Nature’s “Break Through” Discovery

Farther Afield
Tom Willey
T & D Willey Farms

Not a regular reader of the powerhouse scientific journal, Nature, from which a rare article on organic pest control was torn and sent along by a CSA member in last week’s mail, I gave it a go. One glance left a quick impression that submissions to Nature are purposely written in languages unintelligible to all but parochial tribes of scientists.

But the title’s lure: “Organic agriculture promotes evenness and natural pest control” (July 1, 2010) scorched me with dogged determination to digest its substance, so I commenced looking up definitions of each newly encountered, quirky term. Turns out, lead author David Crowder and his entomologist colleagues are conducting just the type of research for which I and other natural systems farmers have long advocated, explaining their article’s near impenetrable complexity.

Any farm is an agroecosystem, a disrupted facsimile or remnant of the natural ecology it replaced, featuring fewer species of plants, insects and microorganisms than it once did in a native state. Crowder’s team set out to compare relative biodiversity on Washington state’s organic and conventional potato farms, focusing on a whole complex of insect predators, parasitic nematodes and fungi which contribute to natural suppression of the dreaded Colorado potato beetle.

These researchers’ “break through” discovery, which landed a coveted Nature publication, was that the absolute number of species present in a potato field (richness) was less important than the relative abundance of each species (evenness).

Organic farms exhibited vastly more balanced predator populations of insects, nematodes and fungi, than did conventional potato fields. Greater population evenness on these organic potato farms led to 18% fewer pests and 35% larger plants. Concerned they might be observing a phenomenon that would not play out on a broader landscape, the team scoured scientific literature for similar evenness comparisons on other farms growing other crops.


The nearly forty relevant studies they unearthed all agreed with their findings in Washington potato fields. Like careful scientists, they don’t speculate as to the reasons for such results, but the late Harry Shorey, UC Kearney entomologist always startled listeners with his claim: “The key to effective insect control is to keep pesticides off plants”.

“Balance of nature” is a term we bandy about but rarely investigate at levels of complexity embraced by Crowder’s ambitious team.

Their work provides a glimpse into the interwoven world of food webs our best next-generation young minds will need to penetrate to sustain the success of humanity’s agricultural revolution.

–Tom Willey

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