APPLICATION OF THE MAXIMUM PEST LIMIT CONCEPT TO QUARANTINE SECURITY STANDARDS FOR THE MEXICAN FRUIT-FLY (DIPTERA, TEPHRITIDAE)

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 np, Anastrepha ludens (Loew). Ecological parameters including proportion of fruit infested and the number of pests per in fested fruit were collected. under various pest management scenarios f or mangoes and citrus in regions of Mexico that are infested with Mexi can fruit fly. Various calculations were performed using techniques de veloped by statisticians in New Zealand and the United States to deter mine the probability of a single reproductive pair of Mexican fruit fl ies surviving in a shipment of fruit, or the required post-harvest ins ecticidal treatment of fruit that would be required to assure that a r eproductive 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 leve l following a postharvest treatment that has been shown to be at least 99.9968% effective. Standard pest management practices such as insect icide al,plication, sterile insect release, or the selective harvest o f fruit reduced the predicted survival rate in treated fruit to levels below 2 flies per shipment. This approach suggests that the requireme nt for a postharvest quarantine treatment with demonstrated efficacy c orresponding to at least 99.9968% (probit 9) mortality is effective in maintaining a predicted pest survival of < 1 reproductive pair of fli es per shipment only when combined with current pest management practi ces.