They Love Olives

CTAHR faculty and staff were instrumental in discovering a new fruit fly pest that’s recently been identified in Hawai‘i for the first time: the olive fruit fly (OLFF), Bactrocera oleae. According to the New Pest Advisory from the Hawai‘i Department of Agriculture, the OLFF can attack all species of Olea, including the common olive (Olea europaea) and the African olive (Olea europaea subsp. cuspidata), unfitting them for either oil processing or table consumption. 

Damaged olive fruit were found at the Lālāmilo Research Station in Waimea in 2019, in trees that were planted in 2011. Subsequent surveys by HDOA personnel also found the OLFF at other sites on Hawai‘i Island and Maui.

The timing was unfortunate for the pest’s arrival—for the humans, if not the insects—since there was a bumper crop of olives at Lālāmilo in 2019. Average yield per tree by cultivar at Lālāmilo in 2019 ranges from 15.10 lbs per tree for the ‘Mission’ variety’s five trees to a whopping 82.35 lbs. per tree of the seven ‘Koroneiki’ trees! ‘Arbosana’ is nearly as prolific, at 70.39 lbs. per tree. But many of the fruits were spoiled by the pest.

Olives can only be grown in a relatively few areas in the Islands, since they require chilling to induce flowering and do best at high elevations. Lālāmilo is 2,500 ft. above sea level, while the Maui Agricultural Research Center in Kula, where olives are also being grown by CTAHR, is at 3,100 ft.