Application of the Maximum Pest Limit Concept to Quarantine Security Standards for the Mexican Fruit Fly (Diptera: Tephritidae)

Abstract

A maximum pest limit approach is used to determine the probability of pest introduction into the United States when commodities are hosts to the Mexican fruit fly, Anastrepha ludens (Loew). Ecological parameters including proportion of fruit infested and the number 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 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 postharvest treatment that has been shown to be at least 99.9968% effective. Standard pest management practices such as insecticide application, sterile insect release, or the selective harvest of fruit reduced the predicted survival rate in treated fruit to levels below 2 flies per shipment. This approach suggests that the requirement for a postharvest quarantine treatment with demonstrated efficacy corresponding to at least 99.9968% (probit 9) mortality is effective in maintaining a predicted pest survival of <1 reproductive pair of flies per shipment only when combined with current pest management practices.