Age at pollination modifies relative male and female reproductive success in a monoecious fig tree

Plants that depend on a single species of insect pollinator must often contend with infrequent and unpredictable visitation. Prolongation of floral receptivity comes at the cost of reduced male and/or female reproductive success among older flowers. Fig trees (Ficus spp.) have a highly specific pollination symbiosis and individual inflorescences (syconia) that remain receptive for days or weeks. Reproductive success in monoecious fig trees involves production of both seeds and fig wasp offspring. We assessed whether the reproductive output of individual syconia changes with the length of time they waited for pollination, and whether the relative female and male reproductive success also changes. A pollination experiment was conducted in an SE Asian monoecious fig tree Ficus curtipes, in which receptive syconia were covered with mesh bags to exclude wasps and pollinated by single pollinators of this fig tree at their different receptive ages. When the syconia matured their size and contents were recorded. Seed quality was also assessed. The results showed that pollinators entered syconia that had been waiting for up to 36?days. The frequencies of abortions among syconia pollinated at different ages were low throughout. The number of un-utilised flowers increased progressively in older syconia. Seed production was highest in syconia entered on the first day of receptivity, whereas pollinator production peaked in syconia pollinated on day 12, then declined in older syconia. Consequently, overall reproductive efficiency declined with syconium age and floral sex allocation became more male-biased in older syconia. Older syconia also produced lighter seeds. These results suggest that un-pollinated syconia of F. curtipes can remain receptive for several weeks. This makes pollination of each syconium more likely, but at the cost of reduced productivity and with more ovules allocated to male function. However, the prolongation of floral receptivity has significance for the co-adaptation between syconia and fig wasps and for the evolution of the fig tree-fig wasp symbiosis.     

Seasonality of Leaf and Fig Production in Ficus squamosa,a Fig Tree with Seeds Dispersed by Water

The phenology of plants reflects selection generated by seasonal climatic factors and interactions with other plants and animals, within constraints imposed by their phylogenetic history. Fig trees (Ficus) need to produce figs year-round to support their short-lived fig wasp pollinators, but this requirement is partially de-coupled in dioecious species, where female trees only develop seeds, not pollinator offspring. This allows female trees to concentrate seed production at more favorable times of the year. Ficus squamosa is a riparian species whose dispersal is mainly by water, rather than animals. Seeds can float and travel in long distances. We recorded the leaf and reproductive phenology of 174 individuals for three years in Chiang Mai, Northern Thailand. New leaves were produced throughout the year. Fig production occurred year-round, but with large seasonal variations that correlated with temperature and rainfall. Female and male trees initiated maximal fig crops at different times, with production in female trees confined mainly to the rainy season and male figs concentrating fig production in the preceding months, but also often bearing figs continually. Ficus squamosa concentrates seed production by female plants at times when water levels are high, favouring dispersal by water, and asynchronous flowering within male trees allow fig wasps to cycle there, providing them with potential benefits by maintaining pollinators for times when female figs become available to pollinate.     

Some pollinators are more equal than others: Factors influencing pollen loads and seed set capacity of two actively and passively pollinating fig wasps

The nursery pollination system of fig trees (Ficus) results in the plants providing resources for pollinator fig wasp larvae as part of their male reproductive investment, with selection determining relative investment into pollinating wasps and the pollen they carry. The small size of Ficus pollen suggests that the quantities of pollen transported by individual wasps often limits male reproductive success. We assessed variation in fig wasp pollen loads and its influence on seed production in actively pollinated (Ficus montana) and passively pollinated (Ficus carica) dioecious fig trees.The ratios of number of male flowers on number of female flowers in a glasshouse-maintained F. montana population were highly variable. When fig wasps were introduced into receptive female figs, the resulting seed numbers were strongly linked to the numbers of pollinators that had been seeking access to pollen, relative to the number of anthers in their natal figs. In F. carica estimates of the amounts of pollen produced per fig and the quantities of pollen carried by emerging fig wasps suggest that less than 10% of the pollen is transported. Pollinators of F. carica that emerged earlier from figs carried more pollen, and also generated more seeds when introduced into receptive female figs.We show here that all pollinators are not equally valuable and producing more pollinators is not necessarily a good option in terms of Ficus male fitness. Previous results on F. montana figs showed that only around half of the flowers where pollinators lay eggs produced adult offspring. The amount of pollen collected by young female fig wasps may be a major determinant of their reproductive success.     

Sexual specialization in two tropical dioecious figs

Ficus species (figs) and their species-specific pollinator wasps are involved in an intimate mutualism in which wasps lay eggs in some ovaries of the closed inflorescences (syconia), and mature, inseminated offspring carry pollen from mature syconia to fertilize receptive inflorescences. In monoecious species, each syconium produces seeds and wasps. In functionally dioecious fig species, making up approximately half the figs worldwide, male and female functions are separated; hermaphrodite (functionally male) trees produce wasps and pollen only, while female trees produce seeds only. This sexual separation allows selection to act independently on the reproductive biology of each sex. Examining sexual specialization in a tight mutualism allows us to determine aspects of the mutualism that are flexible and those that are canalized. In this study, we quantified the phenology of two species of dioecious figs, F. exasperata and F. hispida, for 2 years by following the fates of several thousand syconia over time. In studying each of these species in a dry and a wet site in south India, we tested specific predictions of how dioecious figs might optimize sexual function. On female trees of both species, more inflorescences matured during the wet (monsoon) season than in any other season; this fruiting period enabled seeds to be produced during the season most suitable for germination. In F. exasperata, functionally male trees released most wasps from mature syconia in the dry season, during peak production of receptive female syconia, and thus maximized successful pollination. In F. hispida, “male” trees produced more syconia in the dry and monsoon seasons than in the post-monsoon season. In both species, male and female trees abscised more unpollinated, young inflorescences than pollinated inflorescences, but abscission appeared to be more likely due to resource- rather than pollinator- limitation. The phenology of F. exasperata requires that male inflorescences wait in receptive phase for scarce pollinators to arrive. As expected, male inflorescences of this species had a longer receptive phase than female inflorescences. In F. hispida, where pollinators are rarely scarce, duration of receptive phase was the same for both sexes. Duration of developing phase was longer in female syconia of both species than in male syconia, most likely because they need a longer period of investment in a fleshy fruit. Variation in developing phase of female syconia in one species (F. exasperata) was also greater than that in male syconia, and enabled female trees to sample a variety of germination environments in time. The strong sexual differences in both fig species support the hypothesis that selection for sexual specialization has strongly influenced the reproductive biology of these species. Received: 28 May 1997 / Accepted: 2 February 1998     

Making the most of your pollinators: An epiphytic fig tree encourages its pollinators to roam between figs

Ficus species are characterized by their unusual enclosed inflorescences (figs) and their relationship with obligate pollinator fig wasps (Agaonidae). Fig trees have a variety of growth forms, but true epiphytes are rare, and one example is Ficus deltoidea of Southeast Asia. Presumably as an adaptation to epiphytism, inflorescence design in this species is exceptional, with very few flowers in female (seed‐producing) figs and unusually large seeds. Figs on male (pollinator offspring‐generating) trees have many more flowers. Many fig wasps pollinate one fig each, but because of the low number of flowers per fig, efficient utilization by F. deltoidea''s pollinators depends on pollinators entering several female figs. We hypothesized that it is in the interest of the plants to allow pollinators to re‐emerge from figs on both male and female trees and that selection favors pollinator roaming because it increases their own reproductive success. Our manipulations of Blastophaga sp. pollinators in a Malaysian oil palm plantation confirmed that individual pollinators do routinely enter several figs of both sexes. Entering additional figs generated more seeds per pollinator on female trees and more pollinator offspring on male trees. Offspring sex ratios in subsequently entered figs were often less female‐biased than in the first figs they entered, which reduced their immediate value to male trees because only female offspring carry their pollen. Small numbers of large seeds in female figs of epiphytic F. deltoidea may reflect constraints on overall female fig size, because pollinator exploitation depends on mutual mimicry between male and female figs.     

The occurrence of fig wasps in the fruits of female gynodioecious fig trees

Fig trees are pollinated by wasp mutualists, whose larvae consume some of the plant's ovaries. Many fig species (350+) are gynodioecious, whereby pollinators generally develop in the figs of ‘male’ trees and seeds generally in the ‘females.’ Pollinators usually cannot reproduce in ‘female’ figs at all because their ovipositors cannot penetrate the long flower styles to gall the ovaries. Many non-pollinating fig wasp (NPFW) species also only reproduce in figs. These wasps can be either phytophagous gallers or parasites of other wasps. The lack of pollinators in female figs may thus constrain or benefit different NPFWs through host absence or relaxed competition. To determine the rates of wasp occurrence and abundance we surveyed 11 dioecious fig species on Hainan Island, China, and performed subsequent experiments with Ficus tinctoria subsp. gibbosa to identify the trophic relationships between NPFWs that enable development in female syconia. We found NPFWs naturally occurring in the females of Ficus auriculata, Ficus hainanensis and F. tinctoria subsp. gibbosa. Because pollinators occurred only in male syconia, when NPFWs also occurred in female syconia, overall there were more wasps in male than in female figs. Species occurrence concurred with experimental data, which showed that at least one phytophagous galler NPFW is essential to enable multiple wasp species to coexist within a female fig. Individuals of galler NPFW species present in both male and female figs of the same fig species were more abundant in females than in males, consistent with relaxed competition due to the absence of pollinator. However, these wasps replaced pollinators on a fewer than one-to-one basis, inferring that other unknown mechanisms prevent the widespread exploitation by wasps of female figs. Because some NPFW species may use the holes chewed by pollinator males to escape from their natal fig, we suggest that dispersal factors could be involved.     

Phenological Adaptations in Ficus tikoua Exhibit Convergence with Unrelated Extra-Tropical Fig Trees

Flowering phenology is central to the ecology and evolution of most flowering plants. In highly-specific nursery pollination systems, such as that involving fig trees (Ficus species) and fig wasps (Agaonidae), any mismatch in timing has serious consequences because the plants must balance seed production with maintenance of their pollinator populations. Most fig trees are found in tropical or subtropical habitats, but the dioecious Chinese Ficus tikoua has a more northerly distribution. We monitored how its fruiting phenology has adapted in response to a highly seasonal environment. Male trees (where fig wasps reproduce) had one to three crops annually, whereas many seed-producing female trees produced only one fig crop. The timing of release of Ceratosolen fig wasps from male figs in late May and June was synchronized with the presence of receptive figs on female trees, at a time when there were few receptive figs on male trees, thereby ensuring seed set while allowing remnant pollinator populations to persist. F. tikoua phenology has converged with those of other (unrelated) northern Ficus species, but there are differences. Unlike F. carica in Europe, all F. tikoua male figs contain male flowers, and unlike F. pumila in China, but like F. carica, it is the second annual generation of adult wasps that pollinate female figs. The phenologies of all three temperate fig trees generate annual bottlenecks in the size of pollinator populations and for female F. tikoua also a shortage of fig wasps that results in many figs failing to be pollinated.     

Plasticity and diversity of the phenology of dioecious Ficus species in Taiwan

While Ficus present a series of traits often associated with dioecy, the prevalence of dioecy in Ficus is atypical. In Asian floras, dioecious Ficus species generally outnumber monoecious ones. Further this is also true in relatively northerly locations for Ficus such as the island of Taiwan. Ficus are pollinated by species-specific wasps that use fig flowers as breeding sites. In dioecious fig species, pollinators develop only in the inflorescences of male fig trees. In this study, we investigated the reproductive phenology of four dioecious Ficus species with distinct ecologies in several locations in northern and southern Taiwan. The two first species (Ficus erecta and Ficus septica) were investigated in four locations. Reproductive phenology was quite different among sites, even within a single species. For example, F. erecta presented well-defined crops at the population level in its usual high-elevation habitat but continuous fig production at low elevations, especially in South Taiwan. The two other fig species (Ficus pedunculosa var. mearnsii and Ficus tinctoria subsp. swinhoei), are shrubs growing together along seashores in exposed locations on coral reef remnants. These two species presented quite different traits allowing the survival of pollinating wasp populations. Ficus pedunculosa var. mearnsii produced figs continuously so that fresh receptive figs were always available for the pollinating wasps while F. tinctoria subsp. swinhoei extended the period of receptivity of its figs, so that receptive figs that had been waiting for pollinating wasps were almost always available. In summary, dioecious figs in Taiwan showed remarkable variation in their phenology, within species among locations or among species within location. Nevertheless, despite this variation, the phenology of the trees always allowed survival of pollinating wasp populations. Dioecious figs seem to have adopted a differentiated set of strategies which result in high resilience of pollinator populations. This resilience could help explain the atypical prevalence of dioecy in Ficus.     

Living on the edge: Fig tree phenology at the northern range limit of monoecious Ficus in China

Fig trees (Ficus) are a species-rich group of mainly tropical and subtropical plants that are of ecological importance because of the large numbers of vertebrates that utilise their figs for food. Factors limiting their distributions to warmer regions are still poorly understood, but are likely to include factors linked to their specialised pollination biology, because each Ficus species is dependent on one or a small number of host-specific fig wasps (Agaonidae) for pollination. Adult fig wasps are short-lived, but some species are capable of dispersing extremely long distances to pollinate their hosts. Close to its northern range limit we investigated the phenology of Ficus virens, the monoecious fig tree that reaches furthest north in China. Relatively few trees produced any figs, and very few retained figs throughout the winter. Despite this, new crops produced in spring were pollinated, with seasonally migrant pollinators from plants growing further south the most likely pollen vectors. An inability to initiate new crops at low temperatures may limit the distribution of monoecious fig trees to warmer areas.     

Variation in inflorescence size in a dioecious fig tree and its consequences for the plant and its pollinator fig wasp

The host-specific relationship between fig trees (Ficus) and their pollinator wasps (Agaonidae) is a classic case of obligate mutualism. Pollinators reproduce within highly specialised inflorescences (figs) of fig trees that depend on the pollinator offspring for the dispersal of their pollen. About half of all fig trees are functionally dioecious, with separate male and female plants responsible for separate sexual functions. Pollen and the fig wasps that disperse it are produced within male figs, whereas female figs produce only seeds. Figs vary greatly in size between different species, with female flower numbers varying from tens to many thousands. Within species, the number of female flowers present in each fig is potentially a major determinant of the numbers of pollinator offspring and seeds produced. We recorded variation in female flower numbers within male and female figs of the dioecious Ficus montana growing under controlled conditions, and assessed the sources and consequences of inflorescence size variation for the reproductive success of the plants and their pollinator (Kradibia tentacularis). Female flower numbers varied greatly within and between plants, as did the reproductive success of the plants, and their pollinators. The numbers of pollinator offspring in male figs and seeds in female figs were positively correlated with female flower numbers, but the numbers of male flowers and a parasitoid of the pollinator were not. The significant variation in flower number among figs produced by different individuals growing under uniform conditions indicates that there is a genetic influence on inflorescence size and that this character may be subject to selection.     

Ecology of a fig ant–plant

Mutualistic interactions are embedded in networks of interactions that affect the benefits accruing to the mutualistic partners. Figs and their pollinating wasps are engaged in an obligate mutualism in which the fig is dependent on the fig pollinator for pollination services and the pollinator is dependent on fig ovules for brood sites. This mutualism is exploited by non-pollinating fig wasps that utilise the same ovules, but do not provide a pollination service. Most non-pollinating wasps oviposit from outside the inflorescence (syconium), where they are vulnerable to ant predation. Ficus schwarzii is exposed to high densities of non-pollinating wasps, but Philidris sp. ants patrolling the syconia prevent them from ovipositing. Philidris rarely catch wasps, but the fig encourages the patrolling by providing a reward through extra-floral nectaries on the surface of syconia. Moreover, the reward is apparently only produced during the phase when parasitoids are ovipositing. An ant-exclusion experiment demonstrated that, in the absence of ants, syconia were heavily attacked and many aborted as a consequence. Philidris was normally rare on the figs during the receptive phase or at the time of day when wasp offspring are emerging, so predation on pollinators was limited. However, Myrmicaria sp. ants, which only occurred on three trees, preyed substantially on pollinating as well as non-pollinating wasps. F. schwarzii occurs in small clusters of trees and has an exceptionally rapid crop turnover. These factors appear to promote high densities of non-pollinating wasps and, as a consequence, may have led to both a high incidence of ants on trees and increased selective pressure on fig traits that increase the payoffs of the fig–ant interaction for the fig. The fig receives no direct benefit from the reward it provides, but protects pollinating wasps that will disperse its pollen.     

Floral constraint resulting from intersexual mimicry in a gynodioecious fig tree

Fig trees (Ficus: Moraceae) are pollinated by female fig wasps (Agaonidae) whose larvae develop inside galled flowers of unusual inflorescences (figs). Most fig trees also support communities of non‐pollinating fig wasps. Figs of different species display great size variation and contain tens to tens of thousands of flowers. Around one‐half the species of fig trees have the gynodioecious breeding system, where female trees have figs that produce seeds and male trees have figs that support development of pollinators. Mutual mimicry between receptive male and female figs ensures that pollinators enter female figs, even though the insects will die without reproducing, but the need to give no sex‐specific cues to the pollinators may constrain differences in size between receptive male and female figs. We compared relationships between inflorescence size and some measures of reproductive success in male and female figs of Ficus montana grown under controlled conditions in the presence of the pollinator Kradibia tentacularis and its main parasitoid Sycoscapter sp. indesc. Female figs that contained more flowers produced more seeds, but male figs did not increase the production of female pollinator K. tentacularis fig wasps in proportion of the flower number. Although more flowers were galled by the pollinators in male figs containing more female flowers, the high larval mortality caused by parasitism and nutritional limitation prevented the increase in the production of adult female offspring. Selection may favor the increase in flower numbers within figs in female plants of F. montana, but contrarily constrain this attribute in male plants.     

A comparison of growth and reproduction, under laboratory conditions, of males and females of a dioecious fig tree

The interaction between Ficus spp. (Moraceae) and their pollinating wasps (Chalcidoidae: Agaonidae) is a highly co-evolved mutualism. Approximately half of all fig species are monoecious and produce a mixture of wasps and seeds within the same fig. In functionally dioecious fig trees male and female functions are separate. Figs on male trees produce wasps and pollen, whereas figs borne on female plants produce only seeds. Dioecious fig phenology provides an excellent opportunity to investigate the effect of sexual specialization on the obligate fig?Cfig wasp interaction and the non-pollinators associated with the system. Here we describe laboratory studies of phenological variation between two sexes in terms of vegetative growth and fig production in a dioecious fig tree Ficus montana. We also describe reproductive output in terms of wasp production in males and seeds in females. Intrasexual asynchrony was observed for the plants, with synchrony between the sexes with year-round production of figs. Male plants grew more rapidly, but leaf phenology was very similar. Crop sizes and development times were the same for males and females. Seasonal effects were strong for leaf phenology and fig initiation, but had a very limited effect on fig composition. The results show that the phenological differences described for other dioecious figs do not apply to all species.     

影响对叶榕及其传粉者繁殖的生态学因素

在西双版纳,分别统计了对叶榕(Ficus hispida)雌花期雌雄果的进蜂量和花后期雌雄果繁殖的多个特征值,以此来探讨自然条件下,影响对叶榕及其传粉榕小蜂(Ceratosolen solmsi marchali)繁殖的因素。结果表明:单果内有效进蜂数量是影响种子生产和传粉榕小蜂繁殖的首要因素,而雌花期进果的传粉榕小蜂并不是都能全部进入果腔传粉或产卵,大部分蜂还未进到果腔就被夹死在顶生苞片层的通道里,能进入雌果内传粉的榕小蜂为(2.72±2.04)只·果^-1,约占总进蜂量的52%;而在雄果里,能进入果腔的蜂量只有(2.08±1.65)只·果^-1,占35%左右。由于雌果内的雌花显著比雄果内的雌花多,结合单果进蜂量雌多雄少的格局,最终单果生产的种子数量 (1 891.63 ± 471.53)比传粉榕小蜂的数量 (367.20 ± 208.02) 多5倍有余。在雌果里,供给传粉的雌花数量与所生产的种子数量之间呈显著的正相关,而没有接受到花粉或不能正常受精的雌花数量与种子数量呈显著的负相关。雄果不仅生产花粉,也是传粉榕小蜂繁殖的场所,在相关于传粉榕小蜂自身繁殖力的因子中,传粉榕小蜂产卵制造的瘿花数量对其种群数量有最大的影响;影响次之的是发育过程中死亡的个体数量,它可降低30%左右的传粉榕小蜂数量;影响排在第三位的是寄主的雌花数量。此外,3类非传粉者的存在,单果内平均可减少30多只传粉小蜂。     

THE STABILITY OF THE SYMBIOSIS BETWEEN DIOECIOUS FIGS AND THEIR POLLINATORS: A STUDY OF FICUS CARICA L. AND BLASTOPHAGA PSENES L.

Each Ficus species depends on a specific mutualistic wasp for pollination. The wasp breeds on the fig, each larva destroying a female flower. It is, however, not known why the wasps have not evolved the ability to use all female flowers. In “dioecious” figs, the wasp can only breed in the female flowers of the “male” trees, so that pollination of a female tree is always lethal. The wasps should therefore be selected to avoid female trees. Field data is presented showing that the fruiting phenology of the dioecious fig Ficus carica is such that this selection does not occur: syconia are not receptive at the same time on “male” and female trees. Most wasps are forced to emerge from the syconia of “male” trees at a time when they will not be able to reproduce, whether they avoid female trees or not. This aspect of the life cycle of the wasp, although noticed, has been obscured in most previous studies. It is shown that the fruiting phenology of Ficus carica, which stabilizes the symbiosis, is the result of short-term selective pressures on the male function of the trees. Such selective pressures suggest a possible pathway from monoecy to dioecy in Ficus under seasonal climates.     

Phenology of a common roadside fig in Sarawak

The phenology of a dioecious fig (Ficus fulva, Reinw. ex Bl.; 25 female, 26 male trees) was studied at Lambir Hills National Park, Sarawak. Dioecious fig phenology provides an excellent opportunity to investigate the influence of climate and sexual specialization on the obligate fig–fig pollinator/ovule parasite interaction. Leaf phenology was strongly correlated between sexes. Trees dropped leaves during drought and initiated new leaf growth after the renewal of rain. Before the production of large crops of syconia, trees shed their leaves and then new leaves and syconia were initiated together. Syconia were produced in synchronous crops with asynchrony between trees maintaining a relatively even production of syconia within the tree group. Syconia abortion on male but not female trees, was negatively correlated with the proportion of trees with male phase syconia. A severe drought in early 1998 significantly disrupted the phenology thereafter. The duration of crop development was approximately twice as long on female trees as on males, and total syconia production was much higher on male trees. Plots of syconia diameter versus dry weight suggest sexual specialization in the investment profile during crop development. Male trees also sometimes produced a small crop of syconia immediately before a large crop, probably to supply wasps for the main crop. Sexes had different growth strategies with male trees growing more as small individuals and slightly delaying reproduction. Diameter at breast height was significantly correlated with total syconia production in male trees but not in females. Syconia production was best predicted by canopy width.     

Measuring the discrepancy between fecundity and lifetime reproductive success in a pollinating fig wasp

Lifetime reproductive success in female insects is often egg‐ or time‐limited. For instance in pro‐ovigenic species, when oviposition sites are abundant, females may quickly become devoid of eggs. Conversely, in the absence of suitable oviposition sites, females may die before laying all of their eggs. In pollinating fig wasps (Hymenoptera: Agaonidae), each species has an obligate mutualism with its host fig tree species [Ficus spp. (Moraceae)]. These pro‐ovigenic wasps oviposit in individual ovaries within the inflorescences of monoecious Ficus (syconia, or ‘figs’), which contain many flowers. Each female flower can thus become a seed or be converted into a wasp gall. The mystery is that the wasps never oviposit in all fig ovaries, even when a fig contains enough wasp females with enough eggs to do so. The failure of all wasps to translate all of their eggs into offspring clearly contributes to mutualism persistence, but the underlying causal mechanisms are unclear. We found in an undescribed Brazilian Pegoscapus wasp population that the lifetime reproductive success of lone foundresses was relatively unaffected by constraints on oviposition. The number of offspring produced by lone foundresses experimentally introduced into receptive figs was generally lower than the numbers of eggs carried, despite the fact that the wasps were able to lay all or most of their eggs. Because we excluded any effects of intraspecific competitors and parasitic non‐pollinating wasps, our data suggest that some pollinators produce few offspring because some of their eggs or larvae are unviable or are victims of plant defences.     

Moths boring into Ficus syconia on Iriomote Island, south-western Japan

Herbivory in the syconia of six Ficus (Moraceae) species (F. superba, F. varieagata, F. virgata, F. irisana, F. bengutensis and F. septica) was examined in March 2002 on Iriomote Island, south‐western Japan. Larvae of two lepidopteran species, Pachybotys spissalis (Guenée) (Pyralidae: Pyraustinae) and Stathmopoda sp. (Stathmopodidae) were observed to bore into the Ficus syconia. The attack rate by the moths varied from 0 to 38.5% across Ficus trees. The interiors of the syconia were heavily grazed by the moth larvae. Because figs (syconia) can be regarded as galls and seeds, according to sex and developmental stage, the moth larvae could be considered as gall or seed herbivores, and predators of fig wasps. Moth attack in the Ficus syconia could cause the destruction of fig wasp populations, as fig wasps develop in the syconia.     

Ecological factors associated with pre-dispersal predation of fig seeds and wasps by fig-specialist lepidopteran larvae

In brood pollination mutualisms, predation of developing fruit can have large negative repercussions for both plant and pollinator population dynamics. The Sonoran Desert rock fig Ficus petiolaris and its highly-coevolved wasp pollinator are subject to frequent attack by lepidopteran larvae that consume fig fruit and the developing seeds and larval pollinators they contain. We used generalized linear mixed models to investigate how the phenology, quantity, and spatial distribution of fig fruits is associated with variation in lepidopteran damage intensity on individual trees at nine geographic locations spanning a 741 km latitudinal transect along Mexico's Baja California Peninsula. We found lepidopteran damage to be strongly positively associated with more synchronous fig crops and larger trees, and only weakly associated with lower local host tree density. These results imply that fruit production that is asynchronous within trees and spread out over time, as observed in several fig species, benefits female and male components of fitness (pollen disperser and seed production, respectively) by reducing pre-dispersal predation by frugivores.     

西双版纳热带雨林对叶榕传粉生物学(英)

研究了西双版纳热带雨林地区雌雄异株植物对叶榕 (FicushispidaL .)的生物学、传粉物候学以及榕小蜂(CeratosolensolmsimarchaliMayr)的传粉和繁殖行为。研究结果表明 :雌雄异株的对叶榕与其他雌雄同株的榕属植物不同 ,它的种子形成与传粉者有着更为复杂的相互关系。对叶榕一年结隐花果 6～ 8次 ,结果高峰期 4～ 5次 ,其中雄性植株仅产生花粉和孕育榕小蜂 ,而雌性植株 (无雄蕊 )则需榕小蜂带花粉进入隐花果内 ,进行传粉授精 ,使之发育成种子。对叶榕的成熟花粉不能从花药开裂处自行散发出来 ,必须由榕小蜂采集才能散落。榕小蜂雌蜂羽化、交配后 ,找到雄花区 ,用足、触角、口器在推动中采集花粉。雌蜂飞出熟榕果找寻雌株或雄株榕树上的幼嫩隐花果 ,一般需 3～ 6 7min ;一部分雌蜂在雄株中寻找幼嫩的隐花果 ,进去产卵繁殖 ,另一部分雌蜂则寻找雌株雌花期嫩隐花果进去传粉。雌蜂在雌株榕树的隐花果内传粉时间为 15～ 2 3h ,在雄株榕树的隐花果内产卵时间为 6～ 9h。对叶榕小蜂在雌株上进入单个隐花果的数量多少关系到雌花结实率 ;观察表明 ,每个隐花果最佳进蜂数为 2头 ;榕小蜂传粉后榕树成熟种子形成率在 5 4 .1%～ 82 .5 %之间 ,平均为 73.8% ;而在雄株上雌蜂进蜂数量则关系到榕小蜂在隐花果内的产卵率 ,