Shows some defects as a homozygote.
Transheterozygotes are pharate adult lethal (at 18oC lethality is at light pupal stage), exhibit a mutant brain phenotype and meiotic defects, although mobile mature sperm is produced. Transheterozygotes with stg2 or stg4 are viable and fertile. Transheterozygotes with stgAR2 are pharate adult lethal, the few escapers exhibit rough eyes, missing bristles and defective abdominal cuticle, and have low fertility. Homozygous escapers exhibit the same mutant phenotype.
Phenotype assayed in trans with a multiple mutant chromosome carrying mutations of polo, mgr, asp, stg and gnu.