Partial excision of the P{lacW} element; a portion of the P{lacW} element remains but there is a disruption in the element that inactivates the w+mC marker allele.
Homozygous flies show a reduced avoidance response to the olfactory repellents 3-octanol, ethyl acetate and 4-methylcyclohexanol in an olfactory T maze. Neural degeneration is not seen in adult flies, even when aged 3-4 weeks.