How California eradicated an invasive grapevine moth

Since 2009, California farmers and agricultural officials of California have been at war with the European grapevine moth. The invasive species threatened the region's massive wine and grape industry and threatened to throw off the balance of the local ecosystem.

But now, after seven years, the war is over. The moth has been declared eradicated from the United States.

The European grapevine moth, Lobesia botrana, is native to southern Europe. The insect's larvae feed on grape bud clusters as well as the developing fruit, exposing them to damaging fungi and other pests.

The appearance of the moths came as a surprise. In October of 2009, multiple moths and larvae were discovered in a Napa County vineyard, according to a 2010 press release from the County of Sonoma Agricultural Commissioner's office. In response, several measures were put in place to combat the invasive species. The USDA and CDFA quickly quarantined the affected vineyards and began setting up traps to keep track of the moth population.

It is still unknown how the insects got to the US, but they quickly spread to other counties in California, and their numbers quickly climbed to a peak in 2010, when more than 100,000 moths were detected through traps. By that time, 52,170 acres of California vineyards had been put under quarantine, according to The Press Democrat.

The explosion in the population of moths is common among invasive species. In their native habitats, there are natural checks and balances in the population of species. When they are introduced to somewhere new, a lack of natural predators and reduced competition for food can cause the species to grow unchecked and cause substantial damage to the ecosystem.

This was of particular concern for the grapevine moths in California, whose grapevines power a multibillion dollar wine industry, according to the California Wines website. The potential economic impact of a rapidly growing pest prompted cooperation from the grape industry, environmentalists, as well as local, state, and government officials to come together to eradicate the moth.

A coordinated campaign to keep growers informed was put in motion and laws concerned with preventing contamination of non-quarantined vineyards were put in place. Congress approved 65 million dollars in federal funding for the elimination of the pest, according to a recent press release.

Seven years and 65 million dollars later, US Department of Agriculture’s Animal and Plant Health Inspection Service, or APHIS, has declared the eradication of the European grapevine month a success.

“This is a very significant accomplishment,” said Tony Linegar, the agricultural commissioner for Sonoma County, California, to The Press Democrat. “Any time you propose to eradicate an insect from a continent, that is a very lofty goal.”

Most invasive-species-eradication efforts do not go nearly as well. According to the US Fish and Wildlife Service, there are about 4,300 species in the United States that have been considered invasive. Once entrenched, they push out native species by preying on them or out-competing them. As a result, they are very hard to eradicate without doing further damage.

Other invasive species in the US include the brown marmorated stink bugs and Asian carp. These species have resisted all efforts of eradication and continue to increase their territory, according to the National Wildlife Federation's website.

Usually the best one can hope for is that an invasive species will never be brought to a nonnative habitat in the first place. But rising temperatures across the globe are prompting many species to leave home and set up life elsewhere. According to the National Wildlife Federation, approximately 42 percent of all threatened or endangered animal species are primarily threatened by the invasion of other species into their habitats.

The European grapevine moth's eradication is an unusual victory in the battle against invasive species. Early recognition of the problem and cooperation was the key to eliminating the moth before it was too late. 

In addition to quarantines and pesticides, a lab-created pheromone that rendered male moths unable to find mates, helped defeat the pest.

“Left unchecked and untreated, this infestation would have grown and grown,” Dave Whitmer, former Napa county agriculture commissioner, told the Press Democrat. “I would venture we wouldn’t have had the success without the use of the pheromone.” 

Many locals are doubtful that the moth has indeed been eradicated, according to Capital Berg. But the last official sighting of the moth was in 2014, which has given APHIS enough confidence to give the all-clear.

While the moth is finally out of the US, the battle against the invasive species rages on in Chile, where it was first detected in 2008.