High temperature forced-air treatments with fixed time and temperature for 'Dancy' tangerines, 'Valencia' oranges, and 'Rio Star' grapefruit

High temperature forced air treatments for 'Dancy' tangerines, 'Valencia' oranges and 'Rio Star' grapefruit were tested and confirmed as quarantine treatments against Mexican fruit fly, Anastrepha ludens (Loew). Our approach was to initially determine fruit tolerance to potentially insecticidal time-temperature combinations, then perform dose-response tests on larvae within fruit to determine mortality levels corresponding to 99.9968% mortality (= LD9). Lastly, we confirmed treatment efficacy by killing the required number of larvae in fruit. We developed an estimation method for LD9 mortality by examining dose-response data, heating rates, and tolerances of larvae at fixed treatment temperatures for 3 types of citrus fruit. Use of the upper 95% confidence estimate from probit analysis provided an illogical conclusion because the upper 95% confidence estimate of LD9 for faster heating oranges required a longer treatment time than for slower-heating grapefruit. An estimate of LD9 in fruit was made by taking the average of 3 different probit analyses including the 99% confidence estimate of 99% mortality, the 95% confidence estimate of LD9 mortality, and the heating time plus the 95% confidence of LD9 mortality of larvae in water at the given treatment temperature. A reduction in the treatment for oranges (to 230-min), however, resulted in survivors in the confirmatory tests. A treatment time of 210-min at 45 degrees C for tangerines, 250-min at 46 degrees C for oranges and 300-min at 46 degrees C for grapefruit achieved LD9 at the 95% confidence interval in confirmatory trials