Biodiversity is the key

"Biodiversity is key: Organic agriculture best means of tackling pest control and producing larger plants

A study released by Washington State University in the Journal ‘Nature’ has found organic agriculture gives better pest control and produces larger plants than conventional farming due to a higher level of biodiversity.

The researchers found that more balanced animal and plant communities typical of organic farms work better at fighting pests and growing a better plant and highlights the importance of biodiversity.

The researchers looked at insect pests and their natural enemies in potatoes and found organic crops had more balanced insect populations in which no one species of insect has a chance to dominate. And in test plots, the crops with the more balanced insect populations grew better.

"Organic agriculture promotes more balanced communities of predators," says David Crowder, a post-doctorate research associate in entomology at Washington State University.

"What our study suggests is that organic agriculture is promoting these more balanced natural enemy communities and they may have better, organic pest control."

"I think 'balance' is a good term," says David Crowder. "When the species are balanced, at least in our experiments, they're able to fulfill their roles in a more harmonious fashion."

Crowder and colleagues use the term "evenness" to describe the relatively equal abundance of different species in an ecosystem.

Conservation efforts more typically concentrate on species richness - the number of individual species - or the loss of individual species. Crowder's paper is one of only a few to address the issue and the first to look at animal and fungal communities at multiple points in the food chain.

The researchers say their results strengthen the argument that both richness and evenness need to be considered in restoring an ecosystem.

The paper also highlights insect predator and prey relationships at a time when the potato industry, including large French fry retailers like McDonald's and Wendy's, is being pushed to consider the ecological sustainability of different pest-control practices.

Conventional pest -management on farms often leads to biological communities being dominated by a few species.  Looking at conventional and organic potato farms in central Washington State's Columbia Basin, Crowder found that the evenness of natural pests differed drastically between the two types of farms."
This was sent to me in an email from a fellow member of the
Australian Plants Society Newcastle Group who also happens to be a passionate organic gardener.