Can European grapevine moth, Lobesia botrana (Lepidoptera: Tortricidae)be eradicated from California?


Abstract: Lobesia botrana (Denis & Schiffermüller), European grapevine moth, was reported forthe first time in North America in mid-September 2009 in vineyards in Napa County, California.Moths have since been detected in eleven California counties, as determined by a programdeploying pheromone-baited traps at densities of 6 to 10 traps per square kilometer in all grapegrowingregions of California. State and federal agencies mounted a rapid response to thedetections, and implemented aggressive quarantine and treatment programs. Quarantined areashave been established in an 8-kilometer radius from detection after 2 or more moths within 4.8kmor any other life stage are detected in a generation. As of August 2011, an area of approximately6000 square kilometers in 10 California counties is under quarantine for European grapevinemoth. A single moth was found in an 11th county that is not in quarantine. In 2010, the treatmentprograms targeted all vineyard acreage within 200m (Napa) or 1000m (all other counties) of adetection. Insecticide applications were recommended for all three generations, and matingdisruption dispensers were recommended in Napa County only. In 2011, recommendations wereto treat the first two of the three generations on all vineyard acreage within 500m of a life stagedetection and to apply mating disruption, except in areas of the state that are attempting to bereleased from quarantine regulations. The aggressive treatment programs reduced Napa Countypopulations from 99,266 moths trapped during the first flight of 2010, to 1,329 and 281 in thesecond and third flights, respectively. As of August 2011, traps in Napa County have caught 96and 16 moths during the first and second flights, respectively. Detected infestations in the other10 counties are very low, with a total of 128 males caught in 2010 and 33 males in the 1st and 2ndgenerations of 2011. In field trials, we demonstrated the efficacy of various insecticide productsused in the treatment programs. Ongoing surveys of host plants cited in the literature have notidentified any alternate hosts of consequence in Napa County. Although we detected eggs andlarvae in olive flowers during the first generation of 2010 only, the populations were three-foldlower than in adjacent vineyards, and subsequently we have not detected any life stages in olive.We collected and analyzed data on the treatment programs in Napa and Sonoma counties, wherepopulations are the largest or most persistent. Given the aggressive treatment programs, theavailability of very effective tools such as insecticides and mating disruption, the lack of alternatehosts of consequence, and the apparently high level of compliance with treatment and quarantineprograms, the question remains: Have we temporarily lowered populations to undetectable levelsor is eradication of L. botrana from California feasible?

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