DOI: 10.5061/dryad.dv41ns243
title: Global flows of insect transport and establishment: the role of biogeography, trade, and regulations

description: Aim: Non-native species are part of almost every biological community
 worldwide, yet numbers of species establishments have an uneven global
 distribution. Asymmetrical exchanges of species between regions are likely
 influenced by a range of mechanisms, including propagule pressure, native
 species pools, environmental conditions, and biosecurity. While the
 importance of different mechanisms is likely to vary among invasion
 stages, those occurring prior to establishment are difficult to account
 for. We used records of unintentional insect introductions to test 1)
 whether insects from some biogeographic regions are more likely to be
 successful invaders, 2) whether the intensity of trade flows between
 regions determines how many species are intercepted and how many
 successfully establish, and 3) whether the variables driving invasion
 success differ pre- and post-introduction. Location: Canada, mainland USA,
 Hawaii, Japan, Australia, New Zealand, Great Britain, South Korea, South
 Africa. Methods: To disentangle processes occurring during the transport
 and establishment stages, we analysed border interceptions of 8,199 insect
 species as a proxy for transported species flows, and lists of 2,076
 established non-native insect species in eight areas. Results: During
 transport, the largest species flows generally originated from the
 Nearctic, Panamanian and Neotropical regions. Insects native to eight of
 twelve biogeographic regions were able to establish, with the largest
 flows of established species on average coming from the Western
 Palearctic, Neotropical, and Australasian/Oceanian regions. Both the
 biogeographic region of origin and trade intensity significantly
 influenced the size of species flows between regions during transport and
 establishment. The transported species richness increased with Gross
 National Income in the source country and decreased with geographic
 distance. More species were able to establish when introduced within their
 native biogeographic region. Main conclusions: Our results suggest that
 accounting for processes occurring prior to establishment is crucial for
 understanding invasion asymmetry in insects, and quantifying regional
 biosecurity risks.
description: # Global flows of insect transport and establishment This repository
 contains all the necessary files to carry out the analyses in ?Global
 flows of insect transport and establishment: the role of biogeography,
 trade, and regulations?. The code is available in the ?flows\_script? R
 script. ## The data uploaded are: transport\_flows\_updated.csv - the
 number of insect species ("richness") intercepted during border
 inspections per unique combination of source country, destination,
 associated commodity class and decade intercepted. The variables in this
 file are: * source: the ISO3 code of the source country * years: the
 decade of port interception * destination: the area of interception *
 class: identity of 14 broad commodity classes insects were associated with
 during transport * flow: the source and destination pair * region: the
 biogeographic region of origin (errors corrected 31.10.23) * richness: the
 number of intercepted species * clim\_dist: the climatic dissimilarity
 between the source and destination, from 0 (no dissimilarity) to 1
 (complete dissimilarity) * geo\_dist: the geographic distance between the
 source and destination centroids (km) * NIT: the number of treaties,
 legislation and regulations relating to IAS that the source country
 adheres to * NIT\_dest: the number of treaties, legislation and
 regulations relating to IAS that the destination country adheres to *
 intra\_inter: whether species are transported within the same
 biogeographic region (intra) or not (inter) * area: the land area of the
 source country in square km * GDP: the Gross National Product of the
 source country * log\_value\_usd: the commodity import value in US dollars
 per flow * log\_insect\_estimate\_ants: the estimated size of the native
 insect pool in the source country, based on ant diversity * log\_GNI: the
 Gross National Income of the source country * plant\_richnes: the size of
 the native vascular plant species pool in the source country
 establishment\_flows.csv - the number of insect species
 ("richness") established in the destination area, per unique
 combination of native biogeographic region, destination, and estimated
 decade established. The variables in this file are: *
 country\_established: the area where insect species have established *
 native\_region: the biogeographic region where the insect species are
 native to * years: the decade of establishment first record * richness:
 the number of established insect species per flow * intra\_inter: whether
 species have established within the same biogeographic region (intra) or
 not (inter) * NIT\_dest: the number of treaties, legislation and
 regulations relating to IAS that the destination country adheres to *
 log\_plant\_trade: the log value of plant products imported per flow in US
 $ * wood\_trade: the value of wood products imported per flow *
 agri\_trade: the value of agricultural commodities imported per flow *
 total\_trade: the total value of commodity imports per flow *
 plant\_trade\_prev\_decade: the value of plant products imported in the
 decade prior to insects establishing * wood\_trade\_prev\_decade: the
 value of wood products imported in the decade prior to insects
 establishing * agri\_trade\_prev\_decade: the value of agricultural
 commodities imported in the decade prior to insects establishing *
 total\_trade\_prev\_decade: the value of total commodity imports in the
 decade prior to insects establishing