Update on the Lobesia botrana Program in California

Abstract: Lobesia botrana (Denis & Schiffermüller), European grapevine moth, was discovered for the first time in North America towards the end of the 2009 growing season in Napa County, California. Upon confirmation of the first detection, the United States Department of Agriculture Animal and Plant Health Inspection Service established a regulatory program. To delimit the area of the infestation, the program deployed pheromone-baited traps at densities of 3 to 10 traps per km2 in vineyards and high-risk urban areas throughout California. When 2 or more moths within 4.8 km of each other or any other life stage were detected, an 8-kilometer-radius quarantine area surrounding the find was established; the radius was decreased to 5-kilometers in 2012. Moths were detected in 11 California counties, 10 of which were regulated. The largest population was in Napa County where 100,831 moths were trapped in 2010, compared to 128 total moths in the remaining counties. The treatment programs targeted all vineyard acreage within 200 m (Napa) or 1000 m (all other counties) of detections in 2010; subsequently the treatment area was standardized to 500 m. In 2010, insecticide applications were recommended for all three generations and thereafter for the first two generations. At least one application of a conventional insecticide or two applications of an organic insecticide were timed based on degree-day accumulations (and vine phenology). Isomate Shin-Etsu pheromone dispensers were used in Napa County in 2010 through 2014 and other select counties in 2011. Mating disruption was not used in areas of California that were attempting to be released from quarantine regulations. After 2013, insecticide treatments were recommended for vines within 500 m of all finds from the previous two years. In urban areas within 500 m of a detection, property owners with grapevines were given the choice of flower and fruit removal or applications of Bacillus thuringiensis during the first two generations. All control measures in urban areas were performed by the California Department of Food and Agriculture. Areas that met the following requirements were deregulated: no moth captured during five consecutive generations; insecticide was applied to the first two larval generations; during the final two full generations mating disruption dispensers were not deployed and trapping density increased to 39 traps per km2. Peak quarantine area of 6048 km2 across portions of 10 California counties occurred in 2011. Four counties were deregulated in early 2012 and five additional counties were deregulated partially or in full at the end of 2012. The quarantine area in 2013 was reduced to include most of Napa County (1434 km2) and areas of two neighboring counties within 5 km of Napa traps that caught adult moths. One moth was caught in 2014 and no moths were caught in 2015. Monitoring of vineyard acreage outside the quarantine continues without detections. Ongoing surveys of host plants cited in the literature have not identified any alternate hosts of consequence in California.