Variation in nuptial gift quality in bush crickets (Orthoptera: Tettigoniidae)

Males of many insect species provide the female, during courtshipand copulation, with a nuptial gift consisting of a prey itemor synthesized material (e.g., spermatophores). The studiesperformed so far have mainly focused on effects of nuptial giftsize on male and female reproductive success. However, the qualityof the nuptial gift can differ substantially between taxa andmay potentially have a large impact on male and female reproductiveperformance. In this study the effects of. variation in dieton nuptial gift quality is investigated in several bush cricketspecies with different diets. The effect of diet on nuptialgift quality (e.g., protein in the spermatophylax) and femalereproductive output and, in turn, die effect of variation inspermatophylax quality on female reproductive output are investigated.Female reproductive output and male spermatophore size weremainly found to be influenced by differences in diet betweenspecies. Spermatophylax quality (i.e., protein concentration)was also correlated with differences in diet. There was a largevariation in protein content of the spermatophylax widiin aswell as between species. Moreover, larger spermatophylaxes hada lower protein concentration, indicating a possible trade-offbetween spermatophylax size and quality. Consequendy, productionof larger spermatophylaxes, required for protection of the male'ssperm carrying ampulla during insemination, can lead to a reducedprotein concentration, because the total amount of protein maybe limited. This pattern is also consistent with die idea diatthe spermatophylax functions primarily to ensure sperm transfer.Finally, there was no correlation between the amount of proteinin the spermatophylax and female reproductive output eitheracross diets or within each diet category, further supportingthe finding that female reproductive output is mainly affectedby differences in diet.     

Diet influences male-female interactions in the bushcricketRequena verticalis (Orthoptera: Tettigoniidae)

The influence of diet on the courtship roles of male and female Requena verticaliswas investigated in the laboratory. The protein content of available food was found to affect the frequency of mating attempts. Pairs which were fed on a low-protein diet were involved in fewer mating attempts than pairs which were fed on a high-protein diet. Diet also influenced the relative frequencies of male and female rejections. Males rejected their virgin female partners more often than females rejected their male partners when the pairs were kept on a low-protein diet. The opposite was found when the female had mated once before. No difference in the frequency of male and female rejections was found when the pair was kept on a high-protein diet irrespective of the mating status of the female.     

Differential mating success of virgin female katydidsRequena verticalis (Orthoptera: Tettigoniidae)

Male katydids (Orthoptera: Tettigoniidae) invest in offspring through nutrients provided in a large spermatophore. Previous research with Requena verticalishad shown that almost all of the investment of males mating with recently mated (4 days previously) females is in eggs fertilized by the female's previous mate. Thus males are predicted to discriminate against such females as mates. In experiments placing males with both a virgin and a female mated 4–5 days previously, virgin females obtained almost all matings. Although male discrimination of mates was noted in the experiments, there was no evidence that such discrimination was against nonvirgins in both this experiment and one in which a single virgin or mated female was placed with a male. Instead, the results suggest that the differential mating was a result of interfemale competition. The mating advantage held by virgin females over nonvirgins appeared to be lost once the latter had oviposited. Finally, there was no evidence from both single- and paired-female experiments that males preferred larger females as mates.     

Female preferences for large, heavy mates inSchistocerca americana (Orthoptera: Acrididae)

The significance of female choice in shaping mating systems remains problematic. The following study clearly documents female preferences in a species of grasshopper,Schistocerca americana, over the course of 3 years. Three sets of animals were observed in an outdoor seminatural cage. Females were found to mate more often with large, heavy males. Furthermore, remating by a female within a week was less likely if she mated with a large or heavy male. Because females were found to oviposit 2 days after a mating on average, these large heavy males may also be chosen cryptically (as defined in the literature) and father more offspring.     

The plurennial life cycles of the European Tettigoniidae (Insecta: Orthoptera)

Summary The effect of drought on embryonic development and on hatching was studied in 13 European Tettigoniidae species. Drought can affect development in three different ways: (1) Embryonic development proceeds slower than if the eggs are in contact with water; (2) it stops (for final diapause) in an earlier embryonic stage; (3) it affects maintenance and termination of the initial embryonic diapause.In many Tettigoniidae species, the initial diapause is prolonged, and may last several years. Without draught stress, between 1 and 7 cold treatments in the laboratory, and with eggs of the Tettigonia-species between 1 and 6 winters in the field were necessary to enable all eggs to complete initial diapause. In Central European species, the number of eggs maintaining initial diapause significantly increased when the eggs had no contact with water at the time when they should recover from diapause. In contrast, termination of initial diapause in Tettigonia caudata from Greece, when the environment became favorable for growth again, was highest in that group of eggs that had lost most water in a preceding period of drought. The importance of the prolonged initial diapause for the survival of unpredictable adverse conditions is discussed.     

Condition-dependent spermatophore size is correlated with male's age in a bushcricket (Orthoptera: Phaneropteridae)

During mating, male bushcrickets transfer a spermatophore that consists of a sperm-containing ampulla and a product of the accessory glands, the spermatophylax, which females directly ingest. In the present study, we demonstrate male spermatophore allocation in the bushcricket Poecilimon zimmeri . Males of this species show condition-dependent spermatophore investment. This investment depended upon the age at first mating of males, with older individuals transferring larger spermatophores than younger ones of the same body mass. Independently of age, heavier males transfer larger spermatophores, but the size of males (as measured by femur length) was not a good predictor. Heavier males allocate a lower proportion of their mass to spermatophores and reach their maximal investment point earlier than less heavy males. Spermatophylax production levelled off to a species specific maximum earlier than that of sperm investment (measured as ampulla mass), suggesting that males face high levels of sperm competition.  © 2009 The Linnean Society of London, Biological Journal of the Linnean Society , 2009, 96 , 354–360.     

Reliable acoustic cues for female mate preference in a katydid (Scudderia curvicauda, Orthoptera: Tettigoniidae)

The call of male Scudderia curvicauda (Orthoptera: Tettigoniidae)consists of a series of phrases, and each phrase contains syllables.Females respond to the male signal with ticks that follow malephrases after a specific period of time. Pair formation takesplace after males locate the female using her response sounds.Repeated recordings of males revealed that the average numberof syllables produced per phrase was a table, within-male parameterand that this parameter was a reliable predictor of male size(pronotum length). Thus, phrase length could be a reliable cueby which females evaluate males. We presented virgin femaleswith a sequential choice of two tape-recorded male calls thatdiffered only in the mean number of syllables produced per phrase.Two different playback tapes were used, and each female wastested on each of 5 consecutive days with the same playbacktape. Females responded more often and with a greater numberof ticks to calls containing more syllables per phrase, andthis preference was maintained throughout the testing period.Male size was a poor predictor of the size of the spermatophorefood-gift produced by the male; therefore, females are probablynot selecting males for this attribute. For one of the playbacktapes, there was a significant increase in female responsivenessover several playback trials, suggesting that females may employa falling-threshold tactic with respect to mate preference.     

Taxonomic Study of the Genus Conocephalus Thunberg in Korea (Orthoptera: Tettigoniidae: Conocephalinae)

ABSTRACT The genus Conocephalus Thunberg in Korea was taxonomically studied. As the result, five species were confirmed to Korean fauna including a newly recorded species, Conocephalus bambusanus Ingrisch. The key to species, distributional data and comparative figures for identification are given.     

Reproductive energetics of the role reversing bushcricket,Kawanaphila nartee (Orthoptera: Tettigoniidae: Zaprochilinae)

Theory predicts that sexual differences in reproductive strategies arise because of differences in the magnitude of investment made by males and females in reproduction. In some bushcrickets, the typical sex role of competitive male and choosy female is reversed when populations are subject to nutrient stress. Here I present an energetic analysis of reproduction for the role reversing bushcricket, Kawanaphila nartee, that supports the contention that this sex role reversal is a consequence of reversal in the pattern of relative reproductive investment. When fed ad libitum, males spent 16% of their daily energy reserves on the spermatophore compared with 26% spent on calling to attract a mate. Females spent 29% of their daily energy reserves in producing and laying eggs. However, when allowed only limited access to food, female expenditure in eggs was reduced to 23% of daily reserves while male expenditure remained unchanged. After accounting for the incorporation of male nutrients into eggs, female energy expenditure in reproduction exceeded male expenditure when animals were fed ad libitum, but male expenditure exceeded female expenditure when diet was limited. This role reversal in relative energy expenditure that is associated with courtship role reversal supports classical and contemporary theories on the control of sexual selection.     

The biology of the phonotactic parasitoid, Homotrixa sp. (Diptera: Tachinidae), and its impact on the survival of male Sciarasaga quadrata (Orthoptera: Tettigoniidae) in the field

Abstract.

• 1 Unlike most parasitoids, tachinid flies of the tribe Ormiini use sound to locate their hosts. Although thought to exert selection pressure on their host's calling behaviour, little is known about the biology of ormiines. Accordingly, this study reports the biology and impact of the ormiine Hornotrixa sp. upon calling males of the univoltine bushcricket Sciarasaga quadrata Rentz in south-western Australia.
• 2 Populations of adult S.quadrata were monitored in the field over two successive calling seasons. Females, which do not call, were not parasitized by Hornotrixa sp., but the risk of parasitism for males increased as the 3-month calling season progressed. Parasitism did not commence until c. 2 weeks into the calling season, but by the end of the season up to 87% of surviving males were parasitized.
• 3 Parasitized males lived for 14 days and were found singing until their penultimate evening before death in the field. Unparasitized males lived on average 69 days and a maximum of 119 days.
• 4 Multiparasitism of hosts was common, with up to sixteen fly larvae found within parasitized males. The number of fly larvae within hosts significantly increased at the end of the season. However, successful emergence of fly larvae from hosts, as well as pupal size, significantly decreased as more than one fly larva developed within the host.
• 5 Hornotrixa sp. has a long pupal duration of 30–31 days at 20°C. As a consequence, only one complete fly generation, which overwinters in the pupal stage, is likely within each host generation.
• 6 No evidence for differential (size-bias) mortality by Hornotrixa sp. on male S.quadrata was found. The size of parasitized and unparasitized males collected in the field was not significantly different.
• 7 It is concluded that Hornotrixa sp. is a significant mortality factor acting on the survival of adult male S.quadrata.

     

Female preference for preferred males is reversed under low oxygen conditions in the common goby (Pomatoschistus microps)

Female preference for males that already have eggs in theirnest has beenreported in many fish species. The presence ofeggs may provide a cue forcopying the choice of previous femalesand may indicate that high-quality carewill be available. Consistentwith a review of 13 studies, we found thatfemale common gobies(Pomatoschistus microps) preferred to spawn withmales thathad already been chosen by females and whose nests thereforealreadycontained eggs. However, this preference was reversed underconditionsof low dissolved oxygen. We would not expect thisreversal if the secondfemale were using eggs as a signal ofmale genetic attractiveness to otherfemales unless the benefitswere outweighed by direct selection. The reversalalso couldnot be explained by differences in active courtship by males,ascourtship rates did not differ under low oxygen between maleswith or withouteggs. Low oxygen conditions corresponded witha nearly threefold increase inmale ventilation of eggs anda reduction in time spent near a selectingfemale. The reversalis therefore most likely due to females avoiding malesthatwould be unable to meet the demands of care of a second clutchunder lowoxygen conditions. Thus, an abiotic feature of theenvironment revealsplasticity of female choice, consistentwith hypothesized changes in benefitsof mating with preferredmales.     

Mate feeding, offspring investment, and sexual differences in katydids (Orthoptera: Tettigoniidae)

Food stress in the katydid Requena veriicalis (Orthoptera: Tettigoniidae)decreases the relative availability of males able to supplynutritious spermatophores to females and increases the valueof the male courtship meal (i.e., relative male parental investment).These changes cause female sexual competition in katydid populations.Here we examine the effect of food stress on male and femaleinvestment in single offspring and test the prediction thatmale-derived nutrients in eggs increase relative to nutrientsfrom the female's reserves. We varied the diet of female R.veriicalis and determined the fate of nutrients from male andfemale sources using I4C and 3H radiolabeled amino acids. Low-dietfemales retained more nutrients from male and female sourcesin somatic tissues and invested less in reproduction both becausethey produced fewer eggs and because they invested less peroffspring (egg) than females maintained on a high-quality diet.Moreover, opposite to our prediction, relative male investmentin individual eggs decreased in foodstressed females; femalesretained more nutrients in somatic tissues from the male sourcethan the female source. Food-stressed females may retain nutrientreserves, particularly those from the male, as an adaptive trategyfor immediate survival needs and future reproduction. Such afemale strategy is unlikely to compromise male reproductivesuccess; first-male sperm precedence means that males matingwith virgin females are likely to father most eggs laid, evenin future reproductive bouts. The decrease in male investmentin eggs of low-diet females does not conflict with the contentionthat relative parental investment controls male intrasexualcompetition because, in mate-feeding species, male investmentinfluencing this competition includes more than investment incurrent offspring; females should compete for males if courtshipgifts aid survival and later reproduction.     

Distribution of Tettigoniinae (Orthoptera, Tettigoniidae) bush-crickets in Turkey: the importance of the Anatolian Taurus Mountains in biodiversity and implications for conservation

The distribution of Tettigoniinae (Orthoptera, Tettigoniidae) specieswithin four phytogeographical provinces in Turkey is reviewed and presented onthe basis of field and collection studies during 1987–2001 andmiscellaneous data from previous literature. One hundred and sixty speciesbelonging to 28 genera have been recorded. The Anatolian species constituteapproximately 30% of the world-wide species of the subfamily, with a very highproportion (83%) being endemic or semi-endemic, nearly all of which arebrachypterous. Regarding the numbers of total and endemic species, theprovinces can be ordered as follows: Mediterranean > Irano-Anatolian >Euxin > Mesopotamia. Also, Anatolian Tettigoniinae have a very high rate ofendemism in each province; 84.1% in the Mediterranean, 78.1% in Irano-Anatolia,56.3% in Mesopotamia and 42.4% in Euxin. The two provinces in Anatolia havingthe greatest species diversity are also the two most mountainous provinces, soit is suggested that a primary factor in Tettigoniinae diversity is theAnatolian Taurus mountains. Finally, some conclusions are drawn on biodiversityand conservation of Tettigoniinae species in Anatolia and I have suggested 23species to be included in the 'IUCN Red List' under VU B2+ac.     

Female preference for male courtship flashes in Photinus ignitus fireflies

In Photinus fireflies, males produce spontaneous bioluminescentcourtship flashes. Females preferentially respond to particularmale flashes with flashes of their own. This study exploredvariation in female flash responsiveness as a function of maleflash duration, female condition, lantern size, and lanterndistance, as well as the relationship between male characteristicsand spermatophore mass in Photinus ignitus fireflies. We determinedfemale preference by scoring female flash response to simulatedmale flashes and determined variation in overall female flashresponsiveness for laboratory-mated, laboratory-fed, and controlP. ignitus females. Flash duration, lantern size, and body masswere recorded for field-collected males. Males were then matedto determine spermatophore mass. Females exhibited greater preferencefor artificial flashes representing the upper range of conspecificmale flash duration and lantern size as well as flashes producedat a closer distance. Both laboratory-mated and laboratory-fedP. ignitus females showed lower overall responsiveness acrossall flash durations relative to control females that did notmate or feed in the laboratory. Male flash duration predicteda significant proportion of the variation in spermatophore massfor early-season males. These results suggest that female Photinusignitus may prefer long flashes in order to obtain the directbenefit of larger spermatophores and may adjust their overallflash responsiveness as the relative importance of this benefitvarieswith changing female condition.     

Female Preferences for Male Song Characters in the Bush-Cricket Isophya camptoxypha (Orthoptera, Tettigonioidea)

Female preferences for two male song characters (duration of syllables [DS], syllable repetition period [SRP]) have been studied in Isophya camptoxypha, an Eastern European duetting bush-cricket. Songs with modified DS or SRP were presented to virgin females and their response songs were recorded and counted. Female preference functions were unimodal for both characters. But while in the case of SRP the obtained female preference function reached its maximum at the mean value of that character, in the case of DS females preferred modified songs with a DS slightly higher than the natural range of that character. A comparison between the obtained preference functions and the DS and SRP values measured in sympatric Isophya species (with similar song structure) suggests that the two examined characters and female preferences for them may be effective components of the species-specific mate recognition system of I. camptoxypha. Moreover DS values may also convey information about the quality of the singing male.     

Scale effects and constraints for sound production in katydids (Orthoptera: Tettigoniidae): correlated evolution between morphology and signal parameters

Male katydids (Orthoptera: Tettigoniidae) produce mating calls by rubbing the wings together, using specialized structures in their forewings (stridulatory file, scraper and mirror). A large proportion of species (ca. 66%) reported in the literature produces ultrasonic signals as principal output. Relationships among body size, generator structures and the acoustic parameters carrier frequency (f_c) and pulse duration (p_d), were studied in 58 tropical species that use pure‐tone signals. A comparative analysis, based on the only available katydid phylogeny, shows how changes in sound generator form are related to changes in f_c and p_d. Anatomical changes of the sound generator that might have been selected via f_c and p_d are mirror size, file length and number of file teeth. Selection for structures of the stridulatory apparatus that enhance wing mechanics via file‐teeth and scraper morphology was crucial in the evolution of ultrasonic signals in the family Tettigoniidae.     

Effects of female deprivation on mating propensity and mate selectivity by maleRequena verticalis (Orthoptera: Tettigoniidae)

This study examined the effects of female deprivation on the mating propensity and size selectivity of male Requena verticalis,an Australian katydid in which males provide a large spermatophylax to females during mating. Specifically, I tested the hypotheses that mating readiness would increase, while mate discrimination would decrease (i. e., females would be accepted independently of their size, an indicator of fecundity) as the period of female deprivation increased. Fieldcaught males were held in isolation for 1, 5, or 14 days in the laboratory and then presented with virgin females. As expected, males held for 5 and 14 days were more likely to mate than males held only a single day. However, in none of the treatments did males discriminate among females on the basis of size. These results are compared with those obtained in a similar study on a zaprochiline katydid.