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Coffee Berry Borer and Climate Change

I read an interesting report this week entitled: “Some Like it Hot: The Influence and Implication of Climate Change on Coffee Berry Borer (Hypothenemus hampei) and Coffee Production in East Africa”. Experts believe that rising temperatures will result in higher populations and spread of the coffee berry borer, which could have far reaching consequences for high quality Ethiopian and Kenyan coffees, some of my personal favourites.

What is a Coffee Berry Borer

The coffee berry borer is one of the most feared pests for a coffee farmer. This beetle makes the coffee berry its home. Fertile females will tunnel into a berry to lay up to 60 eggs. These eggs hatch, eat the berry from the inside out before flying off to find a new home in another berry. Needless to say a berry infected with the borer is no longer fit for harvest. It’s estimated that borer attacks cost farmers USD500 million a year worldwide and that this problem affects more than 25 million rural households involved in coffee production.
There’s some good information on the coffee berry borer on the University of Hawai’i website.

Climate Change

The report focuses on the problem of rising temperatures in East Africa and what effects this will have on coffee production. It used to be the case that Arabica production was largely unaffected by coffee berry borers as it’s normally grown at too high an altitude for the borer. Up until 10 years ago, there were no reports of borers found attacking coffee plantations over 1,500m.

However, temperature increases over the last decade have enabled the borer to live at higher altitudes. In 2009, borers were found at altitudes of 1,800m on the slopes of Mt. Elgon, Uganda. On Mt. Kilimanjaro, Tanzania, this beetle is now found at elevations 300m higher than 10 years ago. As temperatures are predicted to continue rising, the spread of the borer to higher and higher altitudes is set to continue and more and more Arabica crops will be attacked.

The other problem with rising temperatures is that it will cause an increase in the population of borers, as higher temperatures speed up the life cycle of this beetle. Currently, in East Africa, a borer is able to complete between 1 to 4.5 generations per a year. By 2050, the number of generations is predicated to increase to 5-10, possibly even higher at lower altitudes (below 1,300m).

It’s difficult to see clearly what’s happening from the maps. As I interpret them (I could be wrong) by 2050 the area where conditions are favourable to the borer will have vastly shrunk; I guess mainly because it’s getting too hot. So the borer will be seeking refuge at higher altitudes such as on Mt. Kilimanjaro and Mt. Kenya. South West Ethiopia looks particularly badly affected by the predicted rise in temperature.

Solution

The spread of coffee berry borers to higher altitudes is very bad news for both the coffee farmers and for those of us who absolutely love high quality East African coffee. So a solution needs to be found.

With borers moving higher, the most obvious solution would be to move the coffee plantations even higher, so the Arabic crops are once again out of reach of the borer. However, this immediate presents a problem, as the higher you go up a mountain the narrower it gets. So at higher altitudes there’s less land available.

Also with the population of East Africa predicted to rapidly increase, coupled with lower yields of crops caused by less rainfall, there’s going to be an increasing strain on food supplies. So it’s likely that any available arable land will be used for food crops rather than crops like coffee.

The authors of this report think that shade trees are possibly the best solution to the borer problem. Shade trees have been demonstrated to have a positive affect on coffee systems, by altering the microclimate and creating diversity. But more importantly, in the fight against borers, the shade they offer can decrease temperatures around coffee berries by as much as 4°C. A 4°C reduction could slow or even halt the borer’s life cycle.

Whilst I agree with the authors, that shade trees will help in the fight against borers (there is evidence to support this), I’m wondering whether the solution is too long term. I imagine that most farmers will have to grow trees from seeds as they won’t be able to afford saplings or older trees. I’m also guessing that to grow a tree, from seed to reaching a height and spread where it can offer significant shade to coffee bushes, is going to take at least 10 years, probably much longer. By this time borers could be found at altitudes in excess of 2000m. Clearly there needs to be a plan in the short term to reduce the risk and to control any borer attacks, otherwise good quality East African coffee could become even scarcer.

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