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Phytosanitary Measures to Prevent the Introduction of Invasive Species 379
21.3.2.7 Hot Water Immersion
Immersion of mangoes in 46.1 °C water for 65–110 min, depending on shape
and weight, is used to disinfest nearly all mangoes imported by the US from
Latin America of tephritid fruit fly eggs and larvae. This treatment replaced
ethylene dibromide when it was banned in the mid-1980s. It is also approved
for disinfesting longans and lychees of tephritids from Hawaii for export to
the continental US.
Fresh commodities often tolerate heated air better than heated water (Shellie
and Mangan 2000). Damage in heated water can be alleviated in some cases
by gradual heating (McGuire 1991), or preconditioning the fruit with sublethal
heating before the actual heat treatment (Jacobi et al. 2001). A unique
problem with heated water treatments is that people have actually died from
eating hot-water treated fruit! Mangoes absorb a small amount of water
through the stem end upon heating, and a widely dispersed case of salmonella
poisoning in the US in late 1999 was traced to an unsanitary hot water immersion
facility. This problem should be avoidable with proper levels of chlorination
of both the water used for heating, and any water used for cooling fruit
after heating.
21.3.2.8 Pesticidal Dips or Sprays
Insecticides are often used as phytosanitary treatments for items not to be
consumed, such as bulbs, seeds, other plant propagative materials, and dry
plant material. Some insecticides may be allowed on tobacco; for example, the
insect growth regulator, methoprene, considered rather safe for mammals, is
permitted by some countries for control of cigarette beetle, Lasioderma serricorne,
and tobacco moth, Ephestia elutella. Many countries do not permit
post-harvest insecticide applications to fresh fruits or vegetables. Australia is
an exception; fenthion or dimethoate at 400 ppm in water are used for interstate
movement of quarantined fruit, but are not used for any fruit exported
from that country (Heather 1994).
21.3.2.9 Ionizing Irradiation
Irradiation using an ionizing source to remove electrons from their normal
orbits, resulting in free radicals that often recombine in ways different from
the original, was postulated as a phytosanitary treatment in the 1920s (Hallman
2001). It was not until 1995 that it began to be used as a commercial
phytosanitary treatment on a continuous basis. Unlike all other commercial
phytosanitary treatments, irradiation does not provide acute mortality;