from Nathan
Collins
August 7, 2015
August 7, 2015
Pest control is especially important on farms. It costs a lot of money, and if you overdo it on pesticides, you can seriously disturb nearby ecosystems. A new report
lays out simple actions farmers could take to increase biodiversity and
foster interactions between insect species to help keep pests under
control.
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"Our research suggests that agronomic practices that
promote high levels of ... diversity fundamentally require fewer
agronomic inputs," such as pesticides, write Jonathan Lundgren, an ecologist at the United States Department of Agriculture's Agricultural Research Service, and Scott Fausti, a professor of economics at South Dakota State University.
To get a handle on how the insect population as a
whole might impact pests, Lundgren and Fausti inventoried 106 insect
species — a total of more than 37,000 individual insects — on 53 corn
farms in the Northern Great Plains. Based on that collection, they
computed each farm's species diversity,
a particular measure of biodiversity that incorporates the number of
species present, as well as how evenly each species is represented. For
example, even if Lundgren and Fausti found 100 species on one farm, they
wouldn't call it diverse if 99 percent of individual insects were
common black ants.
The
more diverse the insect population was, the fewer pests Lundgren and
Fausti found. But the researchers didn't stop there, choosing instead to
examine networks of interactions between species. Lundgren and Fausti
built those by looking for correlations between species — that is, how
often the same species showed up on the same farms. The pair constructed
10 such networks, each for a different level of pest abundance. The
first network, for example, represented links between insects found on
the five farms with mildest pest infestation.
Analyzing those networks revealed that it wasn't
just species diversity that mattered for pest control, but also the
structure of interactions between insects. As the average number of
links between insect species increased, for example, the abundance of
pests decreased. Similarly, farms had the fewest pests when insect
species had about the same number of links to each other.
The results, Lundgren and Fausti write, suggest a
new way of looking at pest control. "The importance of the association
of biodiversity and ecological network structure with low pest
populations provides goals that can be targeted with sustainable
cropping systems that require minimal inputs for pest management," the
researchers write today in Science Advances. In particular,
they suggest, farmers could use less insect-lethal strategies, like
simply tilling the soil less or planting a wider variety of plants to
preserve insect biodiversity without sacrificing crop yields.
of The Week magazine.
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