UCR entomologist tackles Rwanda’s agricultural pest

Courtesy of UCR Newsroom

UC Riverside Entomology Professor and Jefferson Science Fellow Thomas Miller has ventured to Rwanda in order to investigate the defects resulting in a “potato-tasting” coffee plant.

This peculiar deficiency is thus far sourced to the Antestia bug, whose activity is hindering Rwanda’s exports on the international frontier. Scientists from both the US and Europe have been sent to Rwanda through an international non-profit organization, Global Initiative Knowledge (GKI), which sponsors the Learning and Innovation for Network for Knowledge and Solutions (LINK) Program–currently funding Miller’s research in Rwanda.
Antestia bugs, a genus of the shield bug, commonly attack coffee cherries as they feed. The consequence of their feeding is an unwanted “potato taste” left behind on the coffee beans, although the link has yet to be scientifically proven.

“The main problem with potato taste is that it shows up after roasting and during tasting. By then it is way too late to weed out the few beans that seem to be the source of the taste and odor among hundreds of beans,” explained Miller in an interview with the Highlander. Miller further elaborated that the occurrence of potato taste can ruin an entire shipment of coffee beans, resulting in the disposal of the entire load and inflicting hundreds of thousands worth of damage across the country. However, the lack of concrete evidence behind the exact cause of potato taste poses an issue on its own—one which Miller has fully embraced. “I find this part of the project absolutely fascinating. It is like a mystery novel with a great deal at stake. You don’t know who done it,” remarked Miller.

While the task to unravel the potato taste problem may seem challenging, the UC Riverside entomologist expressed delight in his travels. “There is really great expectation and appreciation from our hosts that we are willing to help them. The hospitality is amazing. Rwanda is the land of 1000 hills, yet the roads are excellent and transportation [is] all organized,” stated Miller.

Thomas Miller joins French scientist Christian Cilas in solving the mystery of the potato taste and its unproven cause. Their two-week stay in Rwanda, which began Jan. 7, will be used to gather information that could reveal ways to resolve the coffee defects. “We will devise a multi-pronged strategy for ridding Rwanda’s specialty coffee of potato taste defect,” stated Miller. “And we will also assist Rwanda in reaching out and making contacts with people grappling with similar problems globally.”

Last week, Miller and Cilas attended many meetings including workshops, joining with researchers from the National University of Rwanda on Jan. 9 and meeting with the Ministry of Agriculture on Jan. 12. “We are exactly in the middle of our project here, defining a response to the problem in coffee,” stated Miller. “Coffee from Rwanda has gained world fame and that reputation is threatened by the potato taste problem, something peculiar to east Africa.” This week, the researchers are doing field visits, including a trip to the Volcano National Park.

With the antestia bug jeopardizing the quality and quantity of Rwandan coffee, the country’s export market faces stiff threats from international buyers, who would decline to buy products that are not of the highest quality. Coffee from these sectors accounts for 26 percent of Rwanda’s agricultural exports. The Ministry of Agriculture Resources lists cropping as the country’s key pillar in growth and poverty reduction, as more than 90 percent of the population are engaged in agriculture production. With few natural resources and having coffee as one of the main exports, Rwanda is a country whose growth heavily relies on the maintenance of world prices on such products.

The sudden attention placed on the bug, however, has prompted questions regarding the history of the bug and the timing of efforts to eliminate the pest. According to Miller, the interest in ridding Rwanda of the bug arose following the country’s decision to revamp its coffee production and improve its standing in the international community of producers. Naturally, the bug now possesses a great threat to the Rwandan economy since coffee holds a much more important role in the export market.

“For the past ten odd years Rwanda decided to focus on the specialty coffee market. They are also trying hard to qualify for organic certification, which is very difficult to do, but once achieved, will provide a plus income above premium…Any small amount of potato taste or odd flavors showing up in coffee bean batches makes the specialty reputation difficult to maintain. That is the problem being addressed here,” stated Miller, addressing the relationship between the timing of extermination efforts and the rise in prominence of coffee production in Rwanda.

The economic impact of the bug was also discussed by a report by the GKI, stating, “Smallholder farmers saw their coffee profits leap from 20 cents a kilo to $2.00 per kilo, mainly through quality improvements, investments in technological upgrading and capacity building.  Now, these gains are at risk.”

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