Invasive Species Linked to 31% Drop in Native Insects — Scientists Urge Urgent Biosecurity

A major analysis led by the U.K. Centre for Ecology and Hydrology and published in Nature Communications finds that invasive species are associated with an average 31% decline in native insect abundance and a 21% reduction in insect species richness in affected areas.

The study is among the first to quantify how biological invasions directly harm insect communities worldwide. Lead author Grace Skinner, a data scientist, emphasized the need to view insects as both invaders and victims:

"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." — Grace Skinner

Examples such as the spotted lanternfly and the tiger mosquito illustrate how some non-native insects can destabilize ecosystems by displacing native species, degrading habitats and outcompeting or consuming limited resources. The authors stress, however, that impacts vary by species and context — not every non-native insect causes the same level of harm.

Why Insects Matter

Insects support ecosystems and human wellbeing in multiple ways:

• Food-web support: Research published in Ornithological Applications indicates about 96% of bird species feed insects to their young, so insect declines ripple up the food chain.
• Pollination: The U.S. Department of Agriculture estimates roughly 75% of flowering plants and about 35% of global food crops depend on pollinators such as bees and butterflies.
• Decomposition and nutrient cycling: Insects break down dead plants and animals and return nutrients to the soil, maintaining healthy ecosystems.

Recommendations and Next Steps

The researchers call for strengthened cross-border biosecurity to reduce accidental introductions and for conservation efforts that prioritize the insect species and habitats most vulnerable to invasions. Co-author Dr. Joseph Millard of the University of Cambridge noted that future research should examine how invasions interact with other pressures such as climate change, which could alter invasive species' ranges and magnify their impacts.

Practical local actions — from removing invasive plants in gardens to promoting consumption of invasive fish where appropriate — can complement policy measures. The authors say their analysis aims to raise awareness and help direct resources toward the most at-risk insects and ecosystems.

By quantifying these impacts, the study provides a stronger evidence base for policymakers, conservationists and communities seeking to protect insect biodiversity and the services it provides.