Pesticide exposure is a growing global concern for pollinator conservation. While most current pesticide studies have specifically focused on the impacts of neonicotinoid insecticides toward ...honeybees and some native bee species, wild pollinators may be exposed to a broader range of agrochemicals. In 2016 and 2017 we collected a total of 637 wild bees and butterflies from the margins of cultivated agricultural fields situated on five Conservation Areas in mid-northern Missouri. Pollinators were composited by individual genera (90 samples) and whole tissues were then analyzed for the presence of 168 pesticides and degradation products. At least one pesticide was detected (% frequency) in the following wild bee genera: Bombus (96%), Eucera (75%), Melissodes (73%), Ptilothrix (50%), Xylocopa (50%), and Megachile (17%). Similarly, at least one pesticide was detected in the following lepidopteran genera: Hemaris (100%), Hylephila (75%), Danaus (60%), and Colias (50%). Active ingredients detected in >2% of overall pollinator samples were as follows: metolachlor (24%), tebuconazole (22%), atrazine (18%), imidacloprid desnitro (13%), bifenthrin (9%), flumetralin (9%), p, p′-DDD (6%), tebupirimfos (4%), fludioxonil (4%), flutriafol (3%), cyproconazole (2%), and oxadiazon (2%). Concentrations of individual pesticides ranged from 2 to 174 ng/g. Results of this pilot field study indicate that wild pollinators are exposed to and are potentially bioaccumulating a wide variety of pesticides in addition to neonicotinoids. Here, we provide evidence that wild bee and butterfly genera may face exposure to a wide range of insecticides, fungicides, and herbicides despite being collected from areas managed for conservation. Therefore, even with the presence of extensive habitat, minimal agricultural activity on Conservation Areas may expose pollinators to a range of pesticides.
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•Analyzed wild bees and butterflies for 168 pesticides and degradation products•16 pesticides and degradation products were detected in pollinator tissues.•Bumblebee queens contained fungicides, herbicides, and insecticide degradates.•Wild pollinators are exposed to a range of pesticides beyond neonicotinoids.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UILJ, UL, UM, UPCLJ, UPUK, ZAGLJ, ZRSKP
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.
•Despite equal species richness among strata, woodlots had vertically stratified bee communities.•We found higher overall diversity and more female bees in the canopy.•The traits of nesting habitat ...and sociality were strongly predictive of strata occupancy.•Canopy cover (leaf-out) was negatively associated with understory but not canopy bee abundance.•Regional amount of coarse woody debris correlated with understory abundance of some trait groups.•We speculate females forage for canopy pollen; we recommend maintaining above-ground deadwood.
Temperate hardwood deciduous forest is the dominant landcover in the Northeastern US, yet its canopy is usually ignored as pollinator habitat due to the abundance of wind-pollinated trees. We describe the vertical stratification of spring bee communities in this habitat and explore associations with bee traits, canopy cover, and coarse woody debris. For three years, we sampled second-growth woodlots and apple orchard-adjacent forest sites from late March to early June every 7–10 days with paired sets of tri-colored pan traps in the canopy (20–25 m above ground) and understory (<1m). Roughly one fifth of the known New York state bee fauna were caught at each height, and 90 of 417 species overall, with many species shared across the strata. We found equal species richness, higher diversity, and a much higher proportion of female bees in the canopy compared to the understory. Female solitary, social, soil- and wood-nesting bees were all abundant in the canopy while soil-nesting and solitary bees of both sexes dominated the understory. Canopy cover increased with leaf-out, and was negatively associated with understory but not canopy bee abundance. Site-level volume of coarse woody debris (CWD) did not predict bee abundance, while approximated landscape-scale availability of woody debris was positively correlated with understory wood-nesting and solitary-bee abundance. This work expands our understanding of habitats where bees are likely foraging and reveals vertically stratified behavior. We emphasize deciduous forests as an important habitat for wild bee conservation and recommend further research into the behavior and diets of bees occupying the canopy, speculating that females forage for anemophilous tree pollen. Forest management plans that conserve above-ground deadwood may provide nest sites for wood-nesting bees.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UILJ, UL, UM, UPCLJ, UPUK, ZAGLJ, ZRSKP
Fungicides account for more than 35% of the global pesticide market and their use is predicted to increase in the future. While fungicides are commonly applied during bloom when bees are likely ...foraging on crops, whether real-world exposure to these chemicals – alone or in combination with other stressors – constitutes a threat to the health of bees is still the subject of great uncertainty. The first step in estimating the risks of exposure to fungicides for bees is to understand how and to what extent bees are exposed to these active ingredients. Here we review the current knowledge that exists about exposure to fungicides that bees experience in the field, and link quantitative data on exposure to acute and chronic risk of lethal endpoints for honey bees (Apis mellifera). From the 702 publications we screened, 76 studies contained quantitative data on residue detections in honey bee matrices, and a further 47 provided qualitative information about exposure for a range of bee taxa through various routes. We compiled data for 90 fungicides and metabolites that have been detected in honey, beebread, pollen, beeswax, and the bodies of honey bees. The risks posed to honey bees by fungicide residues was estimated through the EPA Risk Quotient (RQ) approach. Based on residue concentrations detected in honey and pollen/beebread, none of the reported fungicides exceeded the levels of concern (LOC) set by regulatory agencies for acute risk, while 3 and 12 fungicides exceeded the European Food Safety Authority (EFSA) chronic LOC for honey bees and wild bees, respectively. When considering exposure to all bees, fungicides of most concern include many broad-spectrum systemic fungicides, as well as the widely used broad-spectrum contact fungicide chlorothalonil. In addition to providing a detailed overview of the frequency and extent of fungicide residue detections in the bee environment, we identified important research gaps and suggest future directions to move towards a more comprehensive understanding and mitigation of the risks of exposure to fungicides for bees, including synergistic risks of co-exposure to fungicides and other pesticides or pathogens.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UILJ, UL, UM, UPCLJ, UPUK, ZAGLJ, ZRSKP
Most of the world's crops depend on pollinators, so declines in both managed and wild bees raise concerns about food security. However, the degree to which insect pollination is actually limiting ...current crop production is poorly understood, as is the role of wild species (as opposed to managed honeybees) in pollinating crops, particularly in intensive production areas. We established a nationwide study to assess the extent of pollinator limitation in seven crops at 131 locations situated across major crop-producing areas of the USA. We found that five out of seven crops showed evidence of pollinator limitation. Wild bees and honeybees provided comparable amounts of pollination for most crops, even in agriculturally intensive regions. We estimated the nationwide annual production value of wild pollinators to the seven crops we studied at over $1.5 billion; the value of wild bee pollination of all pollinator-dependent crops would be much greater. Our findings show that pollinator declines could translate directly into decreased yields or production for most of the crops studied, and that wild species contribute substantially to pollination of most study crops in major crop-producing regions.
Neonicotinoid insecticides can have sub‐lethal effects on bees which has led to calls from conservationists for a global ban. In contrast, agrochemical companies argue that neonicotinoids do not harm ...honeybees at field‐realistic levels. However, the focus on honeybees neglects the potential impact on other bee species. We conducted a meta‐analysis to assess whether field‐realistic neonicotinoid exposure has sub‐lethal effects on non‐Apis bees. We extracted data from 53 papers (212 effects sizes) and found that it largely consisted of two genera: bumblebees (Bombus) and mason bees (Osmia), highlighting a substantial taxonomic knowledge gap. Neonicotinoid exposure negatively affected reproductive output across all bees and impaired bumblebee colony growth and foraging. Neonicotinoids also reduced Bombus, but not Osmia, individual development (growth and body size). Our results suggest that restrictions on neonicotinoids should benefit bee populations and highlight that the current regulatory process does not safeguard pollinators from the unwanted consequences of insecticide use.
We conducted a meta‐analysis to assess whether field‐realistic neonicotinoid exposure has sub‐lethal effects on non‐Apis bees. Neonicotinoid exposure negatively affected reproductive output across all bees and impaired bumblebee colony growth and foraging. Our results suggest that restrictions on neonicotinoids will benefit bee populations and highlight that the current regulatory process does not safeguard pollinators from the unwanted consequences of insecticide use.
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BFBNIB, FZAB, GIS, IJS, KILJ, NLZOH, NUK, OILJ, SBCE, SBMB, UL, UM, UPUK
Orchid bees have been considered as good ecological indicators of habitat disturbances but recently Añino et al. (2019. Sociobiology, 66: 194-197) highlighted reasons why Euglossini role as ...indicators should be reevaluated. Despite agreeing with some points raised by them, we present an alternative view for the use of orchid bees as indicators. For us, the main problematic issues are: (i) the authors do not present a clear definition of ecological indicator, including its role as an indirect measure of biota response to disturbed environments; (ii) they do not properly acknowledge the relative good taxonomic status of orchid bees when compared with the remaining bees; (iii) and they do not distinguish the use of particular Euglossini species as indicators in certain circumstances. In spite of some knowledge gaps, we argue that Euglossini is a good candidate to be ecological indicators in tropical forests, maybe the best candidate among all the bees.
Agricultural systems in Central Europe were redesigned during the last century to attain maximum yields. The results often lead to homogeneous landscapes with only few structures of ecological value ...and have concurrently exacerbated habitat fragmentation. Perennial wildflower strips have become a significant agri-environmental measure (AEM) to counteract the ecological consequences for wild bees and other pollinators in agricultural landscapes. The effectiveness of AEMs depends on the landscape context, but information about geodata sources and spatial scales relevant for the analysis of landscape effects on wild bees is lacking. This study uses data from various sources on land cover and agricultural practices to assess their applicability in an evaluation of perennial wildflower strips as AEM for wild bees in Saxony-Anhalt, Germany. We investigated the relationships of wild bee species diversity and abundance to the landscape context at spatial scales from 200 m to 10 km considering several factors: land cover/land use, protected areas, crop types, agri-environment schemes/greening, intensity of agriculture, and intensity of grassland farming. In general, our results revealed that landscape effects were more relevant for solitary than social wild bees on flower strips, pointing to a higher limitation of solitary wild bees in nesting resources as compared to social wild bees. Numbers of wild bee species and individuals benefitted from bare soil and ecological focus areas in the surroundings up to 3 km distance, whereas the share of Red List solitary bee species was positively influenced by a variety of factors (e.g., wood structures and grasslands) especially at large scales up to 10 km. The comparison of models based on different land cover data sources showed that the lack of geodata resolution can mask landscape effects on wild bees. Altogether, our results suggest a high potential of data from the Basic Digital Landscape Model (DLM), together with the Integrated Administration and Control System (IACS), to indicate effects of landscape structures and agricultural practices on the species composition and distribution of wild bee assemblages in Germany.
•Landscape context affects wild bees on flower strips at multiple spatial scales.•Bare soil and ecological focus areas promote high species diversity and abundance.•Red List bee species benefit from wood structures and grassland in > 3 km distance.•Data on land cover and agricultural practices are key to analyse wild bee habitats.•Multi-scale spatial analyses are essential to evaluate the effectiveness of AEMs.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UILJ, UL, UM, UPCLJ, UPUK, ZAGLJ, ZRSKP
•Bee communities in recent clearcuts are species diverse but functionally similar.•Hardwood forests are centers of functional diversity in the bee community.•Nesting habitat indicators explained 53% ...of the variation in bee communities.•Wood nesting bees respond to the presence of downed wood but not standing dead trees.•Soil nesting bees dominate clearcut communities.
The role of nesting resources has been largely neglected in wild bee community ecology studies. Anthropogenic forest openings such as clearcuts and roads are common features within the managed forest matrix which may have varying impacts on bee nesting habitats and thus, drive their community structure. We sampled wild bees in mature hardwood, managed pine, and regenerating clearcuts across a gradient from the edge of a road into each site-type. Each site was surveyed for nesting habitat indicators including depth of duff layer, volume of downed wood, decay class of downed wood, and number of snags. Regenerating clearcuts had higher alpha diversity of wild bees than other sites, but displayed higher functional overlap in the bee community, favoring soil nesting groups. Forested sites, especially hardwoods provided more nesting niche opportunities leading to higher functional dispersion, evenness and higher beta diversity, and supported more cavity nesting, softwood nesting, solitary, and early season bees. Nesting habitat indicators explained 53% of the variation in nest guild composition. Cavity nesting bees responded positively to the volume of downed wood, and in a bimodal way to woody decay class. Soil nesting bees responded negatively to the depth of duff layer and presence of snags. Overall, results indicate that regenerating clearcuts are foci of species diversity, while hardwood forests are foci of functional diversity. Hardwood forests may be source of functionally diverse groups of bees, and maintaining patches or swaths of hardwood forests with some downed wood accumulation may be critical for maintaining functional diversity of bees in managed forested ecosystems.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UILJ, UL, UM, UPCLJ, UPUK, ZAGLJ, ZRSKP
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