杂种小麦繁制种研究和实践

用2个偏型不育系ms(ven)-149和ms(ven)-6901为供试材料,结合在近年来利用CMS和CHA法进行杂种小麦研究和应用中,有关亲本繁殖及杂交种制种技术的研究和实践,对杂种小麦繁制种技术进行分析研究,试验表明,用作杂种小麦制种的母本柱头生活力约持续15d左右,CMS母本较CHA母本柱头生活力持持续时间长,在进行花期调节时,CMS母本可比父枰早2－6d,CHA母本可比父本早2－4d,最佳父母本行比以1：2较为适宜,基本播幅为1．6m,在花期相遇不好的情况下,人工辅助授粉可明显提高异交结实率,为了保证繁制种质量,安全隔离和彻底去杂是杂交种繁制的重要措施。     

Inheritance of species differences in female receptivity and song requirement between Drosophila virilis and D. montana

Females of two Drosophila virilis group species, D. virilis and D. montana, have different requirements for the courting males. In the present study we have examined species differences in female receptivity and male courtship song requirement using females' acceptance signal instead of copulation for measuring female readiness to mate. Behavior of D. virilis and D. montana females and F1 and backcross hybrid females was observed in a single-pair courtships with D. virilis and D. montana males and normal and wingless (mute) F1 hybrid males. D. virilis females were very receptive and they commonly accepted the courtship of males unable to produce courtship song. D. montana females, on the contrary, had a low receptivity and these females accepted the courting male only after hearing his song. Interspecific F1 and backcross (BCm) females resembled D. virilis more than D. montana in their receptivity. These females, however, resembled D. montana in their song requirement. These findings suggest that female song requirement and female receptivity are determined by different genetic factors.     

Effect of parthenocarpy on ovule development in cucumber (Cucumis sativus L.) after pollination with normal and irradiated pollen

In nonparthenocarpic cucumber, analysis of the interaction between season and female receptivity demonstrated two different modes of fruit development and seed set. Spring climatic conditions induced significantly longer ovaries at anthesis with an autonomous fruit set as in natural parthenocarpy. Autumn climatic conditions induced smaller ovaries with fruit set influenced by the pollination stage of the female flower. These differences involve, during fruit development, a regulation of the empty seed number especially at both ends of female receptivity period. Indeed, seasons have no effect on ovule receptivity and fertility measured by full seed number. It is supposed that priority is given to seeds with an embryo in the competition for limited maternal resources in spring as well as in autumn. In spring, the use of irradiated pollen during the whole female receptivity period did not modify the seed set profile. Moreover, a cytological study of 6-day-old ovules pollinated by irradiated pollen has revealed a similar precocious embryogenesis compared to the control. In cucumber, pollination with irradiated pollen involves stenospermocarpy rather than induced parthenocarpy. However, we have not been able to determine whether the early abortive embryogenesis induced by irradiated pollen is gynogenetic or abnormal zygotic.     

Stability in and correlation between factors influencing genetic quality of seed lots in seed orchard of Pinus tabuliformis Carr. over a 12-year span

Coniferous seed orchards require a long period from initial seed harvest to stable seed production. Differential reproductive success and asynchrony are among the main factors for orchard crops year-to-year variation in terms of parental gametic contribution and ultimately the genetic gain. It is fundamental in both making predictions about the genetic composition of the seed crop and decisions about orchard roguing and improved seed orchard establishment. In this paper, a primary Chinese pine seed orchard with 49 clones is investigated for stability, variation and correlation analysis of factors which influence genetic quality of the seed lots from initial seed harvest to the stable seed production over a 12 years span. Results indicated that the reproductive synchrony index of pollen shedding has shown to be higher than that of the strobili receptivity, and both can be drastically influenced by the ambient climate factors. Reproductive synchrony index of the clones has certain relative stability and it could be used as an indication of the seed orchard status during maturity stage; clones in the studied orchard have shown extreme differences in terms of the gametic and genetic contribution to the seed crop at the orchard's early production phase specifically when they severe as either female or male parents. Those differences are closely related to clonal sex tendency at the time of orchard's initial reproduction. Clonal gamete contribution as male and female parent often has a negative correlation. Clone utilization as pollen, seed or both pollen and seed donors should consider the role it would play in the seed crop; due to numerous factors influencing on the mating system in seed orchards, clonal genetic contribution as male parent is uncertain, and it has major influence on the genetic composition in the seed orchard during the initial reproductive and seed production phase.     

Effects of soil resources on expression of a sexual conflict over timing of stigma receptivity in a mixed‐mating plant

While environmental factors strongly influence plant growth and reproduction, less is known about environmental effects on sexual selection and sexual conflict. In this study on mixed‐mating Collinsia heterophylla we investigated whether soil resource environment affected traits associated with sexual conflict. In C. heterophylla a sexual conflict over timing of stigma receptivity occurs. Early stigma receptivity benefits pollen parents by securing paternity while late stigma receptivity benefits female fitness in terms of increased seed production. We performed hand‐pollinations combining recipients and donors grown either in high or low resource environments and asked whether these treatments influenced sexual conflict traits – recipient‐ and donor‐based influence on timing of stigma receptivity – and conflict costs related to reduced early seed production. We also asked whether resource environment affected eight traits related to general fitness and mating system. Sexual conflict‐associated traits – timing of stigma receptivity and seed production – were generally unaffected by resource environment. While no universal effect of resources was detected, we did observe donor‐specific responses to environment, suggesting that environment can nonetheless contribute to variation in timing of stigma receptivity. Recipients grown under low resources showed pronounced differences among donors for number of seeds per capsule, indicating that recipients favour some donors over others under resource‐low conditions. Moreover, high resources increased number of flowers but reduced pollen germination rate, while other traits were unaffected, indicating variation in the response to resource environment for fitness‐ and mating system‐traits. Our results suggest that even though soil resource environment had a low impact on the sexual conflict traits and related costs in C. heterophylla, it generated variability in pollen donor‐influence on this trait and in recipient sorting among donors. Thus, it is possible that both sexual conflict and sexual selection is affected by environmental factors not only in animals but also in plants.     

Genetic analysis of the related traits of flowering and silk for hybrid seed production in maize

In the field, asynchrony of flowering and silk for male and female plants always occurs under different abiotic stresses, and reduces yield in the seed industry. Under stress conditions, a female parent with a short duration of silk emergence and a long time of silk receptivity can decrease the risk of the asynchrony for flowering and silking in the process of hybrid seed production. For dissecting the genetic basis of the related traits of flowering and silk in maize, a set of recombinant inbred lines (RIL) was evaluated at three different environments. Correlation analysis showed that anthesis silk interval (ASI) had a significant positive relationship with day to silk (DTS) and duration of silk emergence (DSE). Silk receptivity (SR) had a significant negative correlation to DTS, DSE, and ASI. This implied that the female parent with a long DTS, DSE, and ASI could easy lose its SR, and required synchrony of pollen shedding for the male parent in the field. A total of sixteen different QTLs were identified for the seven traits of flowering and silking traits, including three QTLs for day to tassel (DTT), two for day to pollen (DTP), two for duration of pollen shedding (DPS), three for SR, two for DTS, two for DSE, and two for ASI. The QTLs detected for the related traits of flowering and silk could select ideal traits for male and female parents to raise the yield in the seed industry under certain stress conditions.     

Temporal variation in the female components of reproductive success over the extended flowering season of a Mediterranean perennial herb

We examined the reproductive success of the perennial herb Lobularia maritima during its extended flowering and fruiting season. The within- and between-year variability of the female components of reproductive success (from flower, fruit and seed production to seed survival, seed germination and seedling establishment) were analysed during four flowering seasons. All the components of reproductive success studied showed a significant within- and between-year variation. September was the period of the year with the maximum values of flower and fruit production, and the highest germination and establishment rates. Nevertheless, seed losses due to both predispersal and postdispersal seed predation during this period were also the highest, seriously reducing seed output in this period. On the other hand, in those periods in which seed production was low, i.e. January and May, the percentage of seeds lost to seed predators was the lowest. Reproductive success in each period of the flowering season was estimated using a simple demographic model, in which the information concerning all the components already calculated was integrated. The two variables used to estimate reproductive success in each period, i.e. the number of new individuals produced per plant and the probability of a seed becoming an adult plant, showed relatively small differences over the year. These results suggest a counter-balance of the different components of reproductive success in this species, with favourable and unfavourable periods for the different components being compensated during its extended flowering season.     

Induction of sexual receptivity in the female lizard, Anolis carolinensis: Effects of estrogen and the antiestrogen CI-628

Daily behavioral testing revealed that there is a latency period of at least 48 hr from the administration of a single injection of estradiol benzoate (EB) to the first significant increase in female sexual receptivity in the ovariectomized female lizard, Anolis carolinensis. This latency period did not vary with dosage of EB used in these experiments (i.e., 0.8, 1.4, and 4.0 μg) nor with method of injection (subcutaneous vs intraperitoneal for dose of 1.4 μg EB). Following a single EB injection, female sexual receptivity increased after the 48-hr latency period, reached an observed peak from Day 3 to Day 6, and thereafter declined to pretreatment levels by Day 19. Although both 1.4 and 4.0 μg of EB produced higher levels of female sexual receptivity than did treatment with 0.8 μg of EB, results obtained with 4.0 μg EB did not differ from those obtained with 1.4 μg EB. Administration of the nonsteroidal antiestrogen CI-628 (80 μg) at either 4 or 24 hr following a single subcutaneous injection of 1.4 μg EB significantly reduced subsequent female sexual receptivity. These results suggest that there is a critical length of time during which estrogen must act on the brain and support the concept of an estrogen “maintenance” effect during this priming period.     

A re-examination of the lordosis response in female rats given high doses of testosterone propionate or estradiol benzoate in the neonatal period

High lordosis quotients (LQ) were observed when female Wistar rats injected with 1.25 mgm of testosterone propionate (TP) on Day 4 of postnatal life were tested as intact adults. The high LQ was not due to testing during the lights-on period, the age at which the females were tested, the use of a strain that was insensitive to the masculinizing action of TP or estradiol benzoate (EB), the age at which the females were injected with TP or EB, or an abnormal response to estrogen. High LQ values were found in similar tests on adult female rats of two other strains injected with 1.25 mgm TP on Day 4 of life. A marked reduction of the facilitatory action of progesterone on receptivity in estrogen-primed animals was demonstrated in the females of all three strains treated with TP or EB during the neonatal period and for males after castration as adults.Analysis of the experimental records of the mating tests showed that females anovulatory following TP or EB administration during the neonatal period and tested either intact and under the influence of endogenous hormones or under the influence of exogenous estrogen showed a rapid and highly significant increase in receptivity during the course of prolonged (20 min) tests with two or three active stimulus males. This effect was very much reduced if the treated females were under the influence of exogenous estrogen plus progesterone. The effect was not seen in males castrated as adults and treated with estrogen, or in females not treated with steroids in the neonatal period and tested intact at proestrus alone or under the influence of exogenous steroids after ovariectomy. A significant increase in LQ during the test period was observed in females of the Wistar strain which were anovulatory as a result of exposure to constant light and were tested intact without any exogenous hormone being administered.It is suggested that although tests involving a limited number of mounts or attempts to mount at low rates over a short period of time may be adequate to determine the degree of receptivity of normal female rats they are not adequate to establish the capacity of female rats treated with steroid hormones during the neonatal period to display the lordosis response.     

Is the dichogamy ofSalvia verbenaca (Lamiaceae) an effective barrier to self-fertilization?

Though dichogamy is generally interpreted as a means of preventing self-fertilization, the efficiency of this mechanism has been questioned. Little attention has been paid to functional aspects of male/female timing, such as variation over time in pollen germinability and in stigma receptivity. In the present study these aspects of male/female timing were investigated in the protandrous speciesSalvia verbenaca. To evaluate the effects of selfing, fruit set, total seed weight produced and seed/ovule ratio were also determined, (a) following artificial crossing, (b) following selfing (i.e. bagging) and (c) under natural conditions. Both pollen germinability and stigma receptivity peaked on the last day (day 3) of the flower's life, which presumably favours selfing. Neither fruit set nor seed/ovule ratio were significantly affected by pollination regime, but the total seed weight produced by artificially crossed plants was significantly higher than that produced by bagged or untreated plants. Neither fruit set, seed/ovule ratio nor total seed weight differed significantly between the two years of study. Thus, if aS. verbenaca flower receives outcrossing pollen it will produce a greater weight of seeds (with consequent advantages in terms of female reproductive success). However, the peaking of both pollen germinability and stigma receptivity on day 3 of the flower's life means that selfing is likely to occur if outcrossing pollen has not been received over the early part of the flower's life.     

Floral biology and pollen viability of parental lines of onion hybrids

Parental lines (inbred and hybrid male-sterile lines and inbred pollinators) of prospective F, hybrids from the NVRS spring-sown bulb onion breeding programme were examined to study their floral biology and aspects of pollination under glasshouse conditions. Inbreeding depression occurred in both pollinator and male-sterile inbreds in terms of reduced flower numbers per umbel and a greater proportion of defective pistils. Male-sterile and male-fertile lines differed in their stigma and style characteristics and pattern of development. At flower opening, the styles of male-sterile lines were longer and the stigmatic knob became receptive relatively sooner. The inbred male-sterile line II/3 ms appeared to have a reduced receptive area on its stigmatic knob and remained receptive for a relatively shorter period. Individual lines differed for time of flowering, nectar content and its sugar concentration, and in their effectiveness as male and female parents as judged from pollen tube growth down the style in specific pairings. Assessment of pollen viability using the fluorescein diacetate test did not correlate with assessments based on pollen grain germination and subsequent growth down the style, perhaps as a result of differential receptivity in the inbred lines tested. These results are discussed in relation to future hybrid seed production.     

A study of sexual receptivity in Blabera craniifer Burm. (Blattaria)

In females of the Blaberidae sexual receptivity is inhibited during the preoviposition period and during gestation. Similarly affected are oöcyte development and corpora allata activity during pregnancy. Roth (1964b) believes causation to be due to the mechanical action of the oötheca, but Engelmann (1964) believes it is due to the intervention of a humoral agent.In normal females of Blabera craniifer sexual receptivity is linked to the presence or absence of the oötheca in the brood sac. If the oötheca is not placed in the brood sac receptivity appears sooner than in a pregnant female.If certain afferent pathways are suppressed (by severing the nerve cord), or upset (by anaesthesia or in surgical controls) during pregnancy, only a partial receptivity is shown: straddling of the female on the male abdomen, ‘licking’ of tergal secretions, but no insertion by the male occurs. Such reactions are repeated over several days, giving an alternation of partial receptivity/non-receptivity which differs from that shown in normal animals. At times desynchronization between the receptivity and laying cycles is observed. This leads to the same conclusion as Roth and Barth (1964) that receptivity is not directly controlled by the corpora allata. We believe that the control ‘centre’ of receptivity has an autonomous rhythm, which is normally hidden but which appears when the afferent pathways are lacking or upset. The control mechanism of mating behaviour is probably a neuro-endocrine mechanism.     

Influence of number of pollinations and pollen load size on maternal fitness costs in Collinsia heterophylla: implications for existence of a sexual conflict over timing of stigma receptivity

Costs related to pollen competition have rarely been considered, but are expected in the case of sexual conflict where male and female sexual functions have opposing evolutionary interests. In Collinsia heterophylla, delayed stigma receptivity is beneficial as it enhances pollen competition. A sexual conflict over timing of stigma receptivity has been proposed in this species as early pollination, following one-time pollinations, is advantageous to pollen donors at a cost of reduced maternal seed set (measured as seed number). In this study, we explored whether the maternal cost was still present following an additional pollination. We hypothesized that the cost is caused either by harm related to early pollen presence or by factors unrelated to harm. We performed pollinations at different stages of floral development, either one or two pollinations (24-h time lag), and varied the size of the first pollen load in the latter category. Early pollination reduced seed biomass also after two-time pollinations, suggesting a persistent maternal cost of early pollen presence. Further, pollen load size modified seed production, possibly indicating that dose-dependent harm influences the maternal cost of early fertilization. Our results strongly suggest negative effects of pollen competition on maternal fitness following early pollination, which is consistent with the existence of a sexual conflict over timing of stigma receptivity. In conclusion, we propose that much could be gained if more plant studies considered the potential for fitness costs in relation to sexual conflict, particularly those investigating pollen-pistil interactions.     

Female sex behaviors in the South African clawed frog, Xenopus laevis: gonadotropin-releasing, gonadotropic, and steroid hormones

The goals of this study were to characterize sex behaviors of female South African clawed frogs, Xenopus laevis, and to explore the behavioral effects of endocrine manipulation. The responses of females to clasp assaults by sexually active males were observed. Two patterns of female responses predominated. In one, females exhibited extreme leg extension and ticking vocalizations when clasped (unreceptive behaviors). In the other, females responded to being clasped by adduction of the thighs and increased flexion at the knee; ticking vocalizations were absent (receptive behaviors). When the female was unreceptive, clasps by males generally lasted less than 1 min. With a receptive female, on the other hand, amplexus could last up to 2 days. In intact females, injection of human chorionic gonadotropin (HCG) or of luteinizing hormone-releasing hormone (LHRH) into the dorsal lymph sac results in significant increases in receptivity. These hormones do not promote receptivity in ovariectomized females. Neither estradiol (E) nor progesterone (P) when administered alone was effective in restoring receptivity to ovariectomized females. In combination, E + P increased sexual receptivity. The releasing hormone, LHRH, when given to ovariectomized, E + P-treated females, further increased receptivity and led to the prolonged amplexus otherwise observed with an HCG-injected intact female. The behavioral effects of LHRH may be independent of action on the pituitary since they are not mimicked by gonadotropin.     

Development of new cytoplasmic-genetic male-sterile lines in pigeonpea from crosses betweenCajanus cajan (L. Millsp. andC. scarabaeoides (L.) Thouars

Exploitation of hybrid vigour is quite possible in cross-pollinated crops. However, pigeonpea is a grain legume crop with a moderate level of cross-pollination (20-70%), which is mainly aided by insect pollinators. As a first step, hybrids based on genetic male sterility (GMS) were developed in pigeonpea, but the hybrid seed production technique is not farmer-friendly, because in the hybrid seed production plot 50% of the population, which are male-fertile in the female rows, have to be eliminated in time before contamination. This requires skilled labour and is a time-consuming process, which increases the cost of hybrid seed production. Therefore, the objective of this study was to develop cytoplasmic-genetic male-sterile (CGMS) lines in pigeonpea through wide hybridization, which would be very suitable for hybrid seed production. Two CGMS lines, viz. CORG 990052 A and CORG 990047, were developed by interspecific hybridization of Cajanus cajan and C. scarabaeoides. Restorers were identified and three CGMS-based pigeonpea hybrids were developed. The hybrid COPH 3 is found to be promising in Tamil Nadu State, India.     

The interplay of pollination,costs of reproduction and plant size in maternal fertility limitation in perennial <Emphasis Type="Italic">Paeonia officinalis</Emphasis>

Although several factors can limit female fertility in perennial plants, rarely have they been jointly studied in a single species over several years. In this study we experimentally manipulate seed production and simultaneously analyse the potential contribution of pollen limitation, costs of reproduction and plant size to variation in seed output over a 3-year period in the perennial herb Paeonia officinalis, in southern France. Since this rare species is threatened by forest closure in many sites we also examine the causes of female fertility variation in relation to habitat closure (open habitat vs. woodland). P. officinalis has a partial self-incompatibility system and only very low ability for autonomous self pollination in the absence of pollinators. However, supplementary pollination of individual plants in three consecutive years did not significantly increase seed production above natural levels. Forest closure was associated with a decline in ovule and seed production, which again was not due to pollen limitation since supplementary pollination had no significant effect on seed set in the woodland habitat. Comparison of the maternal fertility of plants which were previously excluded from reproduction with those which were hand pollinated to maximise seed set in two previous years produced no evidence that seed production in year three is limited by costs associated with prior reproduction. Likewise, flowering probability was not related to prior seed production but was however positively related to plant size. The absence of any influence of pollen limitation or prior reproduction on seed production suggests that sub-maximal seed production in long-lived perennial herbs may be part of a size-dependent strategy that maximises life-time seed production and fitness without compromising survival.     

A straight-forward seed production technology system for foxtail millet (Setaria italica)

For autogamous crops, a precondition for using heterosis is to produce sufficient pure male-sterile female parents that can be used to produce hybrid seeds. To date, cytoplasmic male sterility (CMS) and environment-sensitive genic male sterility (EGMS) have been used commercially to exploit heterosis for autogamous species. However, neither CMS nor EGMS has been established for foxtail millet (Setaria italica). Here, we report on the establishment and application of a seed production technology (SPT) system for this crop. First, we established a DsRed-based SPT system, but found that it was unsuitable because it required the use of a fluorescent device for seed sorting. Instead, we constructed an SPT system with de novo betalain biosynthesis as the selection marker. This allowed us to distinguish transgenic seeds with the naked eye, thereby facilitating the identification of SPT maintainer line seeds. In this system, a seed sorter was not required to obtain sufficient seeds. The key point of the strategy is that the seed pool of the SPT maintainer line is propagated by artificial identification and harvesting of male-fertile individuals in the field, and the male-sterile line seed pool for hybrid production is produced and propagated by free pollination of male-sterile plants with the SPT maintainer line. In a field experiment, we obtained 423.96 kg male-sterile line seeds per acre, which is sufficient to plant 700.18 acres of farmland for hybrid seed production or male-sterile line reproduction. Our study therefore describes a powerful tool for hybrid seed production in foxtail millet, and demonstrates how the SPT system can be used for a small-grained crop with high reproduction efficiency.     

Drosophila melanogaster sex peptide stimulates juvenile hormone synthesis and depresses sex pheromone production in Helicoverpa armigera

Previous studies demonstrate that virgin female adult Helicoverpa armigera (Lepidoptera: Noctuidae) moths exhibit calling behaviour and produce sex pheromone in scotophase from the day after emergence, and that mating turns off both of these pre-mating activities. In the fruit fly Drosophila melanogaster, a product of the male accessory glands, termed sex peptide (SP), has been identified as being responsible for suppressing female receptivity after transfer to the female genital tract during mating. Juvenile hormone (JH) production is activated in the D. melanogaster corpus allatum (CA) by SP in vitro. We herein demonstrate cross-reactivity of D. melanogaster SP in the H. armigera moth: JH production in photophase virgin female moth CA in vitro is directly activated in a dose-dependent manner by synthetic D. melanogaster SP, and concurrently inhibits pheromone biosynthesis activating neuropeptide (PBAN)-activated pheromone production by isolated pheromone glands of virgin females. Control peptides (locust adipokinetic hormone, AKH-I, and human corticotropin, ACTH) do not inhibit in vitro pheromone biosynthesis. Moreover, SP injected into virgin H. armigera females, decapitated 24 h after eclosion, or into scotophase virgin females, suppresses pheromone production. In the light of these results, we hypothesize the presumptive existence of a SP-like factor among the peptides transmitted to female H. armigera during copulation, inducing an increased level of JH production and depressing the levels of pheromone produced thereafter.     

Changes in male sexual responses from silk cues of females at different reproductive states in the wolf spider Schizocosa malitiosa

Male wolf spiders are capable of recognising sexual signals associated with female silk threads. In the wolf spider Schizocosa malitiosa variations in female receptivity have been studied, but changes in female silk attractiveness remain unknown. We analysed the sexual responses of adult males (leg shaking, papal drumming and searching) exposed to silk cues from subadult, virgin and mated females of different ages, and females that were or were not carrying an egg-sac. Penultimate and recently moulted adult females elicited low levels of male sexual behaviour, while those of virgin females (21–40 days old) were the most attractive. Silk threads slowly became less attractive after mating. Cues from females carrying an egg-sac as well as females in the inter egg-sac period were fairly attractive. The low attractiveness of recently moulted females disagrees with their high sexual receptivity. In contrast, females continued to elicit strong male responses during a 10-day period after mating, despite the fact that they immediately become sexually reluctant, suggesting strong selection for male searching ability. Low attractiveness during the egg-carrying period could reflect the fact that females do not require any further sperm. Concordances and discordances between attractiveness and sexual receptivity suggest that they respond to different physiological mechanisms.     

When figs wait for pollinators: the length of fig receptivity

In plant species with an obligate species-specific pollinator, gamete encounter is a critical phase in the success of reproductive strategies. One of the key factors in the success of gamete encounter, the length of female receptivity, has been rarely studied experimentally. In Ficus species (Moraceae), each exclusively associated with its specific pollinating wasp, the receptive female phase of individual syconia was believed to last only a few days. This estimate, based on field observations of pollinator arrivals, neglected the possibility that unpollinated syconia may remain receptive for a prolonged period. In two distantly related fig species (F. carica and F. aurea), we measured experimentally the duration of receptivity of individual syconia protected from pollinator visits. For these two species, receptivity lasted from 2 to 3 wk. Syconia pollinated at any time during this period of receptivity are capable of setting seeds. Furthermore, it has been assumed that female syconium receptivity stops quickly after pollinator visitation. Our experiments showed that syconia of both species are able to extend their receptive period for a few days longer when visited only by a single wasp. The demonstration of a long duration of female receptivity has important consequences for understanding the maintenance of the fig-wasp mutualism.