A new infestation of a stink bug in California has led to concerns that the pest could invade local vineyards, destroy crops, and leave a foul taste in the area's wines.
While the threat isn't imminent, a population of brown marmorated stink bug (BSMB) has been discovered in a Sacramento neighborhood – the first time the bug has been found outside Los Angeles County. An outreach adviser from the University of California's agriculture division (UCANR), Chuck Ingels, described it as "the worst invasive pest" ever encountered in the state.
Ingels is asking growers to be on the lookout for the stink bugs. "Because they are strong fliers, it's just a matter of time before they reach farms," he said. The pest can fly up to half a mile at a time and also travels long distances by hitching rides in vehicles or inside furniture or other articles when they are moved, often during winter months, reports UCANR.
Ingels said there was no danger to this year's grape harvest and a major threat is also unlikely in 2014. However, he was in no doubt that "their populations will grow over time."
The stink bug feeds on a myriad of crops, from apples and corn to tomatoes and grapes. "In grapes, berries collapse and rot increases," said UCANR. "Wine tasters have been able to detect stink bug odor in wines made from grapes that had 10 bugs in a 35-pound lug [crate]."
The pest releases its pungent smell through holes in its abdomen as a defense mechanism; Ingels describes a strong odor that is reminiscent of "something awful mixed with cilantro."
The BMSB is native to China, Japan and Korea. Its presence in the United States was first documented in 2001 in Pennsylvania, but it's thought to have arrived several years earlier. UNCAR estimates that the bug is now established in at least 15 states and there have been occasional sightings in over a dozen more.
Despite the damage that the BMSB can do to crops, Ingels reports that "there is no funding to attempt to eradicate it, nor is there a mandate to do so."
He is advising grape growers in the Sacramento area to ensure that all their employees know what the pest looks like, and to place special pheromone traps out amongst the vines to monitor whether the bug is around.
According to UCANR, "the pest can be distinguished from ordinary brown stink bugs by its large size, marble-like coloring on its shield and white markings on the extended edge of the abdomen." It also has distinctive white bands on the antennae and legs.
"When the pests start getting close, the best thing to apply to the vineyards is footprints or ATV wheels," said Ingels. "Monitoring is key. Then, if the pest arrives, the grower needs to know what to apply and when."
UCANR said that broad spectrum pesticides such as organophosphates and carbamates had been found to work on farms, but brought their own issues: "Growers have worked hard to develop effective integrated pest management programs, and the use of these sprays will set these programs back."
For organic growers, controlling the stink bug would be most troublesome, requiring the use of row covers, trap crops, pheromone traps and predator insects.
In Asia, the BSMB is largely controlled by parasitic wasps. Researchers from the U.S. department of agriculture have collected examples of the wasps, but extensive testing is required before they can be released in California. No breakthrough is likely before 2016.
"Parasitism is our best hope for reducing populations," said Ingels. "Chemical control of BMSB is very challenging."