Fitness,reproduction and longevity among European aristocratic and rural Finnish families in the 1700s and 1800s

The life histories of two socio-economically different groups of humans comprising birth cohorts from the 1700s and 1800s were investigated. It was discovered that fertility selection was greater among European aristocrats and mortality selection greater among rural Finns. The life history of the rural Finns involved shorter female life spans, a considerably longer period of reproduction, higher juvenile mortality, a greater total production of offspring and slightly higher individual fitness. In a comparison of parental cohorts, it was discovered that longevity and progeny survival improved significantly from the 1700s to the 1800s. Out of the three factors investigated, longevity was found to influence reproduction and fitness more than socio-economic group or birth cohort. The reproductive efficacy and fitness of women increased along with their life span. However, reproductive success and fitness were lower among women with the longest life span (over 80 years). Among men, reproductive success improved consistently along with the increase in longevity. When birth intervals were examined, it was discovered that the sex of previous offspring did not influence the interval between births.     

Lifetime reproductive success, longevity, and reproductive life history of female yellow baboons (Papio cynocephalus) of Mikumi National Park, Tanzania

The relationship between longevity and lifetime reproductive success (LRS) was studied in free-ranging female baboons of Mikumi National Park, Tanzania. A severe population decline occurred between the 12th and 20th years of the study. The total sample consisted of 72 females born and reaching adulthood before the start of the population decline. There were 27 females who were adult at the start of the study and 45 who became adult within the 12 years prior to the decline. The subjects were studied until all 72 were dead and all of their offspring were either dead or at least six years old; this took 24 years. The relationship of longevity to LRS was statistically significant for the total sample and for both sub-samples, with 70% of the total variance in LRS accounted for by longevity. Longevity was linked to LRS via a chain of statistically significant relationships: The longer the life span, the longer the reproductive life; the longer the reproductive life, the more offspring produced; the more offspring produced, the higher the LRS. Mean LRS, life span, and reproductive longevity all differed between the two sub-samples. Since the sub-samples were time-linked to a population decline affecting longevity, either sub-sample separately would fail to reflect the broader picture. This illustrates the importance of appreciable sample sizes from long-term studies in helping understand the dynamics between life history estimates and ecological conditions in variable environments.     

Female reproductive success in captive Ammotragus lervia (Bovidae, Artiodactyla). Study of its components and effects of hierarchy and inbreeding

Four components of female reproductive success in captive Saharan arrui (Barbary sheep), Ammotragus lervia sahariensis (Rothschild, 1913), have been analysed: longevity, fecundity, offspring one-month survival rate and the age at first birth. Longevity accounts for 69.9% of the variance of reproductive success, fecundity for 54.2%, offspring one-month survival rate for 29.8%, and the age at first birth for 10.4%. A detailed study of these components leads to the following conclusions: (a) longevity is higher in those individuals in better physical condition; (b) fecundity is related to age and social rank; (c) heavier offspring at birth have a higher probability of surviving during their first month of life; and (d) the age at first birth is delayed by high levels of population density, inbreeding coefficients, and birth weights. On the other hand, highranking females are characterized by shorter inter-birth intervals and give birth to a higher proportion of twins.     

樟叶蜂两性生殖与孤雌生殖方式下雌虫生殖适合度及子代生活史特征的比较

【目的】樟叶蜂Mesoneura rufonota是危害樟树Cinnamonum campora的重要食叶性害虫,该虫的繁殖策略包括两性生殖和孤雌生殖两种模式。本研究旨在明确孤雌生殖在樟叶蜂生活史中的生物学意义。【方法】在室内25℃恒温条件下,测定并分析了樟叶蜂孤雌生殖和两性生殖两种生殖方式在亲代生殖适合度(雌虫寿命、产卵量和卵孵化率)和子代生活史(各虫态发育历期、死亡率、子代性比和产卵量等)特征上的差异。【结果】孤雌生殖的樟叶蜂雌虫寿命显著长于两性生殖的雌虫寿命,而雌虫产卵量和卵孵化率在两种生殖方式间均无差异。子代各虫态的发育历期和死亡率以及子代单雌产卵量在两种生殖方式间均无差异,但子代成虫性比在两种生殖方式间存在显著差异,表现为孤雌生殖大多产雄性子代,而两性生殖大多产雌性子代。【结论】樟叶蜂的孤雌生殖延长了亲代雌虫的寿命,且为产雄孤雌生殖。这些研究结果表明,樟叶蜂的孤雌生殖不但具有自身建群的能力,同时在种群繁衍中可以提供大量的雄虫以弥补两性生殖后代雄性个体的不足。     

Multiple mating in the traumatically inseminating Warehouse pirate bug, Xylocoris flavipes: effects on fecundity and longevity

Optimal mating frequencies differ between sexes as a consequence of the sexual differentiation of reproductive costs per mating, where mating is normally more costly to females than males. In mating systems where sexual reproduction is costly to females, sexual conflict may cause both direct (i.e. by reducing female fecundity or causing mortality) and indirect (i.e. increased risk of mortality, reduced offspring viability) reductions in lifetime reproductive success of females, which have individual and population consequences. We investigated the direct and indirect costs of multiple mating in a traumatically inseminating (TI) predatory Warehouse pirate bug, Xylocoris flavipes (Reuter) (Hemiptera: Anthocoridae), where the male penetrates the female's abdomen during copulation. This study aimed to quantify the effects of TI on female fecundity, egg viability, the lifetime fecundity schedule, longevity and prey consumption in this cosmopolitan biocontrol agent. We found no difference in the total reproductive output between mating treatments in terms of total eggs laid or offspring viability, but there were significant differences found in daily fecundity schedules and adult longevity. In terms of lifetime reproduction, female Warehouse pirate bugs appear to be adapted to compensate for the costs of TI mating to their longevity.     

Sexual cooperation: mating increases longevity in ant queens

Divergent reproductive interests of males and females often cause sexual conflict . Males of many species manipulate females by transferring seminal fluids that boost female short-term fecundity while decreasing their life expectancy and future reproductivity . The life history of ants, however, is expected to reduce sexual conflict; whereas most insect females show repeated phases of mating and reproduction, ant queens mate only during a short period early in life and undergo a lifelong commitment to their mates by storing sperm . Furthermore, sexual offspring can only be reared after a sterile worker force has been built up . Therefore, the males should also profit from a long female lifespan. In the ant Cardiocondyla obscurior, mating indeed has a positive effect on the lifetime reproductive success of queens. Queens that mated to either one fertile or one sterilized male lived considerably longer and started laying eggs earlier than virgin queens. Only queens that received viable sperm from fertile males showed increased fecundity. The lack of a trade-off between fecundity and longevity is unexpected, given evolutionary theories of aging . Our data instead reveal the existence of sexual cooperation in ants.     

水稻二化螟的交配行为

在室内条件下,对水稻二化螟Chilo suppressalis的交配行为及能力进行了研究.结果表明：大多数二化螟雌蛾一生只交配一次,平均0.92次;而雄蛾具有多次交配能力,最多达4次,平均2.72次.二化螟雌蛾的日龄影响其交配率、交配起始时间和持续时间,随二化螟雌蛾日龄的增加,其交配率逐渐下降,交配起始时间逐渐提前,而交配持续时间逐渐上升.相反,二化螟雄蛾日龄对其交配率、交配起始时间和持续时间没有明显影响.交配日龄对二化螟雌蛾的生殖力也存在显著影响,随着二化螟雌蛾交配日龄的增加,雌蛾产卵量下降,卵孵化率降低,产卵期缩短,它们都与雌蛾交配日龄存在显著的负相关;而雌蛾产卵前期和雌蛾寿命随雌蛾交配日龄的增加而延长,与雌蛾交配日龄存在显著的正相关.但二化螟雄蛾交配日龄对雌蛾的生殖力没有明显影响,二化螟雄蛾一生都具有较强的交配繁殖能力.同时,不同交配史的雄蛾与雌蛾交配,对雌蛾的生殖力也没有显著影响.表明二化螟的交配活动是由雌蛾主导控制的.最后,对这些结果在二化螟性信息素防治中应用的可行性进行了探讨.在应用性信息素控制二化螟的实践中,可以在两方面取得实效,一是性信息素可以阻碍雌雄之间正常交配,降低交配率;二是可以推迟二化螟雌虫的交配,使其产卵量和卵孵化率降低.     

Effect of pollination on floral longevity and costs of delaying fertilization in the out-crossing Polygala vayredae Costa (Polygalaceae)

Background and Aims

The effect of pollination on flower life span has been widely studied, but so far little attention has been paid to the reproductive consequences of delayed pollination in plants with long floral life spans. In the present study, Polygala vayredae was used to answer the following questions. (1) How does male and female success affect the floral longevity of individual flowers? (2) How does delaying fertilization affect the female fitness of this species?

Methods

Floral longevity was studied after experimental pollinations involving male and/or female accomplishment, bagging and open pollination. The reproductive costs of a delay in the moment of fertilization were evaluated through fruit set, seed–ovule ratio and seed weight, after pollination of flowers that had been bagged for 2–18 d.

Key Results

Senescence of the flowers of P. vayredae was activated by pollen reception on the stigmatic papillae, while pollen removal had no effect on floral longevity. Nonetheless, a minimum longevity of 8 d was detected, even after successful pollination and pollen dissemination. This period may be involved with the enhancement of male accrual rates, as the female accomplishment is generally achieved after the first visit. Floral life span of open-pollinated flowers was variable and negatively correlated with pollinator visitation rates. Delayed pollination had a major impact on the reproductive success of the plant, with fruit set, seed–ovule ratio and seed weight being significantly diminished with the increase of flower age at the moment of fertilization.

Conclusions

A strong relationship between pollination and floral longevity was observed. Flowers revealed the ability to extend or reduce their longevity, within some limits, in response to the abundance of efficient pollinators (i.e. reproductive fulfilment rates). Furthermore, with scarce or unpredictable pollinators, a long floral life span could maintain the opportunity for fertilization but would also have reproductive costs on production of offspring. Reduced female fitness late in the flower''s life could shift the cost–benefit balance towards a shorter life span, partially counteracting the selection for longer floral life span potentially mediated by scarce pollination services.Key words: Delayed pollination, endemic species, flower longevity, life span, pollen limitation, pollination, pollinator scarcity, Polygala vayredae, Polygalaceae, reproductive consequences, secondary pollen presentation     

枸杞木虱啮小蜂繁殖生物学研究

枸杞木虱啮小蜂Tamarixa lyciumiYang是枸杞木虱Paratrioza sinica Yang&Li若虫期的重要寄生性天敌。在实验室对其繁殖生物学特性进行了研究,结果如下:枸杞木虱啮小蜂大多进行两性生殖,孤雌生殖后代均为雄性,其自然性比为1.80:1。在15～35℃间,随温度升高,枸杞木虱啮小蜂发育历期缩短;从卵发育到成虫时需要8.22℃以上的有效积温217.21日·度。枸杞木虱啮小蜂在25℃恒温条件下繁殖力最高,35℃最低,寿命随温度的升高而缩短。在不同营养条件下,喂食20%蜂蜜的条件最适宜其繁殖,其次为20%蔗糖溶液,补充清水只可延长其寿命而不能提高繁殖力。5℃冷藏枸杞木虱啮小蜂蛹15d以内,不影响其正常羽化,冷藏20d或20d以上,羽化率显著降低;冷藏30d内对羽化后雌雄蜂寿命无明显影响,且从冷藏蛹中羽化的雌蜂寄生能力未受显著影响。     

SEXUAL SIZE DIMORPHISM AND SELECTION IN THE WILD IN THE WATERSTRIDER AQUARIUS REMIGIS: LIFETIME FECUNDITY SELECTION ON FEMALE TOTAL LENGTH AND ITS COMPONENTS

Darwin's fecundity advantage model is often cited as the cause of female biased size dimorphism, however, the empirical studies of lifetime selection on male and female body size that would be required to demonstrate this are few. As a component of a study relating sexual size dimorphism to lifetime selection in natural populations of the female size-biased waterstrider Aquarius remigis (Hemiptera: Gerridae), we estimated coefficients for daily fecundity selection, longevity selection, and lifetime fecundity selection acting on female body size and components of body size for two consecutive generations. Daily fecundity was estimated using females confined in field enclosures and reproductive survival was estimated by twice-weekly recaptures. We found that daily fecundity selection favored females with longer total length through direct selection acting on abdomen length. Longevity selection favored females with smaller total length. When daily fecundity and reproductive longevity were combined to estimate lifetime fecundity we found significant balancing selection acting on total length in both years. The relationship between daily fecundity and reproductive longevity also reveals a significant cost of reproduction in one of two years. We relate these selection estimates to previous estimates of sexual selection on male body size and consider the relationship between contemporary selection and sexual size dimorphism.     

Good reindeer mothers live longer and become better in raising offspring

Longevity is the main factor influencing individual fitness of long-lived, iteroparous species. Theories of life history evolution suggest this is because increased longevity allows individuals to (i) have more breeding attempts (time component), (ii) accumulate experience so as to become better able to rear offspring (experience component) or (iii) because individuals reaching old age have above-average quality (quality component). We assess empirically the relative influences of time, experience and quality on the relationship between longevity and individual fitness among female reindeer. Fitness increased with longevity due to all three processes. All females increased in success with age up to their penultimate year of life (experience component), the success of the terminal-breeding occasion was strongly dependent on longevity. Long-lived females had more successful breeding attempts during their life (time component), and had higher reproductive success at all ages, especially during the last year of life (individual quality component) than short-lived females. Our study reveals a more complex relationship between longevity and fitness in large mammals than the simple increase of the number of reproductive attempts when living longer.     

Early reproductive investment,senescence and lifetime reproductive success in female Asian elephants

The evolutionary theory of senescence posits that as the probability of extrinsic mortality increases with age, selection should favour early‐life over late‐life reproduction. Studies on natural vertebrate populations show early reproduction may impair later‐life performance, but the consequences for lifetime fitness have rarely been determined, and little is known of whether similar patterns apply to mammals which typically live for several decades. We used a longitudinal dataset on Asian elephants (Elephas maximus) to investigate associations between early‐life reproduction and female age‐specific survival, fecundity and offspring survival to independence, as well as lifetime breeding success (lifetime number of calves produced). Females showed low fecundity following sexual maturity, followed by a rapid increase to a peak at age 19 and a subsequent decline. High early life reproductive output (before the peak of performance) was positively associated with subsequent age‐specific fecundity and offspring survival, but significantly impaired a female's own later‐life survival. Despite the negative effects of early reproduction on late‐life survival, early reproduction is under positive selection through a positive association with lifetime breeding success. Our results suggest a trade‐off between early reproduction and later survival which is maintained by strong selection for high early fecundity, and thus support the prediction from life history theory that high investment in reproductive success in early life is favoured by selection through lifetime fitness despite costs to later‐life survival. That maternal survival in elephants depends on previous reproductive investment also has implications for the success of (semi‐)captive breeding programmes of this endangered species.     

Social facilitation affects longevity and lifetime reproductive success in a self-fertilizing land snail

Factors that reduce the reproductive output of self-fertilizing hermaphrodites are receiving increasing attention. The combined effects of reduced fecundity of selfing parents and inbreeding depression of the progeny have been referred to as self-fertilization depression. In isolated freshwater snails the reproductive output of selfing individuals also decreases due to the lack of social facilitation (absence of a conspecific). We examined the effect of social facilitation on lifetime reproductive success (number of young produced and longevity) over two generations in the simultaneously hermaphroditic land snail Balea perversa . In a parallel study we showed that B. perversa kept singly and in pairs reproduced exclusively by self-fertilization. In the parent generation, snails kept singly produced less offspring than snails kept in pairs. The difference in lifetime number of young was mainly due to differences in adult life span. Snails of the two groups did not differ in reproductive rate (number of young produced per 100 d of reproductive life) and hatchling size. In the offspring generation, snails kept singly did not differ from individuals kept in pairs in the lifetime number of young and hatchling survival. As in the parent generation, snails kept singly reproduced during a shorter period than snails kept in pairs. However, the shorter reproductive life span of snails kept singly was compensated for by a slightly (but not significantly) higher reproductive rate which resulted in a similar number of offspring produced for both groups. In both generations, snails of the two groups did not differ in size at first reproduction, adult growth rate and size at death. These findings suggest that social facilitation may affect longevity in selfing B. perversa .     

Are reproductive and somatic senescence coupled in humans? Late, but not early, reproduction correlated with longevity in historical Sami women

Evolutionary theory of senescence emphasizes the importance of intense selection on early reproduction owing to the declining force of natural selection with age that constrains lifespan. In humans, recent studies have, however, suggested that late-life mortality might be more closely related to late rather than early reproduction, although the role of late reproduction on fitness remains unclear. We examined the association between early and late reproduction with longevity in historical post-reproductive Sami women. We also estimated the strength of natural selection on early and late reproduction using path analysis, and the effect of reproductive timing on offspring survival to adulthood and maternal risk of dying at childbirth. We found that natural selection favoured both earlier start and later cessation of reproduction, and higher total fecundity. Maternal age at childbirth was not related to offspring or maternal survival. Interestingly, females who produced their last offspring at advanced age also lived longest, while age at first reproduction and total fecundity were unrelated to female longevity. Our results thus suggest that reproductive and somatic senescence may have been coupled in these human populations, and that selection could have favoured late reproduction. We discuss alternative hypotheses for the mechanisms which might have promoted the association between late reproduction and longevity.     

Effects of size at metamorphosis on stonefly fecundity, longevity, and reproductive success

Many organisms with complex life cycles show considerable variation in size and timing at metamorphosis. Adult males of Megarcyssignata (Plecoptera: Perlodidae) are significantly smaller than females and emerge before females (protandry) from two western Colorado streams. During summer 1992 stoneflies from a trout stream emerged earlier in the season and at larger sizes than those from a colder fishless stream, and size at metamorphosis did not change over the emergence period in either stream. We performed two experiments to determine whether variation in size at metamorphosis affected the fecundity, reproductive success and longevity of individuals of this stonefly species and if total lifetime fecundity was affected by the number of matings. In the first experiment, total lifetime fecundity (eggs oviposited) was determined for adult females held in small plastic cages in the field. Males were removed after one copulation, or pairs were left together for life and allowed to multiply mate. Most copulations occurred in the first few days of the experiment. Females in treatments allowing multiple matings had significantly lower total lifetime fecundity and shorter adult longevity than females that only mated once. Multiple matings also reduced longevity of males. Fecundity increased significantly with female body mass at emergence, but only for females that mated once. While multiple matings eliminated the fecundity advantage of large female body size, number of matings did not affect the significant positive relationship between body mass at metamorphosis and longevity of males or females. In a second experiment designed to determine if body mass at emergence affected male mating success, we placed one large and one small male Megarcys in an observation arena containing one female and recorded which male obtained the first mating. The large and the small male had equal probabilities of copulating with the female. Copulations usually lasted all night, and the unmated male made frequent, but unsuccessful attempts to take over the copulating female. Our data suggest that selection pressures determining body size at metamorphosis may operate independently on males and females, resulting in evolution of sexual size dimorphism, protandry, and mating early in the adult stage. We emphasize the importance of interpreting the fitness consequences of larval growth and development on the timing of and size at metamorphosis in the context of the complete life cycle. Received: 1 July 1997 / Accepted: 12 November 1997     

Factors affecting the duration of nest defense and reproductive lifespan of female sockeye salmon, Oncorhynchus nerka

Reproductive success of female animals is often affected by a combination of fecundity and parental care. In female salmonid fishes, acquisition of nest (redd) sites and prevention of their use by other females are critical to reproductive success. These factors are particularly important for stocks that spawn at high densities. Body size is positively correlated with fecundity and egg size, and has been hypothesized to control the outcome of intrasexual competition and longevity. We tested this hypothesis by evaluating the influences of body size, intrasexual aggression and arrival date on duration and success of redd guarding by female sockeye salmon, Oncorhynchus nerka, in a small Alaskan creek. Contrary to the hypothesis, larger females guarded their redds no longer than smaller females, and did not live as long in the stream. Aggression was not related to body size or overall longevity but was positively correlated with residence period on the redd. Females that entered the creek earlier lived longer, spent longer on their redds, and spent more time guarding their redds after spawning than females that entered the creek later. However, despite their longevity, early-arriving fish were more likely to have their redds reused by another female because they died before all the females had selected redd sites. The small average body size in this stock is consistent with weak selection for large size, and with our evidence that size provided little if any advantage in nest guarding.     

Offspring are lighter at birth and smaller in adulthood when born after a brother versus a sister in humans

In mammals, including humans, it is more costly to produce sons than it is to produce daughters, with maternal survival and subsequent reproductive success diminished more by producing male over female offspring. It is therefore predicted that offspring who are produced by mothers who have previously produced sons versus daughters will be compromised by the relatively high cost their mother incurred in the previous reproductive episode. Such effects are potentially important because characters that determine offspring survival and fecundity ultimately contribute to maternal fitness. Using questionnaire-based data from a contemporary human population, I show that birthweight (irrespective of their sex) is lower in individuals born after an elder brother than in those born after an elder sister. In addition, I show that both men and women who were born after a male versus a female sibling have reduced adulthood height, a known correlate of reproductive success in both sexes. The results suggest that producing sons may have a negative effect on the fitness of subsequent offspring, which has implications for calculations of maternal fitness and for optimal sex allocation.     

Effect of mother’s physical condition during pregnancy and lactation on postnatal growth and reproductive success of offspring in water vole <Emphasis Type="Italic">Arvicola terrestris</Emphasis>

Postnatal growth, life span, and probability of reproduction in the adult state depended on the mother’s physical condition during pregnancy and lactation in water vole. The white fat weight in the female abdominal cavity was shown to significantly increase in pregnancy and to decrease in late lactation. As an indicators for nutritional state of females, their body weight difference after parturition (or in late lactation) and expected from the regression equation relating individual body weight at the beginning and the end of each reproductive stage were used (physical condition indexes in pregnancy or lactation). The correlation of the physical condition index in pregnancy with the storage fat weight was 0.67. The metabolic resources of the mother’s body proved to favor faster offspring development. The female offspring weight at the age of 3 and 10 weeks as well as adult ones positively correlated with the mother’s nutritional state in pregnancy, while the male offspring weight demonstrated a similar correlation at the age of 3 and 6 weeks. Increased negative energy balance during lactation proved to decrease the offspring weight in both sexes after separation from mother and at the age of 6 weeks. High nutritional state of mother in pregnancy favored both the probability of reproduction and life span of female offspring. The reproduction of male offspring did not depend on the mother’s physical condition. The life span peaked in male offspring of mothers in a nutritional state below average in pregnancy and above average in lactation. Thus, the physical condition of the mother’s body is an important sex-dependent factor of phenotypic variation in the offspring body weight, reproductive competence, and life span.     

Effect of mother's physical condition during pregnancy and lactation on postnatal growth and reproductive success of offspring in water vole Arvicola terrestris L

Postnatal growth, life span, and probability of reproduction in the adult state depended on the mother's physical condition during pregnancy and lactation in water vole. The white fat weight in the female abdominal cavity was shown to significantly increase in pregnancy and to decrease in late lactation. As an indicators for nutritional state of females, their body weight difference after parturition (or in late lactation) and expected from the regression equation relating individual body weight at the beginning and the end of each reproductive stage were used (physical condition indexes in pregnancy or lactation). The correlation of the physical condition index in pregnancy with the storage fat weight was 0.67. The metabolic resources of the mother's body proved to favor faster offspring development. The female offspring weight at the age of 3 and 10 weeks as well as adult ones positively correlated with the mother's nutritional state in pregnancy, while the male offspring weight demonstrated a similar correlation at the age of 3 and 6 weeks. Increased negative energy balance during lactation proved to decrease the offspring weight in both sexes after separation from mother and at the age of 6 weeks. High nutritional state of mother in pregnancy favored both the probability of reproduction and life span of female offspring. The reproduction of male offspring did not depend on the mother's physical condition. The life span peaked in male offspring of mothers in a nutritional state below average in pregnancy and above average in lactation. Thus, the physical condition of the mother's body is an important sex-dependent factor of phenotypic variation in the offspring body weight, reproductive competence, and life span.     

延迟交配对山楂叶螨繁殖的影响

为了探索雌螨延迟交配对整个种群的负面效应, 采用叶碟饲养法, 在室内条件下研究了延迟交配对山楂叶螨Tetranychus viennensis Zacher繁殖及种群增长的影响。结果表明: 雌螨延迟交配主要影响寿命、产卵量, 进而影响种群增长率; 随着雌螨交配时间的延迟, 影响的程度逐渐加剧。交配延迟达到或超过7 d, 雌螨的寿命比对照延长20.17%, 产卵量比对照下降26.74%, 但对后代的孵化率、存活率无明显影响。对生命表参数的分析结果表明, 雌螨交配延迟达到或超过7 d, 会导致净生殖率显著下降、平均世代周期历期显著延长, 而内禀增长率则在交配延迟3 d时显著降低。未经交配的雌螨只能营孤雌生殖, 寿命延长了31.14%, 产卵量减少了30.08%。营孤雌生殖的雌螨可以通过与其后代回交而实现两性生殖。结果提示延迟交配会导致山楂叶螨的繁殖力降低。