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More plant diversity, less pesticides



More plant diversity, less pesticides

Over the course of two years, the scientists gathered data from two similar grassland experiments, including the Jena Experiment in Germany. Credit: Matthias Ditscherlein

Increased plant diversity enhances the natural control of herbivore insects. Species-rich plant communities support natural predators and at the same time provide less valuable food to herbivores. This was discovered by a team of researchers led by the German Integrated Biodiversity Research Center (iDiv) who conducted two similar experiments in Germany and the US. Their results have been published in Scientific advance and showed that increased plant biodiversity could help reduce pesticide inputs in agricultural systems by enhancing natural biological control.


Biodiversity, the biodiversity of all species on Earth, their interactions and the diverse ecosystems they form, are vital to providing and maintaining functions. and services of grasslands and natural ecosystems. With the growing need to feed the world̵

7;s growing population by enhancing agriculture, these pastures are also under pressure. Herbivorous insect species are causing an estimated 18-26% loss in global crop production, which has spurred significant growth in the use of environmentally costly pesticides.

To investigate whether increasing plant diversity could naturally reduce the effects of herbivores on plants, a team of international researchers led by the Center for Biodiversity Research Integration of Germany (iDiv), the University of Leipzig (UL) and the University of Friedrich Schiller Jena (FSU) led two long-standing grassland biodiversity experiments in Europe and North America: Jena in Germany and Cedar Creek Biodiversity Experiment in Minnesota (USA). Over the course of two years, the scientists gathered data from these two similar experiments, providing insight into the food web structure of species-rich monoculture and grassland. Senior author Nico Eisenhauer, professor at UL, and lead research team at iDiv said: “These two long-term experiments have provided invaluable insight, both for fundamental and applied research. , helps shed light on the importance of maintaining biodiversity. as a speaker on the Jena Test.

Species-rich plant communities are less attractive to herbivores

The researchers found that plants in more diverse communities lose significantly less energy to herbivores. In blends of high diversity, the feeding rate of herbivores per gram of plant biomass was 44% lower than that of monosodium glutamate. Consequently, for every gram of plant biomass produced, plants lose about half the energy of arthropods when grown in rich species. “That ultimately means where multiple species are grown together, this will yield more vegetation biomass per square meter and each individual tree in the diverse mix will get lower losses from herbivores, ”iDiv’s first author and alumni Andrew Barnes, is currently a senior lecturer at Waikato University in New Zealand.

In compartments with a higher plant diversity, arthropods have a lower chance of encountering their favorite plant species – which makes them more likely to stay in these highly diverse plots. less than. In addition, previous research has shown lower tissue protein (nitrogen) levels in plant communities with a high species richness, making these plants less nutritious for herbivores.

More plant diversity, less pesticides

Diverse plant communities offer many benefits and can help control harmful herbivores. Credit: Anne Ebeling

Predators benefit from increased plant diversity

Although the total biomass of herbivores and carnivores both increased in species-rich grassland, predators benefit more from diverse plant communities: Compared to monoculture, they increase significant both in terms of total biomass and feeding rates. One possible explanation could be that arthropods such as spiders, some species of beetles or wasps benefit significantly from the more complex habitats of highly diverse plant communities. This reduces the risk of predation by predators such as birds and mammals.

Therefore, increased diversity of plants has some positive side effects: Compared to monoculture communities, highly diverse plant communities produce more total biomass. Additionally, both natural predators and resource concentrations work in concert to limit the negative effects of herbivores on crop performance. Andrew Barnes says: “In other words, more diverse plant communities pose a double-edged problem with herbivores – that is, more predators and less fancy food – can help. minimizing the impact of herbivores naturally. “

Plant biodiversity can limit herbivore outbreaks

Conversely, pest control heavily reliant on pesticides can lead to an adverse re-outbreak of herbivores as the use of pesticides can destabilize natural predator communities. . “Our experiments show that preserving plant diversity has many benefits for the control of herbivores, which may play a key role in reducing herbivores,” Andrew Barnes said. inputs of agrochemicals and improving crop yields. Nico Eisenhauer added: “Ultimately, this study demonstrates that biodiversity support can promote the sustainable management of ecosystems and benefit humans.”


Fertilization threatens the stability of the pasture


More information:
Biodiversity enhances the polymorphic control of arthropods. Scientific advance (Year 2020). DOI: 10.1126 / sciadv.abb6603

Provided by Germany’s Integrated Biodiversity Research Center

Quote: More plant diversity, less pesticides (2020, November 6) retrieved November 7, 2020 from https://phys.org/news/2020-11-diversity-pesticide.html

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