Effects of recent climate change have already been detected in many species, and, in particular, in insects. The present paper reviews the key impacts of global warming on insect development and ...dispersal. The effects of climate change appear to be much more complex than a simple linear response to an average increase in temperature. They can differ between seasons and bioclimatic regions. Earlier flight periods, enhanced winter survival and acceleration of development rates are the major insect responses. Differential response of insects and hosts to warming up might also lead to disruption of their phenological synchrony, but adaptive genetic processes are likely to quickly restore this synchrony. In a number of cases, warming results in removing or relocating the barriers that limit present species' ranges. It is also likely to facilitate the establishment and spread of invasive alien species. Finally, knowledge gaps are identified and future research interests are suggested.
Although research on human-mediated exchanges of species has substantially intensified during the last centuries, we know surprisingly little about temporal dynamics of alien species accumulations ...across regions and taxa. Using a novel database of 45,813 first records of 16,926 established alien species, we show that the annual rate of first records worldwide has increased during the last 200 years, with 37% of all first records reported most recently (1970-2014). Inter-continental and inter-taxonomic variation can be largely attributed to the diaspora of European settlers in the nineteenth century and to the acceleration in trade in the twentieth century. For all taxonomic groups, the increase in numbers of alien species does not show any sign of saturation and most taxa even show increases in the rate of first records over time. This highlights that past efforts to mitigate invasions have not been effective enough to keep up with increasing globalization.
Our ability to predict the identity of future invasive alien species is largely based upon knowledge of prior invasion history. Emerging alien species—those never encountered as aliens ...before—therefore pose a significant challenge to biosecurity interventions worldwide. Understanding their temporal trends, origins, and the drivers of their spread is pivotal to improving prevention and risk assessment tools. Here, we use a database of 45,984 first records of 16,019 established alien species to investigate the temporal dynamics of occurrences of emerging alien species worldwide. Even after many centuries of invasions the rate of emergence of new alien species is still high: One-quarter of first records during 2000–2005 were of species that had not been previously recorded anywhere as alien, though with large variation across taxa. Model results show that the high proportion of emerging alien species cannot be solely explained by increases in well-known drivers such as the amount of imported commodities from historically important source regions. Instead, these dynamics reflect the incorporation of new regions into the pool of potential alien species, likely as a consequence of expanding trade networks and environmental change. This process compensates for the depletion of the historically important source species pool through successive invasions. We estimate that 1–16% of all species on Earth, depending on the taxonomic group, qualify as potential alien species. These results suggest that there remains a high proportion of emerging alien species we have yet to encounter, with future impacts that are difficult to predict.
Recent comprehensive data provided through the DAISIE project (www.europe-aliens.org) have facilitated the development of the first pan-European assessment of the impacts of alien plants, ...vertebrates, and invertebrates — in terrestrial, freshwater, and marine environments — on ecosystem services. There are 1094 species with documented ecological impacts and 1347 with economic impacts. The two taxonomic groups with the most species causing impacts are terrestrial invertebrates and terrestrial plants. The North Sea is the maritime region that suffers the most impacts. Across taxa and regions, ecological and economic impacts are highly correlated. Terrestrial invertebrates create greater economic impacts than ecological impacts, while the reverse is true for terrestrial plants. Alien species from all taxonomic groups affect "supporting", "provisioning", "regulating", and "cultural" services and interfere with human well-being. Terrestrial vertebrates are responsible for the greatest range of impacts, and these are widely distributed across Europe. Here, we present a review of the financial costs, as the first step toward calculating an estimate of the economic consequences of alien species in Europe.
The advent of simple and affordable tools for molecular identification of novel insect invaders and assessment of population diversity has changed the face of invasion biology in recent years. The ...widespread application of these tools has brought with it an emerging understanding that patterns in biogeography, introduction history and subsequent movement and spread of many invasive alien insects are far more complex than previously thought. We reviewed the literature and found that for a number of invasive insects, there is strong and growing evidence that multiple introductions, complex global movement, and population admixture in the invaded range are commonplace. Additionally, historical paradigms related to species and strain identities and origins of common invaders are in many cases being challenged. This has major consequences for our understanding of basic biology and ecology of invasive insects and impacts quarantine, management and biocontrol programs. In addition, we found that founder effects rarely limit fitness in invasive insects and may benefit populations (by purging harmful alleles or increasing additive genetic variance). Also, while phenotypic plasticity appears important post-establishment, genetic diversity in invasive insects is often higher than expected and increases over time via multiple introductions. Further, connectivity among disjunct regions of global invasive ranges is generally far higher than expected and is often asymmetric, with some populations contributing disproportionately to global spread. We argue that the role of connectivity in driving the ecology and evolution of introduced species with multiple invasive ranges has been historically underestimated and that such species are often best understood in a global context.
The accelerating rates of international trade, travel, and transport in the latter half of the twentieth century have led to the progressive mixing of biota from across the world and the number of ...species introduced to new regions continues to increase. The importance of biogeographic, climatic, economic, and demographic factors as drivers of this trend is increasingly being realized but as yet there is no consensus regarding their relative importance. Whereas little may be done to mitigate the effects of geography and climate on invasions, a wider range of options may exist to moderate the impacts of economic and demographic drivers. Here we use the most recent data available from Europe to partition between macroecological, economic, and demographic variables the variation in alien species richness of bryophytes, fungi, vascular plants, terrestrial insects, aquatic invertebrates, fish, amphibians, reptiles, birds, and mammals. Only national wealth and human population density were statistically significant predictors in the majority of models when analyzed jointly with climate, geography, and land cover. The economic and demographic variables reflect the intensity of human activities and integrate the effect of factors that directly determine the outcome of invasion such as propagule pressure, pathways of introduction, eutrophication, and the intensity of anthropogenic disturbance. The strong influence of economic and demographic variables on the levels of invasion by alien species demonstrates that future solutions to the problem of biological invasions at a national scale lie in mitigating the negative environmental consequences of human activities that generate wealth and by promoting more sustainable population growth.
Socioeconomic legacy yields an invasion debt Essl, Franz; Dullinger, Stefan; Rabitsch, Wolfgang ...
Proceedings of the National Academy of Sciences - PNAS,
01/2011, Volume:
108, Issue:
1
Journal Article
Peer reviewed
Open access
Globalization and economic growth are widely recognized as important drivers of biological invasions. Consequently, there is an increasing need for governments to address the role of international ...trade in their strategies to prevent species introductions. However, many of the most problematic alien species are not recent arrivals but were introduced several decades ago. Hence, current patterns of alien-species richness may better reflect historical rather than contemporary human activities, a phenomenon which might be called "invasion debt." Here, we show that across 10 taxonomic groups (vascular plants, bryophytes, fungi, birds, mammals, reptiles, amphibians, fish, terrestrial insects, and aquatic invertebrates) in 28 European countries, current numbers of alien species established in the wild are indeed more closely related to indicators of socioeconomic activity from the year 1900 than to those from 2000, although the majority of species introductions occurred during the second half of the 20th century. The strength of the historical signal varies among taxonomic groups, with those possessing good capabilities for dispersal (birds, insects) more strongly associated with recent socioeconomic drivers. Nevertheless, our results suggest a considerable historical legacy for the majority of the taxa analyzed. The consequences of the current high levels of socioeconomic activity on the extent of biological invasions will thus probably not be completely realized until several decades into the future.
Global warming is predicted to cause distributional changes in organisms whose geographic ranges are controlled by temperature. We report a recent latitudinal and altitudinal expansion of the pine ...processionary moth, Thaumetopoea pityocampa, whose larvae build silk nests and feed on pine foliage in the winter. In north-central France (Paris Basin), its range boundary has shifted by 87 km northwards between 1972 and 2004; in northern Italy (Alps), an altitudinal shift of 110-230 m upwards occurred between 1975 and 2004. By experimentally linking winter temperature, feeding activity, and survival of T. pityocampa larvae, we attribute the expansions to increased winter survival due to a warming trend over the past three decades. In the laboratory we determined the minimum nest and night air temperatures required for larval feeding and developed a mechanistic model based on these temperature thresholds. We tested the model in a translocation experiment that employed natural temperature gradients as spatial analogues for global warming. In all transects we transferred colonies of T. pityocampa larvae to sites within zones of historical distribution, recent distribution, and outside the present range. We monitored air and nest temperature, incoming solar radiation, larval phenology, feeding activity, and survival. Early-season temperature effects on phenology were evident, with delayed development of colonies in the more extreme (colder) sites. In the coldest months, our model was consistent with the observed patterns of feeding activity: Feeding was progressively reduced with increasing latitude or elevation, as predicted by the lower number of hours when the feeding threshold was reached, which negatively affected final survival. Insolation raised nest temperature and increased feeding activity on the south but not the north aspect. Prolonged temperature drops below the feeding thresholds occurred at all sites, leading to starvation and partial mortality. Nonetheless, even the most extreme sites still allowed some feeding and, consequently, up to 20% colony survival and successful pupation. Given that the present distribution of the oligophagous T. pityocampa is not constrained by the disribution of its actual or potential hosts, and that warmer winters will cause the number of hours of feeding to increase and the probability of the lower lethal temperature to decrease, we expect the trend of improved survival in previously prohibitive environments to continue, causing further latitudinal and altitudinal expansion. This work highlights the need to develop temperature-based predictive models for future range shifts of winter-limited species, with potential applications in management.
The international seed trade is considered relatively safe from a phytosanitary point of view and is therefore less regulated than trade in other plants for planting. However, the pests carried by ...traded seeds are not well known. We assessed insects and fungi in 58 traded seed lots of 11 gymnosperm and angiosperm tree species from North America, Europe, and Asia. Insects were detected by X-raying and molecular methods. The fungal community was characterized using high-throughput sequencing (HTS) and by growing fungi on non-selective agar. About 30% of the seed lots contained insect larvae. Gymnosperms contained mostly hymenopteran (Megastigmus spp.) and dipteran (Cecidomyiidae) larvae, while angiosperms contained lepidopteran (Cydia latiferreana) and coleopteran (Curculio spp.) larvae. HTS indicated the presence of fungi in all seed lots and fungi grew on non-selective agar from 96% of the seed lots. Fungal abundance and diversity were much higher than insect diversity and abundance, especially in angiosperm seeds. Almost 50% of all fungal exact sequence variants (ESVs) found in angiosperms were potential pathogens, in comparison with around 30% of potentially pathogenic ESVs found in gymnosperms. The results of this study indicate that seeds may pose a greater risk of pest introduction than previously believed or accounted for. A rapid risk assessment suggests that only a small number of species identified in this study is of phytosanitary concern. However, more research is needed to enable better risk assessment, especially to increase knowledge about the potential for transmission of fungi to seedlings and the host range and impact of identified species.
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