Hawaii County

The macadamia nut industry is concerned about continuing crop damage caused by green southern stink bugs.

Bug wreaks havoc
on Big Isle

The stink bug might cause more than
$1 million damage to mac nut crops

By Gary T. Kubota

WAILUKU >> The green southern stink bug will cause crop damage far in excess of a million dollars to macadamia nut farmers on the Big Island, according to industry observers.

"It's pretty catastrophic," said James Trump, whose Island Harvest Inc. manages four farms in the northern part of the Big Island.

Trump said the stink bug usually causes about 5 percent crop damage, but this year, it has caused his farms in Kohala about 50 percent to 80 percent for an estimated loss of 1.5 million pounds, or $850,000.

State agricultural officials said the stink bug caused macadamia nut damage estimated at $1 million in 2000-2001 and $795,000 in 2001-2002, but that was statewide, and the losses were less than 10 percent of the total crop yield.

"It's going to be way over that," said Mike Nagao, a horticulturist with the University of Hawaii's College of Tropical Agriculture & Human Resources.

Scientists said they are still researching the cause of the problem but speculate that more rain fueled the growth of weeds that the stink bugs eat.

Stink bugs use their needlelike mouth to attack the macadamia nut kernel. Fungal spores and bacteria from the bug ruin the kernel.

Peter Follett, an entomologist with the U.S. Pacific Basin Agricultural Center, said previous research indicated the stink bug mainly attacked the kernels once they were on the ground. But his research indicates the stink bug attacks the kernels on the trees as well.

"This kind of catastrophe points out the holes in our knowledge," he said.

Nagao said one way to determine if stink bugs are increasing at a high rate is to develop traps in the groves to monitor their number.

Follett said ways to control the bug include mowing nearby weeds to reduce their food source, and treatment with herbicides to control the weeds.

The University of Hawaii has also received a $50,000 federal grant to find biological methods of controlling the bug, including the release of a wasp that eats the bug and its eggs.

The stink bug, whose scientific name is Nezara viridula, was first seen on Oahu in 1961 and spread to the Big Island and Maui by 1963.

County of Hawaii

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