Parasite Dynamics in Biological Invasions

Parasite dynamics in biological invasions encompass the complex suite of interactions that ensue when non‐native species enter and establish in novel ecosystems. Invaders frequently benefit from enemy release as they escape co‐evolved parasites and pathogens, enabling a shift in resource allocation from immune defence towards enhanced reproduction and dispersal. At the same time they may acquire endemic parasites or introduce exotic ones, a dual process of spillover to native fauna and spillback of novel parasites into resident hosts. These shifts in host–parasite associations can reshape community assembly, alter trophic networks and influence ecosystem resilience, sometimes with cascading effects on human and animal health. Key factors governing these outcomes include propagule pressure, host specificity, immune trade‐offs and environmental suitability for parasite life‐cycles. Integration of eco‐immunological insights, network ecology and genomic tools has advanced our understanding of the mechanisms underpinning invasion success and impact. Recognising parasite dynamics is therefore critical for devising biosecurity policy, refining risk assessment and implementing adaptive One‐Health strategies that safeguard biodiversity, agricultural productivity and public well‐being on a global scale.

Research from Nature Portfolio

Recent studies have applied genomic and immunological approaches to uncover how immune gene variation influences parasite escape and adaptation during invasion. Research on the invasive raccoon in Europe demonstrates that despite variation in gastrointestinal parasite prevalence among populations, non-MHC immune genes exert only marginal effects on infection intensity. Instead, a diverse repertoire of MHC-DRB alleles appears to maintain host resistance against newly encountered parasites in the invasive range. These findings refine the evolution of increased competitive ability framework by showing that relaxation of parasite-mediated selection permits reduced investment in general immunity without compromising host defences against novel pathogens. Such insights underscore the importance of host adaptive immunity in modulating parasite dynamics during biological invasions.

Parasite Dynamics in Biological Invasions publication trend

The graph below shows the total number of articles in parasite dynamics in biological invasions across all publications each year (not limited to Nature Index journals).

Technical terms

Enemy release hypothesis: The theory that invasive species succeed because they escape their native parasites and pathogens, reducing ecological and evolutionary pressures on host defences.

Evolution of increased competitive ability (EICA): A hypothesis proposing that invaders reallocate resources from costly immune defences to growth and reproduction following release from co-evolved parasites.

Parasite spillover: The transmission of parasites from invasive species to native hosts within the invaded range.

Parasite spillback: The process by which invasive species acquire endemic parasites that subsequently infect native hosts at elevated rates.

Propagule pressure: The number and frequency of individuals of a species introduced to a new area, influencing establishment success.

One‐Health approach: An integrated framework recognising the interconnected health of humans, animals and ecosystems in managing disease risks.

References

1. A one-health approach to non-native species, aquaculture, and food security. Water Biology and Security (2024).
2. Non-MHC immunity genes do not affect parasite load in European invasive populations of common raccoon. Scientific Reports (2023).
3. Invasive alien species and disease risk: An open challenge in public and animal health. PLOS Pathogens (2020).