Researchers studying an organic coffee farm in Mexico may have stumbled on a clue explaining how organic and integrated farming techniques work so well—and keep pests under control naturally.

On the coffee farm, the key players that keep the ecosystem thriving are a few ant species, coffee pests, and beetles. Their interactions and interdependence on each other are essential to the health of the farm in subtle ways that can be—and have been—easily overlooked.

Intricate relationships
Read the study summary for the full explanation, but it essentially works like this:

Ants live in about three percent of shade trees on the farm, but only in clusters of trees, and not scattered about randomly. Ants have a cozy, symbiotic relationship with the ‘green coffee scale,’ a coffee pest that is a real problem in some areas. But the lady beetle feeds on the scale.

Ants fend off the beetles because the ants like scales for their honeydew secretion. That’s the exchange: honeydew for the ants, protection for the scale. A delicate balance ensues:

The beetles also seem to influence the ants’ distribution patterns by preying on the scale, on which the ants depend for honeydew. The researchers explored the relationship using theoretical modeling and found that if ants take over the whole plantation, the beetle goes extinct because adult beetles can’t get enough to eat. If the ants disappear from the farm, the beetles go extinct because the larvae starve. But if ants are confined to clusters, due to the influences of both beetles and parasitic flies, the beetles thrive and keep the scale insects under control.

A large point of the study is to prove, as the summary says, “it’s increasingly clear that the ‘naïve’ view of nature working in harmony closely matches the scientific facts.”

Instead of trying to pinpoint the problem and finding a “magic-bullet” solution, the way many in modern agriculture do, said one of the researchers, “Our approach is to understand systems that are working well, where there are no problems. By doing that, we can define systems that are more resilient and resistant to pest outbreaks.”

The researchers are now looking at the interactions of other insects that affect coffee plants. With coffee already threatened by climate change-loving beetles, now seems like a great time to understand integrated farm management and to learn how these beetles work their magic.

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