Killer beetle threatens Florida’s avocado groves

Florida’s avocado industry could be severely affected if the invasive redbay ambrosia beetle continues its path south, according to a researcher at North Carolina State University who is tracking its progress.

Dr Frank Koch is a research assistant at the university who works with the United States Forest Service to monitor invasive insect species. He has warned that the insect could bring disaster to Florida’s $15m to $30m avocado industry as the trees are the same genus as the redbays affected further north.

Koch and his team are hoping to come up with a plan to halt the beetles’ predicted progress into southwest Miami but said: “No one knows quite what to do.”

The tiny, two-millimeter-long beetles kill trees by spreading a fungus which causes a deadly disease called laurel wilt that blocks their water and nutrient supply. Once infected, trees begin to wilt, and die within two to four weeks. Part of the difficulty in slowing the beetles’ progress is that the disease is often only detected after trees have begun to die.

Possible solutions

“Some are trying to figure out if they can protect avocado trees with fungicides,” said Koch. “Others wonder if it is possible to closely watch the avocado orchards and isolate and remove any infected trees as soon as they begin to show signs of wilting.”

Researchers are still investigating the possible effectiveness of these options in the hope of safeguarding avocado groves.

However, Koch said that the beetles are migrating very quickly and predicts that they could reach the 7,500 acre avocado-producing region within one or two years.

“The avocado industry is very concentrated…and an invasion by these beetles could cause major damage to the production of avocados,” he said.

The beetle was first detected in the US in Georgia in 2002 where it caused extensive destruction of redbay trees, spreading into coastal South Carolina by 2004. Unusual mortality of redbays was first noticed in northern Florida in spring 2005.

Koch said: “There are thousands of species of ambrosia beetles, but they usually don't cause damage to this extent. This particular beetle is very serious because the fungus it carries is remarkably lethal.”