Transportation of nonindigenous species via soil on international aircraft passengers’ footwear

Abstract

The potential for transported soil to harbour and spread nonindigenous species (NIS) is widely recognised and many National Plant Protection Organisations (NPPOs) restrict or prohibit its movement. However, surprisingly few studies have surveyed soil while it is in transit to provide direct support for its role in accidental introductions of NIS. Moreover, there are few border interception records for soil organisms because they are neither easily detected nor routinely isolated and identified. Better data would improve evaluations of risks from soil transported via different pathways, enable targeting of management resources at the riskiest pathways, and support development of new risk management methods. We surveyed organisms present in soil that had been removed from footwear being carried in the baggage of international aircraft passengers arriving in New Zealand and recorded high incidences, counts and diversities of viable bacteria, fungi, nematodes and seeds, as well as several live arthropods. These included taxa that have not been recorded in New Zealand and were therefore almost certainly nonindigenous to this country. In each gram of soil, there was an estimated 52-84% incidence of genera that contain species regulated by New Zealand's NPPO, which suggests many were potentially harmful. Variation in the incidences and counts of soil organisms with sample weight, footwear type and season at the port of departure indicated it may be possible to develop methods for targeting management resources at the riskiest footwear. Comparisons with previously published data supported the hypothesis that survival of soil organisms is greater when they are transported in protected (e.g. in luggage) rather than unprotected environments (e.g. external surfaces of sea containers); this offers opportunities to develop methods for targeting management resources at the most hazardous soil pathways.

Oscheius tipulae in Italy: Evidence of an Alien Isolate in the Integral Natural Reserve of Montecristo Island (Tuscany)

“…Field surveys, aiming at assessing the actual presence of alien plants, were also conducted in the years 2013-14. Nomenclature is after CelestiGrapow et al (2009) and Banfi and Galasso (2010); for the additional data on the taxa, native range, introduction mode, and the invasion status terminology, we followed Blackburn et al (2011), Celesti-Grapow et al (2009, 2010a, 2010b Surviving ability to desiccation of Oscheius tipulae: As discussed in McNeill et al (2011), since the soil of footwear (in particular hiking boots) contains nonindigenous species such as nematodes, we performed an experiment to assess the risk of a possible introduction of O. tipulae through soil adherence to footwear. Laboratory experiments were conducted to investigate desiccation stress tolerance of O. tipulae collected from Montecristo soil.…”

Defining the biosecurity risk posed by transported soil: Effects of storage time and environmental exposure on survival of soil biota

“…Similarly, 11% of seeds from construction vehicle soil were viable (Hughes et al 2010) c.f. 69% in footwear soil (McNeill et al 2011). McCullough et al (2006) recorded a lower diversity of organisms from soil on cargo arriving by sea and air than from soil in luggage, and a recent study (McNeill et al unpublished) recorded generally lower incidences and counts of organisms/g of soil from sea containers compared to air passengers' footwear (McNeill et al 2011).…”

“…For example, previous research suggests soil transported by sea, which will have had relatively long transport durations, contains fewer organisms than soil transported by air: Construction vehicles shipped by sea contained 0.002 nematodes/g (Hughes et al 2010) and soil from sea containers contained 0.07 nematodes/g (Marshall and Varney 2000), while soil from air passengers' footwear contained 41 nematodes/g (McNeill et al 2011). Similarly, 11% of seeds from construction vehicle soil were viable (Hughes et al 2010) c.f.…”

“…69% in footwear soil (McNeill et al 2011). McCullough et al (2006) recorded a lower diversity of organisms from soil on cargo arriving by sea and air than from soil in luggage, and a recent study (McNeill et al unpublished) recorded generally lower incidences and counts of organisms/g of soil from sea containers compared to air passengers' footwear (McNeill et al 2011). Marshall and Varney (2000) suggested that soil organisms transported on the external surfaces of sea containers might suffer high mortality rates due to exposure to solar radiation and sea water.…”

Scientific Opinion on the Pest Risk Analysis onPhytophthora ramorumprepared by the FP6 project RAPRA

“…• the pathogen has been found on shoes and bicycles (tested, both in USA and UK, SOD 3rd Science Symposium; see also McNeill et al, 2011) • this pathway mostly concerns contamination into the EU (which has already taken place) • felling operation within hotspots or where large amount of soil is moved may require an additional certification…”