fru^0-1/fru^sat males exhibit reduced midline crossing of ppk23- expressing axons.

During courtship, fru^sat/+ males show similar wing switching (wing switching index) compared to controls. In homozygotes, courtship bouts are very short (if any).

The P1 neurite terminals in the contralateral hemisphere consistently fail to turn ventrally in fru^NP0021/fru^sat males.

fru^NP0021/fru^sat mutants exhibit a loss of the male specific muscle of Lawrence. Mutant also exhibit markedly reduced courtship behaviour towards males as well as females

Expression of 5-HT in serotonergic-abdominal ganglion neurons in adult males is defective; relatively few neurons express 5-HT compared to wild type.

fru¹/fru^sat males mated individually to a single virgin female show vigorous courtship behaviour, comparable to that of wild-type males. High levels of abdominal bending are seen in the males that show courtship behaviour. However, the proportion of males that mate is reduced compared to wild type; 38% of the transheterozygous males court but do not mate. The fertility of the males (as assayed by the ability of the mated females to produce progeny) is reduced compared to wild-type males. The transheterozygous males show longer than normal mating-initiation latencies compared to heterozygous controls. Mating duration is also longer than normal and shows a far more scattered distribution than that of wild-type males.

The number of progeny (number of resulting pupae) obtained from a fertile mating between a fru¹/fru^sat male and a wild-type female are not significantly different to wild type.

The varicosities of the sAbg neurons which are associated with the reproductive organs are less extensive than normal in fru^sat males.

Males show low levels of courtship, with either fru^sat males or wild type females. Residual courtship is not normal. Sine-song bouts are short and no song pulses are generated. Mutant males exhibit tapping and licking but no attempted copulation. Males grouped together display courtship chaining with numerous wing extensions. Sterile over Df(3R)P14 and Df(3R)fru^w24 with occasional fertile heterozygotes over Df(3R)Cha^M5. fru¹/fru^sat males are weakly fertile, at a rate similar to that for fru¹/fru³ or fru¹/fru⁴.

Homozygous males show high levels of head-to-head interactions compared to wild-type males. Most of these would-be aggressive actions involve bringing their heads together but not escalating the interactions into the rising-up and boxing motions that are displayed by wild-type males. The level of head-to-head interactions shows a temporal dependency; when males are grouped together on the day they eclose they do not show significantly higher than normal head-to-head interactions, but the frequency of head-to-head interactions shows a marked increase beginning on day 2 and peaking on days 4-5. Mutant males aged individually for 5-7 days and then grouped together show low levels of head-to-head interactions 1 day after being grouped together, but show an increase in the frequency of head-to-head interactions by days 4-5. These flies (which were aged individually) show lower levels of head-to-head interactions compared to mutant males that have been aged for essentially the same number of days, but in the presence of other males since eclosion, indicating a social component in the phenotype. Mutant males show some chaining behaviour. Chaining also show temporal dependence, with the frequency of chaining showing a marked increase beginning on day 2 and peaking on days 4-5.

Homozygous fru^sat mutant male flies court less than wild-type control flies. Homozygous fru^sat mutant male flies hardly court male targets.

Males show male preference in courtship and completely lack the muscle of Lawrence. Expression of fru^AM.hs using heat shock during either the embryo to third larval instar or during the third larval instar to pupal stage results in lethality in fru^sat males. Expression of fru^{B.Scer\UAS.cUa} under the control of Scer\GAL4^D42 in fru^sat females results in the formation of the muscle of Lawrence (MOL) in most of these flies (91%). Some of these females have one to three MOLs in the A4 and A3 segment in addition to a pair of MOLs in the A5 segment.

Homozygous males do not court with either homozygous fru^sat or wild-type females, whereas homozygous fru^sat females are highly receptive to courting by wild-type males. fru¹/fru^sat males mate with females, although less often than wild-type males do, and they are fertile. Homozygous fru^sat and fru¹/fru^sat males form courtship chains. Homozygous fru^sat males lack the muscle of Lawrence. fru^sat/Df(3R)BX5, fru^sat/Df(3R)P14 and fru^sat/Df(3R)gl-BX10 males mate with wild-type females less often than wild-type males do. fru^sat/Df(3R)Cha7 males do not mate with wild-type females. fru^sat/Df(3R)gl-BX1 males mate with wild-type females at a normal frequency.

Males are homosexual, only courting with males. Heterozygotes with In(3R)fru are bisexual.

fru[+]/fru^sat, robo1^Δ3 has abnormal courtship behavior | male phenotype

Scer\GAL4^53B, fru^sat, tra^UAS.cFa has abnormal courtship behavior phenotype