Quarantine Strategies for Olive Fruit Fly (Diptera: Tephritidae): Low-Temperature Storage, Brine, and Host Relations

Abstract

A dose–response relationship was not observed in olive fruit fly, Bactrocera oleae (Gmelin), larvae exposed to acetic acid concentrations (0–2.5%) used in commercial brine solutions to cure olives. Immersion in a 1% acetic acid brine solution impeded emergence of the immature stages. A 1-wk exposure of olives infested with olive fruit fly larvae to low-temperature storage as a postharvest treatment at 0–1°C resulted in 8% survival of the population, and exposures of 2 through 5 wk further reduced pupal and adult emergence to <1.0%. One- to 2-wk exposures at 2–3°C resulted in a significant decrease in survival from 20 to 3%, respectively, and longer durations of 3–5 wk reduced survival to <1.0%. Mean daily fruit pulp temperatures in olives in the top, middle, and bottom of plastic bins stored at 2–3°C decreased by 5–8°C from the first to the second day. Lowest temperatures were observed in the top, and highest temperatures were observed in the middle layer of fruit, which attained a mean temperature of 3.8°C on day 5. Laboratory choice tests showed that olive fruit fly oviposited at a higher rate in late season Mission olives that were green than in fruit that were in the red blush maturity stage in tests with 1- and 3–4-d exposure periods, and an increase in duration of exposure was related to an increase in the total number of ovipositional sites. Higher percentages of olive fruit fly third instars, pupae, and adults were reared from green fruit than from fruit in the red blush stage after a 1-d exposure to oviposition. Manzanillo olives were more attractive for oviposition by olive fruit fly than Mission olives, and significantly more third instars, pupae, and adults developed in Manzanillo fruit than in Mission fruit in the red blush stage. These differences were related to the better quality and higher flesh content of the Manzanillo versus Mission olives used in the tests.