DOI: 10.5061/dryad.vmcvdnctz
title: Tube locations of the red imported fire ant (RIFA)

description: Solenopsis invicta Buren, also known as the red imported fire ant (RIFA),
 has had a large negative impact on human and livestock health. However,
 few studies have further investigated the influence of human land use,
 which is an important factor affecting the habitats of insects, on the
 expansion of RIFAs. In addition, there is a lack of knowledge of the
 empirical associations between RIFA diffusion and land use within
 countries. Therefore, the objectives of this study were to provide an
 approach to delineate the areas of RIFA infestations and explore how
 land-use influences the spatiotemporal diffusion of S. invicta. We used
 RIFA data from 2008 to 2015 from the RIFA surveillance system, which was
 conducted by the National RIFA Control Center in Taiwan. Two regions in
 Taiwan with different RIFA infestation levels were investigated. The
 ordinary kriging method was applied to show the spatial intensity of RIFAs
 and the extreme distance estimator method was applied to determine the
 critical dispersal distances which showed the distance of the highest
 probability of RIFAs in two consecutive years. In addition, network
 analyses were used to identify RIFA invasion routes between land-use
 types. Finally, bivariate local indicators of spatial association were
 used to capture the invasion process in time and space. The results showed
 paddy fields, main roads, and warehouses were identified as the top three
 land-use types of diffusion sources. On average, the critical RIFA
 dispersal distances were 600 and 650 m in two consecutive years in high-
 and low-infestation regions, respectively. Finally, RIFAs were likely to
 diffuse between main roads and warehouses in the low-infestation region.
 Therefore, it is suggested that RIFA control activities be implemented at
 least 600 m from the observed spot. Additionally, control activities
 should be conducted on the identified three land-use types of diffusion
 sources in the high-infestation region, and the roadsides between main
 roads and warehouses in the low-infestation region to prevent the
 accidental spread of RIFAs.
description: The RIFA data were obtained from the <i>S.
 invicta</i> surveillance system, which was conducted by the National
 RIFA Control Center in Taiwan. The system included coordinates of sample
 tubes, collection date, and presence or absence of <i>S.
 invicta</i> in tubes. The sample tube (12 cm long × 1.5 cm radius)
 was a RIFA trap. The
 tube contained a piece of potato chip on the top (Bao,
 Kafle, & Shih, 2011). Potato chips are a common method used for
 monitoring and detecting RIFAs (Bao et al., 2011; Lin et al., 2011;
 Stringer et al., 2011; Vogt, Smith, Grantham, & Wright, 2003; Yang
 et al., 2009), and they are a frequent method used in Taiwan for RIFA
 sampling (Lin et al., 2011; Yang et al., 2009).
description: Each record stands for a location of a positive sample tube.
 There is no missing data. All of the sample tubes were systematically
 placed across the study areas except in mountain areas. In Taoyuan, one
 tube was placed per 200 × 200 m<sup>2</sup> in 2008. In 2009,
 based on the 2008 RIFA data, the tube densities were adjusted to one tube
 per 100 × 100 m<sup>2</sup> in highly invaded areas and one
 tube per 200 × 200 m<sup>2</sup> was used in the remaining
 areas. In 2010, Taoyuan was further divided into the high-, middle- and
 low-invasion areas (one tube per 100 × 100 m<sup>2</sup>, one
 tube per 200 × 200 m<sup>2</sup>, and one tube per 600 × 600
 m<sup>2</sup>, respectively). The tube density was reset to
 one tube per 200 × 200 m<sup>2 </sup>in 2011. In Hsinchu, the
 sample density was uniform, with one tube per 200 × 200
 m<sup>2</sup> in each year during the study period of
 2012–2015. The column names of X and Y standards for coordinates of X and
 Y (CRS: TWD97-TM2).  The column names of label_C1 and label_C3 represent
 the types of land use.