Pollination and seed set of an obligatory outcrossing plant in an urban–peri-urban gradient

Urban land use strongly affects pollinators and plant pollination due to fragmentation and isolation of natural plant populations. On the other hand, urban land use can potentially be beneficial to pollinators through the presence of urban gardens and parks which are usually designed to ensure abundant flowering. However, little is known about the effects of urban land use on bees and the pollination services they provide. In an urban–peri-urban gradient around Leuven, Belgium we studied flower visitation rates to, and seed set of Trifolium repens (white clover) in public lawns. T. repens is an obligatory outcrossing plant and is therefore sensitive to reductions in pollinator services. We related our results to both local and regional variables using Boosted Regression Trees. The two variables that best explained the variability in visitation rates and seed set were the amount of green areas (gardens, parks, grasslands) in the surroundings and the abundance of T. repens in the lawns. Surprisingly, an increasing amount of green areas in the surroundings had a negative effect on both flower visitation rates to, and seed set of T. repens. Flower visitation rates by bumblebees responded positively to urban land use resulting in higher visitation rates and increased seed set in the more urban sites. This may point either to increased abundance of bumblebees in more urban sites or to a concentration effect of bumblebees in our urban study sites due to a lack of alternative forage resources. Responses will likely differ for other bee and plant species, but this shows that at least for T. repens, pollination is not compromised by urban land use.     

Visual ecology of Indian carpenter bees II: adaptations of eyes and ocelli to nocturnal and diurnal lifestyles

Most bees are diurnal, with behaviour that is largely visually mediated, but several groups have made evolutionary shifts to nocturnality, despite having apposition compound eyes unsuited to vision in dim light. We compared the anatomy and optics of the apposition eyes and the ocelli of the nocturnal carpenter bee, Xylocopa tranquebarica, with two sympatric species, the strictly diurnal X. leucothorax and the occasionally crepuscular X. tenuiscapa. The ocelli of the nocturnal X. tranquebarica are unusually large (diameter ca. 1 mm) and poorly focussed. Moreover, their apposition eyes show specific visual adaptations for vision in dim light, including large size, large facets and very wide rhabdoms, which together make these eyes 9 times more sensitive than those of X. tenuiscapa and 27 times more sensitive than those of X. leucothorax. These differences in optical sensitivity are surprisingly small considering that X. tranquebarica can fly on moonless nights when background luminance is as low as 10⁻⁵ cd m⁻², implying that this bee must employ additional visual strategies to forage and find its way back to the nest. These strategies may include photoreceptors with longer integration times and higher contrast gains as well as higher neural summation mechanisms for increasing visual reliability in dim light.     

Bio-Inspired Binary Bees Algorithm for a Two-Level Distribution Optimisation Problem

<正> Two uncoupleable distributions, assigning missions to robots and allocating robots to home stations, accompany the use ofmobile service robots in hospitals.In the given problem, two workload-related objectives and five groups of constraints areproposed.A bio-mimicked Binary Bees Algorithm (BBA) is introduced to solve this multiobjective multiconstraint combinatorialoptimisation problem, in which constraint handling technique (Multiobjective Transformation, MOT), multiobjectiveevaluation method (nondominance selection), global search strategy (stochastic search in the variable space), local searchstrategy (Hamming neighbourhood exploitation), and post-processing means (feasibility selection) are the main issues.TheBBA is then demonstrated with a case study, presenting the execution process of the algorithm, and also explaining the change ofelite number in evolutionary process.Its optimisation result provides a group of feasible nondominated two-level distributionschemes.     

Facial area and hairiness of pollinators visiting semi-natural grassland wild plants predict their facial pollen load

1. Consequences of a decline in pollination function in semi-natural ecosystems are largely unknown due to variability in pollinator effectiveness, that is, their contribution to pollen deposition alone. While pollination effectiveness has been shown to be related to body size and hairiness of pollinators for some crops, studies encompassing a wide diversity of pollinators interacting with wild plant communities are lacking. 2. Thus, the relationships between pollen load, which is a measurement of pollen transport ability and a proxy of pollinator effectiveness, and morphological traits of pollinators sampled in 16 grasslands in Moselle, France, were investigated. The area, hairiness, and pollen load of each pollinator's face were measured for 658 individuals from 127 bee and fly species interacting with 36 wild plant species. Pollinator dry mass was also measured on 543 individuals from 109 species. 3. Dry body mass and facial area of pollinators were positively linked. This study highlights that bees transported significantly more pollen grains on their face than flies. Furthermore, bees' faces were larger and hairier. We also found that pollinators' facial pollen load increased with facial area and hairiness when we considered all pollinators. However, hairiness is not significant within pollinator group (bees or flies), mirroring a potential phylogenetic signal. 4. Hence, this study shows a wide diversity of pollinator and plant species in which larger and hairier pollinators may transport more pollen grains, at least on their face. However, future studies involving other pollinator body parts are needed to generalise these relationships.     

Variable flowering phenology and pollinator use in a community suggest future phenological mismatch

Recent anthropogenic climate change is strongly associated with average shifts toward earlier seasonal timing of activity (phenology) in temperate-zone species. Shifts in phenology have the potential to alter ecological interactions, to the detriment of one or more interacting species. Recent models predict that detrimental phenological mismatch may increasingly occur between plants and their pollinators. One way to test this prediction is to examine data from ecological communities that experience large annual weather fluctuations. Taking this approach, we analyzed interactions over a four-year period among 132 plant species and 665 pollinating insect species within a Mediterranean community. For each plant species we recorded onset and duration of flowering and number of pollinator species. Flowering onset varied among years, and a year of earlier flowering of a species tended to be a year of fewer species pollinating its flowers. This relationship was attributable principally to early-flowering species, suggesting that shifts toward earlier phenology driven by climate change may reduce pollination services due to phenological mismatch. Earlier flowering onset of a species also was associated with prolonged flowering duration, but it is not certain that this will counterbalance any negative effects of lower pollinator species richness on plant reproductive success. Among plants with different life histories, annuals were more severely affected by flowering–pollinator mismatches than perennials. Specialized plant species (those attracting a smaller number of pollinator species) did not experience disproportionate interannual fluctuations in phenology. Thus they do not appear to be faced with disproportionate fluctuations in pollinator species richness, contrary to the expectation that specialists are at greatest risk of losing mutualistic interactions because of climate change.     

Effects of perceived danger on flower choice by bees

Studies on animal–flower interactions have mostly neglected the third trophic level of pollinators' predators, even though antipredatory behaviour of pollinators may affect patterns of pollinator visitation, pollen transfer and floral traits. In three experiments, it was found that honeybees showed sensitivity to perceived danger at flowers by preferring apparently safe flowers over equally rewarding alternatives harbouring either a dead bee or a spider, and avoiding revisitation of a site where the bees had escaped a simulated predation attempt. These results suggest that bees, like other animals, take antipredatory measures, which may have far reaching effects on animal–flower interactions.     

Comparative effectiveness of wild bee pollination on the post-harvest characteristics of Grewia asiatica (Malvaceae)

Measuring the pollination potential of different native bees is helpful in identifying the most efficient species for their conservation and proper utilization. The current study was carried out at the Research Farm of The Islamia University of Bahawalpur to compare the pollination efficiency of four native bee species: Apis dorsata, Megachile bicolor, M. cephalotes and Megachile (Callomegachile) sp. Apis dorsata was the most abundant floral visitor of Grewia asiatica comprising 36.46% of floral visitors following by M. cephalotes and Megachile sp. The peak abundance of A. dorsata and M. bicolor was recorded at 12:00 and 08:00, respectively whereas for M. cephalotes and Megachile sp. at 16:00. Visitation frequency, stay time, body and proboscis length were significantly higher in A. dorsata whereas visitation rate, pollen load and pollen deposition were significantly higher in M. bicolor. The maximum fruit weight was recorded when M. bicolor and Megachile sp. had been the pollinators. The post-harvest fruit weight loss was lower in M. bicolor pollinated fruit -with more gradual wrinkling- than in fruit that had resulted from pollination by A. dorsata, M. cephalotes and Megachile sp. Our results suggest that M. bicolor was better pollinator of G. asiatica in terms of its reproductive success and post-harvest qualities. Further studies should focus on conservation of M. bicolor in the region.     

传粉蜂在设施农业中的应用及挑战

昆虫为植物传粉是自然生态系统中的重要环节,在农业和自然生态系统的平衡与调控方面发挥着重要作用。以蜜蜂、熊蜂为代表的传粉蜂因其高效传粉及可人工饲养的特点,已成为设施农业中的优势传粉昆虫。本文总结了传粉蜂在设施农业中的应用现状,并从温湿度、农药、重金属等非生物因素和蜂种、病原生物、天敌、蜜源植物等生物因素两大方面讨论了传粉蜂在应用中面临的诸多挑战。此外,本文初步探讨了植物病虫害对传粉昆虫传粉效率的影响,并对传粉蜂未来的研究和应用方向进行了展望,旨在推动实现传粉蜂在农业中的高效授粉功能,为农产品增产增效服务。     

Pollination biology of Albizia lebbeck (L.) Benth. (Fabaceae: Mimosoideae) with reference to insect floral visitors

Indian siris, Albizia lebbeck (L.) Benth. (Fabaceae: Mimosoideae) has significant importance to human beings for its multipurpose use. Insects play a crucial role in the pollination biology of flowering plants. In the current study, we studied the pollination biology of A. lebbeck with special reference to insect floral visitors. The effectiveness of floral visitors was investigated in term of visitation frequency, visitation rate and pollen load during 2012 and 2013. In the second experiment, effect of pollinators on yield of A. lebbeck was studied in open and cage pollination experiments. Floral visitor fauna of A. lebbeck included eight-bees, two wasps, two flies, and two butterflies species. Among them, Apis dorsata, Apis florea, Amegilla cingulata, and Nomia oxybeloides had maximum abundance ranging from 349–492, 339–428, 291–342 and 235–255 numbers of individuals, respectively during two flowering seasons. A. dorsata had the highest visitation frequency (6.44 ± 0.49–8.78 ± 0.48 visits/flower/5min) followed by Amegilla cingulata (6.03 ± 0.43–7.99 ± 0.33 visits/flower/5min) and A. florea (3.61 ± 0.31–4.44 ± 0.18 visits/flower/5min). A. dorsata, N. oxybeloides, and Amegilla cingulata had the highest visitation rates (18.904 ± 1.53–11.43 ± 1.17 flower visited/min) and pollen load (15333 ± 336.22–19243 ± 648.45 pollen grains). The open pollinated flowers had significantly higher capsule weight (4.97 ± 0.21 g), seed weight (1.04 ± 0.05 g), seed numbers per pod (9.80 ± 0.34) and seed germination percentage (84.0 ± 1.78%) as compared to caged flowers. The results suggested bees especially A. dorsata, N. oxybeloides and Amegilla cingulata could be effective pollinators of A. lebbeck.     

Floral divergence and convergence in the genusPelargonium (Geraniaceae) in southern Africa: Ecological and evolutionary considerations

Based on field observations and a survey of the available literature, the functional and evolutionary significance of floral characters ofPelargonium is investigated in relation to a recent infrageneric re-classification. Most of the 208Pelargonium taxa (recognized as species, subspecies or varieties) involved show bee and long-proboscid hovering fly pollination syndromes (about 60% and 25%, respectively), only 7% of the taxa are pollinated by butterflies, some 2 to 4% by hawkmoths and presumably 1% by birds. The heterogeneity ofPelargonium in terms of structural blossom types and pollination syndromes indicates an independent and repeated evolution of convergent flower morphs in the genus and even in sections.