald, 1947; Osburn, 1949). These organochlorine pesticides were later banned due to their high toxicity to living organisms and high persistence in the environment. impacts and environmental Apart contamination, contact pesticides primarily killed foraging workers only and not the intra-nidal colony members or queens (Montgomery et al., 2022). Thus, a much safer and more effective method, i.e., ant baiting, has been widely adopted to manage this invasive species from non-target Displacement of native ant species and other arthropods is well documented in the regions where W. auropunctata has been introduced (Clark et al., 1982; Le Breton et al., 2003; Lubin, 1984; Vonshak et al., 2010). Since it is still considered a relatively recent introduction in Taiwan (less than 5 years), further ecological studies are needed to assess the true impacts of W. auropunctata on insect biodiversity in this region. Nevertheless, W. auropunctata workers have frequently been observed being highly aggressive toward native ant species in the Wuri and Heping Districts, displaying behaviors such as biting interference competition) (Fig. 5b). In addition, insect carcasses have commonly been found inside the nests of W. auropunctata, further highlighting the ecological threats this invasive ant species poses to insect communities. stinging opponents and As with other ant species, food lures have been the primary tool used for detecting the presence of W. auropunctata or monitoring its population dynamics, allowing control centers and personnel to verify whether management programs are successful. Studies have shown that to W. auropunctata (Montgomery et al., 2020; Williams & Whelan, 1992). Hence, lipid-rich foods or protein-rich foods such as peanut butter, hotdogs, or soybean oil, are often used as food lures during ecological studies to attract the foraging W. auropunctata ants (Montgomery et al., 2022). For example, on the Galapagos Islands and in Israel, wooden sticks smeared with peanut butter were placed on the ground for at least one hour, after which they were checked for W. auropunctata (Causton et al., 2005; Vonshak et al., 2010). Montgomery et al. (2020) demonstrated that foraging ants of W. auropunctata were less attracted to carbohydrate-rich and protein-rich foods compared to lipid-rich lures under field conditions. It is worth mentioning that the use of less attractive or suboptimal food lures might lead to an underestimation of lipid-rich foods are highly attractive (i.e., 154 (Fig. 5a). Since high population levels of homopterans are known to cause sooty mold growth, which subsequently inhibits the photosynthetic activity of crop trees, there is a risk of reduced crop yield and quality (Farsi et al., 2013; Montgomery et al., 2022). 4.1 Monitoring
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