Research on coffee growing

Research on coffee growing

Coffee berry borer update

The coffee berry borer (CBB, Hypothenemus hampei) is one of the most serious pests of coffee. The larvae of this beetle, which is native to Africa, live and feed exclusively on coffee beans. It has spread to coffee farms across the world and despite strict monitoring and prevention measures, showed up in Hawaii a decade ago. It has since island-hopped, most recently being found on Kauai. (Coffee rust, another serious threat to coffee, has also just been found in Hawaii.)

Because it lives inside the coffee cherry and bean, detection and particularly control can be challenging. Due to intense interest in the effects of shade/sun management, biological control (including by birds), and climate change impacts on this insect, I have published a number of posts about it. Although for many years I added CBB research to my coffee bibliography, but it became rather overwhelming and it goes only into early 2016. In 2015, the Journal of Insect Science published a more comprehensive literature review on CBB, which is open access. Google Scholar can provide links to peer-reviewed papers published since that time.

Here are my other previous posts on CBB:

Background information / Research on coffee growing

Coffee growing bibliography update

journalsI have made another periodic update to my coffee bibliography, peer-reviewed papers that deal with various ecological and economic aspects of coffee growing.  Now that the list is over 400 papers, I thought it might be useful to publish a list of the most recent additions when I update the larger list.

Here are the most recent ones. Note that not all are new publications, because when I read new literature, I often find references to older papers I missed. I’ve included the abstracts of papers I found particularly interesting, revealing, or relevant. Warning: long and nerdy!

Barham, B.L., M. Callenes, S. Gitter, J. Lewis and J. Weber. 2011. Fair Trade/Organic coffee, rural livelihoods, and the ”agrarian question”: southern Mexican coffee families in transition. World Development 39: 134—145.

Barham, B.L. and J.G. Weber. 2012. The economic sustainability of certified coffee: recent evidence from Mexico and Peru. World Development 40: 1269—1279.

Consumers increasingly act on preferences for a more just and sustainable world by purchasing certified agricultural products. Using survey data from coffee growers in Mexico and Peru, we explore the economic sustainability of certified coffee, looking at conventional, Fair Trade/organic, and Rainforest Alliance certified growers. The analysis reveals that yields rather than price premiums are most important for increasing net cash returns for coffee growing households. Given the link between net returns and producer participation in certified coffee schemes, the findings suggest that certification norms that permit improving yields are essential for improving grower welfare and attracting and maintaining growers.

De Beenhouwer, M., L. Geeraert, J. Mertens, M. Van Geel, R. AcuÁ±a Castillo, K. Vanderhaegen and O. Honnay. 2016. Biodiversity and carbon storage co-benefits of coffee agroforestry across a gradient of increasing management intensity in the SW Ethiopian highlands. Agriculture, Ecosystems & Environment 222: 193—199.

Bravo-Monroy, L., S.G. Potts and J. Tzanopoulos. 2016. Drivers influencing farmer decisions for adopting organic or conventional coffee management practices. Food Policy 58: 49—61.

Colombia is one of the world’s most important producers of Arabica coffee (Coffea arabica), whose coffee-growing zone coincides with a biogeographic hotspot of biodiversity. Given that coffee agroecosystems are grown by both organic and conventional schemes of management in Santander, a region which produces coffees with specialist distinctive flavours, this study aims to better understand the factors that influence the adoption of these different schemes of management. A combination of ethnographic techniques and quantitative methods were used to examine the predominant drivers of adoption and revealed farmer perceptions associated with coffee farming, and the complexity of interacting factors, that surround their decision making. The results of qualitative analysis suggests that social identity of coffee growers, the existence of farming spaces (lived, perceived, rationalised), the influence of coffee institutions, attitudes about management practices, and social relations of production, all play an important role in the process of decision making. In quantitative terms, we identified 18 socioeconomic drivers, some with interacting effects that had significant influence on the decision to adopt either organic or conventional practices. In particular, at local scale, important factors were technology availability, the type of landowner, formal education of farmers, the role of institutions, membership of community organisations, farm size, coffee productivity and the number of coffee plots per farm. Likewise, economic drivers, such as crop profitability, determined how farmers are involved in trade and market networks at broad regional, national, and international spatial scales. By adopting a more integrated approach, combining qualitative and quantitative methodologies, we characterised the complexity of factors that influencing adoption of coffee management schemes and show that not only financial factors but also a variety of other social factors drive farmer decision making. Identifying the most influential behavioural drivers provides policy with opportunities to better support farmer livelihoods.

Chaves, B. and J. Riley. 2001. Determination of factors influencing integrated pest management adoption in coffee berry borer in Colombian farms. Agriculture, Ecosystems & Environment 87: 159—177.

Faure, G., J.-F. Le Coq, I. Vagneron, H. HocdÁ©, G.S. MuÁ±oz and M. Kessari. 2012. Strategies of coffee producers’ organizations in Costa Rica toward environmental and social certification processes. Cahiers Agricultures 21: 162—168.

GuzmÁ¡n, A., A. Link, J.A. Castillo and J.E. Botero. 2016. Agroecosystems and primate conservation: Shade coffee as potential habitat for the conservation of Andean night monkeys in the northern Andes. Agriculture, Ecosystems & Environment 215: 57—67.

Haggar, J., M. Barrios, M. BolaÁ±os, M. Merlo, P. Moraga, R. Munguia, et al. 2011. Coffee agroecosystem performance under full sun, shade, conventional and organic management regimes in Central America. Agroforestry Systems 82: 285—301.

Changes in coffee economics are leading producers to reduce agrochemical use and increase the use of shade. Research is needed on how to balance the competition from shade trees with the provision of ecological services to the coffee. In 2000, long-term coffee experiments were established in Costa Rica and Nicaragua to compare coffee agroecosystem performance under full sun, legume and non-legume shade types, and intensive and moderate conventional and organic inputs. Coffee yield from intensive organic production was not significantly different from intensive conventional in Nicaragua, but in Costa Rica it was lower during three of the six harvests. Full sun coffee production over 6 years was greater than shaded coffee in Costa Rica (61.8 vs. 44.7 t ha−1, P = 0.0002). In Nicaragua, full sun coffee production over 5 years (32.1 t ha−1) was equal to coffee with shade that included Tabebuia rosea (Bertol.) DC., (27—30 t ha−1) and both were more productive (P = 0.03) than coffee shaded with Inga laurina (Sw.) Willd. (21.6 t ha−1). Moderate input organic production was significantly lower than other managements under all shade types, except in the presence of Erythrina poepiggina (Walp.) O.F. Cook. Inga and Erythrina had greater basal area and nutrient recycling from prunings than other shade species. Intensive organic production increased soil pH and P, and had higher K compared to moderate conventional. Although legume shade trees potentially provide ecological services to associated coffee, this depends on management of the competition from those same trees.

Hardt, E., E. Borgomeo, R.F. dos Santos, L.F.G. Pinto, J.P.P. Metzger and G. Sparovek. 2015. Does certification improve biodiversity conservation in Brazilian coffee farms? Forest Ecology and Management 357: 181 — 194.

Socio-environmental certification uses evaluation criteria to promote the conservation of the natural environment and landscape connectivity, with the aim of constructing agricultural landscapes more suitable for biodiversity conservation. To test this, we examine whether socio-environmental certification of Brazilian coffee farms contributes to local conservation, particularly in terms of deforestation control, habitat protection and regeneration, and connectivity. The analysis compared changes in landscape structure and connectivity in certified farms before (1995—2002) and after nine years from the beginning of the certification process (2002—2011), using as a reference the surrounding landscape and a control group of non-certified farms. To quantify changes in landscape connectivity we used probabilistic indices of functional connectivity based on graph theory, and two species of terrestrial mammals with contrasting dispersal capacities and habitat requirements: Priodontes maximus (giant armadillo) and Marmosops incanus (gray slender mouse opossum). Our results show that changes in the last decade have been subtle, but that certified farms differ from surrounding areas for the greater deforestation control and habitat availability for both land cover types, and for the greater connectivity for P. maximus. The difference between certified and non-certified farms is not clear-cut, however, we have evidence that the certified farms contributed more than the surrounding areas to the conservation of the studied species when the balance of gains and losses of connectivity is considered. The subtle differences in temporal changes and groups might be partially explained by the fact that certified farms already had a different conservation profile at the beginning of the certification process. Despite the limitations in the sampling size (small number) and time scale (only nine years after certification) which may hinders the detection of certification effects, our findings indicate that certification was important in controlling deforestation and the conversion of new natural areas to agricultural lands.

de JesÁºs-Crespo, R., D. Newsom, E.G. King and C. Pringle. 2016. Shade tree cover criteria for non-point source pollution control in the Rainforest Alliance coffee certification program: A snapshot assessment of Costa Rica’s TarrazÁº coffee region. Ecological Indicators 66: 47—54.

Management of non-point source pollution is of great importance in the context of coffee agriculture, as this land use often coincides with headwater streams that influence water quality at the basin scale. Sustainability certification programs, such as the Rainforest Alliance (RA), provide management guidelines that promote non-point source pollution control in coffee. One of these practices is the maintenance of shade trees within farms, required by RA at a minimum of 40% shade tree cover. Here we assess the effectiveness of this practice in TarrazÁº, a high elevation coffee growing region in Costa Rica. We monitored indicators of non-point source pollution in streams with both high and low shade tree cover. Streams with High Shade Tree Cover (HSTC, N = 5 subwatersheds) had 35—55% cover, approximating or exceeding the RA recommendation of at least 40%; and streams with Low Shade Tree Cover (LSTC, N = 5 subwatersheds), had 18—31% cover. We monitored the ten study streams during the dry (April & December), transition (July), and peak (October) rainfall seasons of 2013, and compared responses using t-tests. We found support for the effectiveness of shade tree cover in controlling non-point source pollution: HSTC streams had significantly (p = 0.042) lower mean annual turbidity and significantly (p = 0.004) lower turbidity during the transition season. HSTC streams also had significantly (p = 0.05) lower conductivity values during the transition period, although this trend was weaker through the year. Subwatersheds with HSTC streams were characterized by a higher percentage of RA-certified coffee than LSTC streams. Our study provides evidence of the benefits of RA shade tree cover criteria for managing water quality within high elevation tropical agro-ecosystems, especially if implemented at the watershed scale. These results contribute to our understanding of the role of agroforestry certification on tropical ecosystem conservation, and are the first account of the effectiveness of a specific coffee certification guideline on non-point source pollution control.

Mansingh, G., H. Reichgelt and K.-M. Bryson. 2007. CPEST: An expert system for the management of pests and diseases in the Jamaican coffee industry. Expert Systems with Applications 32: 184—192.

MarÁ­n, L., S.M. Philpott, A. De la Mora, G. Ibarra NÁºÁ±ez, S. Tryban and I. Perfecto. 2016. Response of ground spiders to local and landscape factors in a Mexican coffee landscape. Agriculture, Ecosystems & Environment 222: 80—92.

MariÁ±o, Y.A., M.-E. PÁ©rez, F. Gallardo, M. Trifilio, M. Cruz and P. Bayman. 2016. Sun vs. shade affects infestation, total population and sex ratio of the coffee berry borer (Hypothenemus hampei) in Puerto Rico. Agriculture, Ecosystems & Environment 222: 258—266.

McCook, S. and J. Vandermeer. 2015. The big rust and the Red Queen: long-term perspectives on coffee rust research. Phytopathology: PHYTO—04—15—0085—RVW.

Milligan, M.C., M.D. Johnson, M. Garfinkel, C.J. Smith and P. Njoroge. 2016. Quantifying pest control services by birds and ants in Kenyan coffee farms. Biological Conservation 194: 58—65.

Ecosystem services, such as pest control and pollination, are critical benefits of biodiversity important for agricultural production. Predators, including insectivorous birds and ants, can provide important biological controls in agroecosystems, boosting crop yield and offsetting the need for expensive inputs such as pesticides. Local habitat and landscape characteristics can affect the delivery of ecosystem services, thereby influencing optimal land allocation for crop production and biodiversity. In order to better understand the relationship between ecosystem services and the surrounding habitat, we conducted a sentinel pest experiment to investigate predation levels in response to a novel pest on coffee farms in central Kenya. The frequency of predation decreased significantly with increasing distance from adjacent forest fragments and was correlated with bird species richness. Predation was also significantly higher on shade compared to sun coffee farms. We conclude that a land sharing approach, via both the integration of shade trees and the conservation of small forest fragments within or adjacent to a farm, can support increased levels of pest control services provided by birds and ants in Kenyan coffee farms.

Perfecto, I., J. Vandermeer and S.M. Philpott. 2014. Complex ecological interactions in the coffee agroecosystem. Annual Review of Ecology, Evolution, and Systematics 45: 137—158.

Rueda, X. and E.F. Lambin [online]. 2013. Responding to globalization: impacts of certification on Colombian small-scale coffee growers. Ecology and Society 18.

Rueda, X., N.E. Thomas and E.F. Lambin. 2014. Eco-certification and coffee cultivation enhance tree cover and forest connectivity in the Colombian coffee landscapes. Regional Environmental Change 15: 25—33.

Segura, H.R., J.F. Barrera, H. Morales and A. Nazar. 2004. Farmers’ perceptions, knowledge, and management of coffee pests and diseases and their natural enemies in Chiapas, Mexico. Journal of Economic Entomology 97: 1491—1499.

Soto-Pinto, L., Y. Romero-Alvarado, J. Caballero-Nieto and G. Segura Warnholtz. 2001. Woody plant diversity and structure of shade-grown-coffee plantations in Northern Chiapas, Mexico. Revista de BiologÁ­a Tropical 49: 977—987.

Valencia, V., S. Naeem, L. GarcÁ­a-Barrios, P. West and E.J. Sterling. 2016. Conservation of tree species of late succession and conservation concern in coffee agroforestry systems. Agriculture, Ecosystems & Environment 219: 32—41.

Valencia, V., P. West, E.J. Sterling, L. GarcÁ­a-Barrios and S. Naeem. 2015. The use of farmers’ knowledge in coffee agroforestry management: implications for the conservation of tree biodiversity. Ecosphere 6: 1—17.

Weber, J.G. 2011. How much more do growers receive for Fair Trade-organic coffee? Food Policy 36: 678—685.

Wollni, M. and B. BrÁ¼mmer. 2012. Productive efficiency of specialty and conventional coffee farmers in Costa Rica: Accounting for technological heterogeneity and self-selection. Food Policy 37: 67—76.

Research on coffee growing

Coffee berry borer research

The Journal of Insect Science recently published an open-access paper: A coffee berry borer (Coleoptera: Curculionidae: Scolytinae) bibliography.  This updates previous compilations of research, and now contains nearly 1900 references from mostly peer-reviewed sources. This very useful resource can be downloaded from the journal home page here.

I also maintain a bibliography of peer-reviewed papers focused on coffee growing, biodiversity, certifications, and related issues on this page, updated periodically. I’ve included a link to the coffee berry borer paper there as well.

Birds and other biodiversity / Research on coffee growing

Research: More birds eating coffee berry borers

Forest bolsters bird abundance, pest control, and coffee yield. Karp, et. al., 2013. Ecology Letters.

I’ve summarized several papers from Matt Johnson and his students at Humboldt State University (CA) who study how birds provide pest control on coffee farms in Jamaica by preying on coffee berry borers. Here’s a new paper on the same theme, with the research being done in Costa Rica.

cr-cbb-birds2

From top: Buff-throated Foliage-Gleaner, Rufous-breasted Wren, White-tailed Emerald, Rufous-capped Warbler, Yellow Warbler. Credits below.

These researchers looked at coffee berry borer (Hypothenemus hampei, CBB) predation by both bats and birds; since bats were not found to be significant predators on CBB in this study I won’t go into those findings. The farms examined were “sun coffee” with less than 25% canopy cover, as shade coffee is not common in Costa Rica. To determine what birds were eating CBBs, the authors used DNA analysis of bird droppings.  This is a great way to determine if birds are feeding on the CBB, since the insects are extremely tiny they would be difficult to detect in droppings visually. Still, the bird would have had to have recently fed on CBBs, and the DNA would need to have passed through the digestive system without too much degradation to be detected by this method.

When birds were excluded from the coffee shrubs, the number of shrubs infested with CBB almost doubled, and the CBB drilled deeper into the coffee cherries. Birds were more common in farms that had some embedded or nearby forest cover…and the more forest cover the less severe the borer infestations on control plots. Perhaps surprisingly, very small (less than a hectare) forest patches weaving through the farms provided more of this pest-control benefit than having a large forest reserve nearby.

The authors also calculated the economic benefits the birds provided to farmers. For two farms that formed the core of their study, birds saved between 25 and 70 kg of coffee per hectare annually, for a cost savings of US$75-310 per hectare based on the prices being received. For the smaller farm the total economic benefit of birds preying on CBBs was between US$3500-$9400, and for the larger farm US$17,000-55,100. Since the CBB has only been present in Costa Rica since 2000 and in the vicinity of the study sites since 2005, cost savings provided by the birds may be even higher when CBBs are more-well established.

Bird species that were found to have preyed upon CBBs were:

  • Buff-throated Foliage-Gleaner (Automolus ochrolaemus). A common and widespread resident bird in the tropics which feeds on insects in shady forest situations.
  • Rufous-breasted Wren (Pheugopedius rutilus). A common wren resident wren in parts of Central America that feeds on insects in thickets and forest edges.
  • Rufous-capped Warbler (Basileuterus rufifrons). A resident tropical warbler profiled here in our Know Your Coffee Birds series.
  • White-tailed Emerald (Elvira chionura). A resident tropical hummingbird known for inhabiting shaded coffee farms.
  • Yellow Warbler (Setophaga petechia). While there is a resident form of Yellow Warbler in Costa Rica, it inhabits coastal areas. The Yellow Warblers in this study were migrants that breed in North America.

It’s interesting to note that although CBB have not been in the area for very long, native and migratory birds are already using them as a food source.

These studies on the identification, ecology, and effectiveness of natural predators of CBB are critical, given the expected spread of this pest due to climate change and the fact that they are evolving resistance to the potent insecticides used to combat them.

See also:

 Photo of Buff-throated Foliage-Gleaner by Jerry Oldenettel; Rufous-breasted Wren by Francesco Veronesi; White-tailed Emerald by Michael and Ellen Cox; all under a Creative Commons license. Rufous-capped Warbler and Yellow Warbler by Julie Craves, all rights reserved.

D.S. Karp, C.D. Mendenhall, R. Figueroa Sandi, N. Chaumont, P.R. Ehrlich, E.A. Hadly, & G.C. Daily (2013). Forest bolsters bird abundance, pest control and coffee yield Ecology Letters DOI: 10.1111/ele.12173

Research on coffee growing

Research: Kopi luwak (civet poop) coffee threatens welfare of animals

Observations of small carnivores in Jakarta wildlife markets, Indonesia, with notes on trade in Javan Ferret Badger Melogale orientalis and on the increasing demand for Common Palm Civet Paradoxurus hermaphroditus for civet coffee production. Shepherd, 2012. Small Carnivore Conservation.

Kopi luwak — coffee beans pooped out by small mammals called civets — is the hideous fad that just won’t go away.  In a previous post and review, all the ins and outs of this awful practice and its results are covered.  Theoretically at least, the pooped-out coffee beans used to be collected from the forest floor after the civets ate them while foraging in the wild. The popularity of this type of coffee, however undeserved, has resulted in most luwak coffee coming from animals kept in small cages in unsanitary conditions, fed only coffee cherries. This is not a nutritionally sound diet — note that they are carnivores; meat, not fruit, should be the primary element of their diets. Late last year, The Guardian did a piece on the abuse of animals kept to feed the kopi luwak craze.

This paper, published in Small Carnivore Conservation, the journal of the Small Carnivore Specialist Group of the IUCN (International Union for Conservation of Nature), highlights the plight of these animals in Asian wildlife markets. Common Palm Civets, the species most often used to produce kopi luwak, were the most common small carnivores being offered for sale in markets in Jakarta, Indonesia. Two other civet species were also found.

According to the paper, Common Palm Civets have a quota for capture and trade in Indonesia — only 270 are allowed per year to be sold as pets. However, because this species is also often considered a pest, these quotas are not enforced. Civets are also sold in markets in other Asian countries as “pets”, but the author noted that in Bali, at least one dealer noted the production of kopi luwak as a selling point. In a great piece covering this same paper at the online conservation site Mongabay, the author notes that civets and their relatives are already under pressure from habitat loss and hunting. This exploitation just adds another threat to the health of their populations.

Additionally, the frequently inhumane conditions under which these animals are kept threatens the individual welfare of civets. Unless new regulations are formulated and enforced for kopi luwak “farms,” civets are likely to be continued to be captured and confined, all for the sake of novelty coffee.  A quicker solution is for everyone to reject the notion of kopi luwak and refuse to purchase it, period. I know there are a few companies offering wild-collected kopi luwak, but as long as those purveyors are given a pass, there will be exploiters and liars taking advantage of the market. Just say no to kopi luwak.

More information, including updated links:

C.R. Shepherd (2012). Observations of small carnivores in Jakarta wildlife markets, Indonesia, with notes on trade in Javan Ferret Badger Melogale orientalis and on the increasing demand for Common Palm Civet Paradoxurus hermaphroditus for civet coffee production. Small Carnivore Conservation, 47: 38-41.

Climate change / Coffee and the environment / Research on coffee growing

Is coffee really at risk of extinction?

Recently, a paper was published in the peer-reviewed, open-access journal, PLoS ONE: “The impact of climate change on indigenous arabica coffee (Coffea arabica): predicting future trends and identifying priorities.”

It specifically looked at wild, endemic populations of Coffea arabica in Ethiopia (and a few points in nearby areas). In a nutshell, the authors created computer models using known localities, environmental conditions, and various climate change scenarios to predict current and future distribution of these populations. The models determined a reduction (ranging from very worrisome to nearly complete) in suitable locations in this region by 2080. This is no surprise. I’m not sure I’ve seen any models that do not show some impact on the ranges (whether expansions, contractions, or shifts) of plants and animals under any accepted climate change scenarios. And we all know coffee is a very climate-sensitive species, especially arabica coffee.

It is a big leap to go from what this paper actually examined and concluded to the shrill, frantic headlines and stories pumped out by mainstream  media. For instance, under the headline So Long, Joe? World Coffee Supply Could Be Threatened By Climate Change, US News and World Reports declared “Nearly 100 percent of the world’s Arabica coffee growing regions could become unsuitable for the plant by 2080.” This is way off base, given the study was only looking at wild arabica in the vicinity of southwest Ethiopia. The article also stated that “If Arabica becomes impossible to raise in its native areas, it could wreak havoc on the economies of the mainly third-world countries in which it grows,” which is ridiculous considering that coffee is already grown on millions of acres in dozens of countries around the world where it is not native. Likewise, Salon.com made the even more extreme statement, “By the end of this century, climate change could wipe out nearly all the world’s coffee” in their piece, Coffee beans at risk of extinction.

I could cite more hand-wringing examples of failure by news outlets to make an honest effort at reporting what this paper really said, but you get the gist. As a scientist, journalist, editor, and world citizen, this lack of accuracy disgusts me. First, there is no excuse for it; the paper is open-access and anyone can read it for themselves! Apparently, this dismal reporting stems from incomprehension, laziness, and/or incompetance on the part of writers and their editors, as well as a disregard for actually informing the public in favor of profit for the news outlet via sensationalism.

If you’ve read this far and want a more nuanced analysis of the paper, I’ll give a few of my thoughts.

I thought the  paper was thorough and well-conceived. The bioclimatic modelling used is pretty standard for looking at the distribution of species under future climate change situations. Computer models, of course, are as robust as the data one feeds into them.  In this paper, the bulk of the data used to model current distribution was based on unpublished field work done by one of the authors; the rest was from herbarium specimens or literature reports, some dating back to 1941.  Ergo, it is technically not possible to evaluate the quality of this data. The climate data emphasizes factors like temperature, rainfall, and seasonality. These are all critical for coffee growing, but the models did not integrate other important environmental influences on coffee production such as soil types, microhabitats, and ecological processes, and the authors acknowledge those shortcomings.

The results and discussion provided didn’t stray far beyond these limitations and delivered on the authors intended goals: to identify conservation, monitoring, and research needs for wild, native Coffea arabica. It established baseline data to help assess future impacts of climate change on these populations, having identified suitable localities for them.

Two paragraphs in the discussion are devoted to the implications of the findings for cultivated arabica coffee, and they are also presumed to be negative. Does this mean the news headlines, while not the subject of the actual paper, are true? Not exactly. The authors note that optimum cultivation requirements for arabica coffee will likely become harder to achieve in the face of climate change, productivity will probably be reduced, and more intense management (especially irrigation) will be needed.

Is the potential loss of genetic resources in these populations something to worry about? In their article Climate change threatens sweet smell of morning coffee, Reuters took a stab at trying to interpret what the paper had to say by writing, “Although commercial coffee growers would still be able to cultivate crops in plantations designed with the right conditions, experts say the loss of wild arabica, which has greater genetic diversity, would make it harder for plantations to survive long-term and beat threats like pests and disease.”  Indeed, a reason the authors focused on wild populations of arabica in their native range was that their genes may be valuable for breeding disease and pest resistance and climate resilience into commercially grown coffee. While this is logical, and maybe even likely, the paper did not provide detail on the genetic diversity, number of unique arabica strains, or other features of the coffee being mapped and modelled. In fact, the authors noted that genetic variation in wild arabica still needed to be assessed. Further, other more tolerant species of coffee (primarily Coffea canephora, robusta, and its hybrids) are being used in breeding programs today and probably hold the best hope for resilience in commercial coffee. (This is not to discount the importance of preserving these populations; I’m a strong believer that genetic biodiversity should be preserved regardless of it’s commercial value.)

One point was made in the paper that I thought was not given enough emphasis. The biggest driver of the loss of wild coffee populations has been and is deforestation and land conversion, which themselves exacerbate climate change. We can sit on our hands and watch one of the models in this paper play itself out, with what the authors term as “profoundly negative influence” on coffee. Or we can encourage the production (and consumption) of coffee grown in an ecologically-sustainable manner, using carbon-capturing shade trees and sensible agroforesty techniques — and reward farmers for their troubles by paying more for eco-friendly coffee. The press  could make a real contribution by informing the public on the issues surrounding the sustainability of one of the world’s most popular beverages, rather than thoughtlessly spew out faulty proclamations with little basis in fact and no call to action.

More of my posts on coffee and climate change here.

Davis AP, Gole TW, Baena S, & Moat J (2012). The Impact of Climate Change on Indigenous Arabica Coffee (Coffea arabica): Predicting Future Trends and Identifying Priorities. PloS one, 7 (11) PMID: 23144840

Research on coffee growing

Research: Pollination and fruit set in India

Status of pollinators and their efficiency in coffee fruit set in a fragmented landscape mosiac in South India. Krishnan, Kushalappa, Shaanker, and Ghazoul. 2012. Basic and Applied Ecology 13:277-285.

The role of various types of pollination — self, wind, and insect — on robusta coffee (Coffea canephora) was studied in the Kodagu (Coorg) region in Karnataka state in south India. Robusta coffee is generally thought to be wind-pollinated, with fruit set being enhanced if cross-pollinated by insects.

Many insects (as well as other arthropods and birds) can act as pollinators, but in this study bees made up nearly 97% of the floral visitors to the coffee. The main pollinator was the giant Asian honeybee (Apis dorsata, a relative of the familiar European honeybee).  Apis cerana and Tetragonula iridipennis were the other two bee species that most frequently visited coffee flowers, and together with the giant Asian honeybee comprised 98.3% of all visits to coffee flowers. While pollination can occur from wind, bee pollination increased fruit set by 50% over wind.

Amegilla bee on lantana. This genus of bees were once common in coffee plots, but now feed on non-native lantana flowers. Photo from Wikimedia Commons.

The authors noted that in other countries studied, the suite of pollinators usually comprised of many more species, rather than being dominated by so few as in the present study. They looked at a similar, though limited, study of pollinators of coffee done in the same area in 1915.  In that study, Apis cerana was the most common; this species has recently (early 1990s) declined due to a virus. The older study listed the second most abundant bees pollinating coffee as those in the genus Amegilla; in the present study these made up a mere 0.1% of visits.  The authors observed Amegilla bees foraging instead on a non-native invasive plant, Lantana camara. This indicates that invasive species may change the behavior of coffee pollinators — and this role of invasive species deserves more study.

The giant Asian honeybees nest in nearby forests in large trees. The authors concluded that, given the high dependence on pollination by this species, preservation of these trees in remnant forests within the foraging range of the bee is crucial to the successful production of coffee in this area.

This post is in recognition of Pollinator Week, an international celebration of the valuable ecosystem services provided by bees, birds, butterflies, bats and beetles.

Smitha Krishnan, Cheppudira. G. Kushalappa, R. Uma Shaanker, & Jaboury Ghazoul (2012). Status of pollinators and their efficiency in coffee fruit set in a fragmented landscape mosiac in South India. Basic and Applied Ecology: dx.doi.org/10.1016/j.baae.2012.03.00

Research on coffee growing

Research: How landscape influences coffee pests

Landscape context and scale differentially impact coffee leaf rust, coffee berry borer, and coffee root-knot nematodes. Avelino, Romero-Gurdian, Cruz-Cuellar, and DeClerk. 2012. Ecological Applications.

In ecology, context is important. Ecosystems are comprised of many interdependent organisms, and those interactions are influenced by the environment at different scales. In the case of coffee pests, that can mean the conditions on an individual coffee plant, in a particular patch of coffee, or on one or many neighboring farms. This study looked at how the surrounding landscape — up to 1500 m around coffee plots — impacted the incidence of several coffee pests.

The authors looked at 29 small plots of coffee within larger plantings in Costa Rica. They wanted to see how different land use practices at different scales might influence coffee leaf rust (Hemileia vastatrix), the coffee berry borer (Hypothenemus hampei), and root-knot nematodes (in the genus Meloidogyne).

Populations of the virtually immobile root-knot nematodes did not appear to be correlated with landscape. Not surprisingly, coffee plots embedded in a landscape with a high proportion of other coffee plots facilitated the movement and spread of coffee berry borers.

I found the response of coffee leaf rust to be the most interesting: there were increased epidemics of coffee leaf rust in areas where coffee plots were in a landscape that had open uses such as pasture. The rust spores are spread by wind. The air turbulence produced by gaps of pasture among plots of coffee promoted the release of the rust spores which then dispersed in the landscape.  When the wind turbulence released clusters of spores, they did not travel as far and resulted in locally intense outbreaks of rust.

The landscape-scale effects on the rust and borer varied depending on the distance of the plots from the various landscape features, and also fluctuated during the season, so the effects of landscape are not simple; these are outlined in the paper. However, the results suggest that growing coffee in plots that are separated from others by native forest could hinder the spread of both the borer and the rust, as well as act as reserves and corridors for other biodiversity.

Avelino, J., Romero-GurdiÁ¡n, A., Cruz-Cuellar, H., & Declerck, F. (2012). Landscape context and scale differentially impact coffee leaf rust, coffee berry borer, and coffee root-knot nematodes Ecological Applications, 22 (2), 584-596 DOI: 10.1890/11-0869.1

Research on coffee growing

The quest to grow caffeine-free coffee

The science journal Nature recently ran a great article outlining the problems in growing an ultra-low or caffeine-free variety of coffee, particularly one that would be commercially-viable. It goes over the pitfalls of various attempts at developing and cultivating a species or strain of Coffea that would produce naturally caffeine-free beans, including hybridization and genetic engineering.

Decades of study have clarified how Coffea plants synthesize caffeine, the alkaloid that provides a measure of pest control to the plants. But manipulating the genes in Coffea arabica has not resulted in plants that reliably produce caffeine-free beans.

There are over 100 species of Coffea, and quite a few produce little or no caffeine. I wrote about one caffeine-free species from the Cameroon, described in 2008. Genetic compatibility problems have proven a barrier in transferring the caffeine-free property from other species to Coffea arabica. Wild, low-caffeine species of coffee have other bitter alkaloids that stand in for caffeine as pest protection, so cross-breeding with arabica has resulted in low cup quality. Individual plants of Coffea arabica that produce little or no caffeine have also been found, and arabica seeds have even been soaked in chemicals to induce mutations. Still, cross-breeding, cloning, and other techniques have so far failed to produce coffee with enough of the right stuff and less of the wrong stuff.

The article is open access, and I’ve included a list of related scientific literature below for more information.

Campa, C., Doulbeau, S., Dussert, S., Hamon, S., and Noirot, M. 2005. Diversity in bean caffeine content among wild Coffea species: evidence of a discontinuous distribution. Food Chemistry 91:633—637.

Mazzafera, P., Baumann, T. W., Shimizu, M. M., and Silvarolla, M. B. 2009. Decaf and the steeplechase towards decaffito—the coffee from caffeine-free arabica plants. Tropical Plant Biology 2:63-76.

Nagai, C., Rakotomalala, J. J., and Katahira, R. 2008. Production of a new low-caffeine hybrid coffee and the biochemical mechanism of low caffeine accumulation. Euphytica 164:133—142.

Ogita, S., Uefuji, H., Yamaguchi, Y., Koizumi, N. and Sano, H. 2003. RNA interference: Producing decaffeinated coffee plants. Nature 423: 823.

Silvarolla, M. B., Mazzafera, P. and Fazuoli, L. C. 2004. Plant biochemistry:  A naturally decaffeinated arabica coffee. Nature 429:826.

Photo by Chris Brown (zoonabar) under a Creative Commons license.

Coffee regions / Research on coffee growing

Research: Puerto Rican shade coffee and biodiversity

Shade-grown coffee in Puerto Rico: Opportunities to preserve biodiversity while reinvigorating a struggling agricultural commodity. Borkhataria, Collazo, Groom, and Jordan-Garcia. 2012. Agriculture, Ecosystems, and Environment.

Even though coffee was first planted in Puerto Rico in 1736, we don’t hear much about it. In part, this is because much of the coffee grown there is consumed there. Still, coffee was PR’s major crop in the early 1800s, but hurricanes, high labor costs, low yields and other problems diminished its importance. Government support has been largely responsible for its persistence, and this included recommendations to increase yield by converting to sun coffee in the late 1980s, with any “shade” farms directed to use widely spaced trees and total shade not exceeding 30%. According to agricultural statistics summarized in the first paper noted above, there were 15,144 ha of coffee in PR in 2007 on over 5,600 farms which averaged 20 ha.  Over 69% of this land was characterized as sun coffee.

Authors also surveyed a random sample of 100 coffee farmers (nearly all of which answered the questions regarding shade). A third of the farmers considered their coffee shade coffee, and another 21% said they had both shade and sun coffee. However, when evaluated by the surveyors, the actual number of farms that could be considered traditional or polyculture shade was only 8%. This points out the clear problem of a lack of an agreed-upon definition of “shade”!

Most PR coffee farmers receive some sort of governmental assistance, often in the form of fertilizers. One farmer interviewed said he preferred to grow under shade, but grew a few hectares of coffee in sun in order to have access to incentives. About 70% of the farmers said they’d be willing to plant shade trees if they were encouraged by the government and if shade trees were provided to them.

The authors recommended government practices which would help promote production that protected biodiversity, took advantage of markets that favored sustainable agriculture, and made incentives were more available to farmers wishing to grow shade coffee.

Borkhataria, R., Collazo, J., Groom, M., & Jordan-Garcia, A. (2012). Shade-grown coffee in Puerto Rico: Opportunities to preserve biodiversity while reinvigorating a struggling agricultural commodity Agriculture, Ecosystems & Environment, 149, 164-170 DOI: 10.1016/j.agee.2010.12.023

Coffee regions / Research on coffee growing

The curse of the spud

“Potato taint” in African coffees

Some East African coffees, especially those from Rwanda, but also Burundi, Tanzania, Zambia, and Kenya, are afflicted by the strong flavor of potato peels, not a desirable taste in coffee.  This defect is said to be ultimately caused by one of the pyrazine chemical compounds. How do coffee beans end up with this chemical? The prevailing theory is that coffee cherries are damaged by insects, most notably several species of stink bugs. The damage facilitates contamination of the cherry, which leads to formation of the potato taint compounds.

The connection between the bugs and the taint are not completely understood. Let’s take a super-geeky look at what we know about the bugs — which, whether they cause the potato defect or not, do a lot of damage to coffee cherries — and how they might be responsible for the potato taint.

Bugs that make a stink

The insects that cause damage to coffee cherries in East Africa that are usually associated with potato taint are in the order Hemiptera, the true bugs.  This order includes various bugs that suck plant juices, including cicadas, leafhoppers, aphids, scale insects, shield or stink bugs, and many others.  The stink bugs that are coffee pests are collectively called “Antestia bugs,” after their former generic name (many species in the genus Antestia have been reclassified under another genus, Antestiopsis). Two primary culprits are Antestiopsis orbitalis (formerly Antestia lineaticollis) and Antestiopsis intricata.

A. orbitalis (above right) is a colorful bug about 7 mm long. Various subspecies have slightly different patterns.  This and related species that also attack coffee have similar life histories; for the sake of simplicity I’ll refer to them collectively as variegated coffee bugs. Some species are found in India and southeast Asia. We’ll focus on the ones usually found in Africa.

Three variegated coffee bugs on coffee in Burundi. Photo by Tim Hill of Counter Culture Coffee.

Variegated coffee bugs can complete four generations a year, and reproduce best at temperatures between 19 and 24 degrees C (66-75 F) and humidity between 35-50%.  Eggs are laid on the undersides of leaves. The young are called nymphs, and are similar, but smaller, than the adults. Average life span is three to four months. Like all Hemipterans, variegated coffee bugs have piercing mouthparts adapted to sucking plant juices. Arabica coffee (rarely robusta) is the preferred host, but other plants in the coffee family (Rubiaceae) are also used. Variegated coffee bugs feed on shoots and leaves (causing damage and bud drop) but primarily on unripe coffee cherries.

Not only does this type of feeding itself cause physical damage to the cherry, but fungi (yeast) in the genus Nematospora (N. [=Eremothecium] coryli and N. [=Ashbya] gossypii) can secondarily infect the cherry. Nematospora fungi are not specific to coffee, but when these two species infect coffee, it’s usually called coffee bean rot. The fungi only cause rot in unripe (green) cherries.

It’s believed that the bugs are vectors of the fungi;  that is,the bugs carry the spores and the fungi are dependent on the bugs (though not variegated coffee bugs exclusively) for dispersal. There is some dispute over whether the spores are present internally in the bugs and thus inoculated into plants, or if they are present on the surface of the bugs. Not all cherries pierced by the bugs become infected. It could be that the fungal spores are not present in/on all bugs, or that if they are present internally, they may be too large to pass through the mouthparts of younger (smaller) individuals.

Physical damage to the coffee cherry and the associated rot cause significant losses (up to 45%) on coffee farms infested with variegated coffee bugs. Do these bugs also cause potato taint?

Chemicals that make a stink

A number of chemical compounds produce potato-like odors. The most notable is a methoxypyrazine: 2-methoxy 3-isopropylpyrazine (or “MIPP”*). The odor threshold of MIPP is very low, so it’s easily detected in very small quantities. MIPP has been found in nature in some plants and higher organisms. Various pyrazines can be synthesized chemically and biologically, and MIPP has been produced by cultures of at least one bacteria, Pseudomonas perolens.

Other Pseudomonas cultures also have potato odors. This group of bacteria are free-living, and widely found in soil and water (at least one strain infects the leaves of coffee trees). Several other bacteria, such as some strains of Serratia and Cedecea, produce potato-like odors that are the result of a combination of pyrazine compounds.

Despite my access to vast quantities of scientific literature, I was surprised to find virtually no published research on the chemical processes of coffee bean rot. Does it produce MIPP or a similar compound with a potato odor? If other bacteria are involved in the potato defect, are they connected in some way to the fungal infection that is typically introduced by variegated coffee bugs? Where to the bacteria come from?

One very interesting clue comes from Tim Hill, of Counter Culture Coffee, who provided the photo above left. He said that the potato odor was apparent in the air during a rainstorm in Burundi. This is suggestive that a/the taint-producing bacteria may be present in the soil. While I have been unable to pin down the range of Pseudomonas perolens, there are nearly 200 species of this bacteria worldwide. I have to wonder why the potato defect is largely (exclusively?) considered an East African problem and why it has been historically linked to variegated potato bugs, but not, for instance, coffee berry borers which also penetrate the green cherry. The borers and Pseudomonas are fairly ubiquitous in  coffee-growing nations. It seems to me that there must be a link between the variegated coffee bugs and a bacteria that facilitate the production of stinky pyrazine compounds.

Bringing us to this compelling clue: MIPP (usually going by its synonym IPMP*), is found in some grapes and contributes to pleasant flavors in wines in small amounts, but at higher levels is associated with the off-flavor known as “ladybug taint.”  The ladybugs (Asian multicolored lady beetles, Harmonia axyridis, the non-native species that can be a household pest) do not actually attack or harm the grapes. IPMP is part of the chemical make-up of the ladybugs, and when the insects get mixed in and processed with the grapes, the taint occurs in the wine.

IPMP is present in lots of ladybug species, and many other insects that are “aposematic” — those possessing some kind of warning signal to potential predators. Usually, this is some sort of bright coloration, very often red and black. I have not seen any variegated coffee bugs or close relatives on lists of insects that have been confirmed to have any pyrazines, but their colorful patterns are consistent with other aposematic insects, and some other Hemiptera are classified as aposematic. Recall this group of bugs is known as “stink bugs.”  This is precisely because most have the ability to release a nasty chemical when molested. So further exploration of the chemical make-up of variegated stink bugs surely seems a promising avenue of research.

However these compounds end up in the coffee cherry, they end up altering the bean, which itself does not show damage. (This fact — that the damaged cherries must be identified and discarded prior to processing, after which they cannot be detected until the coffee is roasted or ground — is what makes this defect so frustrating.)

Recent news out of the University of California, Riverside announced that one of their entomologists was going to Rwanda to help solve the mystery of the potato defect. That item said, “there is no definitive link between potato taste and antestia bug, only hypotheses.” While the research I’ve cited (see below) is not very current, the dots seem to be connected right up to the end point of why and how MIPP or a similar compound is produced.

The battle of the bug

Given the fact that one way or another, variegated coffee bugs are pests of coffee, control methods for them will continue to be important. Fungicides do not control the type of infection caused by Nematospora, given that the fungi are introduced within the coffee cherry. Small infestations of the bugs can been battled with hand-picking. Since the bugs like dense foliage, pruning is often recommended. In the long run, both natural and synthetic pyrethrum insecticides have proven ineffective in many cases. The bugs have typically been controlled with multiple applications of pesticides, usually fenitrothion, chlorpyrifos, malathion, trichlorfon, and diflubenzuron. All but the last are organophosphate pesticides that are especially dangerous (to humans and the environment) when not applied according to instructions with full protection, which is often not the case in less-developed nations.

Fortunately, because they are native to East Africa, variegated coffee bugs do have many natural enemies which may be exploited for biocontrol; they are especially vulnerable to a number of native parasitic wasps that attack the eggs. With persistence and luck, reliable biological and cultural control of variegated coffee bugs will hopefully be developed.

As the Rwandan and Burundian specialty coffee sectors grow, the urgency to defeat the potato taint will grow. I’ll be following any progress and research on the exact mechanisms of potato taint and any methods of control and detection that emerge.

Photo of Antestiopsis orbitalis by Lambert Smith, used with permission.

*This compound has several synonyms: 2-Isopropyl-3-methoxypyrazine, 3-Isopropyl-2-methoxypyrazine, or IPMP. The CAS Registry number is 25773-40-4.

Further reading:

    • Cheng, T.-B., G. A. Reineccius, J. A. Bjorklund, and E. Leete. 1991. Biosynthesis of 2-methoxy-3-isopropylpyrazine in Pseudomonas perolens. J. Agric. Food Chem. 39:1009-1012.
    • Cilas, C., B. Bouyjou, and B. Decazy. 1998. Frequency and distribution of Antestiopsis orbitalis Westwood (Hem., Pentatomidae) in coffee plantations in Burundi: implications for sampling techniques. Journal of Applied Entomology. 122:601-606.
    • Crowe, T.J., G.D.G. Jones, and R. Williamson. 1961. The use of pyrethrum formulations to control Antestiopsis on coffee in East Africa. Bulletin of Entomological Research. 52:31-41.
    • Greathead, D.J. 1966. A taxonomic study of the species of Antestiopsis (Hemipteea, Pentatomidae) associated with Coffea arabica in Africa. Bulletin of Entomological Research. 56:515-554.
    • Kirkpatrick, T. W. 1937. Studies on the ecology of coffee plantations in East Africa. II. the autecology of Antestia Spp. (pentatomidae) with a particular account of a Strepsipterous parasite. Transactions of the Royal Entomological Society of London 86:247-343.
    • Le Pelley, R.H. 1932. On the control of Antestia Lineaticollis, Stal (Hem., Pentatom.) on Coffee in Kenya Colony. 1932. Bulletin of Entomological Research. 23:217-228.
    • Le Pelley, R.H. 1942. The food and feeding habits of Antestia in Kenya. Bulletin of Entomological Research. 33:71-89.
    • McNutt, D.N. 1979. Control of Antestiopsis spp. on coffee in Uganda. Tropical Pest Management. 25:5-15.
    • Mehrotra, R. S., and Aggarwhal, A. 2003. Plant Pathology, 2nd Ed. Tata McGraw-Hill, New Delhi.
    • van der Meulen, H.J., and A.S. Schoeman. 1990. Aspects of the phenology and ecology of the antestia stink bug, Antestiopsis orbitalis orbitalis (Hemiptera: Pentatomidae), a pest of coffee. Phytophylactica. 22:423-426.
    • Mitchell, P.L. 2004. Heteroptera as vectors of plant pathogens. Neotropical Entomology. 33:519-545.
    • Nixon, G.E.J. 1941. New Braconid parasites of Antestia Lineaticollis, Stal, and of Sylepta Derogata, F. Bulletin of Entomological Research. 32:93-101.
    • Pickering, G. J, M. Spink, Y. Kotseridis, D. Inglis, I. D. Brindle, M. Sears, and A. Beh. 2008. Yeast strain affects 3-isopropyl-2-methoxypyrazine concentration and sensory profile in Cabernet Sauvignon wine. Australian Journal of Grape and Wine Research. 14:230-237.

 

Birds and other biodiversity / Research on coffee growing

Research: Borer-eating warblers may need nearby forests

Roosting behaviour of a migratory songbird on Jamaican coffee farms: landscape composition may affect delivery of an ecosystem service. Jirinec, Campos, and Johnson 2011. Bird Conservation International.

This is another paper from Matt Johnson and his students from Humboldt State University (CA) who study how birds provide pest control on coffee farms in Jamaica.  Previous papers summarized here include the primary research on which species of North American-breeding birds prey on coffee berry borers on Jamaican farms, and an analysis of how birds controlled the borers on shade and sun farms, and the economic value of the pest reduction.

This study looked at the most important bird species preying on the borers, the Black-throated Blue Warbler. This species was profiled here as part of our Know Your Coffee Birds series.

Researchers captured warblers on two farms in cultivated coffee patches. The birds were fitted with tiny radio transmitters, and the movements of 21 warblers were followed for 7 to 10 days with radio telemetry.

While the birds spend most of their days in the coffee cultivation areas, most (81%) birds roosted (spent the night) in nearby forested habitat patches, not on the coffee farms. Even if a bird roosted within the boundaries of the farm, it was usually in large shade trees or vegetated non-cultivated areas. The average distance between the daytime range and the roost sites was 119 m.

The structure of the vegetation on the farms where the birds foraged was quite different from where the warblers spent the night. Roosting sites had more canopy cover (averaging 94% closed) than the shaded coffee (36% closed). Roosting areas were also very dense. Thus, the Black-throated Blue Warblers in this study appear to choose coffee farms for their good food supply — which includes the coffee berry borer — and forests with dense protective cover to safely spend the night.

This implies that preserving forests, which provide safe haven for roosting birds, in or near coffee farms may encourage them to remain in an area. For farmers to benefit from the pest control services of migratory and resident birds, as well as other ecological services such as pollination provided by other fauna, local land use must be taken into account.

Male Black-throated Blue Warbler banded at the Rouge River Bird Observatory, photo by Julie Craves. All rights reserved.

JIRINEC, V., CAMPOS, B., & JOHNSON, M. (2011). Roosting behaviour of a migratory songbird on Jamaican coffee farms: landscape composition may affect delivery of an ecosystem service Bird Conservation International, 1-9 DOI: 10.1017/S0959270910000614

Research on coffee growing

Endemic Tanzanian coffee threatened by dam

Coffea kihansiensis from Davis and Mvungi 2004.

In 2001, an endemic coffee species, Coffea kihansiensis, was discovered in the Kihansi River gorge in the Udzungwa Mountains of Tanzania. The entire range of this species is estimated at about 17 ha between 775 and 950 m. The habitat was shaped by huge amount of spray from an 800-meter-high waterfall which stabilized temperature and humidity.

A hydroelectric project completed in 1999 diverted over 90% of the flow of the river, severely altering the spray-dependent ecosystems and threatening a range of plant and animal taxa, many of which are unique to this gorge. Prior to the diversion, average temperature and humidity was 70° F and 77% respectively; in 2007 after diversion it was 75° F and 69%. The environmental assessment performed prior to the project initiation only  looked impacts on habitat inundated by the reservoir. It wasn’t until 2001, after completion of the diversion, that monitoring of species at risk from the loss of spray was initiated. This was when Coffea kihansiensis was discovered.

A just-published three-year study (2007-2009)  looked at the health of the coffee trees in the gorge. Because the species was only discovered after completion of the project, pre-diversion parameters are not available. However, field observations made in the immediate years after diversion (2000-2003) found no evidence of insect or other parasitic infestation. In the recent study, over half of the sampled coffee trees had either insect damage (aphids, beetles, or crickets/grasshoppers) or a heartwood-boring insect larva that was usually lethal. The worst infestations were at sites closest to the river which had formerly been constantly drenched in spray. This suggests that the stress of increased temperatures and decreased humidity is making the coffee susceptible to these pests.

Since the general ecology of the area has changed dramatically, it is possible that conditions are now also favorable to the increase in pests; perhaps they were not even present prior to diversion. At least one fruit-eating bird has declined in the gorge, which may have negative effects on the dispersal of Coffea kihansiensis seeds in the area. The reduced flow of the river has also changed the water chemistry and quality. For example, dam releases have resulted in pulses of pesticides from upstream maize farms. The long-term effects of these changes on soils, nutrient dynamics, and the coffee are still not known.

Kihansi Spray Toad, wiped out in the wild by a dam that also threatens an endemic coffee species. Photo Copyright © 2005 Dennis Demello.

Sadly, Coffea kihansiensis is not the poster-child for the environmental damage caused by this project. The Kihansi Spray Toad (Nectophrynoides asperginis) was first described in 1998. It was also endemic to the gorge and dependent on the spray, with a population estimated at nearly 20,000 in a 2-ha range. By 2004, after the diversion, fewer than 5 individuals were found, and it is now extinct in the wild. Fortunately, a group was taken into captivity in 2001, and after much trial and error is now being bred in several zoos.

Ironically, the hydro project was funded by the World Bank and several other development agencies, and now the World Bank is funding much of the spray toad preservation efforts. The World Bank also funded an elaborate, gravity-fed sprinkler system in the gorge designed to mimic the spray from the waterfall. The system has failed at least once due to silt clogs, and it is not known if the toads can be re-introduced in the area because the vegetation changed significantly when the area dried out.

Nobody can begrudge a developing country an opportunity to produce much-needed clean energy. But when can we learn it is less expensive — monetarily and for the environment — to perform due diligence and minimize our impact?

Davis, A., and Mvungi, E. 2004. Two new and endangered species of Coffea (Rubiaceae) from the Eastern Arc Mountains (Tanzania) and notes on associated conservation issues Botanical Journal of the Linnean Society 146:237-245. DOI: 10.1111/j.1095-8339.2004.00328.x

Krajick, K. 2006. The Lost World of the Kihansi Toad Science 311: 1230-1232. DOI: 10.1126/science.311.5765.1230 (PDF)

Rija, A. A., Mwamende, K. A., and Hassan, S. N. 2011. The aftermath of environmental disturbance on the critically endangered Coffea kihansiensis in the Southern Udzungwa Mountains, Tanzania. Tropical Conservation Science 4:359-372. See summary here.

Birds and other biodiversity / Research on coffee growing

Research: Types of fruit trees on shade coffee farms important

The value of fruit security for the conservation of a neotropical frugivore in human-dominated landscapes. Peters and Nibbelink. 2011. Biodiversity Conservation.

This study looked at the feeding patterns of a fruit-eating tropical bird, Blue-throated Toucanet (Aulacorhynchus caeruleogularis) in shade coffee farms in the Monteverde region of Costa Rica.

Blue-throated Toucanets were once considered a subspecies of Emerald Toucanet, which was featured in the Know Your Coffee Birds series here on C&C. The goal was to determine how fruit resources — in particular the reliability of fruit energy throughout the year — influenced the persistence of fruit-eating birds in agroforestry systems like shade coffee.

Finca La Bella is a group of 24 independently owned small farms that grow coffee under a high diversity of shade (unlike much of Costa Rican coffee). Around 20 different tree species per ha are used for shade here, but different farms may have different types of shade trees. The authors looked at the types of fruit growing on six of the organic farms, and measured the fruit calories available to birds over most of the year.

Researchers found that the toucanets were located 20-30% more often on farms that were considered to have ”high fruit security.”  These were farms on which the fruit energy available was greater than 1000 calories for four months or more. This calorie threshold has been found in other studies to be the point at which more birds immigrate into a farm rather than leave to find food resources elsewhere. The home range of toucanets was also found to be smaller on farms with high fruit security, indicating the birds did not have to roam as far to find the fruit they needed.

Although Blue-throated Toucanets have been observed eating many dozens of types of fruits, some are preferred over others. The fig Ficus pertusa accounted for 69% of all observations in this study. The fruits of the familiar Cecropia (Cecropia obtusifolia) and of Firebush (Hamelia patens) were also important.

The authors concluded that to improve the quality of the agroforestry systems for fruit-eating birds, the type of trees used for shade or preserved on the property should be taken into account, including the year-round availability of fruit resources. Ficus were especially important in this study.

Aside from the preservation of biodiversity, fruit-eating birds perform the critical service of seed dispersal in tropical forests. Therefore, managing shade coffee farms to benefit these birds is of high conservation value.

Peters, V., & Nibbelink, N. 2011. The value of fruit security for the conservation of a neotropical frugivore in human-dominated landscapes Biodiversity and Conservation, 20 (9), 2041-2055 DOI: 10.1007/s10531-011-0073-5

Blue-throated Toucanet photo by Scott Ableman under a Creative Commons license.

Climate change / Coffee regions / Research on coffee growing

Climate change threatens east African coffee via borers

Some like it hot: The influence and implications of climate change on coffee berry borer (Hypothenemus hampei) and coffee production in east Africa. Jaramillo et al. 2011. PLoS One.

An important new paper published this week outlines the threat posed by the expansion of coffee berry borers in east Africa due to climate change.

This paper follows up research by the authors that was published in 2009. That paper looked at life history characteristics of the coffee berry borer (CBB), one of the worst pests of coffee, and how they might react to various climate change scenarios. This paper built on that data, looked at current distribution of CBB in east Africa, and modeled the change in distribution by 2050 based on two climate change scenarios.

The models indicated that CBB infestation will be worse in the arabica coffee producing regions of Ethiopia; the Ugandan part of the Lake Victoria and Mt. Elgon regions; Mt. Kenya, particularly in the coffee-producing areas of Embu and Meru, and the western part of Kenya, around Kitale and the Kenyan aide of Mt. Elgon; and most of Rwanda and Burundi. Further, it appears that increasing temperatures will likely double the number of generations of CBB per year in all current arabica-producing areas. Both models (using slightly different projections of climate change) are very similar, one figure is reproduced below.

Suitability of climate for CBB, year 2050. EI values indicate suitability, where 0 is unsuitable, and 100 is perfect. Click to enlarge. From Jaramillo et al. 2011.

Lest you view climate modeling (or climate change) with skepticism, the authors note that as recently as ten years ago, CBB were not reported above 1500 m. Now, due to increasing temperatures in coffee growing regions around the world, CBB can be found at higher altitudes, where arabica coffee is typically grown. CBB have been documented 300 m higher in Tanzania than they were ten years ago. The authors note that some of the changes predicted in their earlier paper, such as increased number of generations and broader distribution, seem to already be occurring.

The damage an increase in CBB to now-untouched coffee growing areas is serious and sobering. These impacts do not even incorporate other changes that are likely to take place with increasing temperatures: a change in the distribution of biological enemies of CBB, and the impact of changes in rainfall patterns, disrupted seasonality, and thermal stress to coffee plants.

The authors state,

We suggest that the best way to adapt to a rise of temperatures in coffee plantations could be via the introduction of shade trees in sun grown plantations.

They note adding shade trees can lead to a decrease in the temperature around coffee berries by up to 4°C, which in turn may reduce the rate of increase in CBB by 34%.  They go on to say shade coffee agroecosystems can serve as a refuge for beneficial arthropods, leading to higher levels of biological control of CBB, and they create a diversified and therefore more resilient system that will perform better under climate change. They conclude that while it is only one of many adaptation strategies, the use of shade trees is “… rational, affordable, and relatively easy for coffee farmers and other stakeholders to implement.”

The paper is open access, and you can read it the whole thing and view all the maps here. A link to an abstract in Spanish is available near the end.

Jaramillo, J., Muchugu, E., Vega, F., Davis, A., Borgemeister, C., & Chabi-Olaye, A. (2011). Some Like It Hot: The Influence and Implications of Climate Change on Coffee Berry Borer (Hypothenemus hampei) and Coffee Production in East Africa PLoS ONE, 6 (9) DOI: 10.1371/journal.pone.0024528