Nesting and biology of Jucancistrocerus caspicus (hymenoptera,vespidae, eumeninae)

Females of Jucancistrocerus caspicus nest in dense clay ground on the vertical surface of cliffs. The nests contain 1–9 cells (on average 2.8) and have a linear-branched construction. Females surmount the entrance of the burrow with a curved chimney which has a laced structure. The cells are positioned vertically in the main burrow and obliquely or horizontally in the lateral tunnels; the cells in a row are separated with double partitions. The size of the cells is 7–9 × 4–4.5 mm, the diameter of the nest burrow is 4 mm. The egg is laid before provisioning and is attached to the cell ceiling with a filament. Females hunt for weevil larvae and store 23–33 larvae (on average 27.8) in each cell. The species is univoltine, with prepupae hibernating in their cocoons. The nests are parasitized by the cuckoo wasps Chrysis rutilans which cause 11.5% of brood mortality. Adult wasps are killed by the spiders Pholcus sp. living near the nests.     

海切叶蜂的筑巢和访花行为

【目的】研究毛乌素沙地重要野生传粉昆虫海切叶蜂Megachile maritima的筑巢和访花行为对保护其栖息环境具有重要意义。【方法】采用目测及拍照等方法对海切叶蜂的整个筑巢过程进行了连续观测;以2 m×2 m 样方的方式观测海切叶蜂的访花频率、单花停留时间及日活动规律等访花行为,其中日活动规律每天连续观测,共观测7天。【结果】海切叶蜂在沙土中筑巢,每巢只有一个巢室,其筑巢过程为：寻找合适的筑巢地点,挖巢,构建巢室,采集蜂粮,产卵,封住巢室,筑完一个巢。它连续筑完一个巢大约需要9 h。海切叶蜂构建一个巢室需要切取26～29片叶子,为每巢室采集蜂粮11～12次,每巢室内产卵1粒;在塔落岩黄芪和细叶益母草上的平均访花频率分别为（13.23±6.49）朵/min和（16.72±4.84）朵/min,平均单花停留时间分别为（3.08±2.48）s和（2.49±1.31）s。晴天,海切叶蜂在12:00～14:00期间活动较活跃。【结论】海切叶蜂不同个体之间的筑巢行为相似。该蜂在塔落岩黄芪和细叶益母草上的访花过程、访花频率及单花停留时间具有显著的差异。     

Competition between the oligolectic beePtilothrix plumata (Anthophoridae) and the flower closing beetlePristimerus calcaratus (Curculionidae) for floral resources ofPavonia cancellata (Malvaceae)

The flowers ofPavonia cancellata, a creeping ruderal half-shrub of northeastern Brazil, open synchronously at 6:00 h with all anthers already dehisced. The oligolectic beePtilothrix plumata was the most effective pollinator. During 90—180 min, female bees make up to 40 brief pollen collection trips to provision their brood cells. The pollen of about 40 flowers ofP. cancellata is needed to feed one bee larva. The most frequent flower visitors, however, are the specialized curculionid beetlesPristimerus calcaratus, which do not crosspollinate the flowers. They perforate the epidermis with their mouthparts, provoking dehydration, and then actively close the loose petals with their legs. Two hours after opening, half of the flowers had already been closed by the beetles. We interpret the fast, uninterrupted pollen foraging ofPtilothrix plumata bees as a strategy adapted to synchronous pollen presentation ofPavonia and to competition withPristimerus calcaratus: the female bees have to provision their brood cells before the beetles succeed in closing the flowers.     

Effectiveness of nectarivorous birds and honeybees as pollinators of Banksia spinulosa (Proteaceae)

Abstract The effectiveness of nectarivorous birds and honeybees (Apis mellifera) as pollinators of Banksia spinulosa (Proteaceae) was investigated. Birds visited inflorescences in the early, mid and late flowering seasons. In contrast, honeybees visited only on days in the late flowering period when maximum temperatures exceeded 15°C. Self pollen remained on pollen presenters of flowers for up to 5 days in the early and mid periods. In the late period, when honeybees visited inflorescences, self pollen was removed within 2 days. Pollen removal was similar for caged (birds excluded) and open inflorescences in the late period, indicating that most pollen was removed by honeybees. In the early and mid periods, honeyeaters pollinated 22% and 27% of flowers on open inflorescences, respectively. In the late period, when both birds and bees visited inflorescences, 64–73% of flowers on open inflorescences were pollinated. Foraging by honeybees resulted in pollen deposition as 38% of flowers on caged inflorescences were pollinated. Throughout the flowering season a similar number of pollen grains was deposited per stigma. There were 3.0–3.7 pollen grains per stigma on open inflorescences in the late period, although only 2.0 grains per stigma on caged inflorescences. In the early and mid periods, fewer caged than open inflorescences produced fruits, indicating the importance of honeyeaters to reproductive success at these times. In contrast, in the late period when honeybees visited inflorescences, fruit-set was similar on caged and open inflorescences. Overall, these results indicate that honeybees were effective pollinators of B. spinulosa.     

The Bizarre Inflorescence of Norantea brasiliensis (Marcgraviaceae): Visits of Hovering and Perching Birds1

The pollination biology of Norantea brasiliensis (Marcgraviaceae) was studied in the rain forest of southeastern Brazil. This plant presents bizarre, brush-type racemous inflorescences bearing numerous flowers and extrafloral cup-shaped nectaries. Flower anthesis is diurnal, nectar production is continuous and copious, and the sticky pollen is readily removed by visitors during the first morning hours. The ruby-coloured inflorescences were visited by eight species of hummingbirds (Trochilidae), and 10 species of passerine birds (three Coerebidae and seven Thraupidae). Hummingbirds hovered while probing for nectar and touched flowers occasionally, whereas passerine birds perched and made contact with flowers habitually. Due to differences in flower-visiting and general foraging behaviour, perching birds act as better pollen vectors than hovering birds. The inflorescence of Norantea brasiliensis seems well fitted for pollination by passerine birds, and the hexose-dominated nectar supports this idea. Pollination syndrome trends within Marcgraviaceae may stem from insect-pollinated, condensed and spike-like inflorescences which would give rise to bird-pollinated, brush-type inflorescences. From the same basic condensed inflorescence, bat-pollinated umbelliform inflorescence may be derived from bird-pollinated, pendulous and corymb-like inflorescences. These postulated inflorescence types are found among the extant species of Marcgraviaceae.     

A ballistic pollen dispersal system influences pollination success and fruit‐set pattern in pollinator‐excluded environments for the endangered species Synaphea stenoloba (Proteaceae)

The critically endangered Synaphea stenoloba (Proteaceae) has numerous scentless flowers clustered in dense inflorescences and deploys a ballistic pollen ejection mechanism to release pollen. We examined the hypothesis that active pollen ejection and flowering patterns within an inflorescence influence the reproductive success (i.e. fruit formation) of individual flowers within or among inflorescences of S. stenoloba in a pollinator‐excluded environment. Our results showed that: (1) no pollen grains were observed deposited on the stigma of their own flower after the pollen ejection system was manually activated, indicating self‐pollination within an individual flower is improbable in S. stenoloba; (2) fruit set in the indoor open pollination treatment and the inflorescence‐closed pollination treatment indicated that S. stenoloba is self‐compatible and pollen ejection can potentially result in inter‐floral pollination success; (3) fruit set in the inflorescence‐closed pollination treatment was significantly lower than that of indoor open pollination, indicating within‐ and between‐flower pollination events in an inflorescence are most likely limited, with pollination between inflorescences providing the highest reproductive opportunity; and (4) analysis of the spatial distribution of cumulative fruit set on inflorescences showed that pollen could reach any flower within an inflorescence and there was no functional limitation on seed set among flowers located at various positions within the inflorescence. These data suggest that the pollen ejection mechanism in S. stenoloba can enhance inter‐plant pollination in pollinator‐excluded environments and may suggest adaptation to pollinator scarcity attributable to habitat disturbance or competition for pollinators in a diverse flora. © 2012 The Linnean Society of London, Botanical Journal of the Linnean Society, 2012, 170 , 59–68.     

Flower choice by honey bees (Apis mellifera L.): sex-phase of flowers and preferences among nectar and pollen foragers

Bees foraging for nectar should choose different inflorescences from those foraging for both pollen and nectar, if inflorescences consist of differing proportions of male and female flowers, particularly if the sex phases of the flowers differ in nectar content as well as the occurrence of pollen. This study tested this prediction using worker honey bees (Apis mellifera L.) foraging on inflorescences of Lavandula stoechas. Female flowers contained about twice the volume of nectar of male flowers. As one would predict, bees foraging for nectar only chose inflorescences with disproportionately more female flowers: time spent on the inflorescence was correlated with the number of female flowers, but not with the number of male flowers. Inflorescence size was inversely correlated with the number of female flowers, and could be used as a morphological cue by these bees. Also as predicted, workers foraging for both pollen and nectar chose inflorescences with relatively greater numbers of both male and female flowers: time spent on these inflorescences was correlated with the number of male flowers, but not with the number of females flowers. A morphological cue inversely associated with such inflorescences is the size of the bract display. Choice of flowers within inflorescences was also influenced predictably, but preferences appeared to be based upon corolla size rather than directly on sex phase.     

Neither insects nor wind: ambophily in dioecious Chamaedorea palms (Arecaceae)

Pollination of Neotropical dioecious trees is commonly related to generalist insects. Similar data for non‐tree species with separated genders are inconclusive. Recent studies on pollination of dioecious Chamaedorea palms (Arecaceae) suggest that species are either insect‐ or wind‐pollinated. However, the wide variety of inflorescence and floral attributes within the genus suggests mixed pollination mode involving entomophily and anemophily. To evaluate this hypothesis, we studied the pollination of Chamaedorea costaricana, C. macrospadix, C. pinnatifrons and C. tepejilote in two montane forests in Costa Rica. A complementary morphological analysis of floral traits was carried out to distinguish species groups within the genus according to their most probable pollination mechanism. We conducted pollinator exclusion experiments, field observations on visitors to pistillate and staminate inflorescences, and trapped airborne pollen. A cluster analysis using 18 floral traits selected for their association with wind and insect pollination syndromes was carried out using 52 Chamaedorea species. Exclusion experiments showed that both wind and insects, mostly thrips (Thysanoptera), pollinated the studied species. Thrips used staminate inflorescences as brood sites and pollinated pistillate flowers by deception. Insects caught on pistillate inflorescences transported pollen, while traps proved that pollen is wind‐borne. Our empirical findings clearly suggest that pollination of dioecious Chamaedorea palms is likely to involve both insects and wind. A cluster analysis showed that the majority of studied species have a combination of floral traits that allow for both pollination modes. Our pollination experiments and morphological analysis both suggest that while some species may be completely entomophilous or anemophilous, ambophily might be a common condition within Chamaedorea. Our results propose a higher diversity of pollination mechanisms of Neotropical dioecious species than previously suggested.     

Nest Enlargement in Leaf-Cutting Ants: Relocated Brood and Fungus Trigger the Excavation of New Chambers

During colony growth, leaf-cutting ants enlarge their nests by excavating tunnels and chambers housing their fungus gardens and brood. Workers are expected to excavate new nest chambers at locations across the soil profile that offer suitable environmental conditions for brood and fungus rearing. It is an open question whether new chambers are excavated in advance, or will emerge around brood or fungus initially relocated to a suitable site in a previously-excavated tunnel. In the laboratory, we investigated the mechanisms underlying the excavation of new nest chambers in the leaf-cutting ant Acromyrmex lundi. Specifically, we asked whether workers relocate brood and fungus to suitable nest locations, and to what extent the relocated items trigger the excavation of a nest chamber and influence its shape. When brood and fungus were exposed to unfavorable environmental conditions, either low temperatures or low humidity, both were relocated, but ants clearly preferred to relocate the brood first. Workers relocated fungus to places containing brood, demonstrating that subsequent fungus relocation spatially follows the brood deposition. In addition, more ants aggregated at sites containing brood. When presented with a choice between two otherwise identical digging sites, but one containing brood, ants'' excavation activity was higher at this site, and the shape of the excavated cavity was more rounded and chamber-like. The presence of fungus also led to the excavation of rounder shapes, with higher excavation activity at the site that also contained brood. We argue that during colony growth, workers preferentially relocate brood to suitable locations along a tunnel, and that relocated brood spatially guides fungus relocation and leads to increased digging activity around them. We suggest that nest chambers are not excavated in advance, but emerge through a self-organized process resulting from the aggregation of workers and their density-dependent digging behavior around the relocated brood and fungus.     

Pollination and seed production in Xerophyllum tenax (Melanthiaceae) in the Cascade Range of central Oregon

Xerophyllum tenax is a mass-flowering, nectarless herb in which self-pollination is unavoidable as anthers shed pollen onto the three, receptive stigmatic ridges attached to each pistil within a few hours after expansion of the perianth. We compared the pollination system with reproductive success in this species through controlled, hand-pollination experiments. Ovaries of flowers sampled from unbagged inflorescences were visited by pollen-eating flies (primarily members of the family Syrphidae), beetles (primarily Cosmosalia and Epicauta spp.), and small bees, and produced normal-sized capsules and mature seeds. Ovaries of flowers from inflorescences bagged to prevent insect pollination produced small capsules containing undeveloped or no seeds. Epifluorescence analyses suggest that 0.95 of the uncovered flowers are cross-pollinated by insects with pollen tubes penetrating style and ovary tissue. Flowers show a "leaky" but early-acting self-incompatibility system. While hundreds of pollen tubes germinate on each stigmatic surface following self-pollination, few pollen tubes penetrate the stigmatic surface and none penetrate the ovary. In contrast, when stigmas are cross-pollinated by hand with pollen from a second inflorescence pollen tubes were seen penetrating style and ovary. Self-incompatibility in X. tenax parallels that of some species of Trillium, a sister genus within the Melanthiaceae.     

Visitation rate of pollinators and nectar robbers to the flowers and inflorescences of Tabebuia aurea (Bignoniaceae): effects of floral display size and habitat fragmentation

Large floral displays favour pollinator attraction and the import and export of pollen. However, large floral displays also have negative effects, such as increased geitonogamy, pollen discounting and nectar/pollen robber attraction. The size of the floral display can be measured at different scales (e.g. the flower, inflorescence or entire plant) and variations in one of these scales may affect the behaviour of flower visitors in different ways. Moreover, the fragmentation of natural forests may affect flower visitation rates and flower visitor behaviour. In the present study, video recordings of the inflorescences of a tree species (Tabebuia aurea) from the tropical savannah of central Brazil were used to examine the effect of floral display size at the inflorescence and tree scales on the visitation rate of pollinators and nectar robbers to the inflorescence, the number of flowers approached per visit, the number of visits per flower of potential pollinators and nectar robbers, and the interaction of these variables with the degree of landscape disturbance. Nectar production was quantified with respect to flower age. Although large bees are responsible for most of the pollination, a great diversity of flower insects visit the inflorescences of T. aurea. Other bee and hummingbird species are highly active nectar robbers. Increases in inflorescence size increase the visitation rate of pollinators to inflorescences, whereas increases in the number of inflorescences on the tree decrease visitation rates to inflorescences and flowers. This effect has been strongly correlated with urban environments in which trees with the largest floral displays are observed. Pollinating bees (and nectar robbers) visit few flowers per inflorescence and concentrate visits to a fraction of available flowers, generating an overdispersed distribution of the number of visits per inflorescence and per flower. This behaviour reflects preferential visits to young flowers (including flower buds) with a greater nectar supply.     

The pollination ecology of Actaea spicata (Ranunculaceae)

Pollination ecology of Actaea spicata L. (Ranunculaceae) was studied at localities ranging from deciduous to spruce forest. The species is self–incompatible and possibly facultatively apomictic. No anemogamy seems to occur. In deciduous forest, the plant is primarily pollinated by pollen–foraging and mate–searching Byturus ochraceus (Scriba) (Coleoptera). It flowers during a period between emergence of the beetle and onset of anthesis of the prime pollen source and only larval host plant, Geum ur–banum L. (Rosaceae). The beetles sit on the suitably long anther filaments or on top of the stigma. Floral morphology promotes pollination–performing movements by the beetle. The complex floral fragrance seems to induce close–range behaviour, i.e. alighting and/or foraging. Flies become abundant visitors only shortly before anthesis is over, and their contribution is small. Large syrphids are relatively effective as pollinators, since they grasp the stamens near the base and often touch the stigma with pollen–dusted parts of their bodies. Due to lack of its food–plant, B. ochraceus is absent at spruce forest localities and northwards. At these localities flowering is delayed until the main fly appearance, and the flowers are heavily pollinated by several syrphids and muscids. At three deciduous–forest localities a second flowering took place with new, juxtaposed inflorescences on separate stalks. The distribution of such inflorescences within the population along with the distribution and abundance of pollinators among the two generations of flowers suggest that these inflorescences occur as a response to low rate of pollination in the first anthesis.     

Pollen viability reduction as a potential cost of ant association for Acacia constricta (Fabaceae)

Field studies investigating the impact of ants on the reproduction of plants bearing extrafloral nectaries have traditionally focused on seed production, a component of female fitness. The purpose of this study was to test whether ants can affect the pollen viability, a component of male fitness, when they visit flowers of the shrub Acacia constricta. Acacia constricta inflorescences hand-pollinated with flowers over which Formica perpilosa ants had crawled set significantly fewer seed pods than inflorescences hand-pollinated by control flowers that had no contact with ants. Many ant species secrete antibiotic substances onto the integument that render pollen inviable, and these secretions are probably the mechanism for reduced pollen viability in this study. The ratio of seed pods produced by self-pollinated inflorescences to those produced by cross-pollinated inflorescences was 0.16, indicating that A. constricta is largely self-incompatible. Because F. perpilosa workers forage primarily on the acacia tree under which they nest, they are unlikely to serve as efficient vectors of outcrossing. Previous work showed that A. constricta shrubs with F. perpilosa ants produce approximately twice as many seeds as similarly sized plants not so associated. The results indicate that association with F. perpilosa could cause a reproductive trade-off for A. constricta: benefits to female function may be accompanied by costs to male function. Selection to discourage ant visitation to flowers may have affected the pollination biology of this and other ant-associated plant species.     

The earliest fossil evidence of the Hamamelidaceae: Late Cretaceous (Turonian) inflorescences and fruits of Altingioideae

Fossilized pistillate inflorescences, fruits, and pollen grains from the Turonian (～90 million years before present) of New Jersey are described as a new genus, Microaltingia, in the family Hamamelidaceae. The fossils are remarkably preserved in exceptional detail. Several morphological and anatomical characters suggest affinities with Hamamelidaceae. These include capitate inflorescences, florets with a hypanthium, two-carpellate gynoecia, perigynous flowers, tricolpate reticulate pollen, a three-layered carpel wall, scalariform perforation plates with oblique end walls, and scalariform and opposite/alternate intervascular pitting. The gross morphology of pistillate inflorescences, unisexual flowers, phyllome structure, numerous ovules per carpel, and mode of carpel dehiscence indicate affinities with subfamily Altingioideae, which includes the modern genera Liquidambar and Altingia. Cladistic analysis using a previously published morphological matrix and scoring the fossil for available characters supports the position of the fossil as a sister taxon of modern Altingioideae. Although the fossil exhibits a mosaic of characters found within modern Hamamelidaceae, it is not identical to any modern taxon. Based on cladistic analysis, the fossil appears to be a basal "altingioid" that lacks the derived pollen found in extant Altingioideae and retains the more plesiomorphic tricolpate pollen found in the rest of Hamamelidaceae. The floral characters of the fossils, including phyllomes with stomata, short and straight styles, and small perprolate pollen grains, also indicate the possibility of insect pollination.     

Hierarchical patterns of paternity within crowns of Albizia julibrissin (Fabaceae)

The floral architecture and phenology of the tree species Albizia julibrissin (Fabaceae) offer the potential for flowers within inflorescences to share common pollen donors. Patterns of paternity within individual tree crowns may differ among isolated individuals and those in populations due to differences in pollinator foraging behavior. To determine how genetic diversity is partitioned within individual seed pools and whether these patterns differ among isolated and population trees, we obtained all fruits from three inflorescences from four clusters from three isolated trees and from three population trees in Athens, Georgia. We assayed 14 polymorphic allozymes to genotype all progeny within singly sired fruits to determine the multilocus genotype of each fruit's pollen donor. Inflorescences had multiple pollen donors, but simulation analyses revealed that redundancy of pollen donors tended to be more likely within inflorescences than randomly across the crown. Analysis of genetic and genotypic diversity indicated that individual maternal trees received pollen from many donors in uneven frequencies. Results suggest that isolated trees receive pollen from slightly fewer pollen donors and experience more within-plant pollinator movement than trees in populations. However, isolated trees receive qualitatively similar pollen from many sources, suggesting that these trees are not effectively isolated and that pollen moves long distances in this species.     

An analysis of the nesting behaviour of Geotrupes spiniger Marsham (Coleoptera, Scarabaeidae)

Abstract. 1. Female G.spiniger adults working alone made nests each consisting of a vertical shaft leading to a series of horizontal brood chambers filled with dung brood masses. Oviposition near the tip of the brood mass occurred while the egg cell was being completed over the expanded ovipositor. The shaft above each brood mass was filled with soil excavated from the next brood chamber. A similar response also filled artificial diverticula. An avoidance reaction towards buried dung prevented damage to pre-existing brood masses. 2. Virgin females did not make nests and did not avoid buried dung, but after mating (at about 4 weeks after eclosion) both types of behaviour were released within a few hours. 3. The presence of dung was required to initiate but not to maintain nesting behaviour. If dung was removed after oviposition the chamber was filled with soil produced by renewed excavation. Cellulose pulp could substitute for dung in brood mass formation. 4. Beetles interchanged between burrows at different stages before oviposition readily repeated all pre-oviposition behaviour. They appeared to respond to the length of the shaft and of the brood chamber since they extended short shafts and short brood chambers considerably more than those of normal length. After oviposition the beetles continued to make brood masses even under abnormal conditions. 5. Tilting the cage through 90° caused beetles before oviposition to re-orientate their burrowing direction, but tilting just after oviposition caused them to make vertical brood masses. Placing the shaft in a horizontal position towards the end of brood mass formation postponed the termination of this phase. 6. Beetles repeatedly excavated shafts and chambers when transferred to new cages. Conversely they repeatedly made brood masses when maintained in preformed plaster-of-Paris burrows. 7. This nesting behaviour can be described as a reaction chain in which each action generates its own terminating stimulus and initiates the subsequent response. The behaviour before oviposition could be omitted or repeated as required by the environment, but after oviposition there was little response to external interference. These characteristics have direct relevance to the survival of the larvae.     

Lasioglossum (Dialictus) tenax (Sandhouse) (Hymenoptera: Halictidae) as a solitary sweat bee

Summary Nine nests ofLasioglossum (Dialictus) tenax were excavated near Calgary, Alberta, Canada over a time period encompassing the entire brood production period in 1988. Each nest contained a maximum of one active adult female, nest productivity peaked in mid July, protandry was noted and no significant size difference between foundresses and the earlier emerging females was detected. These data suggest that this species is solitary. These results are compared with data for the sympatrically nesting eusocial speciesL. (D.) laevissimum.     

Change of Floral Orientation within an Inflorescence Affects Pollinator Behavior and Pollination Efficiency in a Bee-Pollinated Plant,Corydalis sheareri

Vertical raceme or spike inflorescences that are bee-pollinated tend to present their flowers horizontally. Horizontal presentation of flowers is hypothesized to enhance pollinator recognition and pollination precision, and it may also ensure greater consistency of pollinator movement on inflorescences. We tested the hypotheses using bee-pollinated Corydalis sheareri which has erect inflorescences consisting of flowers with horizontal orientation. We altered the orientation of individual flowers and prepared three types of inflorescences: (i) unmanipulated inflorescences with horizontal-facing flowers, (ii) inflorescences with flowers turned upward, and (iii) inflorescences with flowers turned downward. We compared number of inflorescences approached and visited, number of successive probes within an inflorescence, the direction percentage of vertical movement on inflorescences, efficiency of pollen removal and seed production per inflorescence. Deviation from horizontal orientation decreased both approaches and visits by leafcutter bees and bumble bees to inflorescences. Changes in floral orientation increased the proportion of downward movements by leafcutter bees and decreased the consistency of pollinator movement on inflorescences. In addition, pollen removal per visit and seed production per inflorescence also declined with changes of floral orientation. In conclusion, floral orientation seems more or less optimal as regards bee behavior and pollen transfer for Corydalis sheareri. A horizontal orientation may be under selection of pollinators and co-adapt with other aspects of the inflorescence and floral traits.     

Relationship between floral longevity and sex allocation among flowers within inflorescences in Aquilegia buergeriana var. oxysepala (Ranunculaceae)

Understanding the fitness of plants with inflorescences requires examining variation in sex allocation among flowers within inflorescences. We examined whether differences in the duration of the male and female phases of flowering lead to variation in sex allocation and reproductive success among flowers within inflorescences. In 2002 and 2003, we quantified floral longevity, floral sex allocation, and reproductive success between the first and the second flowers within inflorescences in a protandrous species, Aquilegia buergeriana var. oxysepala. Floral longevity was greater in the first flowers than in the second ones in both years. The male phase lasted longer, and the initial number of pollen grains and the number of pollen grains removed were greater in the first flowers than in the second ones in both years. Within first flowers, the number of pollen grains removed was greater in flowers that had longer male phases, thus duration of the male phase may positively affect male reproductive success in the first flowers. The female phase lasted longer and the number of ovules was greater in the first flowers than in the second only in 2002. However, seed production per flower and female phase duration in both years were not significantly related. The variation in the number of pollen grains among flowers in this species may be caused by the variation in male phase duration.     

沙地毛足蜂筑巢生物学研究

【目的】调查毛乌素沙地的一种群居独栖性野生毛足蜂Dasypoda hirtipes Panzer的巢穴结构及其日活动规律。【方法】采用目测和拍照等方法对沙地毛足蜂的整个筑巢过程进行了连续观测;采用挖掘、测量方法对毛足蜂巢内结构进行了观测。【结果】2008和2009年共挖掘巢穴22个,巢口直径为6.32～10.35 mm,巢穴具有多分枝的支道,一般有4～16个分支道,主道的深度为84～112 cm,巢室分布在主道周围的支道里面,每个支道里面仅有1个巢室,巢室深度为22～54 cm。巢室内壁无蜡层,较光滑,巢室内的花粉球底部有3个均匀大小的用来支撑花粉球的突起。对雌性成蜂日活动行为的观察结果显示,雌性个体一天内采集粉蜜的次数在6～8次,最后一次一般不携带花粉归巢。【结论】在内蒙古毛乌素沙地,该蜂一年1代,日活动时间与菊科植物抱茎苦荬菜Ixeris sonchifolia花序中的单花期相对应,主要的蜜源植物为菊科植物和蒺藜属植物。