More plant diversity means less pesticides

Can increased plant diversity in grasslands enhance the natural control of insect herbivores and will that reduce their impacts on plants?

Te Aka Mātuatua School of Science

Image not foundGrassland with higher plant diversity provides less favoured food for insects and supports their natural predators like spiders and beetles. This means that increasing plant biodiversity could help naturally control herbivore pests and reduce the need for pesticides in agriculture.

Dr Andrew Barnes has published an significant collaborative publication in terrestrial ecology: Biodiversity enhances the multitrophic control of arthropod herbivory

A team of researchers used two long-running grassland biodiversity experiments in Germany and the US, where they studied the natural food webs in monocultures (areas with a single plant species) and biodiverse grasslands. The researchers found insects consume significantly less plant matter in areas with high diversity. whereby their feeding rate (per gram of plant biomass) was 44% lower than in monocultures.

In diverse plant communities, specialised insect herbivores are less likely to find their preferred plant species and therefore remain in lower numbers, relative to plant biomass. At the same time, arthropod predators like spiders, beetles and wasps also increased notably in both their total biomass and feeding rates, potentially because diverse grasslands present more habitat for predators.

Therefore, more diverse plant communities provide more pressure from predators and less preferred food for herbivores that, together, help to naturally reduce herbivore impacts on plants. Ultimately, the study shows that conserving plant diversity provides multiple benefits for controlling herbivore pests, which could play a key role in reducing inputs of agrochemicals and enhancing plant productivity.

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Read the full research publication Biodiversity enhances the multitrophic control of arthropod herbivory.

Dr Andrew Barnes

Senior Lecturer

I am broadly interested in the impacts of global change drivers on natural systems and the resulting functional consequences. My research focuses on how environmental changes alter the seemingly complex relationships between biodiversity, the structure of communities, biotic interactions, and ecosystem functioning.