# 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

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.