LIBRO-CONGRESO-CITRUS

forced-air, vapor heat, cold, and irradiation treatments. Cold treatment appears to be a treatment of choice
by several citrus producing countries, with a multitude of schedules and combinations of low temperature
and treatment duration, depending on species of citrus and the guild of associated fruit fly pests.
Participants are encouraged to join the discussion on evaluating current quarantine treatment schedules and
exploring measures of achieving quarantine security other than Probit 9, including possibilities of integrating
less than probit 9 treatments in developing systems approaches to mitigate risk of fruit fly pests.
Probit analysis is a statistical method for determining a dose-response relationship and calculating the
appropriate dose for a specific response. The probit 9 mortality response estimates 32 survivors, or less, from
1,000,000 treated pest individuals. At the 95% level of confidence, the probit 9 statistics predicts no survivors
in a minimum of 93,613 test insects.
The probit 9 efficacy (99.9968% desired response, e.g., mortality) is the unofficial obligatory de facto standard
of treatment efficacy for high risk pests in highly susceptible hosts adapted by the United States and many
countries. For naturally poor hosts, the probit 9 standard may be too rigid and impractical, and treatment
efficacy lower than probit 9 may be sufficient to achieve the desired quarantine security. In the alternative
treatment efficacy approach, risk may be defined either as the number of survivors or as the probability
of a mating pair being present in a shipment, rather than as the effective mortality of the treated infesting
individuals.
The less than probit 9 approach has regulatory recognition and acceptance. Japan, Australia, and New Zealand
accept quarantine treatment efficacy at 99.99%. Furthermore, 99.99% mortality, or survivorship of 0.0001, is
the experimental benchmark for verifying the conditional non-host status of a fruit or vegetable commodity
to a fruit fly pest. The 99.99% mortality at the 95% confidence level is approximately probit 8.72.
Probit 9 treatments are mandated in many situations without regard to rates of natural infestation;
gregariousness (single versus multiple infestation); survival and reproductive capacity of the pest; inherent
hardiness of the pest to environmental stress during packaging and shipment; seasonality of shipment;
distribution of the commodity in the importing country; and other biological and nonbiological parameters.
However, risk managers are familiar with them; a number of precedent-setting probit 9 treatments have
been established based on accords during bilateral agreement to facilitate trade, with scientific justification
possibly from liberal extrapolation of meager technical data.
Thus, a discussion of these approaches is needed to effectively mitigate the risk of fruit fly pests for a specific
host commodity and the infesting pest of interest.
XII INTERNATIONAL CITRUS CONGRESS 2012 - 23