Results of this research successfully established
three important parameters that support the use
of the APHIS approved cold treatment for disinfestation
of tephritid fruit flies in ‘Sharwil’ avocados.
First, the cold treatment as listed in the
APHIS treatment manual will meet or exceed
probit 9 efficacy for late stage C. capitata eggs.
Since C. capitata eggs are more cold tolerant than
other developmental stages of C. capitata, B. dorsalis,
or B. cucurbitae in cold treated carambola
(Armstrong et al., 1995), the treatment protocol
should be effective against these species in avocado.
Our results showed no survivorship of C.
capitata eggs after 9 days of cold treatment. Second,
we determined that a heat-shock treatment
used to prevent skin discoloration and improve
fruit quality of ‘Sharwil’ avocados followed by
exposure of up to 16 days of cold treatment had
no conditioning effect on C. capitata eggs. Our
findings suggest that C. capitata eggs showed a
lower survival in every case when exposed to a
heat-shock prior to the cold treatment as compared
with non-heat-shocked infested fruit. In our
experiments, heat-shock of infested fruit resulted
in no survivors in the test fruit after 8 days of cold
for any of the four tests conducted. Third, a
transient (ca. 2–3 h) breach in the temperature
during the course of a simulated in-transit cold
treatment did not affect the overall efficacy of the
treatment as long as the treatment was allowed to
resume, and the full treatment schedule allowed to
proceed to completion. We based these results on
a temperature spike of ca. 4.2–4.5°C which approximated
an actual commercial situation in
which a temperature spike of 3°C occurred during
in-transit cold treatment of ‘Sharwil’ avocado
shipped from Hawaii to Seattle in 1998.