Coffee Filter

shade coffee2It’s hard obviously to imagine a house which doesn’t have a door. I saw one one day, several years ago, in Lansing, Michigan. It had been built by Frank Lloyd Wright…[T]here appeared something like an open-work roof that was practically indissociable from the vegetation that had invaded it. In actual fact, it was already too late to know whether you were indoors or out…A dozen more or less similar houses were scattered through the surrounds of a private golf club. The course was entirely closed off. Guards…were on duty at the one entrance gate. –Georges Perec (1974)

Dosage and tolerance mark the thin line between palliative and poison.

The caffeine that perks up one patron in the coffeehouses of snowbound Minnesota can rocket another into rare tachycardia and cardiovascular collapse. It’s a chance many are willing to take. Even the jitters tell us we’re still alive in -40 wind chill. And look on the bright side, as one must here under the penalty of death, should a slurper keel over, a table in a popular joint is suddenly free for the rest of the day.

The devotional’s exploding global appeal—and increasing consolidation—obfuscates its modest origins. The genus Coffea grew naturally in the Horn of Africa, its purine alkaloids caffeine and theobromine herbivore irritants and insecticides. Lure and lore parlayed the bean into a regional then an imperial prerogative and today a record 150 million-60-kg-bag and US$100-billion-a-year global industry, second only to Big Oil, employing, across production, trade and retail, as many as 500 million people.

Blue Mountain, Colombian, Ethiopian Harar, Hawaiian Kona, Java, SL28, and on and on, manifold varieties and hybrids are grown across seventy countries. At $1000 per kg, the priciest is an Indonesian bean swallowed and shat out by a caged luwak or Asian palm civet. The kind of arbitrary appreciation slash commoditization that’ll eventually slash slash slash the civet population to oblivion.

The differences in species, soils, sunlight and cultivation help produce beans of a variety of balance, bouquet, bright and body. According to an extraordinary line of research by University of Michigan’s Ivette Perfecto, John Vandermeer and their colleagues, coffee ecosystems also differ in their capacity to naturally control pest insects and plant diseases that can devastate a Coffea crop.

Control in Coffea canephora, the major Latin American variety, emerges from more than the plant’s biochemistry and bred-in disease resistance. The thatch of ecological relationships—predation, mutualism, competition, etc.—up and down the food web in which the plant finds itself can box out pest damage. Resistance and resilience are found in the field rather than the object, emerging out of these interconnections and their redundancy. Should one control cascade fail, another steps up or steps in.

For ten years plus, on a 300-hectacre organic coffee farm in operation for nearly 100 years in the Soconusco region of Chiapas, Mexico, Perfecto and Vandermeer’s team have worked to tease out the multiple spatioecological layers that buffers shade coffee from the worst of pest outbreaks.

Coffee rust disease fungus Hemileia vastatrix, the coffee berry borer Hypothenemus hampei, the green coffee scale Coccus viridis, and the leaf-mining moth Leucoptera coffeella are four of potentially 200 now-endemic pests, each alone capable of destroying a coffee crop, and yet, here, have not. The PVC team identified a web of dynamic and contingent relationships across, if you’re keeping score at your local, thirteen kinds of organisms and six ecological processes, keeping the four pests largely in check.


The swarming Azteca instabilis ant serves as the keystone species for the control network.

Queens of the polygynous ant ‘bud’ off and with some of their brood colonize new nests on coffee plants nearby. Colony diffusion is constrained in part by a Pseudacteon phorid fly, which lays brain-eating offspring inside the worker ants. Phorid attacks are nest-density-dependent. The more Azteca nests in the vicinity, the more attacks in the area, producing a power law distribution of nests across the farm.

That distribution, in turn, helps a lady beetle species Azya orbigera control the green coffee scale, our first pest. How? It gets all Robert Altman, so pay attention.

The ants and green scales are—perhaps a surprise—mutualists. Azteca offer the scale protection, including against the adult beetle, in return for honeydew the scales secrete. Protection Azteca cannot provide, however, against the beetle larvae. The larvae’s waxy protuberances gum up Azteca mandibles and the young’uns chaw on the scale to their heart’s content. The larvae score a daily double as Azteca also scares away parasitic wasps that feed on—and would control—the larvae in the ant’s favor.

Without Azteca’s indirect protection, the beetle larvae wouldn’t be able to survive its own parasitic tormenters in order to control the green scale. In short, as Perfecto and colleagues describe, the beetle helps produce the very spatial distribution it needs to survive. Dialectical biology in action.

There is a second, if indirect, means by which the distribution of Azteca is circumscribed to 3-5% of the farm. The white halo fungus Lecanicillium lecanii attacks the scale on which Azteca depends when the scale is locally abundant (which occurs largely under Azteca protection).

White halo also attacks the coffee rust, our second pest, but, as we see, does so only because Azteca protects scales to densities white halo attacks. In other words, the scale and rust are by indirect means mutually constraining.


Something puzzled the PVC team. How do adult beetles—viciously attacked by Aztecaoviposit their similarly vulnerable eggs on a plant on which only their larvae survive?

Remember the phorid fly whose larvae feed on Azteca? What do we want? Brains! When do we want it? Brains! The fly offspring locate the ant colony by detecting its alarm pheromone and any one individual host by its movement. The ants respond by retreating to the nest or standing stock still in such a way as to avoid the fly’s motion detection and, when able, to attack its phorid tormenter.

The ants produce a second ‘phorid’ pheromone alerting other ants to enter their defensive catatonia. The female beetles looking to oviposit their eggs unmolested can detect this second pheromone, finding areas of the plant in which Azteca have entered their collective freeze frame.

It appears, then, that Azteca distribution, natural pest control, and likely other such distributions in the forest and farm, arise from no single cause but a nonlinear complex of interactions distributed across the ecological network, an important lesson for those of us in the fields of livestock disease and public health.

The complications pile on, however.

If the coffee scale needs Azteca’s protection, how does a new ant colony find scale elsewhere? PVC discovered that although not nearly as effective as Azteca, at least five other ant species that forage in the area tend the scale. In essence, the various species, occupying different parts of the farm canopy act as indirect mutualists maintaining scale densities across the farm, including the local outcrops a new Azteca colony needs.

One ground ant Pheidole cfp, which while feeding on scales (and like Azteca on leaf miners and berry borers, our final two pests), offers Azteca additional help by outcompeting a third ant, an Azteca competitor, Pseudomyrmex simplex.

Other ant species meanwhile act as Azteca antagonists, if only because they do not co-tend scales. Pheidole protensa, for one, which also feeds on berry borers in old fallen seeds that offer borers off-season refuge, outcompete Azteca ally Pheidole ctp on the ground.

We are speaking here of an ecological guild of more than eighty ant species that engage in complex interactions of various—and at times simultaneous—mutualisms and competition across canopy niches.


We—or rather nature—can add yet another layer.

To test the effects birds have on pest numbers, the Perfecto-Vandermeer team conducted an exclosure experiment across shade and intensive farms in Soconusco. With 5-cm mesh fishing nets, the researchers excluded birds from 10 x 5 x 3m plots of at least ten coffee plants. They selected control plants open to the elements from parallel rows nearby.

The team placed third and fourth instar larvae of the salt marsh moth and fall armyworm ten per plant in the experimental and control plots, modeling a sudden pest surge from a 2.1 average larvae density.

For each of four days the team placed larvae on the plants before sunrise and counted every three hours until 2pm. The researchers also identified the birds feeding at the coffee layer.

The censuses showed significant differences in the number and density of birds feeding on coffee plants between the shade and intensive plants, with a significant synergistic effect for treatment and site. Many more birds and bird species fed on the shade site, with a significant difference between exclosure and control plots not found on the intensive farm.

In other words, larvae were being removed from the shade controls in a way they were not from those on the intensive farm.

Behavioral observation qualified the results. Contrary to expectations, bird diversity did not appear the direct mechanism by which shade coffee was better protected. Instead, it appeared particularly effective insectivores—including the rufous-capped warbler—foraged repeatedly in shade coffee.

That is, there may be a third effect. Despite the traditional troubles in segregating the effects of bird diversity and density out in the field, it appears the more birds feeding here, the more likely one or a few will be particularly effective, if by chance alone. A sampling effect.


Coffee plants may keep the North Country—and the birds south—awake during the day. But there’s no rest for pests at night. While the Rufous-capped warbler and other birds coop, batsmany seed dispersers and pollinatorstake to the air, some, here, to eat pest insects.

To weigh the predatory effects of bats and birds, Perfecto and Kim Williams-Guillén’s team set up a series of exclosure treatments in Soconusco: birds-only during the day, bats-only during the night, both sets day and night, and a control of no netting. The group censused noncolonial arthropods—insects, spiders, harvestmen and mites—every two weeks over a seven-week period during the dry season and over eight weeks during the wet season.

The dual exclusion left the greatest density of arthropods on individual coffee plants, 46% greater than on the controls. Bats had a significant effect in the wet season, their exclusion leaving 89% greater arthropod density than controls, but less so in the dry. Finally, there appeared no significant interaction between birds and bats, indicating their predation is additive and each predates on different types of pests.

The seasonal difference may arise in part from the influx of overwintering songbirds during the dry season and an increase in bat abundance during the wet season when mothers, doubling their typical food intake, must nurse their offspring.

Which bats are gleaning what? By netting bats over 44 nights and acoustically monitoring echolocation calls sensitive enough to detect a caterpillar chewing a leaf, the team identified 24 insectivores across a continuum of shade and intensive coffee plantations.

Few species were captured on a single type of farm, but they did differ in their preferences. Indeed, while species richness differed little across the farm gradient, open-space bats, such as the greater sac-winged bat, appeared most frequent in the more intensive farms while forest bats, including the Argentinean brown bat, appeared more shade-prone.

A follow-up PCR study identified DNA of the berry borer and cicada Idiarthron subquadratum in bat fecal samples. So, yes, the bats are indeed consuming the insects.

While forest bats fed less, as measured by their feeding buzzes, the more intensive the farming, open-space bats did not feed more along the gradient, indicating intensive coffee, some plantations with higher abundances of pests, scored little protection across the bat ensemble.

What’s the take-home? The team concluded that even areas dominated by intensive agriculture would benefit from forest fragments, which offer roosts for all bat insectivores, including open-air species. However, they continue, fine-grain, spatially contiguous agricultural matrices, including shade cultivation, would offer forest bats and other insectivores the kinds of wildlife-friendly refugia in which they could better survive.

Indeed, Guillén-Williams and Perfecto write, with the pressures of poverty and food insecurity also in the mix, blocking off agroecological landscapes into patches of forest and intensive farming, at the heart of much conservation modeling, can cause declines in local biodiversity. When boxed out of all available land, the poorest farmers clear cut the forest, while the largest operations, Perec’s guard at the entrance, surf their own destructive production along an ever-expanding forest edge.


A self-organized pest control emerges here out of ecological interactions.

Such systems are neither preplanned nor static projects. They’re historically contingent. As PVC describe, coffee plants, and their rusts and berry borers, were imported from Africa. White halo fungus are common to the tropics, the leaf-mining moth to Western tropics, and the ants native to southern Mexico. By dint of conscious cultivation and chance biogeography, this particular combination of organisms happened to converge upon this specific and—at the geological time scale—likely passing control program.

While nature bears a connotation of ancient origins, over geologically short, if anthropologically long, intervals, functional ecologies are time and again disassembled and reconstituted.

To scale us back into humanity’s present and pressing needs, in the short term, say, the next few hundred years, if ecosystems were to be conserved and agriculture integrated into local forest matrices, farmers can enjoy such autonomous ecosystem services largely free of charge.

How exactly such services—soil enrichment, water conservation, pest control, etc.—emerge from place to place and how farmers might harness them, for lack of a better term, will require much more of the kind of research the Perfecto and Vandermeer team has pursued. Forget genetic engineering. That’s all cave man brushing his teeth with a smartphone. This, on the other hand, is the cutting-edge research of the 21st century.

Think on what modern agriculture does in contrast. It strips out the forest and destroys the kind of self-integrated services nature often offers, or, better said, embodies. Agribusiness acts as one big exclosure keeping larger fauna out while soil degrades and bugs continue to munch on. Farmers are left to reproduce these services by firebombing their crops and soils with destructive petrochemicals.

Along with the model’s unsustainability, which serves as a tautological rationale for cutting deeper into the forest that remains, intensive agriculture assigns farmers the absurdist task of nailing—like little Maxwell’s demons—every miniscule pest that comes along. What a waste of time and effort, especially as pests evolve resistance to pesticides as a matter of course. Instead farmers could have a whole ecosystem moving that bit of bother off their margins.

Farmer convenience, however, was never really the point of corporate agriculture. On the contrary. “Cargill is engaged in the commercialization of photosynthesis,” CEO Gregory Page said in 2008, “That is at the root of what we do.” By dispossession, monetizing the sun and soil and air out from underneath the farmer and the forest.

9 Responses to “Coffee Filter”

  1. Andrew McGuire Says:

    They have not really developed anything useful. They have happened upon a chance assemblage that happens to work for the control of some non-native diseases. That did not happen with American elm trees in their forest ecosystem when dutch elm disease came in. There is no self-organization here, just a coincidence of species, each trying to survive as best they can, which happened to have benefits to a introduced species.

    If this is a direction we should go, how does anybody advise we go about it. Throwing all kinds of species together and see what works? Sounds risky. There is no proof that this could happen anywhere else. It is delusional to say from this one example that “farmers can enjoy such autonomous ecosystem services largely free of charge.” And the example is for a non-food crop!

    If you are going to make such mighty claims, give more evidence that this is something that farmers, other than Central American coffee growers, can actually use.

  2. Along with a physics envy many agronomists imbue the criteria by which evidence is weighed with culturally specific notions of pragmatism. If it doesn’t translate into immediate use, it isn’t true.

    The research program here is neither as mature as any of us, Perfecto et al. included, would like, nor the appeal to nature you characterize. Indeed, Andrew, I end the piece with the possibility farmers may yet learn to bend ecosystems in directions more conscious than those that helped set coffee’s lucky trajectory. The Kaffeeklatsch here *wasn’t* just a coincidence of species, but dependent in part on human impact. In other words, self-organization, contingency, and anthropogenics aren’t mutually exclusive. Even your dutch elm disease was introduced multiple times by timber imports.

    The problem I see here is, if your own writing elsewhere is any indication, you see the ‘genius’ of nature, modified by smart and not-so-smart humans notwithstanding, at the individual level alone. That choice in philosophical stance, dismissing a hundred years of ecology, has an impact on the types of agriculture thought explorable (and the studies viewed fundable). You like crop rotation and integrated pest management, but seem almost insulted by the notion non-human species also practice a mutual niche construction we can learn from.

  3. a6m7mcguire Says:

    Dr. Wallace, do you know a lot of agronomists? And they have physics envy? Not sure what this refers to or how it fits in your argument, but I will admit that I, and probably many agronomists are practical. However, I did not say that what was found in the research you reviewed was not true, just not very useful.

    You say that the mix of species described here was not just coincidence, but dependent on human impact. Yes, but it was not designed, it was not preplanned as you say. So, if there was no intent behind it, and the species did not even evolve in the same region, what mechanism is behind this? What mechanism would automatically optimize control of the disease that is new to the ecosystem? You can say “self-organization” but that does not say much at all – we could mix a hundred different assemblages and none of them would work as well as the one studied. Nobody would study those failed systems, or they could say we have the wrong mix of species. Many “ecological principles” have been adopted and then abandoned in a hundred years of ecology and there is much confusion in what current ecological evidence really shows.

    I am not saying we cannot learn from nature, but the breadth of what we can learn for agriculture is much narrower than what agroecologists usually claim. Vanermeer et al 2010, in their introduction, review some critiques of agroecology and present their coffee work as an answer to those critiques. If it is an answer, it should give some guidance about how the specifics or identified principles could be used in other circumstances.

  4. The physics envy is found in the reductionist glasses with which, with all due respect, you appear to view the world and, from an Archimedean vantage point, demand nature view itself.

    The example nature offers isn’t necessarily literal, but, as Darwin riffed in the other direction, an analogy from which we can learn. Nature’s examples allows us to ask the questions, for which, understandably, you demand answers. But you dismiss studies that have yet to be done–and which the Union of Concerned Scientists recently described as having been starved of funding–even as industrial agriculture’s ongoing collapse requires we forge new models that better address the metabolic rift between economy and ecology capitalism imposes.

    Even many of the agricultural innovations you cite as markers of how smart we are–indeed after humanity extirpated megafauna, Neolithic agriculture itself–were as much acts of desperation as brainstorming. Talk about stochasticity! And now we find ourselves once again under circumstances where radical rethinking is required. So if the GMOs you champion, then why not attempts at ecosystemic applications?

    Let me drop in passing here that your repeated allusions to “random” ecosystems seem conveniently stuck in 2001. Theories of community assembly now study the interplay between Hubbell’s neutral processes, niche-based environmental filtering and niche-based species sorting–the latter two old stalwarts of ecological theory and practice. Community phylogeny seems a third-rail here for you perhaps because it raises the possibility humans might be able to select at the level of the ecosystem. Yes, like much agriculture til now as much by trial-and-error as by conscious planning.

    For instance, Noble and Fagen’s hybrid density-dependent Lotka-Volterra shows when intraspecific competition limits population growth, extirpation is delayed longer than expected under neutrality. Walter Fitch and I meanwhile describe the anthropogenic filtering apparently in operation for HPAI (H5N1). Keesing and colleagues review many of the albeit difficult complexities involved in making inroads toward a probiotic agroecology.

    In more practical terms, regional planning is a growing subfield, as much a political project as a intellectual endeavor:

    In contrast, if your riposte to Chris Smaje is any indication–“if people have to eat, and the forest is gone…then copying nature should not be our model”–your stands are pragmatism run amok, utterly entrained into the presumptions of a particular Victorian capitalism, as if we must plan agricultures around that “natural” order first and foremost.

    Smaje made something of a similar point about cultural precepts, one which, while I appreciate your evocative stance, you seem as much to fail to grasp as to reject.

  5. Andrew McGuire Says:

    I am not dismissing studies that have yet to be done, only the ones already done relating to the coffee production that you wrote about. Those are the ones you and the authors point to as a good example of how agroecology might work, and I was just asking how the coffee example might be helpful to other farmers. So if the example here is not literal, what is the analogy that we can learn from?

    I do not champion GMOs, but neither do I demonize them. They could be one useful tool among many.

    Perhaps I am reductionist (never thought of it as physics envy, but I see your point, especially when faced with more inconclusive field trial results) but I prefer to think of it as preferring simple explanations over complex ones where a simple one can explain observations just as well. Maybe that is why I am stuck in 2001, however, now my 13 years out-of-date is much improved over “dismissing a hundred years of ecology.” Are these theories of community assembly predictive or only descriptive? Will they ever be able to explain populations better than something as simple as the quantity and quality of food available to a certain species?

    You lost me between “Hubbell’s…probiotic agroecology” but I did pick up on the “trial-and-error” and the “difficult complexities.” Combining trial-and-error methods with difficult complexities sounds much more risky than making some key changes in our current agriculture, such as adopting no-till to manage erosion, more diverse crop rotations, and cover cropping, along with continued breeding to stay ahead of some pests. These are proven practices which could be adopted much more widely and effectively with many benefits. To some extent, they are mimicing nature,(or are they just pragmatism run amok?) but I think they offer much more than the coffee example you wrote about.

  6. I’ve been slow in realizing what we have here is the spectacle of an organic agronomist who opposes conservation agriculture as a matter of principle. It isn’t about data or hypothesis testing (to which we will return). It’s about a strange Manichean distinction between cultivation and nature. It’s about dismissing ecologies extending out beyond the market’s reification as a source of agricultural innovation. It’s about a failure to recognize the environmental precipices humanity has brought itself and the sources of the various ecosystem services, to use the reductionist term, on which all agricultures–organic, conventional and otherwise–ultimately depend.

    Andrew’s responses are filled with rhetorical devices that I think illuminate the nature of the mind, and supporting epistemology, behind them. For one, Masanobu Fukuoka aside, a scientific exploration of the food web that underlies pest control in shade coffee is not an attempt to refute organic agricultures. These need not be in opposition, as different agricultural regimes are appropriate under different circumstances (and even together). If organic farming is so good, then why pursue conservation? Because under a capitalist model of development–all spatial fixing and Lauderdale’s paradox–even organic practices can drive deforestation, nutrient depletion, and farm dispossession.

    If we view agriculture solely through the eyes of absolute production, even by organics’ standards, then we can miss the seemingly orthogonal sources of causality that in actuality drive farming.

    To his credit Andrew cops to knowing little of community assembly. Understandable–no one knows everything, certainly myself included–except one of the theory’s disputable positions has also long served as a bedrock premise of his argument. He now deploys his ignorance here as an attack and characterizes the 2001 vs hundred years botch as my problem.

    So, again, to clarify, Andrew has repeatedly argued here and elsewhere, ecosystems are randomly assembled, in short, to his surprise, taking Hubbell’s stance, which *failed* in overturning niche theory. I do not feel obligated to fill in his education here, but the latter in essence recognizes populations respond to available resources and competitors. That is, they converge on (or diverge into) functional relationships within the ecosystem that regularly produce conditions by which other organisms may prosper (or fail). In other words, nature has long engaged in what farmers by analogy do as a matter of conscious (or as it often begins lucky) course. In integrating nature’s processes more completely from soil to canopy, we can turn the analogies nature offers into the literal of food production and with conservation back again, recycling resources for the next season, year, or generation.

    We might, paraphrasing Richard Levins, replace both peasant and industrial farming with a planned mosaic of land uses, scaled to the biogeographic features of the region, with each patch contributing its own products, yes, but also services needed for production elsewhere. A forest can regulate water, modulate local climate, offer shade to livestock and workers, and provide homes, as the Guillen-Williams work we reviewed discusses, to enemies of pests. There might be social benefits as well, including spacing labor demand throughout the year.

    But Andrew waves off conservation agricultures as if trial-and-error and difficult complexities haven’t characterize all agricultures, including the ones he favors.

    The proof, he demands, is in the pudding. As Richard Kock and I review, a growing number of such agricultures are in development worldwide, some feeding millions, almost all in conflict with industrial agricultures engaged in greenwashing and land grabbing what ‘virgin’ farmland remains. In the face of national policy aimed at subsidizing conventional irrigated crop agriculture and livestock ranching, community trusts in Northern Kenya, for instance, have established viable integrated land management, diversifying livelihoods while benefiting natural resources and livestock production alike. Using conservation of selected key resources, including grass banks, the environment and wildlife is recovering from a previously degraded state, with the economy and income of the people increasing threefold.

    Perfecto and Vandermeer’s work offers one look at the ecological mechanics underlying such efforts. Yes, what works specifically in Mexico may not work elsewhere (or from crop to crop). But what makes that difficult isn’t necessarily the approach’s weakness. In tailoring agricultures to geographically specific ecologies, we may be able to conserve global biodiversity in a just way. Local communities can take executive initiative beyond so-called “community-led” market-oriented pathways promoted by neoliberal natural resource management. Production becomes tied to conservation rather than *just* the marketplace. Once society decides that might be a way to go, and the political economy offers a green light as it were, the science of conservation agriculture turns suddenly pragmatic.

    In short, agriculture is never just about individual plants or livestock. And we’d do well to avoid cutting our wrists with Occam’s Razor.

  7. Andrew McGuire Says:

    Sorry, I really have a hard time following your argument, so I will return to my original observations.

    Please, in plain language, tell me how one goes about tailoring agriculture to geographically specific ecologies? And how is the coffee research an example of such tailoring?

    I ask this because, as I have been trying to say from my first comment, I do not see any tailoring here, no intentionally planned species interactions. They discovered a unique assemblage of species, but what lessons can we learn from this?

  8. We can tailor in two ways. First, addition by subtraction.

    However arrived at, the assemblage of species in this case protects the coffee. Leaving well enough alone is a reasonable if difficult intervention in the face of capital’s compulsion to commoditize production everywhere.

    The approach may require considerable state and local regulation. We can protect forests where pest-gleaning bats can roost, for instance. We can subsidize shade smallholders. But the notion requires recognizing, as the studies here help us grasp (or relearn), that ecologies extending beyond factorial design have agricultural value.

    Second, addition by multiplication.

    We can actively engage in synergistic regional planning. We can produce mosaic biogeographies of cash crops, the various organic practices you study, including contour and trap cropping, etc., inside a broader mix-and-match of primary and secondary environments. We can *plant* forests for gleaning bats, for instance. Or grow shade coffee instead of sun coffee.

    Unlike the agribusiness model, the specifics–when, where, what–will depend in part on the socioeconomic needs of local people and the historically contingent ecological matrix.

    Landscape agricultures have a long history. Indeed, most agricultures until the late 18th century were by definition agroecological in nature, integrating ecological services and, in turn, producing non-food environmental goods as a matter of course.

    The work reviewed in the post is exciting because it describes the extent to which one ecosystemic service, pest control, can be embedded in the broader landscape. That said, biocontrol has long been a means of controlling pests.

    So the controversy I should think isn’t whether nature helps farmers. The question is, how wild can local agroecologies bend?

  9. Andrew McGuire Says:

    RG, thank you for that reply. I agree that it would take state and local regulation, a systems-level change that we, in general, are not good at, unless forced upon us. The controversy for me, however, is how much we can rely on nature to help farmers, which gets partly at your question of “how wild…” Shall we leave it there?

    I have enjoyed the exchange.

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