Studies on the maximum pest limit concept: case of Anastrepha ludens on fruit imports from Mexico
The probability of introduction into USA of Anastrepha ludens (EPPO A1 quarantine pest) on host fruits from Mexico was studied. A maximum pest limit approach was used, i.e. the presence of less than 2 flies per shipment could be tolerated, because establishment will only be possible if a reproductive pair is introduced. The probability of introduction of a single reproductive pair surviving in a shipment of fruits (citrus and mangoes) was studied by using several calculation models developed by New Zealand and American statisticians. Data used for these calculations (e.g. proportions of fruit infested, numbers of larvae per infested fruit), were collected under various pest management scenarios for mangoes and citrus in regions of Mexico where A. ludens occurs. Calculations were also made to determine the required quarantine treatments of fruits (methyl bromide fumigation for citrus and hot water dip for mangoes) which would be required to ensure that this reproductive pair did not survive. Results showed that infestation levels in shipments will exceed this maximum pest limit if no pest management programmes, such as insecticide applications, sterile insect release or selective harvest of fruit, have been used, even if a quarantine treatment ensuring a 99.9968 % (probit 9) efficacy is later applied on the commodity. It shows that, in the case of A. ludens, a quarantine treatment will be effective in maintaining the predicted pest survival below the maximum limit (;1 reproductive pair per shipment), only if it is combined with pest management practices in the field.
Sources
Mangan, R.L.; Frampton, E.R.; Thomas, D.B.; Moreno, D.S. (1997) Application of the maximum pest limit concept to quarantine security standards for the Mexican fruit fly (Diptera: Tephritidae).
Journal of Economic Entomology, 90(6), 1433-1440.