Submitted to: Journal of Integrated Pest Management
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 7/27/2015
Publication Date: 9/18/2015
Citation: Yokoyama, V.Y. 2015. Olive fruit fly (Diptera: Tephritidae) in California table olives, USA: Invasion, distribution, and management implications. Journal of Integrated Pest Management. 6(1):14. doi: 10.1093/jipm/pmv014.
Interpretive Summary: Olive fruit fly was found in California in late 1998, an event that signaled disaster for the table olive industry in California. The discovery represented the first U.S. invasion and establishment of a destructive tephritid fruit fly from the dreaded Bactrocera group. California is the fruit basket of the nation and is the only producer of canned olives used for pizza toppings, recipe ingredients, and a traditional holiday food. Research was initiated in collaboration with the olive industry to decimate and prevent the spread of the pest in olive trees through the major growing regions. The biology and life history of olive fruit fly in California was studied and evaluated to determine stages that would be vulnerable to climate and lethal control methods. Monitoring larval populations through the years provided insight into surveillance procedures and olive fruit fly reduction tactics to prevent olive crop damage. Summaries of pest infestations provides guidelines for regional control recommendations. Findings help olive growers evaluate their pest problems and devise methods to reduce insect damage in fruit produced for the California canned olive and oil industries.
Technical Abstract: Olive fruit fly, Bactrocera oleae (Rossi), was discovered in California in late 1998. Thereafter, intensive research was conducted to develop pest control methods in table olives. The life history of olive fruit fly was elucidated, and the distribution and abundance of the adults determined through trapping programs. Olive samples from non-commercial trees were collected from 2002-2013 in different locations to determine the maximum number of larvae per fruit. Larvae were most abundant in September and October and ranged from less than 0.5 to 10 per fruit. The date of maximum fruit infestations may differ annually due to the amount of fruit set, fruit size, and weather. Very high numbers of larvae were collected from large green fruit (about 4 g) while smaller fruit (about 2-3 g) supported fewer insects. High larval numbers were found in fruit from areas with cooler summer weather than fruit from the hot inland valleys. Olive fruit fly larval populations were prevalent in locations with high summer temperatures if buffered by cool marine air flow or slightly higher in elevation from the inland valley floor. An arid location with hot summers had high larval infestations suggesting olive fruit fly may adapt to such conditions. Infested fruit was collected from the same locations in subsequent years and the proximity of commercial olive orchards may enhance susceptibility to future infestation. Control methods were summarized including intensive biological control programs and new techniques such as bait stations considered for pest management programs. Basic cultural practices including removal of non-harvested fruit that allow multiple generations, timing of harvest to avoid adult activity, and elimination of standing water required by olive fruit fly adults for survival would be of major importance in reducing pest populations.