Diversity as Natural Pesticide
A study led by the University of California, Davis, and published Oct. 12 in the journal Nature explains that much of it may have to do with the nutritional needs of insects. Returning plant diversity to farmland could be a key step toward sustainable pest control.
“Insects have a perfect nutrient level that they really like,” said lead author William Wetzel, a doctoral student in Population Biology at UC Davis at the time of the study and currently an assistant professor at Michigan State University. “When it’s too high or too low, they do poorly.”
“A monoculture is like a buffet for plant-eating insects where every dish is delicious,” Wetzel said. “A variable crop is like a buffet where every other dish is nasty.”
Many small farms around the world already include a diverse mixture of plants. But in most monocultures, the plants are bred to be as identical as possible. How can larger growers introduce more diversity while maintaining their same level of production?
Wetzel said this sort of genotype mixing for plants is already being done on some rice and wheat fields to reduce the spread of disease among the crops.
“So far people haven’t done that in ways to reduce insects,” Wetzel said. “But it shows that it’s possible to mix varieties and genotypes together. Now we need to think about how to do that to control insects.”
Co-authors on the study include Heather Kharouba from UC Davis Center for Population Biology and University of Ottawa Department of Biology, Moria Robinson from UC Davis Center for Population Biology, Marcel Holyoak from UC Davis Department of Environmental Science and Policy, and Richard Karban from UC Davis Department of Entomology and Nematology.
The study was supported by grants from the UC Davis Center for Population Biology.