To Bag a Bad Beetle, Researchers Tap Forensic Science
[ARS 2006-05-04]

[Photo] Adult Asian longhorned beetle feeding on a twig of a potted Acer mono sentinel tree. Photo by Michael Smith.


Tracking the elusive Asian longhorned beetle (ALB) could soon get a whole lot easier???and weirder. Agricultural Research Service (ARS) scientists have developed a novel "fingerprinting" tool that relies on analyzing, of all things, the invasive beetle's droppings to help give it away.

According to ARS insect geneticist Wayne Hunter, what's so telling about the insect's "frass," is that it has a genetic signature that's totally unique to the beetle. Hunter works in the agency's Subtropical Insects Research Unit at Fort Pierce, Fla.

So Hunter, with help from ARS insect behaviorist Michael T. Smith, developed genetic markers that can be used to screen frass found on trees known to attract ALB. If a sample matches the insect's established genetic profile, beetle hunters will know they've got a potential infestation on their hands.

Two things make the ALB one of the country's most "wanted" invasives. First, its ravenous appetite for hardwoods???like maple, elm and birch???threatens forests and tree-lined neighborhoods across the East. Second, a quiet killer, the beetle inflicts its greatest damage while hidden deep inside trees. Immature ALBs create elaborate tunnels while feeding there, weakening trees until they finally snap in half or must be cut down.

Adding to the ALB control arsenal, Smith has also developed a method for controlling the alien insect. Smith, who works in the ARS Beneficial Insects Introduction Research Unit at Newark, Del., has recently discovered that an insecticide, already in use against other insect pests, is practically 100 percent effective against ALB.

Smith's findings show that the chemical???a pyrethroid called Demand???can knock down adult beetles in just minutes. Using the insecticide as a fast-acting detector, beetle-hunting crews could simply spray trees suspected of harboring the insects and wait for the bugs to fall. Now, crews must climb trees one by one and scrutinize bark for the faintest signs of ALB activity.