Mate selection by female katydids (Orthoptera: Tettigoniidae, Conocephalus nigropleurum)

Female katydids receive a large spermatophore at mating which they subsequently eat. Available evidence indicates that spermatophore nutrients are important to female reproduction. Heavier males produce larger spermatophores. When given the choice between two singing males of different weights, females always mated with the larger individual.     

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.     

两种纺织娘线粒体基因组的比较分析

目前关于螽斯科昆虫的线粒体基因组全序列及其分子进化的研究报道很少。本研究利用L-PCR技术结合嵌套步移PCR扩增获得纺织娘Mecopoda elongata和日本纺织娘M. niponensis的线粒体基因组全序列, 同时对二者之间的碱基组成和结构特点进行了比较分析。结果显示： 纺织娘线粒体基因组（GenBank登录号JQ917910）序列全长15 284 bp, A+T含量71.8%; 日本纺织娘线粒体基因组（GenBank登录号 JQ917909）序列全长15 364 bp, A+T含量72.4%; 2种纺织娘序列长度差异主要是控制区长度不同引起（纺织娘控制区长294 bp, 日本纺织娘控制区长393 bp）。2种纺织娘基因组基因含量、 相对位置及转录方向均与其他已报道的螽斯科昆虫一致, 未发现基因重排现象; 基因组中均存在较长的间隔序列, 在trnA/trnR之间的间隔序列长度分别为63 bp与68 bp, 在trnQ/trnM之间的分别为55 bp和26 bp, 在trnS^UCN/nad1之间的均为21 bp。而最长的基因重叠区域在2种纺织娘trnC/trnW之间均为8 bp, 在atp8/atp6和nad4L/nad4L之间均为7 bp。蛋白质编码基因的碱基组成和密码子使用均具有明显的偏倚性; 除nad1和nad2以特殊的TTG作为起始密码子, cox1使用特殊的起始密码子ATGA外, 其余的10种蛋白质编码基因均使用典型的ATN作为起始密码子。在tRNA基因中, 除trnS^AGN外, 均能折叠形成典型的三叶草形二级结构。在这些tRNA基因中均存在一定数目的以G-U错配为主的碱基错配, 类似现象同样存在于其他已测定的六足动物线粒体基因组中, 表明G-U配对在线粒体基因组中很可能是一种完全正常的碱基配对方式。基因组中控制区的A+T含量略低于线粒体基因组的其他区域, 表明高A+T含量并不是该区域的必要特征。本研究结果为螽斯科系统发生关系重建积累了有价值的数据资料。     

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.     

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.     

Nest building, sexual selection and parental investment

Avian nest building has traditionally been viewed as resulting in natural selection advantages, but it is also been associated with courtship and pair formation. We hypothesize that nest-building activity could be used as a sexually selected display, allowing each sex to obtain reliable information on the condition of the other. In this paper, we test the ‘good parent’ process in a scenario where nest size is a sexually selected trait. Thus, individuals with more extreme displays (larger nests) might obtain benefits in terms of either parental investment or differential parental investment by the partner. We predicted that: (1) species in which both sexes contribute to nest building have larger nests than those in which the nest is built only by one sex, because both sexes are using the nest-building process as a signal of their quality; (2) species in which both sexes work together in the nest-building process invest more in reproduction, because each can assess the other more reliably than in species where only one sex participates in nest building; and (3) in light of the two preceding predictions, nest size should be positively related to investment in parental care. A comparative analysis of 76 passerine species confirmed that nest size, relative to the species' body size, is larger when both sexes build the nest and that species with a larger nest relative to their body size invest more in reproduction. This revised version was published online in July 2006 with corrections to the Cover Date.     

Increase in song frequency decreases spermatophore size: correlative evidence of a macroevolutionary trade-off in katydids (Orthoptera: Tettigoniidae)

In many katydids, the male feeds his mate with a large gelatinous spermatophore. Males of most species also produce elaborate calling songs. We predicted a negative relationship between spermatophore size and call frequency because of trade-offs between these two costly traits. Our comparative analysis controlling phylogeny and body size supported this prediction. Although call frequency is expected to decrease with increasing body size, after controlling for phylogeny, both variables were not related. Finally, given that song frequency and spermatophore size are likely targets of sexual selection, we examined the relationship between these variables and sexual size dimorphism (SSD) which can be influenced by sexual selection on body size. We found that only female body size was positively related to SSD, suggesting that natural and/or sexual selection on female body size may be stronger than sexual selection on male and spermatophore size.     

父方投资与性角色逆转现象: 螽斯类昆虫的婚礼食物及对性选择方向的影响

大多数动物在繁殖过程中,雌性在繁殖过程中要比雄性付出更大投资,如相对于精子较大的卵子细胞,较长的育幼时间等,因而在交配过程中,雌性具有选择权,而雄性之间相互竞争以取得与雌性的交配权。然而自然世界中并不总是竞争的雄性（competitive male）-选择的雌性（selective female）这种婚配形式。在螽斯类昆虫中,雄性同样具有较大的父方投资。在繁殖期间,雄性螽斯争相鸣叫,求偶,且在交配后要给予雌性特殊的营养物质-精包,供雌性取食。因此在特定情况下,雌性之间将进行竞争以获取雄性配偶,雄性变得更具有选择性。影响这种性角色逆转的主要因素是可获得资源的紧缺。父方投资理论和性选择理论预测雄性显著地对后代投资时,雌性将表现出典型的雄性特征,她们竞争追求性活跃的雄性,而雄性将表现出典型的雌性特征,对配偶具有选择性。螽斯类昆虫中这种特殊的性角色逆转现象符合性选择理论和父方投资理论的预测。     

Parental investment, sexual selection and sex ratios

Conventional sex roles imply caring females and competitive males. The evolution of sex role divergence is widely attributed to anisogamy initiating a self‐reinforcing process. The initial asymmetry in pre‐mating parental investment (eggs vs. sperm) is assumed to promote even greater divergence in post‐mating parental investment (parental care). But do we really understand the process? Trivers [Sexual Selection and the Descent of Man 1871–1971 (1972), Aldine Press, Chicago] introduced two arguments with a female and male perspective on whether to care for offspring that try to link pre‐mating and post‐mating investment. Here we review their merits and subsequent theoretical developments. The first argument is that females are more committed than males to providing care because they stand to lose a greater initial investment. This, however, commits the ‘Concorde Fallacy’ as optimal decisions should depend on future pay‐offs not past costs. Although the argument can be rephrased in terms of residual reproductive value when past investment affects future pay‐offs, it remains weak. The factors likely to change future pay‐offs seem to work against females providing more care than males. The second argument takes the reasonable premise that anisogamy produces a male‐biased operational sex ratio (OSR) leading to males competing for mates. Male care is then predicted to be less likely to evolve as it consumes resources that could otherwise be used to increase competitiveness. However, given each offspring has precisely two genetic parents (the Fisher condition), a biased OSR generates frequency‐dependent selection, analogous to Fisherian sex ratio selection, that favours increased parental investment by whichever sex faces more intense competition. Sex role divergence is therefore still an evolutionary conundrum. Here we review some possible solutions. Factors that promote conventional sex roles are sexual selection on males (but non‐random variance in male mating success must be high to override the Fisher condition), loss of paternity because of female multiple mating or group spawning and patterns of mortality that generate female‐biased adult sex ratios (ASR). We present an integrative model that shows how these factors interact to generate sex roles. We emphasize the need to distinguish between the ASR and the operational sex ratio (OSR). If mortality is higher when caring than competing this diminishes the likelihood of sex role divergence because this strongly limits the mating success of the earlier deserting sex. We illustrate this in a model where a change in relative mortality rates while caring and competing generates a shift from a mammalian type breeding system (female‐only care, male‐biased OSR and female‐biased ASR) to an avian type system (biparental care and a male‐biased OSR and ASR).     

Taxonomic Study of Tribe Copiphorini in Korea (Orthoptera: Tettigoniidae: Conocephalinae)

ABSTRACT Five species of the tribe Copiphorini (Orthoptera, Tettigoniidae, Conocephalinae) including a newly recorded species Xestaphrys javanicus Redtenbacher are recognized in Korean fauna. The key to species, characteristic figures, and diagnosis for the newly recorded species are presented.     

Auditory-based defence against gleaning bats in neotropical katydids (Orthoptera: Tettigoniidae)

Neotropical katydids (Orthoptera: Tettigoniidae) are preyed on by gleaning bats, which are known to use male calling songs to locate them. At least one katydid species has been reported to stop singing in response to bat echolocation calls. To investigate the relationship between this behavioural defence and ecological and sensory factors, we surveyed calling song characteristics, song cessation in response to the echolocation calls of a sympatric gleaning bat (Trachops cirrhosus), and T-cell responses (an auditory interneuron sensitive to ultrasound) in five katydid species from Panamá. The two katydid species that stopped singing in response to bat calls (Balboa tibialis and Ischnomela gracilis, Pseudophyllinae) also had the highest T-cell spike number and rate in response to these stimuli. The third pseudophylline species (Docidocercus gigliotosi) did not reliably cease singing and had low T-cell spiking activity. Neoconocephalus affinis (Copiphorinae) produced continuous calling song, possibly preventing males from hearing the bat during singing, and did not show a behavioural response despite high T-cell activity in response to bat calls. Steirodon rufolineatum (Phaneropterinae) did not cease singing and differed in T-cell activity compared to the other species. T-cell function might not be conserved in katydids, and evidence for this idea is discussed.     

The refractory period of female katydids (Orthoptera: Tettigoniidae): sexual conflict over the remating interval?

Female tettigoniids have a refractory period after mating duringwhich they are sexually unreceptive. Because females obtainvaluable nutrients as well as sperm at mating, there is likelyto be sexual conflict over the duration of the refractory period;females should accrue male donations, whereas males should preventtheir mates from accepting additional matings. We examined theeffects of ampulla attachment duration and female diet on theinduction of the refractory period of a zaprochiline tettigoniid.We find that, although the relationship between ampulla attachmentduration and duration of the refractory period holds for femalesmaintained on a high-pollen diet, poorly nourished females onlyshow the typical onset of the refractory period when allowedto consume the spermatophylax. These results suggest that femaleinterests may have a greater influence in determining the outcomeof sexual conflict. Under some circumstances spermatophylaxfeeding may compensate for poor female nutrition leading tothe typical refractory period. Sexual conflict over the rematinginterval could be instrumental in generating larger nutrientinvestments by male tettigoniids. [Behav Ecol 1991;2:276–282]     

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.     

Measuring sexual selection on females in sex‐role‐reversed Mormon crickets (Anabrus simplex,Orthoptera: Tettigoniidae)

Although many studies examine the form of sexual selection in males, studies characterizing this selection in females remain sparse. Sexual selection on females is predicted for sex‐role‐reversed Mormon crickets, Anabrus simplex, where males are choosy of mates and nutrient‐deprived females compete for matings and nutritious nuptial gifts. We used selection analyses to describe the strength and form of sexual selection on female morphology. There was no positive linear sexual selection on the female body size traits predicted to be associated with male preferences and female competition. Instead, we detected selection for decreasing head width and mandible length, with stabilizing selection as the dominant form of nonlinear selection. Additionally, we tested the validity of a commonly used instantaneous measure of mating success by comparing selection results with those determined using cumulative mating rate. The two fitness measures yielded similar patterns of selection, supporting the common sampling method comparing mated and unmated fractions.     

Male-male behavior and sexual dimorphism of the ear of a zaprochiline tettigoniid (Orthoptera: Tettigoniidae)

The external anatomy of the auditory system of an undescribed zaprochiline tettigoniid (Genus nov. 22 Sp. 1, Australian National Insect Collection, Canberra) shows sexual dimorphism: the male appears to have no auditory spiracle equivalent to that seen in the female. Nocturnally active males aggregate around female required nectar sources in a random manner with regard to each other. There is limited evidence, either from song interaction or from their behavior in the field, that males respond to each other by acoustic cues. Laboratory trials, testing male phonotaxis, showed that movement was random with respect to a target group of caged calling males. In the field, the only signs of agonistic behavior consisted of an increased calling rate when males were close together. Taken together, these data suggest that the male may not preceive sound in the same way as the female.     

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.     

Effects of mating status on copulation investment by male bushcricket Gampsocleis gratiosa (Tettigoniidae, Orthoptera)

Male’s copulation investment, including spermatophore and sperm investment were very high in the Chinese bushcricket Gampsocleis gratiosa. The effects of mating status of both males and females on male’s copulation investment were examined in this study. The fresh weight of sper-matophylax increased positively with the weight of males’ body. This indicated that the nutritional in-vestment during copulation depended on male’s quality. Spermatophore investment showed insig-nificant differences in every copula...~