BP Singh

194 Manju Lata Kapurpest, thus preventing its dispersal to an area where it is not knownto occur or is 'of limited distribution. Following traits are of majorconsideration while developing a quarantine treatment.a) Pest tolerance: Theoretically, quarantine pest exclusionimplies pest tolerance limit after a quarantine treatment as zero,i.e., ,it must give 100% kill of the pest. But practically it is notpossi~le. Therefore, the concept of 'probit 9' has been acceptedin quarantine circles (Baker 1939). Statistically, it is survival rateupto three individuals for a total population of 100,000 individuals,determined by a minimum of three separate tests at 95%confidence level. 'Probit 9' is not valid for pests which can developfrom a single organism, or when the pest/its hardiest stage is notavailable for testing. However, it may be feasible to use data fromsmall scale tests and literature on the efficacy of a test along witha 'safety factor' i.e. a slightly higher dosage or longer exposureperiod than the routine control treatments., .b) Commodity tolerance: There is very fine margin between thelethal dose (Probit 9) for insect mortality and phytotoxicity ofplants (Benschoter 1963). A quarantine treatment should cause noor minimum acceptable changes in the commodity, which aregenerally in terms of modifications in appearance, odour, taste,viability and vitality. While using a Quarantine Treatment thatincludes 'safety factor' as mentioned above, commodity tolerancemust be considered, although in the interest of pest security,indentor has to strike a compromise to some extent.c) Residue tolerance : It implies that a quarantine treatmentshould leave no or minimum residue in commodity so that it doesnot harm man, animals or environment. The safe limit of residuetolerance is established by authorised environmental agencies fora Quarantine Treatment before it is put to use, or else tolerancelimit is considered zero. This is disregarded in the interest of pestsecurity only when commodity is not required to be treatedrepeatedly. .d) Time factor: A quarantine treatment must not be very timeconsuming and it should cause only a minimum delay in thequarantine clearance' of the material.