Conditioning Mutations in DROSOPHILA MELANOGASTER Affect an Experience-Dependent Behavioral Modification in Courting Males

One aspect of courtship in male Drosophila melanogaster has been reported to be experience dependent. Males that have courted fertilized females are virtually unresponsive to virgin females for 2–3 hr. Here, this response was utilized as an assay for the effects of conditioning mutations on experience-dependent courtship. Seven strains expressing conditioning mutations (previously isolated and characterized for learning or memory defects in an electrical shock-odor association paradigm, independent of courtship) were all found to be mutant in expression of this experience-dependent change in courtship behavior. By comparison, three control strains that were unselected for conditioning defects all expressed normal experience-dependent courtship. Other results indicate that males of the conditioning-defective strains are able to elicit necessary cues from fertilized females, yet do not then modify their courtship with virgin females. Thus, it is suggested that experience-dependent modification of courtship and the previously reported associative olfactory conditioning with electric shock share common elements of processing. The possibility that experience-dependent courtship represents adaptive behavior is discussed.     

Male courtship in Drosophila: the conditioned response to immature males and its genetic control

Experimentally naive male Drosophila melanogaster respond to sexually immature males with intense courtship. However, this response decreases markedly in a short period of time, and "experienced" males then avoid further courtship with immature males for 4 hr. This subsequent inhibition of the courtship response is specific to immature males; the response to virgin females remains intact. This experience-dependent modification in courtship behavior is designated as "conditioned courtship." Seven mutant strains isolated for their inability to express avoidance conditioning (on criteria independent of courtship) were all found to be mutant with respect to expression of conditioned courtship. The potential application of this phenomenon to mosaic analysis of these mutations is posed. Other results indicate that immature males constitutively release a chemical signal that is sufficient for the expression of conditioned courtship. The interpretation of conditioned courtship as a component of fitness is discussed.     

Reduced Reproductive Success for a Conditioning Mutant in Experimental Populations of DROSOPHILA MELANOGASTER

Male Drosophila melanogaster that have courted newly-emerged males can modify their subsequent courtship behavior to avoid further courtship with immature males for up to 6 hr (previously reported). Here, it was hypothesized that such an experience-dependent modification would afford a mating advantage to normal males over males that carried a mutation that affects learning and memory. Coisogenic lines were constructed which varied at the dunce gene (dnc+ and dncM14 alleles) in order to test this hypothesis. Whether previously experienced with immature males or not, dnc+ and dncM14 males were indistinguishable in their response and mating efficiency when individually paired with virgin females. However, courtship performance of dnc+ and dncM14 males was different if they were first experienced with immature males and were then individually tested in an artificial population of nine immature males and one virgin female. In this situation, dnc+ males spent much less time in courtship with immature males and achieved copulation in one-third the time required for dncM14 males. As a control, the behavior and mating efficiency of courtship-naive dnc+ and dncM14 males in the artificial population was indistinguishable. In competition for a single virgin female, experienced dncM14 males showed a slight mating advantage over experienced dnc+ males. But when competition by experienced males for a single virgin female took place in the presence of nine immature males, dnc+ males were the successful maters in three-fourths of the trials.     

同种雄性竞争对手的存在对星豹蛛雄蛛求偶和交配行为的影响

越来越多的研究发现,雄性产生精子(精液)也需付出代价。雄性除了依据配偶质量和竞争对手的竞争强度适应性调整生殖投入外,雄性在求偶和交配行为上也相应产生适应性反应,求偶和交配行为具有可塑性。目前雄性求偶和交配行为可塑性研究主要集中于雌性多次交配的类群中,在雌性单次交配的类群中研究甚少。以雌蛛一生只交配一次而雄蛛可多次交配的星豹蛛为研究对象,比较:(1)前一雄性拖丝上信息物质对后续雄蛛求偶和交配行为的影响,(2)雌雄不同性比对雄蛛求偶和交配行为的影响。研究结果表明,星豹蛛前一雄蛛拖丝上的信息物质对后续雄蛛求偶潜伏期、求偶持续时间和交配持续时间都没有显著影响,但前一雄蛛拖丝上的信息物质对后续雄蛛求偶强度有显著抑制作用。同时,性比对星豹蛛雄蛛求偶和交配行为都没有显著影响。可见,星豹蛛雄蛛对同种雄性拖丝上的化学信息可产生求偶行为的适应性调整,而对性比不产生适应性反应。     

Chemosensory cues allow male Tenebrio molitor beetles to assess the reproductive status of potential mates

Males of many insect species, including beetles, choose their mates according to their reproductive status. However, the ways in which male beetles evaluate female reproductive status have received little attention. We tested the existence of male mate choice in the mealworm beetle, Tenebrio molitor, by observing mating and courtship behaviour of males given simultaneous access to pairs of females differing in their reproductive status: (1) mature versus immature; (2) virgin versus previously mated; (3) familiar (mated with the experimental male) versus unfamiliar (mated with a different male). Males courted and mated preferentially with mature and virgin females. To determine whether chemical cues played a role in these discriminations, we exposed males to filter paper squares bearing chemical cues from different types of females: (1) virgin versus mated; (2) mature versus immature. Males were significantly more attracted to those squares bearing chemical cues from virgin and mature females, suggesting that males can assess female reproductive status on the basis of chemical cues alone.     

Interactions of the Males and Females of Three Sympatric Drosophila virilis-Group Species, D. montana, D. littoralis, and D. lummei, (Diptera: Drosophilidae) in Intra- and Interspecific Courtships in the Wild and in the Laboratory

Four species of the Drosophila virilis group, D. montana, D. littoralis, D. lummei, and D. ezoana, occur sympatrically in several locations in northern Europe. Courtship interactions between the flies of the three first-mentioned species were observed at malt baits in Kemi, northern Finland, to find out how the flies of different species recognize conspecific individuals and how interspecific courtships differ from intraspecific ones in the wild. Intraspecific courtships (including females of different reproductive stages) and interspecific courtships were also videotaped and analyzed in laboratory. In the wild the males courted both conspecific and allospecific females, even though the species varied in how much the males were attracted to females of different species. Interspecific courtships usually broke off when the male touched the female or when the male and/or the female vibrated his/her wings, producing acoustic cues. In the laboratory males courted conspecific females irrespective of the reproductive stage of the female, even though the courtships directed toward immature and fertilized females usually included only orienting and touching (no licking and singing). D. littoralis, and very rarely D. montana and D. lummei, males courted also allospecific females. In the few interspecific courtships between these three species, where the male proceeded to singing, females responded to male singing by vibrating their wings. This ended the courtship. It is suggested that both the chemical cues affecting female attractivity and the acoustic signals of males and females, which are produced by wing vibration, function in maintaining sexual isolation between these three species.     

The mushroom body D1 dopamine receptor controls innate courtship drive

Mating is critical for species survival and is profoundly regulated by neuromodulators and neurohormones to accommodate internal states and external factors. To identify the underlying neuromodulatory mechanisms, we investigated the roles of dopamine receptors in various aspects of courtship behavior in Drosophila. Here, we report that the D1 dopamine receptor dDA1 regulates courtship drive in naïve males. The wild‐type naïve males actively courted females regardless their appearance or mating status. On the contrary, the dDA1 mutant (dumb) males exhibited substantially reduced courtship toward less appealing females including decapitated, leg‐less and mated females. The dumb male's reduced courtship activity was due to delay in courtship initiation and prolonged intervals between courtship bouts. The dampened courtship drive of dumb males was rescued by reinstated dDA1 expression in the mushroom body α/β and γ neurons but not α/β or γ neurons alone, which is distinct from the previously characterized dDA1 functions in experience‐dependent courtship or other learning and memory processes. We also found that the dopamine receptors dDA1, DAMB and dD2R are dispensable for associative memory formation and short‐term memory of conditioned courtship, thus courtship motivation and associative courtship learning and memory are regulated by distinct neuromodulatory mechanisms. Taken together, our study narrows the gap in the knowledge of the mechanism that dopamine regulates male courtship behavior.     

Behavioral analysis ofDrosophila mutants displaying abnormal male courtship

We describe six recessive autosomal male sterile mutations inDrosophila, generated by mobilization of single P-elements, exhibiting abnormal male courtship behavior. Detailed analysis of courtship behavior elicited by virgin wild type females indicated that five of the six mutants are affected in the early steps of courtship. The sixth mutant is blocked at the step of attempted copulation which occurs later in the courtship sequence. All of the mutants have normal olfactory responses and normal locomotor activity. No defect in the visual modality has been observed for the five mutants affected in the initiation of courtship. The mutant blocked at attempted copulation lacks the ‘on’ and ‘off’ transients, but this appears to be due to genetic background rather than the mutation itself. Abnormal spermatogenesis was observed in five of the mutants. Spermatogenic defects vary and include lesions in the proliferation of the germline, in meiosis, and in the differentiation and maturation of the spermatids into motile sperm.     

The different effects on courtship of volatile compounds from mated and virgin Drosophila females

Virgin Drosophila melanogaster females, which are courted vigorously, emit pheromones which stimulate males to court each other (Tompkinset al., 1980). Females which have recently copulated are courted less vigrously, and volatile compounds produced by mated females stimulate less courtship between males. Analysis of these compounds from fertilized females by gas chromatography and behavioral assays indicates that mated females emit less of the sex attractant made by virgins and may also produce material which inhibits courtship. These changes in pheromone production are initiated after the first few minutes of copulation.     

A Female-Emitted Pheromone Component Is Associated with Reduced Male Courtship in the Parasitoid Wasp Spalangia endius

During courtship interactions, the courted individual may not always be prepared to mate. For example, mating or courtship may be detrimental to its fitness and resistance is expected under these circumstances. As such, various resistance strategies have evolved, from physically fending off courting individuals to producing behavioural signals of unreceptivity. In the parasitoid wasp Spalangia endius, females rarely re-mate and mated females are avoided by males in favour of virgin females. Further, mated females appear to advertise their mating status by the release of a pheromone component (methyl 6-methylsalicylate), but direct evidence of the nature of this release is lacking. Here we used real-time chemical analysis to track the emission of the pheromone component during courtship interactions between virgin males and either virgin or mated females. We found that females actively release methyl 6-methylsalicylate when courted and that significantly greater concentrations are released by previously mated females. Further, high concentrations of this component are associated with both the prevention and termination of courtship.     

The Effect of Male Competition on the Courtship Song of Drosophila melanogaster

The courtship song of Drosophila has been extensively used as a model system for studies of sexual selection and species recognition. Traditionally, the courtship song has been recorded from males placed individually with a female. However, under natural conditions females are exposed to multiple courting males, and the effect of their joint signal on mate recognition by the female is not yet understood. Here, we recorded the courtship behavior of D. melanogaster males singing either individually to a female lpar;1:1) or in the presence of an additional male lpar;2:1). We compared the structure of the male song in the two experimental designs. Our results show that when two males courted a female their songs could overlap each other. Males produced a significantly different signal in the presence of competition; the duration of each song component was significantly shorter and the rate of singing was markedly lower. The present study demonstrates that male competition can dramatically alter the acoustic signal detected by the female.     

Do Psyttalia concolor (Hymenoptera: Braconidae) males gain in mating competitiveness from being courted by other males while still young?

The role of male–male courtship in parasitic wasps is not well understood and nothing has been reported on the implication of learning in regard to homosexual behavior in hymenopteran parasitoids. In Psyttalia concolor (Hymenoptera: Braconidae), a synovigenic koinobiont larval–pupal endoparasitoid of many Diptera Tephritidae of economic importance, courtship and mating attempts are frequently displayed among males. Here we determine whether P. concolor males that are courted while still young by sexually mature males can compete better with other males when they court females. The results showed that P. concolor immature males do not appear to gain from receiving male courtship, but they develop a higher intensity (more wing fanning and shorter latency time) in the successive courtship of the females. The hypothesis that, under some conditions, such higher courtship intensities may increase the probability of gaining a mating advantage is discussed.     

Courtship behavior of Heliconius erato phyllis (Lepidoptera, Nymphalidae) towards virgin and mated females: conflict between attraction and repulsion signals?

Previous observations of Heliconius erato phyllis females being intensively courted a few days after mating contradict the proposal of sexual repulsion caused by a male-transferred antiaphrodisiac. Furthermore, data on courtship in Heliconius butterflies are almost absent from the literature. In this work we aim to describe the courtship behavior of H. erato phyllis and to compare it towards virgin and mated females. Sexual interactions using both kinds of females were observed and filmed in seminatural conditions for subsequent analysis and quantification. Courtship of virgin and mated females differed qualitatively and quantitatively, but the results do not agree with the proposal of sexual repulsion. The differences found indicate that the courtship sequence towards mated females is interrupted in the transition that would lead to the behavior immediately prior to copulation, in such a way that the male continues courting the female in an intermediate phase. Preliminary tests even showed that older females, virgin or not, are much less courted by males. We suggest that there is a trade-off between an attraction pheromone, important for males to locate female pupae, and the male-transferred antiaphrodisiac, so that young, mated females may have both signals active. .     

Competitive Mating Success and Attractiveness of Sterile and Fertile Males of Drosophila montana

The attractiveness and the mating success of fertile (normal and brownie, br) and sterile (rudimentary testis, rt) Drosophila montana males were studied in female-choice experiments (one female + two males). The normal males courted the sterile rt males nearly as much as they courted the females, while they courted other males less frequently. The females required a long courtship with the rt males and accepted them as their mating partner less often than normal males. The courtship behaviour of normal, br and rt males was recorded in single pair situations with a normal female. The courtships of the males of all types proceeded in a similar manner, but the successful courtships of the rt males included more licking and touching than those of the normal and br males. The licking and touching periods are probably the critical phases at which the females are able to detect differences in male fertility.     

Mating Behavior and Reproductive Potential in the Turnip Moth Agrotis segetum (Lepidoptera: Noctuidae)

We investigated the lifetime mating potential and the reproductive behavior of male and female turnip moths Agrotis segetum (Schiff.) under field and laboratory conditions. The sex ratio was 1 : 1 in a lab-reared population as well as in two wild populations. Males were capable of mating repetitively a relatively large number of times (mean of 6.7 ± 2.7 matings) when given access to new virgin females throughout their lifetimes. Females seldom mated more than once (mean ± 1.3 ± 0.6 matings), indicating a male-biased operational sex ratio. The mean potential lifetime mating was five times higher in males, while the coefficient of variance was lower in males. There was no differences in longevity between animals that were allowed to mate and animals not allowed to mate, indicating no direct costs or benefits of mating in physiological terms. In males, the number of matings was positively correlated with longevity, but this was not the case in females. Nor was there a correlation between the number of female matings and the number of fertilized eggs. There was a negative correlation between the number of eggs fertilized and the number of times males had previously mated, indicating that male ejaculates were limited. Male spermatophore size also decreased with number of achieved matings. Laboratory-reared females attracted males in the field throughout their lifetimes, with a peak at 3–7 days of age. Wild males, allowed to choose between pairs of caged females in the field, were attracted in equal numbers to females of different ages. Females did not show any mate-rejection behavior in the field. They mated with the first male that courted them. No incidence of mate replacement by males arriving later to already courted females were recorded.     

Courtship Solicitation by Females of the Barred Sulphur Butterfly (<Emphasis Type="Italic">Eurema daira</Emphasis>) (Lepidoptera: Pieridae)

Virgin females of the subtropical pierid butterfly Eurema daira were observed to actively solicit male courtship. The resulting interactions involved both aggressive contact with male individuals and elaborate female posturing. Cage-based trials showed that there was a direct relationship between the frequency of courtship solicitation attempts and female age. Virgin females under 3 days old showed little or no interest in initiating courtship. By contrast, 23.2 percent of the virgin females over three days old actively solicited available males with peak solicitation behavior exhibited from five day old individuals.     

Generalization of courtship learning in Drosophila is mediated by cis-vaccenyl acetate

Reproductive behavior in Drosophila has both stereotyped and plastic components that are driven by age- and sex-specific chemical cues. Males who unsuccessfully court virgin females subsequently avoid females that are of the same age as the trainer. In contrast, males trained with mature mated females associate volatile appetitive and aversive pheromonal cues and learn to suppress courtship of all females. Here we show that the volatile aversive pheromone that leads to generalized learning with mated females is (Z)-11-octadecenyl acetate (cis-vaccenyl acetate, cVA). cVA is a major component of the male cuticular hydrocarbon profile, but it is not found on virgin females. During copulation, cVA is transferred to the female in ejaculate along with sperm and peptides that decrease her sexual receptivity. When males sense cVA (either synthetic or from mated female or male extracts) in the context of female pheromone, they develop a generalized suppression of courtship. The effects of cVA on initial courtship of virgin females can be blocked by expression of tetanus toxin in Or65a, but not Or67d neurons, demonstrating that the aversive effects of this pheromone are mediated by a specific class of olfactory neuron. These findings suggest that transfer of cVA to females during mating may be part of the male's strategy to suppress reproduction by competing males.     

Effects of male age on the mating behavior of both sexes in the sorghum plant bug, Stenotus rubrovittatus (Hemiptera: Miridae)

In the sorghum plant bug Stenotus rubrovittatus (Matsumura) (Hemiptera: Miridae), mating behavior consists of male courtship and female mating receptivity. Previous studies have found that female age is correlated with ovary development and that mature females with developed ovaries are more receptive to male courtship. Thus, we examined whether male age affects the mating behavior of both sexes and male accessory gland development. Unmated males 0–9 days after emergence and 3-day-old virgin females receptive to male courtship were studied. Immediately after emergence, only 20 % of the males courted females (n = 25). At 3 days old, 68 % of the males courted females (n = 25), the most active age. In contrast, more than 75 % of the courted females were receptive to the male courtship regardless of male age. These results indicate that only male courtship behavior is affected by male age, although it is not enhanced in proportion to male age. Male accessory glands developed with male age. However, no clear relationship was detected between male courtship behavior and accessory gland development. In S. rubrovittatus, it is difficult to explain male courtship behavior solely from male age and accessory gland development.     

Information transmission during intra- and interspecific courtship inEphestia elutella andCadra figulilella

Using information theory, courtship posturing in the moths Ephestia elutella(Hübner) and Cadra figulilella(Gregson) was analyzed for information transmission, which was partitioned into autocovariability (intraindividual transmission) and cross-covariability (interindividual transmission). This two-factor analysis was sufficient to account for more than 60% of the behavioral variance in males of E. elutellaand in both sexes of C. figulilelladuring intraspecific courtships; however, there were large residual variances in the behavior of male and female C. figulilelladuring interspecific courtships and in E. elutellafemales during both inter- and intraspecific courtships. In E. elutella,significant levels of transmission were attributable to both inter- and intraindividual effects, whereas in C. figulilella,only autocovariability was high and no interindividual communication could be assigned to courtship postures. Although courtship in these two species was qualitatively very similar and males readily courted nonconspecific females, high levels of reproductive isolation resulted from courtship. Male C. figulilellahad 94% fewer copulations with E. elutellafemales than with conspecific females and E. elutellamales had 78% fewer copulations with C. figulilellafemales than with conspecifics. These reductions were due to a differential response in both females and males, causing inter-specific courtships to be terminated much earlier than intraspecific courtships. This discrimination indicates that interindividual communication was indeed occurring during courtship and was only partially measured by analysis of postures. Thus, communication took place largely in some other modality, most likely the chemical modality, where species specificity is suggested for both male and female pheromones.     

Temperature-dependent development of the predatory mite <Emphasis Type="Italic">Cheyletus malaccensis</Emphasis> (Acari: Cheyletidae)

The effect of temperature on the development of immature stages of the predator Cheyletus malaccensis Oudemans, produced by either fertilized or virgin females, was studied at 17.5, 20, 25, 30, 32.5, and 35°C, 80 ± 5% relative humidity, in complete darkness, and fed Tyrophagus putrescentiae (Schrank). The population maintained at 15°C failed to reproduce. The thermal data obtained were used for the estimation of the thermal requirements (developmental thresholds, thermal constant, optimum temperature) of this predator by a linear and nonlinear model (Logan type I model). Upper and lower developmental thresholds ranged between 37.4–37.8 and 11.6–12.0°C, respectively. Optimum temperature for development was estimated at between 33.1 and 33.5°C. The thermal constant ranged between 238.1 and 312.5 degree-days. Based on the data of the total pre-imaginal period, immatures’ survival peaked at 25°C. Arrhenotokous parthenogenesis (haplodiploidy) is confirmed in the species: virgin females always produce males, whereas fertilized females give rise to offspring of both sexes. Survival of the immature stages and offspring sex ratio were not significantly influenced by temperature.