Heat induced expression during feeding third instar larvae does not decrease viability, induced expression during late wandering larvae causes 100% lethality. Most die as larvae, they fail to form a puparium and their anterior spiracles never evert. Some larvae do pupariate but develop no further. A slight increase in viability is seen when expression is induced in white larvae but declines again with induced expression 6 hours post-puparium formation. Flies do not develop any discernible adult structures. Heat induced expression 36 hours post-puparium formation causes a small decrease in viability.
1-2 hour heat shock at third instar larvae causes 5 to 20% of the larvae to fail to pupate or die as early pupae. Surviving adults had a stripe of rough region in the eye running dorsoventrally, which corresponds to a stripe of ommatidia with abnormal photoreceptors, which may be broader than the rough stripe. The ommatidial stripe may be greater than 10 rows. While in one substripe the R7 cell is transformed to an outer photoreceptor cell, another substripe lacks the R7 cell. Most ommatidia lacking R7 also lack R8: the R8 precursor undergoes cell death between 6 and 13 hours following ectopic expression of svp.
