More plant diversity means less pesticides

Grassland 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.

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