Spermatophore Size Research Articles

Spermatophore allocation strategy over successive matings in the bushcricket Isophya sikorai (Orthoptera Phaneropterinae)

During mating, male bushcrickets transfer edible spermatophores that consist of a large sperm-free spermatophylax and a sperm-containing ampulla. The effect of consecutive matings on nuptial gift and sperm numbers in the bushcricket Isophya sikorai was examined. Males and females differed in body weight and mating history influenced their weight. Males differed in spermatophore weight, as well as the weights of spermatophylax and ampulla. Spermatophore (spermatophylax + ampulla) and spermatophylax weight of I. sikorai increased with male body weight, but not with ampulla weight. Male age had a significant effect on sperm number, with older males producing more sperm. Female weight but not mating number of female had a significant effect on spermatophore weight. Males increased the size of the spermatophylax and sperm number when presented with larger females, but they did not adjust their ampulla weight. Male age affected spermatophylax weight when mating with heavier females. Males reached their maximal absolute sperm number point at about middle age of their mating period due to an age-dependent shift in covariation between the ampulla and spermatophylax weight and ampulla size increases over a longer period. We conclude that production of a spermatophore and its components is costly, therefore males should strategically adjust their spermatophore components among mating opportunities. Female quality is an important predictor in searching males, and those males transfer significantly larger spermatophore and ejaculates to higher quality (heavier) females. Briefly, this study suggest that male I. sikorai strategically allocate spermatophore size and sperm number with respect to various factors such as his age, sperm competition and female size in a multiple mating system.

Comparison of Sperm Number, Spermatophore Size, and Body Size in Four Cricket Species

This paper examines the relationships between male body size, spermatophore size, and number of sperm per spermatophore, in four cricket species: Teleogryllus commodus, Acheta domesticus, Gryllus bimaculatus, and Gryllus assimilis. Within each species, individuals varied considerably in all three characters measured, and generally, spermatophore size, number of sperm, and body size were all correlated; i.e., ampulla diameter and sperm number per spermatophore significantly increased with body mass (p < 0.001) according to a linear regression function. Interspecific investigations found considerable differences between species: G. assimilis had the largest mean male body mass and length, largest ampullas, and highest numbers of spermatozoa per spermatophore, whilst A. domesticus had a small body mass and length, the smallest ampullas, and lowest sperm numbers. Regression analyses of all four cricket species revealed similar results as intraspecific regression computations. Hence, both intra- and interspecifically, larger males produce larger spermatophores containing more sperm, than do smaller males. These results differ from bush crickets (Tettigoniidae), where larger male body size does not necessarily correlate with larger ampullas and more sperm. Possibly male bush crickets have evolved to invest a higher proportion of their resources in the size of the nuptial gift, as opposed to number of spermatozoa.

Male reproductive system and spermatophores production and storage in Histioteuthis bonnellii (Cephalopoda: Histioteuthidae): A look into deep-sea squids׳ reproductive strategy

Coleoid cephalopods go through a single breeding period in their life cycle, i.e., they are semelparous, although a great flexibility has been observed in their reproductive strategies, which range from simultaneous terminal spawning over a short period at the end of the animal׳s life to continuous spawning over a long period of the animal׳s life. So far, the information available on deep-sea species reproductive strategies is still poor and most of our knowledge about squid reproduction relates to females. In particular, not much is known on what strategy male squids have evolved to store sperm into spermatophores and adapt to semelparity. In this study an investigation of male reproductive strategy of the deep-sea umbrella squid Histioteuthis bonnellii (Férussac, 1835) is presented. The reproductive system was examined in 119 males caught in the Sardinian waters (Central Western Mediterranean) and is described for the first time. Results indicate that this species produces and stores spermatophores over a considerable period of time. The total number of spermatophores found in the reproductive system ranged between 12 and 3097 and the size of spermatophores stored by a single individual varied greatly, up to over 300%. Spermatophore length (SpL) gradually decreased towards the distal end of the reproductive system, so that spermatophores found in the proximal part of Needham׳s Sac were larger than those found in the terminal organ. Body size and SpL of spermatophores from the proximal part of Needham׳s Sac were positively correlated. Both indices of the sperm mass and of the ejaculatory apparatus decreased with the increase of SpL, while the cement body index increased, indicating that larger spermatophores contain less sperm and are equipped with larger cement bodies. Up to 64 spermatangia were found, exclusively in the terminal organ. The large size range of mature males (ML: 60.0–198.0mm; TW: 113.50–2409.00g) and the variation in spermatophore number and size indicate that in H. bonnellii males the allocation and storage of sperm start early in the individual life and extends in time, while animals continue to grow and produce spermatophores presumably more successful in attaching to female tissues. This pattern enlarges the time window available for reproduction and likely maximizes the percentage of mating success as the animals grow older and chances of mating events become comparatively lower, due to the basic low density of specimens in the deep-sea environment. Both aspects are potentially indicative of adaptation to the deep sea.

Virgin and recently mated males are equally able to achieve new matings in Neoleucinodes elegantalis

AbstractLepidopteran male mating success is recognized to be directly related to physical and behavioural traits such as ability, vigour, activity and persistence in courtship. In the tomato fruit borer Neoleucinodes elegantalis Guenée, the mating system is known to be monogamic and therefore males' sexual investment is apparently low. The hypothesis that recently mated males have a remating probability equal to that of virgin males is tested. The impact of body size in remating success and the cost of remating are also analyzed. Mated males show as much propensity to remate as naïve ones. Copula duration and the time taken to copulate are similar in mated and virgin males. However, spermatophore size is not related to male size. The results suggest the ability of N. elegantalis males to remate within 24 h between mating events and their propensity to remate are not affected by copula investment. © 2013 The Royal Entomological Society

Effect of Age, Body Weight and Multiple Mating on Copitarsia decolora (Lepidoptera: Noctuidae) Reproductive Potential and Longevity

Successful behavioral-based control methods rely on the accurate knowledge of the mating dynamics of the target insect. Age at first mating affects reproductive potential and the chance of multiple mating. The cabbage moth, Copitarsia decolora (Guenee) is an important pest of a number of commodities. We investigated combinations of age, body size and mating history to determine how these variables affect insect reproductive capacity. Fecundity and fertility decreased as the age of mating pairs increased, heavy and average sized females laid more eggs than light females. Female multiple mating did not enhance fecundity nor fertility potential. Furthermore, spermatophore size did not determine female re-mating behavior. However, female fecundity and fertility was related to the male mating history. Our results show that SIT is a valuable tool for controlling this pest.

Development of sexual organs and fecundity in Octopus vulgaris Cuvier, 1797 from the Sardinian waters (Mediterranean Sea)

In this paper we report information about the sexual maturity process of 245 Octopus vulgaris specimens (75 females and 170 males) from the Mediterranean Sea. For both sexes, six stages of sexual maturity (immature, developing, maturing, mature, spawning, and spent) are identified on the basis of macroscopic and microscopic observations of the reproductive system and linked with some reproductive indices. A good correspondence between gonad appearance and its histological structure is observed, highlighting, in females, how oviducal gland morphology plays a crucial role in the macroscopic evaluation of maturity. The Gonadosomatic and Hayashi indices, in the two genders, and the Oviducal Gland index in females alone do not allow distinguishing all the stages in an irrefutable way. Data on the potential fecundity, oocyte and spermatophore size are reported and compared with literature. In addition, spermatophore components are also computed. The results reported in this paper lead to easy identification of the different phases of sexual maturation of O. vulgaris and could constitute an important tool for defining assessment models in view of sound management of this species.

Ejaculate investment and attractiveness in the stalk-eyed fly, Diasemopsis meigenii.

The phenotype-linked fertility hypothesis proposes that male fertility is advertised via phenotypic signals, explaining female preference for highly sexually ornamented males. An alternative view is that highly attractive males constrain their ejaculate allocation per mating so as to participate in a greater number of matings. Males are also expected to bias their ejaculate allocation to the most fecund females. We test these hypotheses in the African stalk-eyed fly, Diasemopsis meigenii. We ask how male ejaculate allocation strategy is influenced by male eyespan and female size. Despite large eyespan males having larger internal reproductive organs, we found no association between male eyespan and spermatophore size or sperm number, lending no support to the phenotype-linked fertility hypothesis. However, males mated for longer and transferred more sperm to large females. As female size was positively correlated with fecundity, this suggests that males gain a selective advantage by investing more in large females. Given these findings, we consider how female mate preference for large male eyespan can be adaptive despite the lack of obvious direct benefits.

Age‐Related Male Reproductive Investment in Courtship Display and Nuptial Gifts in a Moth, Ostrinia scapulalis

AbstractDue to a trade‐off between current and future reproduction, costly reproductive investments should be increased towards the end of a lifespan when the probability of reproduction becomes low (terminal investment hypothesis). We investigated age‐related changes in male reproductive investment towards courtship display and the spermatophore in three age classes (young, middle‐aged and old) of a monandrous moth, Ostrinia scapulalis. As predicted, old males had higher mating success than young and middle‐aged males in no‐choice tests. Moreover, two‐choice tests revealed that middle‐aged males had a higher success rate than young males because of their higher courtship frequency rather than any female preference for them. It was found that old males produced a larger spermatophore than young and middle‐aged males, suggesting greater reproductive effort. The protein content of spermatophores also tended to increase with male age. Despite the age‐related variation in spermatophore size and protein content, age did not affect female fecundity or longevity. A decrease in the number of sperm in the older males might counteract the nutritional benefit of larger spermatophores. Alternatively, fitness components other than longevity and fecundity may be influenced by male age.

Linking nutrition and sexual selection across life stages in a model butterfly system

Summary Early nutrition plays an important role in determining adult fitness. Theory proposes that in organisms with complex life cycles, the fitness effects of larval nutritional constraints are mainly captured by two developmental traits: time and size at metamorphosis. However, recent evidence suggests that latent effects, which are independent of these developmental traits, must be included to fully understand how larval nutrition impacts fitness. In this study, I used the cabbage butterfly (Pieris rapae) as a model system to investigate how larval nutrition influences male fitness through development time, adult size and latent effects. Specifically, I examined how variation in dietary nitrogen impacts male fitness by measuring a comprehensive suite of pre‐ and postcopulatory traits. Results indicate a complex role for larval nutrition in determining adult fitness. Larval nutritional constraints influence adult fitness through three different pathways: development time, adult size and latent effects. Longer development times were associated with shorter adult life span and reduced male mating success. Body size was positively correlated with traits related to postcopulatory fitness, such as spermatophore size and protein content. Larval nitrogen availability, independent of the developmental traits, also affected traits associated with male mating success such as wing coloration and latency to first mating. These results provide new insights into how larval nitrogen availability alters adult fitness by revealing novel links between larval dietary nitrogen and various adult fitness components.

Age and multiple mating effects on reproductive success of Grapholita molesta (Busck) (Lepidoptera, Tortricidae)

Age and multiple mating effects on reproductive success of Grapholita molesta (Busck) (Lepidoptera, Tortricidae). The reproductive success of the oriental peach moth was evaluated in four experiments: 1) assessment of the mating duration, fecundity, fertility and longevity of females paired with virgin and immediately mated males; 2) mating duration, spermatophore size, fecundity, fertility and longevity in females paired with virgin and up to four times mated males; 3) receptivity of females to additional copulations after mating with virgin or mated males, and the effects of this behavior in female fecundity, fertility and longevity; 4) influence of insects age in the reproductive output. Males (33%) could copulate immediately after a previous copula. They were fertile until the fourth mating, but only in the first copula they transferred the longest (1.43 ± 0.10 mm) and widest (0.83 ± 0.11 mm) spermatophore, presenting the fastest mating duration (34.8 ± 2.62 min). A high proportion of females copulated by non-virgin males (84%) was receptive to other copulas, in comparison to those copulated by virgin males (32.4%). However, the fecundity, fertility, and longevity were similar among females that copulate once or more. The age was the most important factor affecting reproductive variables, where one and three day old insects had a significant higher fecundity, fertility and presented a shorter mating duration in comparison with older individuals. Results pointed out that the reproductive capacity of Grapholita molesta changes a little with respect to the analyzed factors, highlighting the elevated biotic potential of the species.

Visualisation of the copepod female reproductive system using confocal laser scanning microscopy and two-photon microscopy

We examined mating behaviour in the harpacticoid copepod Tisbe battagliai Volkmann-Rocco, 1972, in particular the process of delivering spermatophore seminal contents to the female urosome. Labelling using 4′6′ diamidino-2-phenylindole (DAPI) coupled with two-photon confocal laser scanning microscopy successfully visualised the spermatophore and female internal reproductive system. Sections of the female urosome were imaged to examine seminal fluid stores. The female tissues were found to auto-fluoresce as red emission under green excitation, requiring no additional tissue labelling. DAPI-labelled seminal fluid stores were identified within the female reproductive system. The details observed agreed with previous descriptions of copepod reproductive anatomy and of spermatophores. Specimens cultured under pH 8.10 and a simulated ocean acidification scenario (pH 7.67) were compared for changes in reproductive anatomy and spermatophore size and site attachment. No differences were observed in spermatophore attachment or the female reproductive system but spermatophore size was reduced significantly at pH 7.67 compared with pH 8.10. This size reduction was, however, in proportion to an overall reduction in female body size at reduced pH. Confocal microscopy is shown here to be a valuable tool to investigate detailed reproductive processes in copepods.

Effect of larval food stress on male adult behaviour, morphology and reproductive investment in the butterfly Pararge aegeria

Males of several animals increase their reproductive success by territorial behaviour. In butterflies, males may defend a territory (i.e., territorial perching tactic), but this is assumed to be an energetically costly way to locate mates. Limitations of the energy budget may affect fight performance, and may, consequently, force males to adopt an alternative non-territorial searching behaviour (i.e., patrolling tactic) to maximize reproductive success. In this study, we tested to what extent behavioural tactics adopted by adult males of the butterfly Pararge aegeria (L.) were affected by the nutritional conditions during the larval stage. We compared the occurrence of territorial versus patrolling behaviour, lipid mass, flight muscle ratio, metabolic rate and spermatophore production of low quality males that were reared as a larva on drought-stressed host plants and control, high quality males. Low quality males were less likely to adopt the territorial perching tactic and emerged as adults with lower lipid mass than high quality males, but they were able to restore their lipid mass through adult feeding (and perhaps the breakdown of flight muscles). Host plant quality also affected spermatophore size. Independent of the larval food treatment, territorial perching males metabolised more lipids than non-territorial males, produced larger spermatophores and copulated for longer than males adopting non-territorial behaviour. We discuss the results relative to the co-existence of the behavioural tactics (perching and patrolling).

Trade‐off between flight capability and reproduction in male Velarifictorus asperses crickets

1. There are numerous data that support the trade‐off between flight capability and reproduction in female wing polymorphic insects, but the relationship between wing form and fitness remains poorly investigated in males.2. In the present study, the development of flight muscle and gonads, spermatophore size, and multiple copulation ability were investigated in both long‐winged (LW) and short‐winged (SW) males to verify this trade‐off, using a wing dimorphic cricket species Velarifictorus aspersus (Walker).3. The LW males had better‐developed wing muscles than the SW males on the day of emergence, and both of them developed wing muscles after emergence, but the peak of weight in SW males was achieved 4 days later than that of the LW males. The accessory glands (AG) of the LW males developed significantly slower than that of the SW males. These results suggest that development and maintenance of flight muscles have a cost on the development of reproductive organs in male V. asperses.4. The SW males produced significantly heavier spermatophores in a single copulation and mated more often than LW males. This indicates the SW males have a higher mating success than the LW males, thereby increasing their chance of siring offspring.

Effects of male ejaculate on female reproductive output and longevity in Photinus fireflies

In many insects, nuptial gifts in the form of spermatophores have been shown to increase female fecundity and to contribute to female somatic maintenance. Examining how variation in male spermatophore size affects female fitness components can provide insight into the evolution of nuptial gifts, as well as insight into potential conflicts between the sexes. Here we present an experimental study on the firefly Photinus obscurellus LeConte, 1851 in which we altered spermatophore size by manipulating male mating history and examined effects on female offspring production and longevity. Females were randomly allocated to one of two mating treatments in which they mated once with a male producing either a large or a small spermatophore. We found that male spermatophore size had no significant effect on lifetime fecundity or daily reproductive rates of female P. obscurellus, but females that received a larger spermatophore showed a tendency toward longer postmating life spans. These results suggest a direct benefit to females from nuptial gifts and also reveal the potential for synergistic effects on multiple facets of female fitness.

Spermatophore Size in Relation to Body Size and Pairing Duration in Northern Corn Rootworm (Coleoptera: Chrysomelidae)

Abstract Female insects may choose to mate with males providing the largest nuptial gift via the spermatophore, which may correlate with fitness related characters such as body size. Here, we examined spermatophore size of northern corn rootworm, Diabrotica barberi Smith &amp; Lawrence (Coleoptera: Chrysomelidae), in relation to body size of males and females and in relation to pairing duration. Virgin males and females of known ages were weighed before and after pairing. Pairs were noted as copulating or not copulating. Copulating males lost significantly more weight than did noncopulating males, whereas copulating females gained significantly more weight than did noncopulating females. For copulating pairs, male and female weight before pairing correlated positively. Spermatophore weight correlated positively with male weight before pairing and was estimated to be 0.37 or 0.38 mg, depending on whether weight change data from males or females were used for estimation. Spermatophore mass accounted for ≈4.4% of male body weight. An effect of pairing duration on spermatophore weight was demonstrable only when weight change data from females were used. Implications of the results for management of rootworm resistance to genetically modified maize are discussed.

Male reproductive investment relative to age and flight behaviour in the monandrous butterfly Pararge aegeria

Male reproductive investment may signify a considerable cost to male insects that produce sperm packages or spermatophores. Male butterflies allocate much of their active time budget to mate location, and they may adopt different behavioural strategies to do so. In the speckled wood butterfly (Pararge aegeria L.), males adopt either a territorial wait-and-fight strategy (territorial perching) or a fly-and-search strategy in wider areas (patrolling). In this study, we analysed the impact of male age, male size and male behaviour (i.e. behavioural strategies and levels of activity) on spermatophore investment (i.e. spermatophore mass, number of eupyrene sperm bundles). As predicted, reproductive investment increased with male age and size. Nevertheless, the increase of spermatophore mass with age and the number of eupyrene sperm bundles (i.e. fertile sperm) was stronger in low-activity males compared to active flying males. This suggests that flight activity has a negative impact on male reproductive investment. However, males that were forced to fly in the laboratory produced more eupyrene sperm bundles than resting males. We discuss the potential effects of male–male competition and predation risk on current versus future male reproduction. Males adopting different mate-locating strategies (perching and patrolling) in outdoor cages did not differ in spermatophore traits as was predicted from their very different flight performances. Copulations of territorial perching males took somewhat longer than copulations with non-perching males. There was a significant family effect of spermatophore size and of the expression of male mate-locating strategies suggesting heritable variation. Female traits (i.e. age and size) did not strongly affect spermatophore production. We discuss the results relative to both ultimate and proximate explanations of the complex relationships between butterfly activity, behavioural strategies, age and spermatophore production.

Daily production of spermatophores, sperm number and spermatophore size in two eriophyoid mite species

Under dissociated sperm transfer, (non-pairing) males deposit spermatophores on a substrate, while females seek spermatophores and pick up sperm on their own. Spermatophore expenditures of non-pairing males should be high, due to the increased uncertainty of sperm uptake by a female. In this study I examined spermatophore expenditures in two eriophyoid species that differed in the degree of dissociation between sexes: (1) Aculus fockeui (Nalepa and Trouessart) males rarely visit quiescent female nymphs (QFNs), and mostly deposit spermatophores all over the leaves, whereas (2) Aculops allotrichus (Nalepa) males guard QFNs for many hours and deposit several spermatophores beside them. Males of both species were collected from the field and tested in solitude. Aculus fockeui males deposited on average 19.1 spermatophores per day, whereas A. allotrichus deposited only 3.6 spermatophores per day, and had a very large coefficient of variation. Males and spermatophores of A. allotrichus were significantly smaller and contained less sperm than those of A. fockeui. In both eriophyoids, spermatophore size was fitted to the size of female genitalia and the height of females. The ratio between the diameter of spermatophore head and the width of a female genital coverflap was 0.6, whereas the ratio between the female leg and the length of spermatophore stalk was 0.5. Several factors could be responsible for the discrepancy in spermatophore expenditures between species. Among other factors, the effects of male size, male reproductive strategy and female genitalia size on spermatophore output and size of spermatophores are discussed.

Increased copulation duration before ejaculate transfer is associated with larger spermatophores, and male genital titillators, across bushcricket taxa

Copulation duration varies considerably across species, but few comparative studies have examined factors that might underlie such variation. We examined the relationship between copulation duration (prior to spermatophore transfer), the complexity of titillators (sclerotized male genital contact structures), spermatophore mass and male body mass across 54 species of bushcricket. Using phylogenetic comparative analyses, we found that copulation duration was much longer in species with titillators than those without, but it was not longer in species with complex compared with simple titillators. A positive relationship was found between spermatophore size and copulation duration prior to ejaculate transfer, which supports the hypothesis that this represents a period of mate assessment. The slope of this relationship was steeper in species with simple rather than complex titillators. Although the data suggest that the presence of titillators is necessary to maintain long copulation prior to ejaculate transfer, mechanisms underlying this association remain unclear.

The quantification of spermatozoa by real‐time quantitative PCR, spectrophotometry, and spermatophore cap size

Many animals, such as crustaceans, insects, and salamanders, package their sperm into spermatophores, and the number of spermatozoa contained in a spermatophore is relevant to studies of sexual selection and sperm competition. We used two molecular methods, real-time quantitative polymerase chain reaction (RT-qPCR) and spectrophotometry, to estimate sperm numbers from spermatophores. First, we designed gene-specific primers that produced a single amplicon in four species of ambystomatid salamanders. A standard curve generated from cloned amplicons revealed a strong positive relationship between template DNA quantity and cycle threshold, suggesting that RT-qPCR could be used to quantify sperm in a given sample. We then extracted DNA from multiple Ambystoma maculatum spermatophores, performed RT-qPCR on each sample, and estimated template copy numbers (i.e. sperm number) using the standard curve. Second, we used spectrophotometry to determine the number of sperm per spermatophore by measuring DNA concentration relative to the genome size. We documented a significant positive relationship between the estimates of sperm number based on RT-qPCR and those based on spectrophotometry. When these molecular estimates were compared to spermatophore cap size, which in principle could predict the number of sperm contained in the spermatophore, we also found a significant positive relationship between sperm number and spermatophore cap size. This linear model allows estimates of sperm number strictly from cap size, an approach which could greatly simplify the estimation of sperm number in future studies. These methods may help explain variation in fertilization success where sperm competition is mediated by sperm quantity.

Pattern of sperm storage and migration in the reproductive tract of the swallowtail butterfly Papilio xuthus: cryptic female choice after second mating

Females of the swallowtail butterfly Papilio xuthus L. (Lepidoptera: Papilionidae) mate multiply during their life span and use the spermatophores transferred to increase their longevity as well as fecundity. Sperm from different males may be stored in the sperm storage organs (bursa copulatrix and spermatheca). To clarify the pattern of sperm storage and migration in the reproductive tract, mated females are dissected after various intervals subsequent to the first mating, and the type and activity of sperm in the spermatheca are observed. When virgin females are mated with virgin males, the females store sperm in the spermatheca for more than 10 days. Sperm displacement is found in females that are remated 7 days after the first mating. Immediately after remating, these females flush out the sperm of the first male from the spermatheca before sperm migration of the second male has started. However, females receiving a small spermatophore at the second mating show little sperm displacement, and the sperm derived from the small spermatophore might not be able to enter the spermatheca. Females appear to use spermatophore size to monitor male quality.