No detectable impact of parasite-infected commercial bumblebees on wild bees in areas adjacent to greenhouses despite diet overlap

Nest site availability and quality are important for maintaining robust populations and communities of wild bees. However, for most species, nesting traits and nest site conditions are poorly known, limiting both our understanding of basic ecology for bee species and conservation efforts. Additionally, many of the threats commonly associated with reducing bee populations have effects that can extend into nests but are largely unstudied. In general, threats such as habitat disturbances and climate change likely affect nest site availability and nest site conditions, which in turn affect nest initiation, growth, development, and overwintering success of bees. To facilitate a better understanding of how these and other threats may affect nesting bees, in this review, I quantify key nesting traits and environmental conditions and then consider how these traits may intersect with observed and anticipated changes in nesting conditions experienced by wild bees. These data suggest that the effects of common threats to bees through nesting may strongly influence their survival and persistence but are vastly understudied. Increasing research into nesting biology and incorporating nesting information into conservation efforts may help improve conservation of this declining but critical group.

Download Full-text

Possible Epigenetic Origin of a Recurrent Gynandromorph Pattern in Megachile Wild Bees

Insects ◽

10.3390/insects12050437 ◽

2021 ◽

Vol 12 (5) ◽

pp. 437

Author(s):

Daniele Sommaggio ◽

Giuseppe Fusco ◽

Marco Uliana ◽

Alessandro Minelli

Keyword(s):

Current Knowledge ◽

Sex Differentiation ◽

General Pattern ◽

Body Parts ◽

Wild Bees ◽

Male And Female ◽

Female Phenotype ◽

In The Wild ◽

Gene Transcripts ◽

Individual Body

Gynandromorphs, i.e., individuals with a mix of male and female traits, are common in the wild bees of the genus Megachile (Hymenoptera, Apoidea). We described new transverse gynandromorphs in Megachile pilidens Alfkeen, 1924 and analyze the spatial distribution of body parts with male vs. female phenotype hitherto recorded in the transverse gynandromorphs of the genus Megachile. We identified 10 different arrangements, nine of which are minor variants of a very general pattern, with a combination of male and female traits largely shared by the gynandromorphs recorded in 20 out of 21 Megachile species in our dataset. Based on the recurrence of the same gynandromorph pattern, the current knowledge on sex determination and sex differentiation in the honey bee, and the results of recent gene-knockdown experiments in these insects, we suggest that these composite phenotypes are possibly epigenetic, rather than genetic, mosaics, with individual body parts of either male or female phenotype according to the locally expressed product of the alternative splicing of sex-determining gene transcripts.

Download Full-text

Wild bees of Chile: a database on taxonomy, sociality, and ecology

Ecology ◽

10.1002/ecy.3377 ◽

2021 ◽

Author(s):

Manuel López‐Aliste ◽

Luis Flores‐Prado ◽

Luisa Ruz ◽

Yanet Sepúlveda ◽

Sharon Rodríguez ◽

...

Keyword(s):

Wild Bees

Download Full-text

Identity of mass-flowering crops moderates functional trait composition of pollinator communities

Landscape Ecology ◽

10.1007/s10980-021-01261-3 ◽

2021 ◽

Author(s):

Nicole Beyer ◽

Felix Kirsch ◽

Doreen Gabriel ◽

Catrin Westphal

Keyword(s):

Faba Bean ◽

Management Practices ◽

Functional Trait ◽

Flower Morphology ◽

Landscape Diversity ◽

Floral Resources ◽

Wild Bees ◽

Natural Habitats ◽

Mass Flowering ◽

Wild Bee

Abstract Context Pollinator declines and functional homogenization of farmland insect communities have been reported. Mass-flowering crops (MFC) can support pollinators by providing floral resources. Knowledge about how MFC with dissimilar flower morphology affect functional groups and functional trait compositions of wild bee communities is scarce. Objective We investigated how two morphologically different MFC, land cover and local flower cover of semi-natural habitats (SNH) and landscape diversity affect wild bees and their functional traits (body size, tongue length, sociality, foraging preferences). Methods We conducted landscape-level wild bee surveys in SNH of 30 paired study landscapes covering an oilseed rape (OSR) (Brassica napus L.) gradient. In 15 study landscapes faba beans (Vicia faba L.) were grown, paired with respective control landscapes without grain legumes. Results Faba bean cultivation promoted bumblebees (Bombus spp. Latreille), whereas non-Bombus densities were only driven by the local flower cover of SNH. High landscape diversity enhanced wild bee species richness. Faba bean cultivation enhanced the proportions of social wild bees, bees foraging on Fabaceae and slightly of long-tongued bumblebees. Solitary bee proportions increased with high covers of OSR. High local SNH flower covers mitigated changes of mean bee sizes caused by faba bean cultivation. Conclusions Our results show that MFC support specific functional bee groups adapted to their flower morphology and can alter pollinators` functional trait composition. We conclude that management practices need to target the cultivation of functionally diverse crops, combined with high local flower covers of diverse SNH to create heterogeneous landscapes, which sustain diverse pollinator communities.

Download Full-text

Nesting, Sex Ratio and Natural Enemies of the Giant Resin Bee in Relation to Native Species in Europe

Insects ◽

10.3390/insects12060545 ◽

2021 ◽

Vol 12 (6) ◽

pp. 545

Author(s):

Sara Straffon Díaz ◽

Luca Carisio ◽

Aulo Manino ◽

Paolo Biella ◽

Marco Porporato

Keyword(s):

Sex Ratio ◽

Natural Enemies ◽

Native Species ◽

Wild Bees ◽

Trap Nests ◽

Native Bee ◽

New Locations ◽

Negative Impacts ◽

Set Up ◽

North Western

Megachile sculpturalis (Smith, 1853) is the first exotic bee species in Europe. Its remarkably fast expansion across this continent is leading to a growing concern on the extent of negative impacts to the native fauna. To evaluate the interactions of exotic bees with local wild bees, we set up trap nests for above-ground nesting bees on a semi-urban area of north-western Italy. We aimed to investigate the interaction in artificial traps between the exotic and native wild bees and to assess offspring traits accounting for exotic bee fitness: progeny sex ratio and incidence of natural enemies. We found that the tunnels occupied by exotic bees were already cohabited by O. cornuta, and thus the cells of later nesting alien bees may block the native bee emergence for the next year. The progeny sex ratio of M. sculpturalis was strongly unbalanced toward males, indicating a temporary adverse population trend in the local invaded area. In addition, we documented the presence of three native natural enemies affecting the brood of the exotic bee. Our results bring out new insights on how the M. sculpturalis indirectly competes with native species and on its performance in new locations.

Download Full-text

Landscape structure affects the sunflower visiting frequency of insect pollinators

Scientific Reports ◽

10.1038/s41598-021-87650-9 ◽

2021 ◽

Vol 11 (1) ◽

Author(s):

Károly Lajos ◽

Ferenc Samu ◽

Áron Domonkos Bihaly ◽

Dávid Fülöp ◽

Miklós Sárospataki

Keyword(s):

Landscape Structure ◽

Honey Bees ◽

Agricultural Landscape ◽

Edge Density ◽

Wild Bees ◽

Natural Habitats ◽

Mass Flowering ◽

Positive Effects ◽

Pollinator Community ◽

Foraging Ranges

AbstractMass-flowering crop monocultures, like sunflower, cannot harbour a permanent pollinator community. Their pollination is best secured if both managed honey bees and wild pollinators are present in the agricultural landscape. Semi-natural habitats are known to be the main foraging and nesting areas of wild pollinators, thus benefiting their populations, whereas crops flowering simultaneously may competitively dilute pollinator densities. In our study we asked how landscape structure affects major pollinator groups’ visiting frequency on 36 focal sunflower fields, hypothesising that herbaceous semi-natural (hSNH) and sunflower patches in the landscape neighbourhood will have a scale-dependent effect. We found that an increasing area and/or dispersion of hSNH areas enhanced the visitation of all pollinator groups. These positive effects were scale-dependent and corresponded well with the foraging ranges of the observed bee pollinators. In contrast, an increasing edge density of neighbouring sunflower fields resulted in considerably lower visiting frequencies of wild bees. Our results clearly indicate that the pollination of sunflower is dependent on the composition and configuration of the agricultural landscape. We conclude that an optimization of the pollination can be achieved if sufficient amount of hSNH areas with good dispersion are provided and mass flowering crops do not over-dominate the agricultural landscape.

Download Full-text

Seasonal feeding plasticity can facilitate coexistence of dominant omnivores in Neotropical streams

Reviews in Fish Biology and Fisheries ◽

10.1007/s11160-021-09648-w ◽

2021 ◽

Author(s):

Mayara P. Neves ◽

Pavel Kratina ◽

Rosilene L. Delariva ◽

J. Iwan Jones ◽

Clarice B. Fialho

Keyword(s):

Seasonal Variation ◽

Fish Species ◽

Resource Availability ◽

Seasonal Changes ◽

Dry Season ◽

Diet Overlap ◽

Isotopic Niche ◽

Neotropical Streams ◽

Feeding Plasticity ◽

The Impact

AbstractCoexistence of ecomorphologically similar species in diverse Neotropical ecosystems has been a focus of long-term debate among ecologists and evolutionary biologists. Such coexistence can be promoted by trophic plasticity and seasonal changes in omnivorous feeding. We combined stomach content and stable isotope analyses to determine how seasonal variation in resource availability influences the consumption and assimilation of resources by two syntopic fish species, Psalidodon aff. gymnodontus and P. bifasciatus, in the Lower Iguaçu basin. We also tested the impact of seasonality on trophic niche breadth and diet overlap of these two dominant omnivores. Seasonal changes in resource availability strongly influenced the consumption and assimilation of resources by the two fish species. Both species exhibited high levels of omnivory, characterized by high diversity of allochthonous resources in the wet season. Terrestrial invertebrates were the main component of diet during this season. However, in the dry season, both species reduced their isotopic niches, indicating diet specialization. High diet overlap was observed in both seasons, but the isotopic niche overlap was smaller in the dry season. Substantial reduction in the isotopic niche of P. bifascistus and a shift toward aquatic invertebrates can facilitate coexistence during this season of resource shortage. Feeding plasticity allows omnivorous fish to adjust their trophic niches according to seasonality, promoting the exploitation of different resources during periods of greater resource diversity. This seasonal variation could be an important mechanism that contributes to the resource partitioning and coexistence of dominant omnivores in Neotropical streams.

Download Full-text