Submitted to: Journal of Economic Entomology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 7/1/1997
Publication Date: N/A
Interpretive Summary: The Mexican fruit fly poses a threat to fruit production in subtropical regions of the United States. Quarantine regulations are applied to prevent this pest from entering the U.S. from Mexico and Central America where the most important host fruits are citrus and mangoes. The current regulations require that the imported fruit come from growing areas that are certified to have pest management that reduces the possibility that fruit is infested with Mexican fruit flies and that fruit is treated to kill at least 99.9968% of pests that may infest the fruit. This study calculates the probability that mangoes and citrus (oranges, tangerines, and grapefruit) grown under various pest management practices will pose a risk of carrying more than 1 surviving Mexican fruit fly per load and the quarantine treatment that would be required to prevent this introduction. We found that if orchards are managed with standard pest management techniques, the current 99.9968% mortality requirements for post-harvest quarantine treatments are sometimes slightly excessive. If management fails to control the flies in the orchard, however, the number of pests surviving in a load can exceed 2 surviving per load even with the quarantine treatment.
Technical Abstract: A maximum pest limit approach is needed to determine probability of pest introduction into the U.S. when commodities are hosts to the Mexican fruit fly (Anastrepha ludens Loew). Ecological parameters including proportion of fruit infested and numbers of pests per infested fruit were collected under various pest management scenarios for mangoes and citrus in regions of Mexico that are infested with Mexican fruit fly. Various calculations were performed using techniques developed by statisticians in New Zealand and the United States to determine the probability of a single reproductive pair of Mexican fruit flies surviving in a shipment of fruit, or the required post-harvest insecticidal treatment of fruit that would be required in order to assure that a reproductive pair did not survive. Results indicated that Mexican fruit fly host infestation levels under conditions with no pest management will frequently allow survival levels exceeding this maximum pest level following a post-harvest treatment that has been shown to be at least 99.9968% effective. Standard pest management practices such as insecticide application, sterile insect release, or selective harvest of fruit, reduced the predicted survival rate in treated fruit to levels below two flies per shipment. This approach suggested that the requirement that a post-harvest quarantine treatment has demonstrated efficacy corresponding to at least 99.9968% (probit 9) mortality is effective in maintaining a predicted pest survival of less than one reproductive pair of flies per shipment only when combined with current pest management practices.