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Invasive Species Impact Record Card

What We Know

Invasive alien species are a severe and growing threat to insect biodiversity

  • › “Insects are crucial to ecosystem functioning but face numerous threats, with invasive alien species likely among the most severe.” (Skinner et al., 2026)
  • › “Invasive alien species reduce the abundance of insects included in our study [Hymenoptera, Coleoptera, Orthoptera, and Hemiptera] by 31%, and species richness by 26%, though these impacts are highly variable across taxa.” (Skinner et al., 2026)
  • › “Stronger negative impacts are found for invasive alien animals on average compared to invasive alien plants, and for Hemiptera (true bugs) and Hymenoptera (bees, wasps, ants) compared to Coleoptera (beetles).” (Skinner et al., 2026)
  • › “Every year, ~200 new alien species are introduced globally through human activities” (IPBES Invasive Alien Species Assessment (2024)), and the threat is expected to continue rising. (Skinner et al., 2026)
  • › “The impacts of invasive alien species are predicted to be exacerbated by climate change, as climatic conditions become more favourable for establishment and ecosystems become less resistant to biological invasion.” (IPBES, 2024; Skinner et al., 2026)

Mechanisms

How invasive alien species affect insects

Direct interactions

  • › “The negative impacts of invasive alien species occur when invasive alien species predate or parasitise native species, compete for resources, transmit pathogens and diseases, or hybridise with natives, leading to homogenisation of biota and driving global extinctions.” (IPBES (2024); Roy et al., (2024); Blackburn, Bellard & Ricciardi (2019), cited in: Skinner et al., 2026)
  • › “Invasive alien animals have stronger negative impacts on terrestrial insect abundance and species richness than invasive alien plants”, in line with findings for native pollinators by Montero-Castaño and Vilà, possibly due to more “direct competition between native insects and invasive alien animals for similar resources, compared to the more indirect effects of invasive alien plants.” (Skinner et al., 2026)

Traits that make alien species invasive

  • › “Invasive insects typically are habitat generalists with high fecundity, short lifespans, and fast development” – consistent with traits that facilitate rapid population establishment and expansion. (Zhao et al., 2023)
  • › “Invasive species have significantly more pathways of introduction, occur in more habitats, have higher fecundities, higher voltinism, and faster development from egg to adult” [than non-invasive relatives]. (Zhao et al., 2023)

Context-dependency and exceptions

  • › “The effects of invasive alien species are not always negative. For example, invasive alien plants can provide pollen and nectar to native pollinators”, and outcomes of biological invasions are highly context-dependent. (Skinner et al., 2026)
  • › “In novel ecosystems where native vegetation has been lost, alien plants might restore some ecosystem functions, whereas in natural ecosystems, invasive alien plants might out-compete and replace native species and diminish faunal communities.” (Skinner et al., 2026)

Interactive effects

  • › “Climate change is predicted to exacerbate the impacts of invasive alien species, as climatic conditions become more favourable for establishment and ecosystems become less resistant to biological invasion.” (IPBES (2024) cited in: Skinner et al., 2026)
  • › “Climate change-induced range shifts also threaten to exacerbate the threat posed by longer-distance invasives. […] Species introduced to temperate regions that may once have struggled to survive the winter […] may begin to spread rapidly as conditions begin to fall within their climatic tolerance.” (Outhwaite et al., 2024)

Consequences

For ecosystem services, natural capital, and human wellbeing

Biodiversity loss

  • › “The most substantive impacts include a 58% reduction in abundance for Hemiptera, and a 37% reduction in abundance and 46% reduction in species richness for Hymenoptera. The magnitude of these losses due to invasive alien species are comparable to estimates of the impacts of historical climate warming and intensive agricultural land use on insects.” (Skinner et al., 2026)
  • › “Losses of species richness exceeding 20% are likely to substantially impair the contribution of biodiversity to ecosystem function and services, and thus adversely affect human wellbeing.” (Skinner et al., 2026)

Ecosystem function and services

  • › “The impacts of invasive alien species on terrestrial insects have the potential to disrupt and destabilise ecosystems, potentially leading to cascading effects that could alter essential insect-driven services including pollination, pest control, decomposition, and food web stability.” (Skinner et al., 2026)
  • › “Any ecosystem changes due to the invasion-driven loss of insects could have knock-on effects on crop yields and food production, with consequences for human health.” (Klein, et al. (2007) and Rodger, et al. (2021), cited in: Skinner et al., 2026)
  • › The extent to which these declines translate into shifts or losses of ecosystem function has yet to be fully assessed. (Wagner et al. (2021), cited in: Skinner et al., 2026)

Freshwater systems

  • › “Across Europe, invasive non-native freshwater insect species have been increasing across the continent”, with non-native species richness (+3.97% per year) and abundance (+3.9% per year) at monitored sites increasing sharply. (Haubrock et al. 2023, cited in: Dicks et al., 2024; Haase et al., 2023)
  • › Urban areas are “hubs of non-native species invasions”, meaning that urbanisation compounds the freshwater biodiversity impacts from both invasive species and pollution. (Haase et al., 2023)

Mitigation Options

Action Feasibility Cost Scale Notes
Prevention and biosecurity High Low–Medium National–Global Preventing introduction is more cost-effective than management after establishment. Reducing the ~200 new alien species introduced globally per year requires improved trade and biosecurity policy. (IPBES, 2024; Skinner et al., 2026)
Early detection and rapid response Medium Medium National–Regional Monitoring for new invasions and rapid management response can prevent establishment (depends on sustained monitoring capacity)
Management and control of established invasives Medium High Local–Regional Eradication or suppression of established invasive alien species can restore native insect communities, but is costly and not always feasible at scale.
Habitat protection and restoration High Medium Local–Regional Protecting and restoring natural habitats increases ecosystem resistance to invasion and supports recovery of native insect communities. (Skinner et al., 2026)
Address interacting drivers High Medium Local–Global “Addressing insect declines will only be possible through dedicated commitment to understand, prevent, and manage biological invasions, and the interactions of invasive alien species with other drivers of biodiversity loss.” (Skinner et al., 2026)
International policy frameworks Medium Medium Global “To maximise usefulness, new indicators and metrics should be developed under the Convention on Biological Diversity, as is underway for Target 6 (Invasive Alien Species).” (CBD 2025, cited in: Bladon et al., 2026)

Evidence Gaps

  • › “The IPBES invasive alien species assessment identifies invertebrates as a critical data gap, underscoring the urgent need to mobilise data and knowledge on insects globally.” (Skinner et al., 2026)
  • › “The extent to which invasion-driven losses of insects translate into shifts or losses of ecosystem function has not yet been fully assessed.” (Skinner et al., 2026)
  • › Data are “spatially biased towards Europe and North America, reflecting known biases in biodiversity studies that are often exacerbated for insects.” (Skinner et al., 2026)
  • › “Insects have been found to be more susceptible to invasive alien species inside the tropics than outside”, yet tropical regions remain severely underrepresented in the evidence base. (Skinner et al., 2026)
  • › “Investigating whether invasive alien species have greater effects on specialists compared to generalists would be valuable”, as this would improve ability to predict which communities are most at risk. (Skinner et al., 2026)
  • › The interactions between invasive alien species and other drivers of insect decline (particularly climate change and pollution) have been recognised but not yet fully disentangled at the global scale. (Skinner et al., 2026; Outhwaite et al., 2024)

GLiTRS References

  • Bladon, A.J. et al. (2026) ‘Global Biodiversity Framework Targets Can Drive Action on Insect Declines, but Lack Robust Indicators to Prove Their Effectiveness’, Conservation Letters, 19(2), p. e70025. Available at: https://doi.org/10.1111/con4.70025.
  • Dicks, L.V. et al. (2024) ‘Insect declines – an overview of current knowledge on the status of the world’s insects’, Routledge Handbook of Insect Conservation. Routledge.
  • Haase, P. et al. (2023) ‘The recovery of European freshwater biodiversity has come to a halt’, Nature, 620(7974), pp. 582–588. Available at: https://doi.org/10.1038/s41586-023-06400-1.
  • Outhwaite, C.L. et al. (2024) ‘Pervasive and synergistic effects of climate change’, Routledge Handbook of Insect Conservation. Routledge.
  • Skinner, G.L.V. et al. (2026) ‘Meta-analysis reveals negative but highly variable impacts of invasive alien species across terrestrial insect orders’, Nature Communications, 17(1), p. 296. Available at: https://doi.org/10.1038/s41467-025-67925-9.
  • Zhao, Z. et al. (2023) ‘The world’s 100 worst invasive alien insect species differ in their characteristics from related non‑invasive species’. Available at: https://besjournals.onlinelibrary.wiley.com/doi/10.1111/1365-2664.14485 (Accessed: 14 April 2026).

Other References

  • IPBES. IPBES Invasive Alien Species Assessment: Full Report. https://zenodo.org/records/11629357 (2024).
  • Roy, H. E. et al. Curbing the major and growing threats from invasive alien species is urgent and achievable. Nat. Ecol. Evol. 8, 1216–1223 (2024).
  • Blackburn, T. M., Bellard, C. & Ricciardi, A. Alien versus native species as drivers of recent extinctions. Front. Ecol. Environ. 17, 203–207 (2019).
  • Klein, A.-M. et al. Importance of pollinators in changing landscapes for world crops. Proc. R. Soc. B: Biol. Sci. 274, 303–313 (2007).
  • Rodger, J. G. et al. Widespread vulnerability of flowering plant seed production to pollinator declines. Sci. Adv. 7, eabd3524 (2021).
  • Wagner, D. L., Grames, E. M., Forister, M. L., Berenbaum, M. R. & Stopak, D. Insect decline in the Anthropocene: death by a thousand cuts. Proc. Natl. Acad. Sci. USA 118, e2023989118 (2021).
  • Haubrock, P.J., Cuthbert, R.N., Haase, P. (2023) Long‑term trends and drivers of biological invasion in Central European streams. Sci Total Environ. 876:162817. https://doi.org/10.1016/j.scitotenv.2023.162817