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Submitted to: Journal of Economic Entomology
Publication Type: Peer Reviewed Journal Publication Acceptance Date: 2/25/2009 Publication Date: 6/1/2009 Citation: Follett, P.A. 2009. Puncture resistance in ‘Sharwil’ avocados to oriental fruit fly and Mediterranean fruit fly (Diptera: Tephritidae) oviposition. Journal of Economic Entomology. 102: 921-926. Interpretive Summary: Avocados, Persea americana Miller, grown in Hawaii cannot be exported to the United States mainland without quarantine treatment for Bactrocera cucurbitae (Cocquillett) (melon fly), Bactrocera dorsalis (Hendel) (oriental fruit fly), and Ceratitis capitata (Wiedemann) (Mediterranean fruit fly). Avocado is a poor host for fruit flies and export using this poor host status may be possible. It is generally believed that host firmness is responsible for lack of oviposition by fruit flies in mature but unripe fruit on the tree. Experiments were conducted to quantify the relationship between infestability of Sharwil avocados by oriental fruit fly and Mediterranean fruit fly and the firmness of the fruit. Infestation rate increased with fruit softness but fruit were generally poor hosts. Fruit with a patch of skin removed produced more flies than intact fruit, suggesting that skin puncture resistance was an important deterrent to oviposition. Our study showed that fruit can be infested within one day after harvest, suggesting that fruit must be transferred to fruit fly proof containers as they are harvested to minimize the risk of attack. While risk of infestation is negatively correlated with fruit firmness, even some firm fruit may become infested. Therefore, fruit firmness cannot be used alone as an indicator to ensure fruit fly free ‘Sharwil’ avocados. Measuring fruit firmness may be a useful component of a multiple component systems approach as an additional safeguard to reduce risk of infestation. Technical Abstract: The physiological basis for host antibiosis or nonpreference to a quarantine pest is often not understood. Studies are needed on the mechanisms that impart resistance in order to better understand how resistance might fail. Experiments were conducted to examine the infestability of ‘Sharwil’ avocados by oriental fruit fly, Bactrocera dorsalis (Hendel) and Mediterranean fruit fly, Ceratitis capitata (Wiedemann) (Diptera: Tephritidae) after harvest, and to quantify the effect of avocado skin hardness on resistance to infestation by oriental fruit fly. Infestation rate increased with fruit softness but fruit were generally poor hosts. Fruit with a patch of skin removed produced more flies than intact fruit, suggesting that skin puncture resistance was an important deterrent to oviposition. Our study showed that fruit can be infested within one day after harvest, suggesting that fruit must be transferred to fruit fly proof containers as they are harvested to minimize the risk of attack. While risk of infestation is negatively correlated with fruit firmness, even some firm fruit may become infested. Therefore, fruit firmness cannot be used alone as an indicator to ensure fruit fly free ‘Sharwil’ avocados. Measuring fruit firmness may be a useful component of a multiple component systems approach as an additional safeguard to reduce risk of infestation. |
