Sub-zero cooling treatments of-10 degrees C and -15 degrees C for 2-6 days
were evaluated as a means of meeting the chilling requirement of diapause a
nd to synchronize post-diapause development in larvae which were held in di
apause for less than 6 months. Sub-zero cooling did not affect male longevi
ty. After six months in diapause, diapause/cooled females were longer lived
than diapause control females but not longer than non-diapause females. In
general, diapause-cooled males passed more spermatophores than males from
control diapause and non-diapause groups. In general, sub-zero cooling did
not consistently affect fecundity and % egg hatch. Non-diapause females lai
d the most eggs after six months in diapause, and diapause-cooled females l
aid the most eggs after seven months in diapause. The duration of sub-zero
cooling had a significant effect on post-diapause emergence in relation to
the duration that the larvae were in diapause. Sub-zero cooling for 4 days
at -10 degrees C significantly reduced the number of days to adult emergenc
e of larvae which had been in diapause for 0-4 months. Sub-zero cooling at
-15 degrees C for durations of 2, 4, and 6 days had more variable effects o
n emergence, but in most cases, sub-zero cooling reduced the amount of time
to and span of adult emergence.