Identification of acoustic stimuli that mediate sexual behavior inDrosophila busckii (Diptera: Drosophilidae)

We have shown that D. busckiimales and females, unlike other drosophilids that have been analyzed in this regard, court and copulate as well in relatively dim red light as they do in bright white light. We have also shown that males and females of this species flutter their wings during courtship and that wing fluttering in both sexes is associated with acoustic stimuli. Wingless males perform vigorous courtship but are incapable of mating, suggesting that females must perceive male song to be receptive to copulation. When they are tested with normal males, wingless females stimulate vigorous courtship, but their copulation frequencies are significantly lower than winged females. This observation suggests that perception of the female's song by either or both sexes facilitates mating.     

Mate choice in Drosophila melanogaster and D. sechellia: criteria and their variation depending on courtship song

Courtship song is one of the most important male signals in Drosophila mating. A female D. melanogaster copulates more readily when given a conspecific type of courtship song. Female D. melanogaster accepted winged D. sechellia more than wingless ones in a no choice test. Copulation frequencies varied between strains and were significantly correlated with male mating propensity of D. sechellia. Females from three of five strains of D. sechellia accepted winged D. melanogaster less than wingless ones in no choice tests, suggesting that D. melanogaster songs reduce mating in D. sechellia females. Multiple choice tests showed that males prefer conspecifics. In female choice tests, D. melanogaster females copulated with winged heterospecific D. sechellia males more than with wingless conspecific D. melanogaster males in the confined condition, suggesting that song differences between D. melanogaster and D. sechellia affect D. melanogaster females less than the absence of courtship song. Copyright 2000 The Association for the Study of Animal Behaviour.     

Inheritance of species differences in female receptivity and song requirement between Drosophila virilis and D. montana

Females of two Drosophila virilis group species, D. virilis and D. montana, have different requirements for the courting males. In the present study we have examined species differences in female receptivity and male courtship song requirement using females' acceptance signal instead of copulation for measuring female readiness to mate. Behavior of D. virilis and D. montana females and F1 and backcross hybrid females was observed in a single-pair courtships with D. virilis and D. montana males and normal and wingless (mute) F1 hybrid males. D. virilis females were very receptive and they commonly accepted the courtship of males unable to produce courtship song. D. montana females, on the contrary, had a low receptivity and these females accepted the courting male only after hearing his song. Interspecific F1 and backcross (BCm) females resembled D. virilis more than D. montana in their receptivity. These females, however, resembled D. montana in their song requirement. These findings suggest that female song requirement and female receptivity are determined by different genetic factors.     

Courtship song recognition in the Drosophila melanogaster complex: heterospecific songs make females receptive in D. melanogaster, but not in D. sechellia

Abstract. The courtship song emitted by male wing vibration has been regarded as one of the most important signals in sexual isolation in the species of the Drosophila melanogaster complex. Inter- and intraspecific crosses were observed using males whose wings were removed (mute) or females whose aristae were removed (deaf). Females of D. melanogaster, D. simulans , and D. mauritiana mated with heterospecific males in the song-present condition (cross between normal females and winged males) more often than in the no-song condition (cross between normal females and wingless males or between aristaless females and winged males) or they showed no preference between the two conditions. It is possible that in these females heterospecific courtship songs play a role as if they were conspecific. In contrast, the females of D. sechellia mated with D. melanogaster or D. simulans males in the no-song condition more often than in the song-present condition, suggesting that they reject males with heterospecific song. Female mate recognition depending on the courtship song in D. melanogaster, D. simulans , and D. mauritiana is considered to be relatively broader and that in D. sechellia narrower.     

The role of acoustic signals in courtship behavior of <Emphasis Type="Italic">Drosophila virilis</Emphasis>

The role of the male acoustic signal in courtship behavior in Drosophila virilis was studied by a video-typing method. Three series of the experiments were performed: tests with intact flies, with wingless males and intact females, and with intact males and females with the aristas removed. It was demonstrated that touching and licking were the most prolonged elements of the male courtship. It was noted that removal of the wings in males or aristas in females resulted in an increase in the duration of almost all elements of the courtship behavior (following, touching, licking, singing, and circling) and in a significant decrease in the portion of successful copulations. It was demonstrated that the courtship structure in the experiments with females without aristas changed to a greater extent than in tests with wingless males.     

Effects of Courtship Song in Interspecific Crosses Among the Species of the Drosophila auraria Complex (Diptera: Drosophilidae)

The courtship behavior and the effects of courtship song in inter- and intraspecific crosses were studied in the four sympatric species of the Drosophila auraria complex: D. auraria, D. biauraria, D. subauraria, and D. triauraria. Orientation, tapping, and vibration (the repertoires of male courtship) were observed in both inter- and intraspecific crosses, suggesting that signals from heterospecific females were enough to elicit such male behaviors. The crossability tests with wingless or winged heterospecific males (tests for wing effects) revealed that winged heterospecific males copulated less than wingless ones in all four species but not all the pairwise cases. Since the crossability tests with aristaless females (deaf) or normal females showed essentially the same results as the tests for wing effects, we concluded that the sound produced by wing vibration plays an important role and that the wing movement itself is less important. These findings suggest that courtship songs are of great importance in mate discrimination and the sexual isolation between the species of this complex.     

Courtship Behavior of Zaprionus indianus (Gupta) (Diptera: Drosophilidae) from Populations Colonizing South America

We describe for the first time the sexual behavior and the courtship song of males of the African fly Zaprionus indianus (Gupta), a recent invader of South America. The male courtship song is formed by monocyclic pulses and the courtship behavior is simple when compared to that of species of Drosophila. Two interpulse interval (IPI) distributions were observed: pre-mounting and mounting. No significant difference was observed between the pre-mounting IPIs of males that descended from three geographical populations from South America. We also observed the songs produced by females and the homosexual behavior exhibited by males. A sequence of bursts is produced by females as a refusal signal against males, while males emit a characteristic song that identifies sex genus, which differs from the courtship song. The short courtship and mating latencies recorded reveal vigorous males and receptive females, respectively.     

Male Courtship Pheromones Affect Female Behaviour in the Swordtail Characin (Corynopoma riisei)

Pheromones constitute an important cue used by both males and females during courtship. Here, we investigate the effect of male pheromones on female behaviour in the swordtail characin (Corynopoma riisei), a species of fish where males have a caudal pheromone gland which has been suggested to affect female behaviour during courtship. We subjected female C. riisei to male courtship pheromones and investigated the effect on both female behaviour and brain serotonergic activity levels compared to a control group. While no difference in serotonergic activity was found, the pheromone‐treated females showed lower stress levels compared to the control group. Furthermore, pheromone‐treated females increased locomotor activity over time, while a decrease in locomotor activity was observed in the control group. These results suggest that the male courtship pheromones may serve to reduce female stress and increase female activity, possibly to aid males in gaining access to females and facilitating sperm transfer.     

Female mate recognition and sexual isolation depending on courtship song in Drosophila sechellia and its siblings

In Drosophila sechellia, females accept males that sing heterospecific songs less than those that do not sing, whereas in D. melanogaster and D. simulans, females accept males that sing heterospecific song more than those that do not sing. Here we studied the sexual isolation of D. sechellia and its siblings using interspecific hybrids to reveal the mechanisms underlying female mate recognition. The females of hybrids mated more with winged males of the parent species than with wingless ones, suggesting that the discrimination against heterospecific songs by D. sechellia females is recessive. Female preference for courtship songs seems to be inherited additively or semidominantly. In addition, we examined female receptivity without the stimuli of courtship songs by comparing the mating frequencies between the crosses using wingless males and found that it is also inherited additively or semidominantly.     

Male singing behaviour and female presence in the territory in whitethroats Sylvia communis

Unmated male songbirds usually change their vocal behaviour when females enter their territories. Either the males court the females by changing the rate or pattern with which their normal long-ranging full songs are emitted, or they shift to special displays and long- or short-ranging vocalisations. In this study we quantified how female presence and behaviour affect the singing behaviour of male whitethroats. In the presence of a female the male frequently performed song flights, maybe to locate the female before it was courted, with sequences of diving-song displays. The courtship was interrupted by periods of perch songs. Female dscharp calls and short movements made the males initiate or resume courtship, whereas short horizontal jumps made the males intensify their courtship. Overall, the males changed their dual-function song activity in females' presence by emitting fewer perch songs and more flight songs. The quiet diving songs were only emitted during direct courtship of a female. The song types emitted immediately before, during, and after courtship are all highly variable, thus allowing for a quick assessment of the male's song repertoire. The courtship was also interrupted by periods of male woid calling, a call that is known to have a deterring effect on rival males. Bouts of woid calls were usually followed by song flights, again probably to locate the female that might have moved out of sight, or maybe to locate potential rival intruders. The latter was supported by an increased intrusion rate during female presence. Communicated by P. McGregor     

Courtship processing in Drosophila melanogaster. II. An adaptation to selection for receptivity to wingless males

Measurements of the locomotor activity in courtship cells of female types from the experiment reported in the previous paper disclosed that the presence of a second animal reduced the activity level of the female being measured. The reduction in activity was greater when the second animal was a courting wingless male than when it was a female. Such lowering of the female's activity during courtship was found to be related to subsequent receptivity to wingless males. Strain differences in activity score and rate of decline in activity over the test period confirmed that this system was probably responsible for the selection gain observed. Further experiments attempted to clarify the causal factors associated with these phenomena.     

Courtship song and immune function in the field cricket Gryllus bimaculatus

It has been assumed that sexual ornaments have evolved to reveal males' health and vigour for females. Choosy females may indirectly use ornaments as an indicator of the presence and effectiveness of genes for resistance against parasites. In this study we tested whether females of the Mediterranean field cricket, Gryllus bimaculatus, can use courtship song as a cue for choosing males with high immunocompetence, measured as encapsulation rate of nylon implants and lytic activity of haemolymph. We found that female crickets preferred courtship songs from males with a high encapsulation rate. Female crickets also had a tendency to prefer courtship songs with high tick rate and long high-frequency tick duration. These preferred song components were positively correlated with encapsulation rate, but negatively correlated with lytic activity of the male. In contrast to previous studies of crickets, there was no correlation between male weight and encapsulation rate or lytic activity. There is some evidence in another cricket species that the ability to encapsulate pathogens is heritable. Thus, in light of this study it seems possible that by preferring males according to their courtship song, females might benefit by increasing the parasite resistance of their offspring.  © 2003 The Linnean Society of London, Biological Journal of the Linnean Society , 2003, 79 , 503–510.     

ALTERED MATING BEHAVIOR IN A CARSONIAN POPULATION OF DROSOPHILA SECHELLIA

Mating behavior was studied in two laboratory populations of Drosophila sechellia and their reciprocal hybrids. The ancestral population was reared on a special medium, optimal for this species, while the derived population was reared on a standard Drosophila food, and underwent a bottleneck while adapting to this new medium, in a manner similar to the “founder-flush” process of Carson (1971). A significant tendency towards mating asymmetry was found, with ancestral females mating significantly less frequently with derived males than derived females with ancestral males. Analysis of hybrids suggested an important role for the male's X chromosome or for a maternal effect. No significant differences were found among parental types for their main female cuticular hydrocarbons, the proportion of courtship spent in various behavioral elements, body weight, or wing length. Significant differences were found in the structure of courtship, male locomotor activity, male cuticular hydrocarbon levels, and male courtship song inter-pulse interval (i.p.i.). None of these differences showed an X-linked effect in the reciprocal hybrids. Hypotheses put forward to explain interspecific mating asymmetries are discussed in the light of these results.     

Drosophila male courtship behavior is modulated by ecdysteroids

Temperature-dependent induction of ecdysteroid deficiency in the ecdysoneless mutant ecd¹ adult Drosophilamelanogaster results in altered courtship behavior in males. Ecdysteroid deficiency brings about significantly elevated male-male courtship behavior including song production resembling that directed toward females. Supplementation with dietary 20-hydroxyecdysone reduces male-male attraction, but does not change motor activity, courtship patterns or attraction to females. These observations support the hypothesis that reduced levels of ecdysteroids increase the probability that male fruit flies will display courtship behaviors to male stimuli.     

Courtship song, male agonistic encounters, and female mate choice in the house cricket,Acheta domesticus (Orthoptera: Gryllidae)

Whether female crickets choose among males based on characteristics of the courtship song is uncertain, but in many species, males not producing courtship song do not mate. In the house cricket,Acheta domesticus, we examined whether a female chose or rejected a male based on his size, latency to chirp, latency to produce courtship song, or rate of the high-frequency pulse of courtship song (“court rate”). We confirmed that females mated only with males that produced courtship song, but we found no evidence that the other factors we measured affected a female’s decision to mate. In addition, we investigated whether the outcome of male agonistic encounters affected the subsequent production of courtship song. In one experiment, we observed courtship and mating behavior when a single female was placed with a pair of males following a 10-min interaction period between the two males. Winners of male agonistic encounters had higher mating success. However, winners and losers of agonistic encounters were not different in their likelihood or latency to produce courtship song or in the number of times they were disrupted by the other male in the pair. In a second experiment, we allowed two males to interact for a 10-min period, but following this interaction period, we placed a female with each male separately and observed courtship and mating behavior. The mating success of winners and losers was not different under these circumstances, and we found no differences between winners and losers in any subsequent courtship or mating behavior examined. We conclude that winning agonistic encounters influences a male’s mating success in ways other than his production of courtship song and this effect is lost when winning and losing males are separated and each is given an opportunity to mate.     

Singing-Related Activity in Anterior Forebrain of Male Zebra Finches Reflects Courtship Motivation for Target Females

A critical function of singing by male songbirds is to attract a female mate. Previous studies have suggested that the anterior forebrain system is involved in this courtship behavior. Neural activity in this system, including the striatal Area X, is strikingly dependent on the function of male singing. When males sing to attract a female bird rather than while alone, less variable neural activity results in less variable song spectral features, which may be attractive to the female. These characteristics of neural activity and singing thus may reflect a male''s motivation for courtship. Here, we compared the variability of neural activity and song features between courtship singing directed to a female with whom a male had previously formed a pair-bond or to other females. Surprisingly, across all units, there was no clear tendency for a difference in variability of neural activity or song features between courtship of paired females, nonpaired females, or dummy females. However, across the population of recordings, there was a significant relationship between the relative variability of syllable frequency and neural activity: when syllable frequency was less variable to paired than nonpaired females, neural activity was also less variable (and vice-versa). These results show that the lower variability of neural activity and syllable frequency during directed singing is not a binary distinction from undirected singing, but can vary in intensity, possibly related to the relative preference of a male for his singing target.     

The behavioural basis of overdominance in competitive mating success at the ebony locus of Drosophila melanogaster

Male files homozygous for the gene ebony¹¹ are partially blind, and at a disadvantage in competitive mating. The courtship of the mutant males is deficient in wing vibration stimulation, which is characterized by a low proportion of sine song and a high intra-pulse frequency. Males heterozygous for ebony have normal vision, but show an increase in courtship song, and are superior in competitive mating to wild type males. The auditory characteristics of courtship song produced by heterozygous males are indistinguishable from those of wild type, and their superiority in competitive mating success is due to overdominance involving this specific element of male courtship behaviour.     

Ultrasonic courtship songs of male Asian corn borer moths assist copulation attempts by making the females motionless

Males of the Asian corn borer moth Ostrinia furnacalis (Guenée) produce an ultrasonic courtship song of extremely low‐intensity during copulation attempts. The song has been shown to significantly increase the mating success of the male; however, the mode of action of the sound in courtship remains to be resolved. Behavioural experiments using pairs with deafened females or muted males show that, without the aid of the sound, 63% of males eventually succeed in mating after several copulation attempts, whereas the remainder (37%) make repeated attempts in vain until interrupted by the escape of the female. Because few (2%) males fail to copulate when females hear the courtship song, it is evident that the song has an effect on females, promoting the success of copulation attempts. In support of this view, males produce louder songs if the first copulation attempt fails, suggesting that the males increase their sound levels to achieve successful copulation. It is suggested that the ultrasonic songs of the male render the females motionless, which is the same response as that to ultrasonic bat calls. Because even slight movements by the female can interfere with the attempt of the male to copulate, it is likely that, by making her motionless, the success rate of a single copulation attempt is increased greatly.     

The role of signals of different modalities in initiating vibratory communication in Nezara viridula

Signals of different modalities are involved in the behaviour of the green stink bug, Nezara viridula (L.) (Pentatomidae, Heteroptera). Long range attraction is mediated by male pheromones, resulting in aggregation of bugs on the same plant where vibratory signals, vision and various chemical signals become important. Both males and females sing spontaneously. When both are on the plant, males start vibratory communication as often as females. Females induce the exchange of vibratory signals spontaneously or triggered by the male pheromone while males initiate the duet either spontaneously or after seeing the female. Males and females sing spontaneously and respond to signals of different modalities more often in the daylight than in the dark. Long lasting autonomous emission of the female calling song is present when triggered by the male pheromone and males respond to female calling predominantly by the emission of the courtship song.     

Song Choice Is Modulated by Female Movement in Drosophila Males

Mate selection is critical to ensuring the survival of a species. In the fruit fly, Drosophila melanogaster, genetic and anatomical studies have focused on mate recognition and courtship initiation for decades. This model system has proven to be highly amenable for the study of neural systems controlling the decision making process. However, much less is known about how courtship quality is regulated in a temporally dynamic manner in males and how a female assesses male performance as she makes her decision of whether to accept copulation. Here, we report that the courting male dynamically adjusts the relative proportions of the song components, pulse song or sine song, by assessing female locomotion. Male flies deficient for olfaction failed to perform the locomotion-dependent song modulation, indicating that olfactory cues provide essential information regarding proximity to the target female. Olfactory mutant males also showed lower copulation success when paired with wild-type females, suggesting that the male’s ability to temporally control song significantly affects female mating receptivity. These results depict the consecutive inter-sex behavioral decisions, in which a male smells the close proximity of a female as an indication of her increased receptivity and accordingly coordinates his song choice, which then enhances the probability of his successful copulation.