By Meg Thode
Recently published in Nature, a study led by scientists at the University of California, Davis suggests that increasing the diversity of plant life in a stretch of farmland is an effective means of limiting the spread of pests and disease.
The study observed 53 different types of insects which commonly prey on agriculture — caterpillars, grasshoppers, beetles, aphids and flies — and drew conclusions about insect eating habits. Their findings supported the belief that a field with variable crops is “healthier” than a monoculture, but they further clarified the mechanisms behind that long-observed phenomenon.
"Insects have a perfect nutrient level that they really like," explains co-author William Wetzel. "When it's too high or too low, they do poorly." To illustrate this idea Wetzel goes on to use an analogy about finding a good meal at a restaurant: A monoculture offers an insect an all-you-can-eat buffet where every dish served is delicious; a polyculture, on the other hand, has a menu where every dish is hit-or-miss. The decreased likelihood of finding a good meal in a polyculture deters many insects from the land.
The team suggests that while small-scale, diverse farms effectively utilize this principle, increasing diversity might not manifest itself as mixed-crop planting at an industrial scale. Instead the study highlights opportunities to “introduce a mixture of genotypes of the same crop species with different nutrient levels” in the same farm. The edible or commercial part of a plant can be identical, while leaf or stalk structures are modified to resist insect populations. This practice is already being implemented to address disease spread among some grains, but "so far people haven't done that in ways to reduce insects," Wetzel said. "Now we need to think about how to do that to control insects."
University of California - Davis. (2016, October 12). Why insect pests love monocultures, and how plant diversity could change that. ScienceDaily. Retrieved October 23, 2016 from www.sciencedaily.com/releases/2016/10/161012134054.htm