SYSTEMS-APPROACH TO QUARANTINE SECURITY - POSTHARVEST APPLICATION OF SEQUENTIAL MORTALITY IN THE HAWAIIAN GROWN SHARWIL AVOCADO SYSTEM

Natural mortality of eggs and larvae after 24 h in mature green avocad o fruit and efficacy of a heat treatment (40 degrees C) applied to inf ested fruit were determined for 3 species of tephritid fruit flies. Th e estimated populations of each immature developmental stage in the fr uit were calculated from estimates of the total numbers of eggs or lar vae placed in the fruit or from actual numbers of insects that survive d to pupae in untreated (control) fruit. Significant natural mortality was associated with the insects being present in the fruit without a postharvest heat treatment. A subsequent heat treatment (40 degrees C, 24 h) further reduced the estimated surviving population by 99.5-100% . A hypothetical population of 100,000 eggs or larvae was subjected to a sequential mortality model in which the likelihood of survival of t he various immature stages in the fruit, as well as after a heat treat ment was determined based on the above mortality estimates. Immatures that survived both the initial natural mortality within fruit and the heat treatment were once again subjected to further stage-specific mor tality within fruits. Application of the sequential mortality concept to both Mediterranean fruit fly, Ceratitis capitata (Weidemann), and m elon fly, Bactrocera cucurbitae (Coquillet), in the avocado system wou ld be sufficient to meet probit 9 (99.9968% mortality) security using our model. Oriental fruit fly, Bactrocera dorsalis (Hendel), eggs and 3rd instars would not meet probit 9 quarantine security. The implicati ons of this study to systems approaches to quarantine security and ris k are discussed.