Hawai‘i is the only state in the United States where coffee is grown commercially, and Hawaiian coffee, often synonymous with Kona, is beloved throughout the world. Coffee farms have started springing up on Maui in recent years. “There are maybe 20 times more coffee farmers than 10 years ago,” says Sydney Smith, owner of Māliko Estate Coffee and president of the Maui Coffee Association.
But a tiny bark beetle from Africa, Hypothenemus hampei, or coffee berry borer threatens the coffee industry throughout the state. The miniscule pest was first detected in Kona in 2010. It spread like wildfire reaching north Kona, Ka‘ū, Hāwī, and Hilo. The beetle lays eggs inside of coffee berries. Its larvae hatch and begin to feed, hollowing out the bean and leaving little to harvest and roast.
“Once infestation levels exceed 50% of the cherries in the field, the coffee is not worth picking,” says Rob Curtiss, entomologist with the Hawai‘i Department of Agriculture (HDOA). He explained that there are farms on Hawai‘i Island with 80-90% infestation. “After [the beetles] are in the coffee [fruit] there is nothing you can do to kill them.”
People are responsible for spreading coffee berry borers, says Curtiss. Moving infested beans and bags moves the insects. A few infested beans in the back of a pickup truck could mean the introduction of the pest to a new farm—where the beetle population then explodes. Each female can lay 120 eggs, of which there are 10 females for every male. When the females mature, they find a new coffee fruit, tunnel inside, and lay eggs immediately. Their life cycle is approximately 27 days, most of which occurs inside the coffee berry. “Every 30 or so days you can multiply the infestation by about 80,” says Curtiss. “In four months’ time one beetle becomes 40,960,000 beetles.”
Coffee farmers in Kona have been working closely with entomologists and researchers at the Hawai‘i Department of Agriculture and the University of Hawai‘i-College of Tropical Agriculture and Human Resources (UH-CTAHR) to find effective ways to manage the infestation.
By combining several methods of control, some farmers on Hawai‘i Island have successfully reduced infestation levels to below 5%. This system of integrated pest management includes protocols for field sanitation, pruning, monitoring, pesticide application, harvest, and shipping. Instructions can be found in an online publication on the UH-CTAHR website titled “Recommendations for Coffee Berry Borer Integrated Pest Management in Hawai‘i 2013”
The long-term solution may lie in the discovery of an effective predator for the beetle. According to Curtiss, coffee berry borer is an ongoing target for biocontrol research for the Hawai‘i Department of Agriculture. The department’s exploratory entomologist may someday make a promising discovery in Africa, the beetle’s native range.
Currently, an interisland quarantine restricts the movement of coffee plants and unroasted or untreated “green” coffee from Hawai‘i Island to prevent the pest’s spread to other islands.
Back on Maui, Sydney Smith has changed the way she runs her farm. “I used to give tours to visitors, but I don’t do that anymore…I’ve removed coffee plants from near our vacation rental.” Smith’s actions stem from concerns that a visitor may have toured an infested coffee farm on Hawai‘i Island and unknowingly be transporting a beetle. “They’re little tiny things that can get in shoes and clothes.”
Coffee berry borer has thus far only been detected on Hawai‘i Island, but Maui coffee farmers have been trained on what to look for. “It’s not if—it’s when,” says Smith.
By Lissa Fox Strohecker. Originally published in the Maui News, November 10th, 2013 as part of the Kia‘i Moku Column from the Maui Invasive Species Committee.