Seasonal Variation in Female Response to Male Calling Song in the Field Cricket, Gryllus rubens

Conspicuous traits that make males attractive to females may make them vulnerable to predators. Females that approach conspicuous males may increase their risk of predation. This means that selection for reduced male conspicuousness in the presence of predators may be due to sexual selection resulting from altered female behavior in the face of increased predator risk. We examine this hypothesis in the field cricket, Gryllus rubens, in which male calling song attracts both conspecific females for mating and parasitoid flies (Ormia ochracea) which kill their hosts within a week. Female crickets are also parasitized by these flies as a result of associating with calling males. In northern Florida crickets that emerge in the spring are not subject to fly parasitism whereas autumn crickets encounter large numbers of flies. We predicted that autumn females should be less attracted to male song than spring females. We tested female response to male calls in a rectangular arena in which male calling song was broadcast from a speaker. Spring females readily approached the speaker but autumn females were less likely to approach and remain in the vicinity of the speaker. These results emphasize the importance of considering how risk affects the evolution of conspicuous male behavior both directly through its effect on the male and indirectly through its effect on female responses to males.     

Settlement Patterns of Mediterranean Fruit Flies in the Tree Canopy: An Experimental Analysis

Males of the Mediterranean fruit fly, Ceratitis capitata (medfly), defend individual leaves of host and non-host trees as mating territories and attract females via production of a sex pheromone (a behavior termed ‘calling’). Males tend to aggregate within the tree canopy, and the present study examined the influence of (1) location and (2) resources on female visitation to male aggregations. Males were placed in screen-covered containers, which were suspended on field-caged trees at two locations selected to differ in only one of the following parameters: height above ground (low versus high), leaf density (sparse versus dense), distance to main trunk (canopy edge versus center), proximity to a food source (bird feces absent or present), and proximity to a host fruit (oranges absent or present). Females were released, and we periodically recorded the number of calling males in each of the test aggregations as well as the number of females sighted within 15 cm of each male aggregation. Male calling did not differ between treatments in any of the experiments. However, females were more frequently sighted near males calling (1) in dense foliage, (2) near the central trunk, (3) near bird feces, and (4) near oranges. In an additional experiment, we compared male settlement (in the absence of females) on leaves in the same sites used previously to determine the degree of congruence between the sexes in microhabitat use. Aside from the lack of center-edge effect, males displayed the same settlement patterns as females. In a final experiment, we found no effect of male calling on the distribution of other males: released males were sighted with equal frequency near cups containing mature, calling males and cups containing immature, non-calling males. Medfly lek behavior is discussed in light of these findings.     

Are Centrally Displaying Males Always the Centre of Female Attention? Acoustic Display Position and Female Choice in a Lek Mating Subterranean Insect

Several conceptual models seek to explain patterns of male display and factors that influence female mate choice in lek mating systems. The central advantage model predicts that males displaying at or near the lek centre should be more attractive to females than are males positioned along the lek periphery. Females may exhibit biases toward these centrally displaying males based on either spatial or display‐related cues. We tested the prediction of the central advantage model in investigating the importance of male display position in the subterranean and lek mating prairie mole cricket (Gryllotalpa major). Gryllotalpa major males form mating aggregations in the early spring and produce an acoustic advertisement signal from a constructed calling chamber at the soil surface. Pair formation occurs in the calling chamber, and males typically maintain these structures for the duration of the reproductive season. To assess whether G. major females exhibit a preference for males calling from centrally located acoustic burrows, we documented the spatial position and number of female attractions for all advertising males across the focal lek. Six spatial attributes related to display position were reduced using principal component analysis and examined for an association with male attractiveness. We found that in general, female attractions were distributed randomly across the lek; male attractiveness was not related to proximity to the lek centre nor to any factor associated with display position. The most highly attractive males, however, were located further from the lek centre and from nearest calling neighbours than other attractive males. Advertising males that segregate themselves within the aggregation and locate nearer the lek margin may gain a geometric advantage resulting in the increased probability of attracting a searching female.     

Fluctuating asymmetry, call structure and the risk of attack from phonotactic parasitoids in the bushcricket Sciarasaga quadrata (Orthoptera: Tettigoniidae)

The acoustically orienting parasitoid Homotrixa alleni (Diptera: Tachinidae) is a significant mortality factor of calling male Sciarasaga quadrata (Orthoptera: Tettigoniidae), with less than 10% of males escaping parasitism within the duration of the calling season. This study examined fluctuating asymmetry (FA) (small, random deviations from perfect symmetry) in five morphological traits in S. quadrata and its relation to the survival of calling males in the field. A significant relationship was demonstrated in only a single trait; across three consecutive field seasons and among each of the collections per season, parasitised males were shown to have significantly more asymmetric hind tibia than unparasitised males. Since the morphological development of males is complete prior to parasitoid attack, this relationship is not caused by the activities of the parasitoid. Further experimentation revealed that there was no relationship between the level of FA in the hind tibia and the success of parasitism, with males artificially parasitised in the laboratory showing no difference in FA from those where parasitism was unsuccessful. Instead, FA was shown to be negatively related to chirp length, an aspect of call structure that significantly affects the survival of calling males under parasitism risk in the field. We explore the possible reasons why more asymmetric males produce calls of shorter chirp length and hypothesise that the difference in hind tibia asymmetry seen between parasitised and unparasitised males in the field is related to host location in H. alleni rather than the inability of S. quadrata to defend itself against parasitoid attack. Received: 14 November 1997 / Accepted: 20 April 1998     

INBREEDING AND ADVERTISEMENT CALLING IN THE CRICKET TELEOGRYLLUS COMMODUS: LABORATORY AND FIELD EXPERIMENTS

If sexually selected traits reveal a male's heterozygosity or condition to females, then such traits should exhibit declines with inbreeding. We tested this by examining the effect of inbreeding on advertisement calling in male crickets Teleogryllus commodus. We investigated the effect of one generation of full‐sibling mating on calling effort and fine‐scale call structure. Inbreeding reduced calling effort but had no effect on call structure. We then compared the attractiveness of inbred and outbred calls in the field by monitoring how many wild females were attracted to each call type. From the field data, we conducted a selection analysis to identify the major axes of linear and nonlinear multivariate sexual selection on call structure. A comparison of multivariate attractiveness of inbred and outbred calls along each major axis of selection revealed no difference in attractiveness. Our results suggest that inbred male calls have a fine‐scale structure that is no less attractive to females than that of outbred calls. However, because inbred males call less often, and female T. commodus prefer males with a higher calling effort, inbred males will suffer reductions in mating success. Females who base mate choice on call rate are therefore using a signal correlated with male heterozygosity and/or condition.     

The courtship behavior of the cabbage moth,Mamestra brassicae (Lepidoptera: Noctuidae), and the role of male hair-pencils

The courtship behavior of the cabbage moth, Mamestra brassicae(L.), was studied in moving air conditions in a wind tunnel, using video techniques. Quantitative analyses were undertaken to determine the behavioral sequence occurring in the courtship. Comparison of successful and unsuccessful courtship suggested that courtship success was more dependent on the behavior of the female than that of the male. In an attempt to elucidate the function of the male hair-pencils (HPs), courtships involving males without HPs were also studied. HP removal did not affect the overall courtship success rate of males, but detailed analysis showed significant changes infernale behavior during such courtships. HP removal also affected female behavior following pair formation, with females struggling more when paired with males without HPs. Consequently, it is proposed that the HP volatiles act as an arrestant for the female, both during courtship and after pair formation, to increase female acceptance and to prevent premature termination of copulation. Experiments were also conducted to test previous hypotheses for HP function. However, no evidence was found to suggest that the HP volatiles in M. brassicaeact to attract females, affect female calling behavior, or affect the behavior of other males. A further possible function of HPs in defense is discussed.     

A FIELD STUDY OF THE CALFBIRD PERISSOCEPHALVS TRICOLOR

The Calf bird Perissocephalus tricolor was studied in the Kanuku Mountains of southern Guyana for three months (January-April 1970), during which time almost daily visits were paid to a lek of four adult males. The adult males owned perches about 30 ft up in understorey trees, where they displayed and called throughout much of the day. Four immature males also visited the lek, particularly in the morning and evening. The immatures also wandered, feeding and occasionally calling together, over an area of forest of approximately 3 miles by half a mile. There was a hierarchy among the adult and immature males, the dominant males owning the most coveted perches at the lek. The male's most far-reaching call, the “moo call”, is a co-operative advertising call, in that birds calling together adjust the timing of their calls so as to follow each other and not overlap. The adult males perform a number of silent agonistic displays on their lek perches. Periodically, adult and immature males and sometimes a female invade the vicinity of a lek perch, usually that of the dominant male. Once a female was briefly mounted by the dominant male on his lek perch during an invasion. On other occasions females visited the lek but no mating occurred. The food of the males attending the lek was recorded by the daily collection of a total of 2,500 regurgitated fruit seeds (mostly drupes) from below the perches. Males also regularly take insects, but in smaller quantities. Three nests were found. The nest is an extremely light structure built entirely of fine twigs. A single egg was laid in each nest. All the nests (and two old ones) were within half a mile of the lek. Two of the nests were only 5 yards apart and the eggs were laid in them within 10 days of each other. The incubation period at one nest was 26–27 days and the fledging period approximately 27 days. The chick on hatching was covered in bright orange-chestnut down. It was fed mostly on insects (predominantly Orthoptera) brought by the female in her beak. There was no evidence of a male attending the nest. The Calfbird's nesting and lek behaviour is compared with that of other species of Cotingidae.     

褛裳夜蛾的交配行为及雄蛾对性腺提取物的反应节律

详细观察了褛裳夜蛾成虫的交配行为,利用风洞、触角电位技术研究了雄蛾对性腺提取物的反应节律,通过林间诱蛾试验进行了验证,旨在为褛裳夜蛾性信息素的精确提取及性信息素组份分离、鉴定提供依据。研究结果表明:成虫的求偶、交配行为均发生在暗期,有一定的节律性:雌蛾在羽化3d以后开始求偶,1周左右表现最为强烈,3-4日龄雌蛾在暗期4-6h开始求偶,最大求偶率在暗期6-8h;5-9日龄在进入暗期就开始求偶,最大求偶率出现在暗期4-6h。风洞试验表明,3-7日龄的雄蛾对性腺提取物均有明显的性行为反应,5日龄雄蛾在暗期4-6h对性腺提取物的反应最为强烈。3-6日龄的成虫在暗期4-6h开始交配,而7-8日龄的成虫于暗期2-4h开始交配,6日龄的成虫交配率最高,交配高峰在暗期4-8h。雄蛾对性腺提取物的触角电位反应也有一定的节律性:雄蛾对4日龄雌蛾性腺提取物开始有电生理反应,对6-7日龄暗期5h性腺提取物反应最为强烈。林间诱蛾试验测定了性腺提取物的引诱活性,7日龄雌蛾性腺提取物林间诱蛾量最高,引诱高峰在暗期4-6h,该结果也验证了褛裳夜蛾雄蛾对性腺提取物的反应节律。     

Disruption of reproductive behavior of grapevine cicada,Cicadatra alhageos,by acoustic signals playback

The grapevine cicada, Cicadatra alhageos (Kolenati) (Hemiptera: Cicadidae), is a key pest of grapevine (Vitis spp., Vitaceae) in the Middle East. The main damage is caused by nymphs that feed on root sap, and adults that oviposit on branches. As males produce sound to attract females, one of the control methods can be disruption of sexual communication. Disruptive effects of acoustic playbacks on singing males were studied. Signals (0.5–10 kHz) were broadcast to disrupt male calling behavior. Playback of acoustic signals interrupted male sexual signalling. To reduce female oviposition behavior in the field, an experiment was conducted based on a completely randomized design with two treatments (control vs. acoustic broadcasting) and four replications over a period of 3 years. Playback of disruption signals in the field reduced female oviposition on grapevine branches that were close to the signal source. Therefore, application of acoustic stimuli may be an effective and low‐cost control method against grapevine cicada.     

Acoustic Competition in Male Midwife Toads Alytes obstetricans and Alytes cisternasii: Response to Neighbor Size and Calling Rate. Implications for Female Choice

Effects of neighbor on male calling behavior was studied through playback experiments of synthetic calls to males of two species of midwife toads. The responses of resident males were scored considering two temporal parameters (call duration and calling rate) and one spectral parameter (dominant frequency). The sounds used for the playback tests included two levels of fundamental frequency (correlated with male size) and two levels of call repetition rate. In both species, resident males only changed their calling rate in the presence of an intruder, and the response was different for synthetic calls with two levels of dominant frequencies and with two calling rates. Resident size was not significantly correlated with the magnitude of the change in the calling rate. On the other hand, resident calling rate was significantly and positively correlated with the magnitude of the increase in calling rate of the stimulus. The maximum relative increase in calling rate was observed in A. cisternasii. In phonotaxis tests, females are preferentially attracted to calls emitted at a higher rate confirming the importance of changes in calling rate for female attraction.     

Agonistic communication between males of a zaprochiline katydid (Orthoptera: Tettigoniidae)

The calls produced by male katydids serve to attract femalesand repel rivals. Males generally exhibit overt aggressive responsesto conspecifics that call within their territories, and intermalespacing is maintained by properties of the call. Here we examinethe acoustic behavior of a zaprochiline katydid in which maleaggressive behavior and even the ability to detect conspecificsappear greatly reduced. Despite reduced hearing sensitivity,males were shown to detect and respond to the calls of conspecificsusing substrate-borne vibrations. During playback experimentsmales increased their calling rates by decreasing the intervalbetween chirps. However, rather than exhibit overt aggressionmales would simply change their calling sites when the intensityof playback song was increased. These results were supportedby observations of natural encounters between males in the field.The interval between chirps decreased as the distance betweencalling males decreased, and encounters were always terminatedwhen one male moved away from the other. We suggest that theloss in auditory sensitivity and reduced aggressive behaviorof this species may be a consequence of the necessity to aggregatearound highly localized feeding sites.     

Conspecific females promote calling behavior in the noctuid moth,Pseudaletia adultera

Changes in female calling behavior in response to the presence of conspecific pheromones (pheromone autodetection) have been demonstrated in a number of moth species. However, the observed changes vary between species, and several ecological and adaptive explanations for autodetection have been proposed. We studied the effect of conspecific females on the calling behavior of the noctuid moth Pseudaletia adultera (Schaus) (Lepidoptera: Noctuidae, Hadenini), by comparing the age of first calling, as well as the onset and pattern of calling, when females were held individually or in the presence of conspecifics. Grouped females started calling at a lower age, a higher percentage of females called during the scotophase, and they called longer compared to females held in isolation. We also demonstrated that female antennae respond to each of the three main components of the sex pheromone – (Z)‐11‐hexadecen‐1‐ol, (Z)‐11‐hexadecen‐1‐yl acetate, and (Z)‐11‐hexadecenal – and that the response patterns differed from those of male antennae. By calling more and extending her calling window in presence of conspecific females, a female may increase her chances of accessing males. However, the potential benefits need to be considered within an ecological context, considering factors such as migration, oviposition, and foraging.     

Inter- and intraspecific variation in nightly calling duration in field crickets,Gryllus integer andG. rubens (Orthoptera: Gryllidae)

The time that male field crickets spend calling was measured electronically in the laboratory to examine nightly calling duration from different species and populations. Male Gryllus integerfrom Davis, CA, and Las Cruces, NM, called approximately 7 h per 24 h, whereas male G. integerfrom San Antonio and Austin, TX, and Norman, OK, and male G. rubensfrom McAlester, OK, and Arkadelphia, AR, called approximately 3 h per 24 h. Variation in duration of calling is discussed in terms of the energetic costs of producing song and selection against calling by acoustically orienting parasites and predators. Duration of calling was also studied infield-collected male G. integer.Males were first observed in field populations and then collected. Those males observed calling in the field later called significantly more in the laboratory than males observed showing non-calling, satellite behavior. Flying G. integercollected under lights were intermediate in their calling duration to calling and satellite males. These data are discussed in terms of the heritability of nightly calling song duration infield crickets.     

Social Correlates of Variation in Male Calling Behavior in Blanchard's Cricket Frog,Acris crepitans blanchardi

I studied variation in male calling behavior and its social correlates in Blanchard's cricket frog, Acris crepitans blanchardi. Calls were produced in distinct call groups, and they increased in duration and complexity from the beginning to end of a call group. Dominant frequency was the only character of 18 quantified consistently correlated with male snout-vent length. Calls from the beginning of a call group varied independently of calls from the middle and end of a call group, and only calls from the beginning of a call group exhibited significant variation among males, thus relative consistency within males. Other characters varied greatly within individual males. Unlike most other anurans, dominant frequency also exhibited tremendous within-male variation. The relative influence of caller density, local caller density, nearest neighbor distance, and nearest neighbor sound pressure level on variation in male calling behavior was examined. Nearest neighbor distance, mediated through the sound-pressure level of neighbor calls, appeared to have the greatest influence on variation in male calling behavior. The most profound changes in calling behavior occurred during aggressive encounters; males altered their calling behavior in a manner suggesting that they respond to competitors with graded aggressive signals. Furthermore, the structure of the communication system suggests that calls are graded not only in response to the level of social competition, but graded over a call group as well.     

Calling Patterns in Male Responses to Conspecific Playbacks in the Johnstone's Whistling Frog Eleutherodactylus johnstonei

Vocal interactions are common in chorusing frogs. Changes in the calling patterns of Eleutherodactylus johnstonei males were analyzed by recording their responses to playbacks of conspecific calls repeated at fixed periods (long: 1.7 s, short: 0.98 s). The call period and timing, estimated through the onset response time, were determined for each male. Males reduced and regularized the period of their calls in response to both stimuli, regardless of their absolute and relative period (i.e., the difference between the male's period and the stimulus period). Males avoided initiating their calls during ongoing stimuli, but did not time their calls in the silent gap between successive stimuli in ways that reduced the probability of overlap: the proportion of calls without overlap did not depart from random expectations when the silent gap was long, and was smaller than expected when the gap was short. This result indicated that males react to the presence of the virtual competitor but not to its particular characteristics. Fixed responses have been described in other anurans, and often relate to trade-offs between female attraction, male competition, predator attraction, and depletion of energy reserves. Lack of coordination with the stimuli, beyond inhibition of calling during an ongoing stimulus, also indicates somewhat rigid vocal strategies, at least under the experimental conditions. Results from the short period trials suggested a compromise between maintaining a call period and avoiding call overlap. Whether female behavior is influenced by call interference and whether males pay selective attention to distant males instead of to close neighbors must be investigated to better understand the vocal behavior of E. johnstonei .     

Individual Male Calling Pattern and Male Mating Success in the European Treefrog (Hyla arborea): Is there Evidence for Directional or Stabilizing Selection on Male Calling Behaviour?

In anurans, call properties are commonly classified based on within‐male variability as being either static or dynamic. Numerous playback experiments in the laboratory have indicated that female preferences based on dynamic call properties are usually strongly directional, while female preferences based on static call properties are often stabilizing or weakly directional. However, there are only few studies demonstrating that female preferences for high values of dynamic call properties indeed exert directional selection on male calling behaviour in natural populations. Moreover, field studies investigating whether female preferences for values of static call properties around the mean of the population lead to currently operating stabilizing selection on male calling patterns in natural populations are completely lacking. Here I investigate for two consecutive breeding seasons male calling patterns and male mating success in a population of individually marked European treefrogs (Hyla arborea), a hylid frog with prolonged breeding season and a lek mating system. Individual male calling pattern as analysed in terms of seven temporal and spectral call properties did not differ between males that survived from one breeding season to the next and those not surviving. None of the seven call properties investigated differed significantly between mated and unmated males, indicating that there is no strong directional selection on male calling behaviour in the study population. However, in one study season males that produced calls with a number of pulses around the mean of the population were significantly more likely to obtain matings than males that produced calls with a number of pulses at the low or high end of the distribution. Thus, this study provides preliminary evidence for the operation of stabilizing selection on a static call property (i.e. the number of pulses per call) in a natural population of an anuran amphibian.     

The possibility of sex and nymph discrimination by the male cockroach,Nauphoeta cinerea

The possibility of sex and nymph discrimination by males was investigated in the cockroach,Nauphoeta cinerea (Olivier). A sexually mature male takes a courting position toward a sexually mature female when he comes into contact with her and recognizes her through antennal contact. In contrast, males often behave aggressively toward each other: they bite at each others; wings and/or legs, chase each other and antennate mutually. The male, however, does not show conspicuous behavior (mating behavior or aggressive behavior) toward nearby nymphs. The male produces audible sounds when he courts a sexually mature but non-receptive female who does not respond to his courtship behavior. We found that the male also stridulates after he repeatedly courts immature teneral females, males and (last-instar) nymphs. After the bodies of teneral insects are sclerotized, the male shows courship and stridulation behavior toward sexually mature but non-receptive females but not toward mature males and nymphs. At this stage the male begins to behave aggressively toward other post-teneral mature males. We think that the variability of the sexually mature male's behavior toward other conspecifics (courtship behavior toward female, aggressive behavior toward male and no conspicuous response toward nymph) results from the male's recognition of adult and nymph.     

Flying in tune: sexual recognition in mosquitoes

Mosquitoes hear with their antennae, which in most species are sexually dimorphic. Johnston, who discovered the mosquito auditory organ at the base of the antenna 150 years ago, speculated that audition was involved with mating behaviour. Indeed, male mosquitoes are attracted to female flight tones. The male auditory organ has been proposed to act as an acoustic filter for female flight tones, but female auditory behavior is unknown. We show, for the first time, interactive auditory behavior between males and females that leads to sexual recognition. Individual males and females both respond to pure tones by altering wing-beat frequency. Behavioral auditory tuning curves, based on minimum threshold sound levels that elicit a change in wing-beat frequency to pure tones, are sharper than the mechanical tuning of the antennae, with males being more sensitive than females. We flew opposite-sex pairs of tethered Toxorhynchites brevipalpis and found that each mosquito alters its wing-beat frequency in response to the flight tone of the other, so that within seconds their flight-tone frequencies are closely matched, if not completely synchronized. The flight tones of same-sex pairs may converge in frequency but eventually diverge dramatically.     

Female competition for availability of males in insects: the Nezara viridula (Linnaeus, 1758) model

Multimodal communication in solitary stinkbugs enables them to meet, mate and copulate. Many plant‐dwelling species exchange information during the calling phase of mating behavior using substrate‐borne vibratory signals. A female‐biased gender ratio induces rivalry and competition for a sexual partner. Female competition for males, first described among Heteroptera in three stinkbug species, revealed species specific differences and opened the question of plasticity in individually emitted temporal and frequency signal characteristics during calling and rival alternation. To address this question and gain an insight into the mechanisms underlying stinkbug female rivalry, we compared the characteristics of alternated signals in the southern green stinkbug Nezara viridula (Linnaeus, 1758) (Hemiptera: Pentatomidae). Compared to male rivalry, female rivalry is more complex, lasts longer and runs through successive phases by a combination of different song types. The male pheromone triggers alternation between females, producing song pulses that occasionally overlap each other. One female initiates the rivalry by changing individual pulses into pulse trains of three different types. The competing female alternates with pulses of changed temporal characteristics at lower levels of rivalry and by varying the frequency characteristics of pulse trains at higher levels. During female rivalry, the male either stops responding or occasionally emits calling and courtship signals in response to the female that has produced signals of steady temporal characteristics. Female rivalry shows complex and species specific patterns of information exchange at different levels with a broad‐range variation of temporal and frequency characteristics of, until now, unidentified vibratory emissions.     

Premating Behavior of Dealates of the Formosan Subterranean Termite and Evidence for the Presence of a Contact Sex Pheromone

Swarming by alates of the Formosan subterranean termite, Coptotermes formosanus Shiraki, occurs around dusk during April–June in Louisiana and adjoining states. Dispersal is the primary purpose for swarming. We studied the premating behavior, following swarming. Loss of wings, especially in females, was essential for successful formation of tandem pairs between the two sexes. No calling was observed and apparently a long-range volatile sex pheromone, reported in some other species of termites, may not be involved in mate attraction in C. formosanus. Males moving randomly use their antennae to detect a female, and, together with maxillary and labial palps, contact is maintained with her while in tandem. Previously mated males paired with virgin females showed tandem behavior. The incidence was very low when both males and females were previously mated and then paired. Males with complete ablation of antennae did not form tandem pairs. Ablation of 10 terminal antennal segments or the labial palps caused a significant increase in the time to initiate tandem behavior. Electrophysiological recordings from gustatory sensilla on both antennae and maxillary palps revealed increased neural activity in response to female abdominal tip extracts compared to activity elicited by a solvent control. Analysis of extracts of male and female abdominal tips using high-performance liquid chromatography showed a peak unique to the female extract. We discuss the presence of a nonvolatile chemical in female C. formosanus and its involvement in the specific premating behavior.