SILENT MENACE:An insidious invasion is threatening to overthrow the local coffee growing industry, with 90 percent of all farms in Gukeng affected by it last year
The coffee industry is under assault from a bug invasion, and farmers and agricultural scientists are set on discovering an effective measure to contain the infestation.
Gukeng Township (古坑) in Yunlin County is a well-known coffee producing region with 60 hectares under cultivation, of which 40 hectares were infested last year by an insect known as the coffee berry borer, a small beetle native to Africa, the Agriculture and Food Agency said.
With a destruction rate of between 20 to 50 percent for the affected farms, the bug has wrought considerable damage. Now, farmers are fearful that the infestation will spread further.
Liu Yi-teng (劉易騰), the head of the coffee cultivation division of Gukeng Township Farmers’ Co-operative, said the beetle attacks the coffee berries, from which coffee beans are extracted.
“The insect bores into the coffee berry and eats from the inside. It also lays eggs inside. The larvae use the berry as their main food source when they hatch,” Liu said.
“It is a big problem for us because maybe only a few small pits are seen on the berry, so it is difficult to tell from the outside if the fruit is infested,” he said.
“The farmer only knows the extent of the blight when the coffee berries’ skins are removed and the inside is found chewed up and rotten,” Liu added.
Liu said only a few farmers mentioned the infestation previously. However, the infestations exploded last year, with 90 percent of all coffee plants in the Gukeng area affected to some degree.
Liu uses a method to fight the infestation in which he incinerates infested coffee fruit at high temperature to kill the bugs off. He believes this cuts the infestation of his harvest to 20 percent.
Sun Wang-tien (孫旺田), an agricultural specialist at Gukeng Township, said the bug blight has spread to a wide area and the infestation is growing increasingly worse.
“It is very serious for coffee farms at lower elevations and is spreading toward the south. It is becoming a big concern for most coffee growers in the country,” he said.
Chen Jung-lien (陳永連), head of Greater Tainan’s Dongshan (東山) coffee industry development association, said his region had a big outbreak five years ago, when more than 90 percent of coffee berries were infested.
“At the time, we used biochemicals to lure and trap the pests. It helped to contain the blight and last year our region saw less than 10 percent of our berries infested,” he said.
Besides Gukeng, other coffee production areas are Huisun Forest (惠蓀林場) in Nantou County, Dongshan in Greater Tainan and other central and southern areas.
In one method used to capture the bug, the insect is lured out of the berry with a one-to-one mixture of ethanol and methanol — a volatile organic chemical that has an odor highly attractive to the beetles — and then drowned in a water trap.
The traps are visible throughout coffee fields in the Dongshan area in various forms — plastic bottles and canisters — and are now being copied and distributed to growers in Gukeng.
Liu said each time he checks, hundreds of drowned beetles are found inside the traps, demonstrating that the method is successful.
Wang Sheng-yang (王升陽), director of National Chung Hsing University’s experimental forest plantation, said measures must be implemented quickly, because Taiwan has favorable conditions for most insects.
It is a relatively recent problem, he said, and most likely was due to people importing and planting raw coffee berries that contained the pest or its larvae, which led to the infestation in Taiwan.
Ko Wen-hsiung (柯文雄), a plant pathologist at the university, advised farmers to pick all the infested coffee berries off before harvest, and to cook them at high temperatures to exterminate the pests.
He said the process had to be followed because the beetles have a very high fertility rate and can lay up to 40 eggs in one life cycle, of which there are four cycles in any given year.
If not well treated, the coffee beans can lose their commercial value within a short time, he added.
Figures from the Agriculture and Food Agency show that 874 hectares of coffee beans are under cultivation nationally, with an annual production of about 813 tonnes.
Additional reporting by Chen Feng-li and Hung Su-ching