Biological control generates ‘desirable outcomes’ within all One Health dimensions

New CABI-led research has revealed that biological control generates ‘desirable outcomes’ within all One Health dimensions – mitigating global change issues such as chemical pollution, biocide resistance, biodiversity loss, and habitat destruction.

However, the scientists, who include those from the University of Minnesota, University of California, International Centre of Insect Physiology and Ecology (icipe), University of Florida and the United Nations Food and Agriculture Organization (FAO), say the cross-disciplinary achievements of biological control remain ‘underappreciated.’

Published in the journal Science of The Total Environment, the research scrutinized biological control endeavours and their social-ecological outcomes through a holistic ‘One-Health’ lens, recognizing that the health of humans, animals, plants, and the wider environment are linked and interdependent.

Societal benefits at the food-environment-health nexus

Dr Urs Schaffner, an author of the research and Head of Ecosystems Management at CABI, based at its centre in Switzerland, said, “Biological control has been effectively exploited by mankind since 300 CE. By promoting the natural regulation of pests, weeds, and diseases, it produces societal benefits at the food-environment-health nexus.

“Nevertheless, the broader contributions of biological control to One Health remain underappreciated.

“Framing biological control in a One Health context helps to unite medical and veterinary personnel, ecologists, conservationists and agricultural professionals in a joint quest for solutions to some of the most pressing issues in planetary health.”

The scientists highlight, regarding human health for example, how the leaf beetle Ophraella communa, that is being used to control a plant that causes allergies in humans can reduce airborne common ragweed pollen concentrations by >80 %.

Between 10-60 percent of people exposed to common ragweed pollen will experience an allergic reaction costing the European economy 7.4 billion Euros a year.

The leaf beetle Ophraella communa is expected to annually reduce Europe-wide health costs by €1.1billion

Based on prospective modelling, O. communa, an adventive species from North America that was first detected in Europe in 2013, is expected to annually reduce Europe-wide health costs by €1.1billion once it has colonised its environmental niche (Schaffner et al., 2020).

And, referring to plant health, the scientists give examples including biological control of the mango mealybug (Rastrococcus invadens) in Benin yielded a benefit-cost ratio of 145:1, with each mango farmer gaining US$328/year for over 20 years (Bokonon-Ganta et al., 2002).

Furthermore, in terms of environmental health, they highlight how at least 15 weed, and 12 insect pest species have been controlled in natural habitats through natural enemy introductions with more such species currently targeted.

Examples include control of the invasive melaleuca tree (Melaleuca quinquenervia) in Florida, which allows restoration of natural vegetation and hydrology in the highly sensitive Everglades wetland ecosystem (Rayamajhi et al., 2019), and control of the cottony cushion scale (Icerya purchasi) in the Galapagos Islands, which has saved some species of endemic plants from likely extinction (Hoddle et al., 2013).

Contribution to forestalling further ecological breakdown

Dr Kris Wyckhuys, a co-author of the study, said, “Biodiversity-driven pest, weed or disease management, or biological control, can provide a real contribution to forestalling further ecological breakdown and defusing some of the world's most urgent human, animal and environmental threats.

“We hope that our review – although not exhaustive – provides compelling evidence for the breadth and transdisciplinarity of the biological control approach.

“We submit that a One Health perspective reveals underappreciated opportunities for biological control that go beyond its well-known application in plant-based production systems.

“We advocate a systems-level, integrated approach to biological control research, policy, and practice that considers its direct and indirect benefits for the four dimensions of One Health.”

For example, the scientists say that the biological control of the invasive cassava mealybug Phenacoccus manihoti in Asia directly benefits plant health through increased cassava production and indirectly benefits environmental health by slowing commodity-driven tropical deforestation by up to 95%.

Other examples of multiple health benefits resulting from biological control practices include the biological control of gastrointestinal parasites and diseases, which directly benefits livestock health and indirectly human health by slowing biocide resistance development.

Another is the biological control of locusts using the highly specific fungus Metarhizium acridum, which directly benefits plant health but also indirectly benefits human, animal and environmental health by avoiding broad-scale aerial insecticide spray applications.

Full potential of biological control remains to be realized

Dr Schaffner added that, “the full potential of the biological control approach to tackle some of the major global challenges, including biodiversity loss, environmental pollution or biocide resistance, remains to be realized.”

The researchers call upon scientists, practitioners and policymakers to join hands, transcending disciplinary or sectoral boundaries and ideological differences, to deliver on its One Health promise.

Dr Schaffner is an advisor on the CABI One Health Hub, a knowledge, learning and evidence platform designed to improve our understanding of the relationship between humans, animals, plants, ecosystems and their shared environment in a transdisciplinary way.

Supported by the UK Foreign, Commonwealth and Development Office (FCDO), the One Health Hub, in collaboration with the Juno Evidence Alliance, will engage with key stakeholders to identify research gaps, carry out evidence synthesis, communicate findings and advocate for use of evidence in research and policy decision making on issues relevant to One Health.

Full paper reference

Urs Schaffner, George E. Heimpel, Nicholas J. Mills, Beatrice W. Muriithi, Matthew B. Thomas, Yubak D. GC, Kris A.G. Wyckhuys, Biological control for One Health, Science of The Total Environment, Volume 951, 2024, https://doi.org/10.1016/j.scitotenv.2024.175800.

The paper can be read full open access here.