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Understanding the socioeconomic drivers of biological invasion informs policy development for curtailing future invasions. While early 20th-century plant trade expansions preceded increased establishments of plant pests in Northern America, increased establishments did not follow accelerating imports later that century. To explore this puzzle, we estimate the historical establishment of plant-feeding Hemiptera in Northern America as a function of historical U.S. imports of live plants from seven world regions. Delays between establishment and discovery are modeled using a previously unused proxy for dynamic discovery effort. By recovering the timing of pest arrivals from their historical discoveries, we disentangle the joint establishment-discovery process. We estimate long delays to discovery, which are partially attributable to the low detectability of less economically important insect species. We estimate that many introduced species remain undiscovered, ranging from around one-fifth for Eurasian regions to two-fifths for Central and South America.

Unprecedented rates of introduction and spread of non-native species pose burgeoning challenges to biodiversity, natural resource management, regional economies, and human health. Current biosecurity efforts are failing to keep pace with globalization, revealing critical gaps in our understanding and response to invasions. Here, we identify four priority areas to advance invasion science in the face of rapid global environmental change. First, invasion science should strive to develop a more comprehensive framework for predicting how the behavior, abundance, and interspecific interactions of non-native species vary in relation to conditions in receiving environments and how these factors govern the ecological impacts of invasion. A second priority is to understand the potential synergistic effects of multiple co-occurring stressors-particularly involving climate change--on the establishment and impact of non-native species. Climate adaptation and mitigation strategies will need to consider the possible consequences of promoting non-native species, and appropriate management responses to non-native species will need to be developed. The third priority is to address the taxonomic impediment. The ability to detect and evaluate invasion risks is compromised by a growing deficit in taxonomic expertise, which cannot be adequately compensated by new molecular technologies alone. Management of biosecurity risks will become increasingly challenging unless academia, industry, and governments train and employ new personnel in taxonomy and systematics. Fourth, we recommend that internationally cooperative biosecurity strategies consider the bridgehead effects of global dispersal networks, in which organisms tend to invade new regions from locations where they have already established. Cooperation among countries to eradicate or control species established in bridgehead regions should yield greater benefit than independent attempts by individual countries to exclude these species from arriving and establishing. Key words: biosecurity, climate change, ecological impact, invasive species, management, risk assessment. Les taux sans precedent d'introduction et de propagation d'especes non indigenes posent des defis croissants a la biodiversite, a la gestion des ressources naturelles, aux economies regionales et a la sante humaine. Les efforts actuels en matiere de biosecurite ne parviennent pas a suivre le rythme de la mondialisation, revelant des lacunes critiques dans notre comprehension et notre reponse face aux invasions. Les auteurs identifient ici quatre domaines prioritaires permettant de faire progresser la science des invasions face aux changements environnementaux mondiaux rapides. Premierement, la science des invasions devrait s'efforcer de developper un cadre plus complet pour predire comment le comportement, l'abondance et les interactions interspecifiques des especes non indigenes varient en fonction des conditions des environnements recepteurs et comment ces facteurs regissent les impacts ecologiques des invasions. Une deuxieme priorite consiste a comprendre les effets synergiques potentiels de multiples facteurs de stress concomitants--notamment les changements climatiques--sur l'etablissement et l'impact des especes non indigenes. Les strategies d'adaptation au climat et d'attenuation devront tenir compte des consequences possibles de la promotion des especes non indigenes, et des reponses de gestion appropriees aux especes non indigenes devront etre elaborees. La troisieme priorite est de s'attaquer a l'obstacle taxonomique. La capacite a detecter et a evaluer les risques d'invasion est compromise par un deficit croissant de competences taxonomiques, qui ne peut etre compense de maniere adequate par les nouvelles technologies moleculaires seules. La gestion des risques de biosecurite deviendra de plus en plus difficile a moins que les universites, l'industrie et les gouvernements forment et emploient du nouveau personnel dans les domaines de la taxonomie et de la systematique. Quatriemement, nous recommandons que les strategies de cooperation internationale en matiere de biosecurite tiennent compte des effets de tete de pont des reseaux de dispersion mondiaux, dans lesquels des organismes ont tendance a envahir de nouvelles regions a partir d'endroits ou ils sont deja etablis. La cooperation entre les pays pour eradiquer ou controler les especes etablies dans les regions de tete de pont devrait donner de meilleurs resultats que les tentatives independantes de chaque pays pour empecher ces especes d'arriver et de s'etablir. [Traduit par la Redaction] Mots-cles: biosecurite, changements climatiques, impact ecologique, especes envahissantes, gestion, evaluation des risques., 1. Introduction Invasion science--the systematic investigation of the causes and consequences of biological invasions--is a rapidly evolving interdisciplinary field. Its explosive growth over the past few decades mirrors societal concern [...]

Periodical cicadas live 13 or 17 years underground as nymphs, then emerge in synchrony as adults to reproduce. Developmentally synchronized populations called broods rarely coexist, with one dominant brood locally excluding those that emerge in off years. Twelve modern 17-year cicada broods are believed to have descended from only three ancestral broods following the last glaciation. The mechanisms by which these daughter broods overcame exclusion by the ancestral brood to synchronously emerge in a different year, however, are elusive. Here, we demonstrate that temporal variation in the population density of generalist predators can allow intermittent opportunities for new broods to invade, even though a single brood remains dominant most of the time. We show that this mechanism is consistent, in terms of the type and frequency of brood replacements, with the distribution of periodical cicada broods throughout North America today. Although we investigate one particularly charismatic case study, the mechanisms involved (competitive exclusion, Allee effects, trait variation, predation, and temporal variability) are ubiquitous and could contribute to patterns of species diversity in a range of systems. [ABSTRACT FROM AUTHOR]