Harlequin larva and moth eggs.
Photo Credit: Bill Phillips
Scientific Frontline: "At a Glance" Summary
- Main Discovery: A groundbreaking global analysis led by the UK Centre for Ecology & Hydrology (UKCEH) establishes that insects are major victims of invasive alien species (IAS), significantly exacerbating global population declines and compromising biodiversity.
- Specific Detail/Mechanism: The reduction in native insect populations is driven principally by invasive animals outcompeting or directly preying upon them, alongside invasive vegetation displacing the native flora that insects rely on for nutrition and habitat.
- Key Statistic or Data: The study, which analyzed data across six continents, indicates that invasive alien species reduce the abundance of terrestrial insects by an average of 31% and decrease species richness by 21%.
- Context or Comparison: Vulnerability varies significantly by order: Hemiptera (true bugs) experienced the steepest decline in abundance at 58%, followed by Hymenoptera (ants, bees, wasps) at 37%, while Coleoptera (beetles) were the least affected with a 12% reduction.
- Significance/Future Application: These findings highlight a critical risk to essential ecosystem services such as pollination and pest control, necessitating urgent prioritization of biosecurity measures and habitat management to mitigate the introduction and spread of damaging invasive species.
- Methodology: This research represents the first comprehensive study to quantify the impact of invasive alien species on insect populations on a global scale, filling a significant gap in the understanding of drivers of insect decline.
Insects are often seen as invaders due to high-profile species like the yellow-legged (Asian) hornet, harlequin ladybird and fire ant. But new research reveals insects are also major victims of invasive alien species – exacerbating population declines and reducing their ability to provide vital services for biodiversity and people, from pollination to pest control.
The first global analysis of its kind, led by the UK Centre for Ecology & Hydrology (UKCEH), revealed that invasive alien species reduce abundance of terrestrial insects by 31% on average and reduce species richness by 21%. Invasive animals outcompete or eat insects while invasive vegetation replaces native plants that insects feed upon.
The study, which analyzed data from six continents, shows certain terrestrial insect groups including bees, wasps, ants, and true bugs are more negatively affected by invasive alien species than others, such as beetles. But the authors point out that the outcomes vary, depending on the dynamics of the local environment – for example, invasive plants might support insects in places where native vegetation has been lost.
Invasive alien species are already recognized by IPBES as one of the five big direct drivers of global biodiversity loss, alongside land- and sea-use change, direct exploitation, climate change, and pollution. These threaten nature, economies, food security, and human health.
Grace Skinner, a data scientist at UKCEH who led the new study, said: “It is crucial that we recognize insects not just as invaders but also as victims of invasion. Insects are undergoing concerning declines across the world and as this trend continues, essential ecosystem services will increasingly be at risk.
“Identifying the insects most vulnerable to biological invasions will support better prioritization of habitat management and action to prevent and control invasive alien species. This is particularly important when resources are limited.”
Co-author Professor Helen Roy, from UKCEH and the University of Exeter, said: “Tackling invasive alien species is achievable but urgent. Enhancing cross-border collaborations on biosecurity are critical to preventing the introduction of damaging invasive alien species. Everyone can make a difference through their actions too by, as an example, following guidance from campaigns such as ‘Be Plant Wise’.”
It is widely acknowledged that insects are struggling globally, though the magnitude of change varies among species and regions. Despite invasive alien species being a major global threat, their effects on insects have been far less studied than other pressures such as urbanization and nutrient enrichment. This is the first study to analyze and quantify the impact of invasive alien species on insects on a global scale.
Scientists warn that the challenges to insects will increase further.
“We hope our analysis encourages more research into how invasive alien species interact with other threats to insect biodiversity – for example how climate change might influence invasive alien species populations and amplify their impacts,” said study co-author Dr Joseph Millard, of the University of Cambridge.
The study has been published in the journal Nature Communications. It focused on four animal orders, representing 62% of all insect species, that experts have identified as being particularly threatened by invasive non-native species.
The analysis found that the average reductions in abundance were: Hemiptera (true bugs) – 58%; Hymenoptera (ants, bees, sawflies and wasps) – 37%; Orthoptera (grasshoppers, locusts and crickets) – 27%; and Coleoptera (beetles) – 12%.
Gardeners are advised to carefully consider their choice of plants, while anglers, boaters and forestry workers, for example, should ‘check, clean, dry’ equipment.
Funding: Natural Environment Research Council
Published in journal: Nature Communications
Authors: Grace L. V. Skinner, Rob Cooke, Helen E. Roy, Nick J. B. Isaac, Charlotte L. Outhwaite, James Rodger, and Joseph Millard
Source/Credit: University of Exeter | Alex Morrison
Reference Number: eco011526_01
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