Ecological intensification at IBC18

Doyle McKey‘s presentation at IBC18 sounds like a doozy. I was alerted to it by Eve Emshwiller on Twitter, who said, among other things:

McKey: ecological intensification, not just green revolution model “intensification” of ag needed. #ibc18

Music to our ears, of course. Here’s a summary from the (very large) Abstract Book of the congress.

The evolutionary ecology of plant chemical defenses in agroecosystems: past, present and future.

McKey, Gleadow, Cavagnaro

Plant chemical defenses mediate interactions between plants, their herbivores and pathogens, and the naturalenemies of these plant parasites. In domesticated plants, farmers are added to this web of interactions. Plant defenses have been subjected to complex selection pressures under domestication, leading both to decreases and to increases in their concentration, and to shifts in their intra-plant distribution. This complexity is explained partly by variation in the kinds of plants farmers chose to domesticate, and partly by the kinds of environments that nature and farmers combined to create in agroecosystems. Today, the interactions mediated by plant defenses are affected by changing climate, rising temperature and increased atmospheric concentrations of carbon dioxide. These changes can threaten food security by lowering not only the production of food but also its nutritional quality. The strategies proposed to counter these threats envisage a wide range of ways, not mutually exclusive, to manage biotic interactions in agroecosystems. These include modifying crop plants’ natural constitutive and induced defenses and other sources of resistance; engineering crop plants to express novel defenses; and increasing the effectiveness of ‘integrated pest management’ (through natural enemies, other components of agrobiodiversity and pesticides) by modifying the structure and functioning of agroecosystems. In this presentation, we examine these proposed solutions through the evolutionary ecologist’s lens: What are their respective costs and benefits, and how do these affect the ecological situations in which each could help farmers produce sufficient amounts of high-quality food? How can the coevolutionary dynamics of interactions between crop plants and their biotic environment be managed to avert catastrophic fluctuation of yield?

Nibbles: Heat, Watermelons, Rye, Apples, Solanum melongena, Pinus edulis, Food systems, Indian rice, Glycene

Nibbles: AnGR, Sustainable diets, MDG, Plantwise, Maize in Africa, Lead farmers, Micro-livestock (again), Cows and climate change

Taro leaf blight confirmed in Nigeria

We’ve blogged a few times about the emerging threat of taro leaf blight in West Africa, and what could be done about it. In case anyone was still in doubt about this threat, here comes the science.

The sequence analysis, morphological characteristics, and pathogenicity test confirmed the taro leaf blight pathogen as P. colocasiae. There are previous reports of occurrence of taro blight-like disease attributed to P. colocasiae in Ethiopia, Equatorial Guinea (1), and more recently in Cameroon, but comprehensive details on pathogen or disease are not available. To our knowledge, this is the first confirmed record in Nigeria of P. colocasiae causing taro blight. This disease poses a serious threat to the production and biodiversity of this important food crop. Urgent interventions are necessary to halt this emerging epidemic in West and Central Africa.

One possible intervention of course, is introducing resistant varieties, and I believe some of the resistant material from various South Pacific breeding programmes has now arrived at IITA from the in vitro genebank at SPC’s Centre for Pacific Crops and Trees.

The history of the effort to breed resistant varieties is described in a recent ACIAR publication. Grahame Jackson, who was involved in the early stages of that work, had this to say about the article in a recent exchange of emails:

Interesting article; but it does not ask the hard, and perhaps more interesting questions: why did it take 5 years before there was a concerted effort to take the only route possible to solve the taro blight problem — to breed for resistance? … How many regional meetings were there over 5 years, until the start of TaroGen; how much money was wasted until a concerted effort was made to tackle the problem? … And in the meantime the Samoa farmers had solved their food insecurity: they had diversified into Alocasia, cassava, breadfruit, and rice. … More recently, another donor said of the disastrous epiphytotic of taro leaf blight in West Africa: “We get half a dozen emails a week describing some outbreak or other, mostly exaggerated. And anyway we can’t do anything until the countries ask.”

Shouldn’t be long now…

Climate change: thanks for all the dead fish

One of the little-appreciated aspects of climate change is that greater variability brings with it more frequent extremes, and if a system is already stressed it doesn’t take much to tip it over the edge. In many places, aquaculture is such a system. The photo 1 is from November 2010, but a glance at the news shows that massive fishkills are a common feature, and not just in The Philippines.

What seems to happen is a series of “unlucky” breaks. The fish are already densely stocked and overfed, and in the morning oxygen levels in the water can be dangerously low because the plants don’t produce oxygen in the dark. Most days, that’s alright, because the algae and plants in the water start to photosynthesise and put out oxygen. A cloudy morning, however, can reduce photosynthesis, and if the day is also hot oxygen levels fall even further as dissolved oxygen escapes. Worse, in hotter water the metabolism of the fish revs up, so they need more oxygen. Throw in a rainstorm, especially if soils around the fish farms are bare, and you get an influx of turbid water that further blocks photosynthesis, dropping oxygen lower still. Tonnes of fish suffocate. And lakes may take years to recover.

Authorities recommend “premature harvest” but that is clearly a Band-aid. The sustainable solution is to make the system more resilient, by decreasing stocking levels and feeding, and trying to ensure that rainwater inflows do not carry too much sediment into the water. Fish farmers cannot control the weather; can they adapt to extremes that can certainly control their business?