Author: Robert Hijmans

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Landscape-agro-ecology

The February issue of BioScience has an article about the connectivity of the agricultural landscape in the USA. Margaret Margosian and colleagues used a graph-theoretical approach to characterize the ‘resistance’ of the American landscape against the spread of crop pests and diseases ((Margaret L. Margosian, Karen A. Garrett, J. M. Shawn Hutchinson, and Kimberly A. With, 2009. Connectivity of the American agricultural landscape: assessing the national risk of crop pest and disease spread. BioScience 59: 141–151)). The idea is that the resistance of the landscape to, say the spread of a maize disease, is higher if there is less maize planted in a region. The authors show that wheat, grown in distinct and poorly connected regions, is less vulnerable than soybean, which is grown in a single contiguous region. They suggest that this approach should be helpful for risk assessment and responding to newly introduced diseases. So far, the results are at the level of a general characterization. It would be great if they could validate their predictions with observed disease data. That will be hard, as there are many other factors, like local weather, that come into play.

But it should be possible. Landscape effects on pest abundance were recently quantified by Douglas Landis and coworkers ((Douglas A. Landis, Mary M. Gardiner, Wopke van der Werf, and Scott M. Swinton, 2008. Increasing corn for biofuel production reduces biocontrol services in agricultural landscapes. PNAS 105(51):20552–20557)). They found that:

Recent biofuel-driven growth in corn planting results in lower landscape diversity, altering the supply of aphid natural enemies to soybean fields and reducing biocontrol services by 24%. This loss of biocontrol services cost soybean producers in these states an estimated $58 million per year in reduced yield and increased pesticide use.

Now think of the work by Claire Kremen and co-workers showing how landscape pattern influences the ‘pollination ecosystem service’ by wild bees ((Kremen, C., Williams, N. M. and R. W. Thorp. 2002a. Crop pollination from native bees at risk from agricultural intensification. PNAS 99:16812-16816)).

And the call for ecological engineering of landscapes to avoid outbreaks of rice pest. And conservationists that work on shade trees in coffee fields, to help birds and other wild organisms — and get high quality coffee.

I think we are witnessing the coming of age of landscape-agro-ecology. The study of agriculture and its biodiversity beyond the field scale.

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Darwin’s kitchen

By Jacob van Etten

It’s January 2009, the Darwin storm breaks loose. A taste of things to come is the publication of a revived and illustrated version of Emma Darwin’s recipe notebook. When authors Dusha Bateson and Weslie Janeway heard about the booklet in the Cambridge University Library they were “very concerned they wouldn’t be able to get a book out of it.” Yet they tried out every recipe and converted dust into gold by publishing them in a colourful cookbook.

Weslie Janeway says:

One of the things that is very clear is that people ate much more seasonally then – although we see the beginnings of modern food supply. For example, they married in 1839, and the railroads were being built. And it began to be possible to have fish away from the coast. Rice was arriving from the rice plantations in America. Basically, they had root vegetables all winter.

The recipe for boiling rice is in Charles Darwin’s own hand.

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No more fish

The Economist had special report on the sea last week, aptly entitled “The tragedy of the sea.” It is a couple of pages long. Read it. After you read my summary and call for action.

The oceans are a common good. Hence we extract from it as much as we can, as quickly as we can, and then dump our trash in it. There is plastic floating everywhere. And we have all but wiped out the large predator fish (cod, tuna, sharks…) that we like to eat so much. We are the main predator now, and a voracious one at that. We have kept the catch from declining with much improved fishing technologies. But that is making things worse in the long run. The remaining fish, lower in the food chain, are getting smaller and smaller. We get more ‘dead zones’, which are quite alive actually, but with slimy and more simple organisms like jellyfish — this is called ‘reverse evolution’. And now we have started big time krill fishing to further undermine life in the oceans. Who knows what that will do. But it is quite likely that fisheries — and perhaps ocean life in general — will collapse.

Some species have already collapsed, but much worse is coming our way. There are many causes. And there are simple solutions. We have to stop dumping our garbage, quit certain fishing methods, we have to manage fish stock rationally, and we should simply eat less fish. Ok, there is fish farming to help. But that ain’t particularly great either (like catching mackerel to raise tuna). Farmed shell fish is probably best. Low in the food chain, and they feed on algae.

Some countries are actually trying to be responsible. For example Iceland and Norway, were fisheries are an important source of income. The European Union is perhaps worst of all. In the EU, the fish business appears to have — improbable as this may seem — an even more disproportionate political influence than the agricultural sector. So the quota are always set too high. And then everybody cheats and catches even more. All that heavily subsidized of course, with most money going to the worst offenders: the Spanish fishermen. ((It seems that the majority of the Spanish fishermen are Basque. I wonder if this these subsidies are an attempt to appease the Basques? Are we killing the oceans to undermine ETA?))

There is not much fish left in European waters, so now they are buying up fishing rights in Africa; and happily deploying illegal fishing methods, and killing massive amounts of ‘by-catch’ such as turtles.

Meanwhile, the EU funds development aid to teach local fisher folk about sustainable fishing. But when the fish is gone, what can they do? Fortunately, in Somalia the fishermen were rather inventive. But who are the real pirates?

Where is the Big Environmental Activism in all this? Greenpeace used to work against nuclear waste dumping and whale killing. They still talk about it, but it seems they have diversified. Perhaps it is not part of their business model to attempt to make their rich constituency change their own behavior. It is perhaps easier to work on scaring us about GMO crops, and the big bad multinationals behind it.

The impeding death of the oceans should be of much more concern.

We need aggressive action. I propose a EU-wide fish-fast. Can we all boycott the EU fishing industry for a year? That should slow things down. ((But don’t replace fish with meat, just with grains, beans and veggies.)) And let’s choose a specific target. Spanish fishers seem to be the worst in the world. So let’s boycott Spain. We can make it the new South Africa. Stop drinking sherry and rioja. Don’t go to the beach ((Sic. Ed.)) of Torremolinos this summer. If you must go to Spain, perhaps because you are a bullfighting aficionado, or to toss goats from a tower, do not eat calamares or other sea creatures. The Spanish are in a bad economic downturn, so we can force them to their knees if we act quickly and decisively. After Spain backs down we’ll take the next target. We have a long list.

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Asweddumized

As designated rice-editor at the Agricultural Biodiversity Weblog, this clipping from The Nation, a Sri Lankan newspaper, landed on my desk. But I am not sure what to make of it.

Researchers (or farmers?) have discovered a (new?) type of rice that can be vegetatively propagated:

The long Mavee rice plant can be cut in pieces and sown to grow as any normal rice. It took the researchers nearly six years to find the specific qualities in the Mavee cultivation, and those plants that contained this quality were later named as Maha Mavee.

Mavee is a variety, maha means wet season (as opposed to yala, the dry season). And as it grows up to “10 feet during flash floods” (that’s quick!) I suppose it is a ‘deep-water’ or ‘floating’ rice type.

So what? Well, the newspaper calls them miracle plants. According to “attorney-at-law and a renowned environmentalist,” Jagath Gunawardane, this is a big deal:

The discovery of this new method of vegetative propagation is likely to revolutionise the entire industry. The Government now needs to help the farmers maintain this cultivation technique, and also prevent companies from claiming patent rights for this ground breaking breakthrough in the agricultural field.

Presumably because of savings in seed cost. Interesting. But then again there are four or five “miracle rices” discovered every year…

To briefly go off on a tangent in an area that I am not a total dummy about, I recently learned the word “asweddumized.” I came across it in the (English language) agricultural statistics of Sri Lanka. I was told that the word was first introduced in 1958 by S.W.R.D. Bandaranayaike, then the Sri Lankan Prime Minister. It stems from the Sinhala word “aswaddanawa,” meaning converting forest land into cultivatable land that has bunds for retaining either irrigation or rainwater, mainly for rice.

But back to the subject at hand. What do you think the prospects are for Maha Mavee? Are there examples of normally seed propagated crops that become vegetatively propagated? Fruit trees through grafting is one example, but that is for a different reason: the propagation of a particular genotype, rather than saving seeds.

People have tried the opposite with potatoes. It seems obvious: ‘true’ (botanical) potato seed is much cheaper than seed tubers, carries fewer diseases, can be stored, etc. But this has not been very successful. Potato was too variable from seed (which makes it so much fun to try this at home), as quality (uniformity and size) is important in the market, and yields were lower. The International Potato Center (CIP) has worked on these issues, and Hubert Zandstra (a former director of CIP) remains optimistic about these seeds, and particularly about their benefits to poor farmers. He thinks that early ‘bulking’ (the formation of tubers) and apomixis may save the day for true potato seed.

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Biodiversity and rice pests

How should farmers deal with rice pests? Spray? Use resistant varieties? Or rely on bio-control ecosystem services?

Brown Plant Hopper Spraying is what many farmers do, to the detriment of their health and environment. It also makes the pest problem worse. Why? Because pesticides also kill the pests’ natural enemies, such as spiders. So you need to spray again, and again. Until the pests are pesticide resistant. This has led to huge outbreaks of brown plant hopper, like in Indonesia in the 1980s, which only stopped after most pesticides were banned. ((Brown plant hopper image from CSIRO.))

Use host plant resistance is what many researchers say. Sounds simple enough, and now there are GMO approaches to get that in different forms. Nature magazine recently had a piece ((Apologies for a post with many references to articles behind a paywall.)) about GM approaches to get insect resistant rice in China. ((Also see this paper by Huang et al. in Science and the critical responses.))

But not everybody agrees. The problem is that some of the major pests occur in large numbers and rely entirely on rice for their life cycle. Strong evolutionary pressure means that these species tend to quickly overcome host plant resistance. In the Nature article, KL Heong calls pest-resistant GM crops a short-term fix for long-term problems caused by crop monoculture and overuse of broad-spectrum pesticides. “Pests thrive where biodiversity is at peril, instead of genetic engineering, why don’t we engineer the ecology by increasing biodiversity?”

This week, in a letter to the editor of Nature, Settele, Biesmeijer and Bommarco also make a case for ecological engineering: the design and construction of ecosystems.

The nice thing about tropical rice is that there is not that much engineering needed to keep pests under control. This is my understanding of how it works:

  • Rule #1: do not kill the beneficial insects (avoid pesticides).
  • Rule #2: help the beneficial insects. For example, by providing ample organic matter to fields, you increase the population of harmless insects and with that the population of generalist predators (see below).
  • Rule #3, maintain a diverse landscape around the rice fields to support useful insects, such as parasitoids that, as adults, need nectar from flowering plants.

William Settle and colleagues studied rice bugs in Indonesia and summed their findings up like this:

By increasing organic matter in test plots we could boost populations of detritivores and plankton-feeders, and in turn significantly boost the abundance of generalist predators. We also demonstrated the link between early-season natural enemy populations and later-season pest populations by experimentally reducing early-season predator populations with insecticide applications, causing pest populations to resurge later in the season.

Irrigated rice systems support high levels of natural biological control that depends on season long successional processes and interactions among a wide array of species. Our results support the conservation of existing natural biological control through a major reduction in insecticide use, and an increase in habitat heterogeneity.

While it seems obvious that relying on and strengthening ecosystem services is the way to go, this is not what is happening. The brown plant hopper is coming back as a major problem, particularly in Vietnam and China. The response? Breeding & Spray, baby, spray.

It is tricky to generalize about agriculture and pests. There are always exceptions and special circumstances. And what if someone can make a rice plant that is truly immune to stem borers and plant hoppers. Well, some other insects would go after the available resources, but it could certainly be beneficial. Also, the biodiversity of insects in tropical rice fields, such as in Indonesia, is much higher than in China (probably largely because of the general relation between latitude and diversity, but perhaps also because of excessive pesticide use in China). So perhaps biocontrol ecosystem services are not as effective in China as in more tropical areas. We should find out.

And we should get serious about ecological engineering.

And not just in rice. Take this article that appeared in this week’s PNAS. It describes the need for maintaining landscape diversity in the USA, to support aphid control in soybeans by ladybugs.