Monitoring and management of the emerging threat of black fig fly in California's fig orchards

The black fig fly (Lonchaeidae: Silba adipata McAlpine 1956) is an emerging invasive pest that poses a significant threat to fig orchards in California. Originally described in Italy in 1917, it has since spread to additional locations, including Mexico in 2020 and southern California in June 2021. Given the prominence of fig production in the state, effective monitoring and management strategies are crucial. Since the main fig production in California is in Central Valley (Fresno and Merced Counties) and there are lots of small growers in coastal and southern California, all these locations were monitored using McPhail-type traps baited with torula yeast and all the locations except Central Valley were infested. To establish an efficient monitoring system, the efficacy of McPhail-type traps baited with torula yeast was compared to alternative lures such as ammonium sulfate, hexanol, ammonium sulfate and hexanol, fig sap, hydrolyzed corn gluten meal (Nu-Lure, Miller Chemical), hydrolyzed protein (Buminal, NABA GmbH), and GF-120 (Fruit Fly Bait, Corteva). The trapping methods were evaluated based on the number of black fig flies captured. Trapping efforts were conducted year-round at three locations to address the limited knowledge of the phenology and life cycle. Biweekly collected black fig fly specimens were identified in the laboratory. Seasonal activity data were summarized separately for each of the three sites. Field trials were also conducted to assess the effectiveness of various chemical control measures, including options suitable for organic production. The outcomes of this research will be presented in this talk.