Mature Females Research Articles

Reproductive Biology of the Invasive Blue Crab Callinectes sapidus in the Thermaikos Gulf (Northwest Aegean Sea, Eastern Mediterranean): Identifying Key Information for an Effective Population Management Policy

The reproductive biology of the invasive blue crab Callinectes sapidus was studied in the Thermaikos Gulf (Northwest Aegean Sea, Eastern Mediterranean). In the two-year survey, 5698 (2897♂/2801♀) crabs were caught with the use of fyke nets. Total sex ratio (♂/♀) reached equality (1.03:1). The female blue crab exhibited a protracted reproductive period. Mature and ovigerous females exhibit short migratory movements from estuarine and inshore waters, where the population mostly congregates (0–3 m), and move to slightly deeper waters (1–3 m) up to 9 m for spawning. A total of 340 ovigerous females were caught. Their number varied both spatially and temporally; they were observed for a 7-month period (April to October) with a clear peak in July–August and at a 3 m depth gradient corresponding to ≈60% of the total number of ovigerous females caught in both years. Size at first sexual maturity (CW50) was estimated at 113.1 mm CW. Average fecundity was ≈790,000 eggs. Experimental trawling showed that inshore waters (<1 m) in the estuaries serve as nursery areas for juveniles. Defining the spatiotemporal and bathymetrical distribution of ovigerous females in any invaded coastal habitat could be considered key information for the implementation of a management policy for the species.

Female Phalangium opilio use fellatio to compensate sexual avoidance

Sexual conflict arises from differences in reproductive interests between the sexes. We allowed the female harvestman Phalangium opilio to sequentially mate with two different males to examine female sexual receptivity in this species. Virgin females were more sexually receptive than non-virgins. Males exhibited a high interest in repeated copulations with the same female, often engaging in aggressive behaviours such as biting and reversed sexual cannibalism. Fellatio, a behaviour in which females lick the male’s penis, was observed in 44% of trials and was associated with female unwillingness to mate and shorter copulation duration. Fellatio was repeatable, suggesting that it is influenced by individual characteristics or underlying physiological factors. Female lifespan was negatively correlated with the total number of eggs produced, suggesting a trade-off between reproduction and longevity. These findings provide evidence of the appearance of fellatio, a female mating strategy that evolved as compensation of avoiding unwanted sexual intercourse.

Heat stress: a major threat to ruminant reproduction and mitigating strategies.

Stress is an external event or condition that puts pressure on a biological system. Heat stress is defined as the combination of internal and external factors acting on an animal to cause an increase in body temperature and elicit a physiological response. Heat stress is a set of conditions caused by overexposure to or overexertion at excess ambient temperature and leads to the inability of animals to dissipate enough heat to sustain homeostasis. Heat exhaustion, heat stroke, and cramps are among the symptoms. For the majority of mammalian species, including ruminants, heat stress has a negative impact on physiological, reproductive, and nutritional requirements. Reproductive functions, including the male and female reproductive systems, are negatively affected by heat stress. It decreases libido and spermatogenic activity in males and negatively affects follicle development, oogenesis, oocyte maturation, fertilization, implantation, and embryo-fetal development in females. These effects lead to a decrease in the rate of reproduction and financial losses for the livestock industry. Understanding the impact of heat stress on reproductive tissues will aid in the development of strategies for preventing heat stress and improving reproductive functions. Modification of the microenvironment, nutritional control, genetic development of heat-tolerant breeds, hormonal treatment, estrous synchronization, timed artificial insemination, and embryo transfer are among the strategies used to reduce the detrimental effects of heat stress on reproduction. These strategies may also increase the likelihood of establishing pregnancy in farm animals.

Recent data of the biology of the twaite shad, Alosa fallax returning for spawning to the Szczecin Lagoon (southern Baltic Sea)

In 2022–2023 specimens of A. fallax are recorded for the first time in approximately 17 years in Szczecin Lagoon. We collected 11 specimens of juveniles, 9 premature and mature females, and 9 premature and mature males (20.3–40.7 cm of total length, aged from 1+ to 4+). The 2+ aged fish was slightly dominated (34.5% of the whole sample). Females in the Szczecin Lagoon were ready to spawn in the age of 3+ and 4+ years, while males partly in 2+, and in the age of 3+ and 4+. Fulton’s condition factor of this fish was 0.93±0.14 and Clark’s 0.78±0.14. Analysis of correlations between the total length and individual weight of fish revealed that the growth of A. fallax was allometric (b < 3.0). The range of gonadosomatic index (GSI) was 0.12–26.59%, while the mean of the absolute and relative fecundity was 58,756 eggs per female and 139,650 eggs per kilogram of body weight. The obtained results indicate the occurrence of an anadromous population of Alosa fallax in the studied water areas. However, there is still a need to obtain detailed information on the population status and the biology of A. fallax in these areas in order to designate special conservation areas (SACs) for their protection, especially taking into account spawning habitats.

Reproductive performance of lumpfish (Cyclopterus lumpus, L. 1758) females: Effects of integrated photoperiod and temperature manipulations on sexual maturation and spawning.

A successful control of sexual maturation is crucial for year-round production of lumpfish juveniles destined as cleaner fish in Atlantic salmon aquaculture. This study investigated the combined effects of photoperiod and temperature manipulations on sexual maturation and spawning in lumpfish females. Lumpfish juveniles were exposed to simulated natural and nine-month compressed annual photoperiods, with subsequent temperature elevation. Body weight (BW), condition factor (K), gonadosomatic index (GSI), ovarian development, plasma levels of 17β-estradiol (E2), testosterone (T) and 11-ketotestosterone (11-KT), and spawning were assessed. Compressing the natural photoperiod caused a clear increase and decrease in GSI, T, 11-KT and E2 towards and during the spawning period. Before the temperature elevation, GSI, T, 11-KT, E2 and ovarian development were advanced in the compressed photoperiod. After the temperature elevation, GSI, T, 11-KT and E2 fluctuated more in the compressed photoperiod, while in the natural photoperiod, E2 declined, and GSI, T and 11-KT increased. Spawning was advanced by 1 month in the compressed photoperiod compared to the natural photoperiod. Temperature elevation led to higher levels, earlier peaks and declines of T, 11-KT or E2 in both photoperiods, and advanced spawning by 1.5 months in the compressed photoperiod compared to the natural photoperiod. Temperature elevation also led to increased ovulation recruitment and increased cumulative weight of spawned eggs in the natural photoperiod. Compressing the natural photoperiod and elevating temperature can thus advance sexual maturation and spawning in lumpfish females. Due to the lower amounts of spawned egg weights in the high temperature compressed photoperiod, further studies on effects of photoperiod and timing of temperature manipulations on spawning, fecundity and egg quality could optimize the photothermal manipulations on lumpfish broodstock.

Sperm depletion and mate choice of the crab spider, Ebrechtella tricuspidata (Fahricius)

Abstract Mounting evidence suggests that male sperm may be gradually depleted after consecutive matings, resulting in the decline of female reproductive output in insect species. It is predicted that females may employ adaptive strategies to avoid the sperm-depleted males, such as mating multiply with different males and/or discriminating against previously mated males (MMs). Similarly, males may exhibit adaptive behaviors toward females varying in mating status. However, in spiders with males lacking primary copulatory organs and their pedipalps modified to transfer sperm, there are few studies on male mating potential and previous mating experience on their subsequent mate choice. In this study, we used a polyandrous crab spider, Ebrechtella tricuspidata, a sit-and-wait predator with female-biased sex ratio as a model system to ascertain whether 1) male mating experiences influence female reproductive fitness; 2) females respond differently to males varying in mating status; and 3) males respond differently to females varying in mating status. Our results showed that female fecundity was independent of male mating experiences, but female fertility markedly declined with the increase of male previous mating experiences in the first eggsac. Counter to our predictions, females preferred to choose and mate with the larger males, regardless of their mating status. In contrast, male mating status influenced their mating preference toward females. Virgin males did not show any preference between virgin and mated females; however, MMs were more likely to prefer the virgin females over the mated ones. Overall, our results indicated that female choice depended primarily on male relative size rather than male mating status, whereas male choice depended on female mating status. Depending on the investigation of reproductive dynamics and mate choice in E. tricuspidata, the study will provide valuable insights into the adaptive behaviors of both males and females exhibiting toward mates varying in mating status.

Supplemental Material for Female Mate Preference in Romantic Cinema: A Study of Hallmark Channel Originals

Supplemental Material for Female Mate Preference in Romantic Cinema: A Study of Hallmark Channel Originals

Mounting exhibited between cows is not associated with sexual motivation

Females of various species exhibit mounting behavior toward other mature females, i.e., female–female (f–f) mounting. Cows exhibit f–f mounting, which is commonly considered a sexual behavior based on a few similarities with male sexual mounting. Here, we hypothesized that the degree of f–f mounting exhibited by cows in estrus would increase when they are sexually motivated by sexually relevant stimuli. To test this hypothesis, two groups of four cows each were prepared. First, estrus was induced in one of the cows in each group by injecting estradiol in the presence of a non-sexually active male steer as a stimulus animal (steer-stimulus condition), and all f–f mounts were recorded. Estrus induction was repeated until induced in all cows. We then changed the stimulus animal from the steer to a sexually active bull (bull-stimulus condition), and the estrus induction procedures were repeated as before. We confirmed that estrus was induced successfully in cows injected with estradiol and that they were sexually motivated by switching the stimulus animal from steer to bull, as they spent relatively more time with the stimulus animal in the bull-stimulus than in the steer-stimulus condition and when not in estrus. However, f–f mounting frequency in the bull-stimulus condition showed no significant difference to that in the steer-stimulus condition. We observed that six of the eight subjects exhibited f–f mounting when not in estrus, which accounted for 44.6 % of f–f mounting we observed (n = 668). These findings suggest that f–f mounting in cows is not associated with sexual motivation.

Dance displays in gibbons: biological and linguistic perspectives on structured, intentional, and rhythmic body movement.

Female crested gibbons (genus Nomascus)perform conspicuous sequences of twitching movements involving the rump and extremities. However, these dances have attracted little scientific attention and their structure and meaning remain largely obscure. Here we analyse close-range video recordings of captive crested gibbons, extracting descriptions of dance in four species (N. annamensis, N. gabriellae, N. leucogenys and N. siki). In addition, we report results from a survey amongst relevant professionals clarifying behavioural contexts of dance in captive and wild crested gibbons. Our results demonstrate that dances in Nomascus represent a common and intentional form of visual communication restricted to sexually mature females. Whilst primarily used as a proceptive signal to solicit copulation, dances occur in a wide range of contexts related to arousal and/or frustration in captivity. A linguistically informed view of this sequential behaviour demonstrates that movement withindances is organizedin groups andfollows an isochronous rhythm-patterns not described for visual displays in other non-human primates. We argue that applying the concept of dance to gibbons allows us to expand our understanding of communication in non-human primates and todevelop hypotheses on the rules and regularities characterising it. We propose that crestedgibbon dances likely evolved from less elaborate rhythmic proceptive signals, similar to those found in siamangs. Although dance displays in humans and crested gibbons share a number of key characteristics, they cannot be assumed to be homologous. Nevertheless, gibbon dances represent a strikingmodel behaviour to investigate the use of complex gestural signals in hominoid primates.

Reproductive and Growth Parameter Estimation Utilizing Length-Stratified Age Samples of Sandbird Octopus (Amphioctopus aegina) near Phetchaburi Province, Thailand

This study aimed to analyze the growth parameters and age-length relationships of the sandbird octopus (Amphioctopus aegina) along the coast of Chao Samran Beach, Phetchaburi Province, Thailand. This included determining reproductive stages, the gonadosomatic index, and size at first maturity. A total of 1,436 specimens comprising 782 males and 654 females were collected using octopus traps during January to December 2021. The mantle length and weight of each specimen were measured. Reproductive stages were assessed to determine the gonadosomatic index and size at first maturity, and growth parameters were estimated using the von Bertalanffy growth equation. Results showed that males exhibited a mantle length range of 3.1—7.5 cm (mean: 5.2±0.7) and a weight range of 5.99—94.00 g (mean: 35.34±11.24). Mantle length at first maturity for males was 4.2 cm, with full maturity at 7.0 cm. Females had a mantle length range of 2.8—9.4 cm (mean: 5.7±0.9) and a weight range of 7.70—105.00 g (mean: 45.43±17.00). Mantle length at first maturity for females was 5.9 cm, with full maturity at 7.5 cm. GSI values were highest in both sexes in February, April, May, June and November, suggesting reproduction occurred through much of the year, and females showed a large peak in May. GSI values were lowest in both sexes in September. The smallest recorded mantle length was 2.8 cm in May, and the largest was 9.4 cm in January. The specific values of t0 for males, females, and both combined sexes were -0.017719, -0.014519, and -0.00672, respectively. These findings provide valuable insights into the growth and reproductive biology of A. aegina, which can inform sustainable management and conservation efforts for this species.

Sperm storage in males of the Neotropical rattlesnake Crotalus durissus (Squamata: Viperidae): Structure and seasonal variation of the distal ductus deferens

In species with asynchronous reproductive cycles, where gamete production is not aligned with the mating season, either males or females must store sperm. This reproductive tactic is an obligatory feature of male rattlesnakes’ reproductive cycle due to asynchrony between spermatogenesis and mating. Given that the ductus deferens is the primary site of sperm storage in male snakes, we aimed to investigate the morphological and histochemical changes in the distal ductus deferens of C. durissus throughout its reproductive cycle. In this species, spermatogenesis begins in spring and peaks in summer, while testes regress during autumn and winter. The distal ductus deferens of 28 mature male specimens was evaluated using histomorphometric and histochemical methods. Spermatozoa were consistently observed within the lumen of the ductus deferens in almost all specimens. The principal cells of the distal region of ductus deferens reacted positively for Periodic Acid-Schiff and Bromophenol Blue. Secretions were observed in the apical region of the principal cells' cytoplasm and along the epithelium edge, which may be related to gamete maintenance. Increased secretory activity of the principal cells was observed during periods of testicular activity. A reduction in the lumen of ductus deferens occurs during testicular regression, indicating possible fluid resorption by epithelial cells. Fluid resorption might be one of the mechanisms to ensure stored sperm viability, as it provides an increase in the glycoprotein’s concentration.

Embryonic development of the world's smallest puffer fish, Carinotetraodon travancoricus - a threatened freshwater fish of the Western Ghats Biodiversity Hotspot.

The Malabar dwarf puffer, Carinotetraodon travancoricus is the smallest known pufferfish (family Tetraodontidae) and one of the smallest freshwater fishes of the Indian subcontinent. Due to their miniature size, wacky behaviour and appearance, they are much preferred in the international aquarium fish trade, although little is known regarding their breeding activity in captivity and their embryonic development. The purpose of this study was to fill these knowledge gaps. Wild-caught Malabar dwarf puffers were acclimatised to conditions, and pairs were introduced to breeding tanks. Adult fishes were fed with live and frozen diets including Artemia nauplii, moina and bloodworm. During spawning seasons, adult fish displayed elaborate courtship behaviour around sunset. Carinotetraodon travancoricus is a batch spawner releasing 1 to 5 eggs per diem. The eggs were spherical, and non-sticky, with a diameter of 1.48 ± 0.1 mm, and hatching took place after 108 to 116 h post-incubation. The newly hatched larvae were 3.5 ± 0.2 mm in length, and weighed 2.9 ± 0.4 mg. The early larvae have substantial yolk and oil globules as an energy reserve. Histological studies on mature females suggested the batch spawning nature of the species and low fecundity. Given its unique reproductive behaviour and characters, in situ protected habitats are required to ensure their continued survival in the wild, apart from encouraging captive breeding to augment the demand in the international aquarium fish trade.

Sex-specific manipulation of sexually cannibalistic mantid mating behavior by hairworms

Abstract Changes in the morphology, physiology, and behavior of parasitized organisms provide an ideal opportunity to examine the extended phenotype of parasites. Because the quality of the host directly affects the fitness of the parasite, parasites may increase their fitness by manipulating phenotypes of low-quality hosts. Males are usually preyed on by females in sexual cannibalism. Thus, the males of sexually cannibalistic species are unsafe and low-quality hosts for parasites, whereas females may be beneficial hosts because of the chance of nutrient intake from cannibalized males. Under passive modes of transmission, parasites cannot choose the host sex. Such parasites exploiting sexually cannibalistic organisms are subjected to contrasting fitness effects and may evolve to manipulate host mating behavior in a sex-specific manner: decreasing male mating to avoid cannibalism and promoting female mating to engage in cannibalism. We examined this hypothesis by a behavioral experiment using a mantid–hairworm system. Parasitized male mantids (Tenodera angustipennis) changed their behavior as expected, exhibiting increased escapes and decreased courtships and mountings, potentially avoiding encounters with the female. Interestingly, male attack behavior was promoted, possibly decreasing contact with the encountered female. However, contrary to our prediction, parasitized females also exhibited decreased propensities of mating, suggesting costs or little benefits of host mating for parasites in the female host. This study provides novel insights into the evolution of parasite strategies in response to sexual differences in host quality.

Male cuticular pheromones stimulate removal of the mating plug and promote re-mating through pC1 neurons in Drosophila females

In birds and insects, the female uptakes sperm for a specific duration post-copulation known as the ejaculate holding period (EHP) before expelling unused sperm and the mating plug through sperm ejection. In this study, we found that Drosophila melanogaster females shortens the EHP when incubated with males or mated females shortly after the first mating. This phenomenon, which we termed male-induced EHP shortening (MIES), requires Or47b+ olfactory and ppk23+ gustatory neurons, activated by 2-methyltetracosane and 7-tricosene, respectively. These odorants raise cAMP levels in pC1 neurons, responsible for processing male courtship cues and regulating female mating receptivity. Elevated cAMP levels in pC1 neurons reduce EHP and reinstate their responsiveness to male courtship cues, promoting re-mating with faster sperm ejection. This study established MIES as a genetically tractable model of sexual plasticity with a conserved neural mechanism.

Male cuticular pheromones stimulate removal of the mating plug and promote re-mating through pC1 neurons in Drosophila females.

In birds and insects, the female uptakes sperm for a specific duration post-copulation known as the ejaculate holding period (EHP) before expelling unused sperm and the mating plug through sperm ejection. In this study, we found that Drosophila melanogaster females shortens the EHP when incubated with males or mated females shortly after the first mating. This phenomenon, which we termed male-induced EHP shortening (MIES), requires Or47b+ olfactory and ppk23+ gustatory neurons, activated by 2-methyltetracosane and 7-tricosene, respectively. These odorants raise cAMP levels in pC1 neurons, responsible for processing male courtship cues and regulating female mating receptivity. Elevated cAMP levels in pC1 neurons reduce EHP and reinstate their responsiveness to male courtship cues, promoting re-mating with faster sperm ejection. This study established MIES as a genetically tractable model of sexual plasticity with a conserved neural mechanism.

Life history traits of the pelagic thresher shark (Alopias pelagicus) in the Eastern-Central Pacific Ocean

Life history traits, such as age, growth, and maturity, are essential in fisheries management. However, Alopias pelagicus lacks the age and growth parameters in Ecuador, despite being the elasmobranch species with the highest number of landings in the country. Therefore, the aim of this work was to estimate the age, growth, and maturity parameters of A. pelagicus in the Ecuadorian Pacific. For this, field trips were carried out in Playita Mía, Manta, Ecuador from June 2021 to May 2022. In these field trips, the vertebrae of 304 individuals were collected. Frequentist and Bayesian multimodels (von Bertalanffy, Gompertz, and Logistic) were used to estimate age and growth parameters. A logistic model was used to estimate the mean size at maturity. The inflection point in males was estimated from a modified logistic model. The best fit was given by the Bayesian logistic model for combined sex (L∞ = 168.16 cm PCL, L0 = 73.76 cm PCL, g = 0.34 year−1) according to leave-one-out-information-criterion (LOOIC). Age and length at maturity were estimated at 5.12 years and 141.28 cm PCL, respectively in males. The inflection point was estimated at 133.67 cm PCL. The information presented here is necessary for future demographic analyses. It is necessary that future studies can estimate the age and length at maturity in females.

Myosuppressin signaling deficiency affects ovarian development via repression of 20-hydroxyecdysone biosynthesis in Grapholita molesta

The steroid 20-hydroxyecdysone (20E) is crucial in regulating ovarian development. However, the neuropeptidergic mechanisms underlying ovarian development via 20E are underexplored. In this study, we investigated myosuppressin (MS) signaling in the dominant fruit pest Grapholita molesta and revealed that MS signaling is necessary for 20E biosynthesis during ovarian maturation. Pharmacological and molecular docking analyses confirmed that the GmMS mature peptide could activate its receptor GmMSR. Additionally, transcript expression analyses of GmMS and GmMSR showed different distribution patterns in adults. Notably, GmMSR was also detected in the ovaries of sexually mature females. RNAi-mediated dysfunction of GmMS or GmMSR specifically decreased fertility in females. Furthermore, GmMS or GmMSR knockdown decreased vitellogenin synthesis and uptake, thereby delaying ovarian development. RNA-seq, gene expression validation, and hormone quantification further revealed that GmMS signaling depletion blocked 20E biosynthesis in the ovary. Finally, exogenous MS rescued most dsGmMS- or dsGmMSR-induced ovarian defects and 20E titers. These results suggest that MS/MSR-to-20E signaling regulates ovarian development through vitellogenesis, providing a new perspective on the development of neuroendocrine targets that suppress pest field populations.

First Report of the Root‐Knot Nematode Meloidogyne incognita Infecting Ficus tikoua in China

ABSTRACTFicus tikoua can be used as resources for fruit and herbal medicine inspiring large‐scale planting in China. Nodular galls were found on the roots of the planted F. tikoua individuals in 2022. The mature females and egg masses of nematodes were extracted from the nodular galls, and microscopic examination suggested Meloidogyne infection. Molecular identification based on ITS, 18S rRNA sequences assigned the infecting species to Meloidogyne incognita, which was further demonstrated by the successful application of specific SCAR marker M. incognita in all samples. The pathogenicity of M. incognita was conducted on F. tikoua cutting seedlings based on Koch's postulates. This is the first report of M. incognita infection in F. tikoua in China.

Current trend of sexual maturity, teeth eruption, and bone fusion in the present female population, relative to documented age and development of prediction model for age of females.

Understanding sexual maturity and bone fusion is crucial in forensic investigations and legal contexts. This study investigates the contemporary trend of sexual maturity and bone fusion in females, comparing the observed age-related characteristics with documented ages. Such analyses contribute to the accuracy of age estimation methods used in medico-legal scenarios. A comprehensive study was conducted involving a diverse sample of females, and their sexual maturity and bone fusion were assessed relative to documented ages. The research utilized a cross-sectional design, collecting data through interviews, medical examinations, and radiographic imaging. Ethical approval was obtained, and participants provided informed consent. Variables included documented age, age of menarche, stages of sexual maturity, dentition, and bone fusion. Validation of model performance was conducted. Among 70 cases studied, the mean age of menarche was 10.48 years (range: 7-12 years). Maternal reports indicated menarche onset between 12-17 years. Tanner's Staging 5 for pubic hair and fully developed breasts occurred at 14 years. Permanent teeth increased with age, with 28 or more teeth present at age 14 or above. Fusion of the distal end of the Radius and Ulna with the parent bone was positive from 15 years onwards. The regression model predicted age accurately (97.99% fit). The results highlight the early onset of sexual maturation, consistent teeth eruption, and bone fusion patterns in females. The observed correlations offer valuable insights for medicolegal practitioners and forensic experts.

Effects of the symbiotic bacteria, Caballeronia insecticola, on the life history parameters of Riptortus pedestris (Hemiptera: Alydidae) and their implications for the host population growth.

This study aimed to investigate the effects of symbiosis on the life history of host insects and address their implications at the host population level. We evaluated the effects of symbiotic bacteria Caballeronia insecticola on its host Riptortus pedestris (Fabricus) (Hemiptera: Alydidae) from cohorts for nymphal development, adult survivorship, and female reproduction. Then, life table parameters were compared between symbiotic and apo-symbiotic groups, and the effects of symbiosis on the abundance of R. pedestris were simulated for varying proportions of symbiotic individuals in host populations. We found that symbiosis significantly accelerated the nymphal development and reproductive maturation of females. However, symbiosis incurred survival cost on adult females, reducing their longevity by 28.6%. Nonetheless, symbiotic females laid significantly greater numbers of eggs than the apo-symbiotic during early adult ages. This early reproductive investment negated the adverse effect of their reduced longevity, resulting in the mean lifetime fecundity to not significantly differ between the 2 groups. Indeed, total cohort fecundity of the symbiotic group was 1.3-fold greater than that of the apo-symbiotic group. Life table analysis demonstrated shorter generation time and greater population growth rate in the symbiotic population. Finally, the simulation model results indicate that an increase in the proportion of symbiotic R. pedestris favored the population growth, increasing the population size by 1.9 times for every 25% increase in the proportion of symbiotic individuals. Our study demonstrates that symbiont-mediated changes in the life history parameters of host individuals favor the host population growth, despite substantial reduction in the female longevity.