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Two species density versus agricultural yield relationships that lead to different conservation strate- gies. ( A ) When species density decreases slowly with ini- tial increases in yield, wildlife-friendly farming can be an effective conservation approach. ( B ) Conversely, when species density decreases rapidly at low levels of yield increase, land sparing is predicted to be the best conservation approach. After Green et al. 251
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Bees pollinate most of the world's wild plant species and provide economically valuable pollination services to crops; yet knowledge of bee conservation biology lags far behind other taxa such as vertebrates and plants. There are few long-term data on bee populations, which makes their conservation status difficult to assess. The best-studied group...
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... in order to maxi- mize their effectiveness? Tscharntke et al . 247 hypothesized an asymmetrical, hump-shaped relationship between landscape heterogeneity and restoration effectiveness (Fig. 1), such that restorations are less effective when done in heterogeneous landscapes (defined as < 80% cropland) where pollinators are present without restorations, most effective in intermediate landscapes (defined as 80–99% cropland), and less effective in homogeneous landscapes (defined as > 99% cropland) where pollinators are largely extirpated and few sources of colonists for restorations exist. Several studies have since tested the relationship between local- and landscape-scale factors and have confirmed that the two interact, and that the effectiveness of local bee restorations increases con- sistently with increasing cover of cropland (which most authors have interpreted as arable, i.e., row crops) in the surrounding landscape. As yet no study has tested the hypothesis that effectiveness declines in the most intensively managed landscapes ( > 99% cropland). In a system where all sites are set within highly heterogeneous landscapes ( < 40% arable cropland), neither local- nor landscape-scale factors explains crop visitation by native bees; rather, native bees are abundant throughout the entire system. 19 , 91 This is consistent with the hypothesis that in highly heterogeneous landscapes, bees are supported by the landscapes themselves and restoration is not required. In a system where the proportion of arable cropland in the landscape varies from 20–95%, bumble bee density in restored patches increases more than linearly with increasing arable crop cover. 248 Similarly, there is an interaction between bee species richness in organic versus conventional wheat fields and surrounding land cover, such that the organic/conventional difference increases with the proportion of arable croplands over a range of roughly 20–85%. 240 Last, the reproduction of a solitary bee species is similar on organic and conventional farms when both are near patches of seminatural habitat, but diverges on farms set within intensively agricultural landscapes. 158 Studies of nonbee taxa have also found that the benefit of organic farming is greatest in the most intensively agricultural landscapes. 249 , 250 These studies are broadly consistent with the work finding that the economic value of pollination services provided by natural habitat outweighs the value of land conversion only in the most degraded landscapes (see above). Restorations can also be accomplished by reducing the intensity of a single land use variable, in which case the biodiversity gains can be plotted against land use intensity as a bivariate relationship. The steepness of the resulting slope indicates where biodiversity gains are greatest for a given incremental change in land use intensity (Fig. 2). A study of plant species richness and nitrogen inputs (a proxy for land use intensity) shows that the benefits of reducing nitrogen inputs are greatest in the least intensive systems 54 —the opposite of the conclusion reached by the studies of organic farming and arable crop cover reviewed above. In reality, the optimal location for a restoration is determined not only by relative benefits, as in Figure 2 or the studies of organic farming above, but also by relative costs. This full cost-benefit approach has not yet been applied to the question of what landscape context offers the best restoration value. The cost-benefit approach has been used for a larger-scale question: whether biodiversity conservation and restoration should be focused on agricultural lands at all. In an influential paper, Green et al . 251 contrasted two approaches to biodiversity conservation: wildlife-friendly farming, which involves integrating conservation into agricultural landscapes through, for example, AES and Farm Bill restorations; and sparing land for nature, which en- tails concentrating agricultural production in high- intensity, low-biodiversity areas while protecting more natural areas elsewhere for biodiversity. Green et al . propose that the relative efficacy of these two approaches can be evaluated by considering how rapidly agricultural yield declines when wildlife- friendly farming is implemented—specifically, by plotting the density of a given species of conservation concern against agricultural yield. If this curve is concave, then wildlife-friendly farming is predicted to be the best conservation approach, because species declines are slower than yield increases as agricultural intensification increases (Fig. 3A). Conversely, if the curve is convex, then intensive agriculture combined with land sparing is predicted to be the best approach because species declines are rapid even when yields are low (Fig. 3B). Note that Green et al . 251 compare the shape of the biodiversity–yield relationship across entire study systems to identify the optimal system for conservation projects (Fig. 3), whereas Kleijn et al . 54 seek the optimal location for restoration within a given system by finding the area with the steepest slope (Fig. 2). If one assumes a fixed global need for food, as assumed by the model of Green et al ., 251 then greater yields will tautologically lead to less land area being used for agriculture because yield is defined as food production per unit area. However, on a per capita caloric basis enough food is already produced globally, which suggests that factors other than the need for food, such as distribution inequities, are driving agricultural land conversion. 252–254 Two ad- ditional factors make it difficult to evaluate the relative effectiveness of the wildlife-friendly farming and land sparing approaches. First, empirical density-yield relationships of the type shown hy- pothetically in Fig. 3 are not yet known for any species. 251 , 255 Although relationships are generally negative for the few taxa that have been investi- gated, 256 , 257 the shape of the relationship is not clear. In addition, the extent to which biodiversity- friendly agriculture reduces crop yields is controversial. Restorations that take land out of production presumably reduce yields, but the transition to organic farming can either reduce or increase yield. 254 Organic farming is, however, more expensive, which suggests that another variable—the cost of production—should be considered in the cost- benefit analysis. Second, there is as yet little evidence that using land for intensive agriculture leads to sparing land for nature elsewhere. 258 Yield and deforestation rates can be negatively correlated, 255 but this is not necessarily a causal relationship. At a local scale, both agricultural yields and the extent of land under production can be limited by the same factors— capitalization and technology—such that when limits on yield are removed, it becomes profitable for farmers to farm more land, not less. 259 Differences between developed temperate and developing tropical systems need to be kept in mind when comparing among approaches to conservation and restoration Agricultural expansion over the next few decades is predicted to occur largely in the developing world. 255 Yet what we know about bee restoration through AES-type approaches is based largely on northwest Europe, which is one of the most agriculturally developed areas of the world. 54 Tropical bees that have only recently encountered agriculture may be less robust to it and in greater need of land-sparing approaches, as compared to the bee fauna that persists in areas with a long history of agricultural land use. Last, in terms of global conservation planning it is important to keep in mind that the per area costs of conservation in USA and UK, including AES-type restorations, are among the highest in the world. 33 For pollinators specifically, several factors weigh in favor of focusing restoration on agricultural lands. First, significant funding for such restorations already exists, at least in the EU and USA, whereas less funding is currently available for nonagricultural restorations. Second, ecosystem services arguments for pollinator conservation are most relevant in agricultural areas. And third, agricultural systems have the potential to provide suitable habitat for at least some bee species. One study has quantita- tively evaluated how AES restorations might affect both bee biodiversity and crop yield. Based on a study of bees in winter wheat fields, an increase in organic farmland from 5% to 20% is predicted to increase the species richness of bees in fallow strips by 50%, and the abundance of solitary bees by 60% and of bumble bees by 150%. 241 These benefits can be compared to the 40% decrease in yield (kg/ha of wheat) incurred by changing from conventional to organic agriculture. 240 In this study, 100% of the bee species were polylectic, indicating that the dietary specialists, which may be in the greatest need of conservation, have likely been lost from the system already. 241 This serves as an important reminder that only a subset of bees, namely those found in agricultural settings, are benefitted by agricultural restorations. This is an important question about which we know surprisingly little. Restoration protocols that restore pollinator biodiversity may not restore ecosystem services, and vice versa, because a small subset of species commonly provide the majority of the ecosystem services ( e.g., Ref. 260). For example, single, common bumble bee species provided 49% of the pollination services to watermelon, out of 46 native bee species found pollinating the crop (Fig. 4; 19 ). It may be that agricultural habitat restoration programs, which tend to protect common species, 55 may be effective for the restoration of ecosystem services even if they are not effective for the conservation of biodiversity. It is striking, given the potential benefits of agricultural pollinator restorations to crop ...
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... (which most authors have interpreted as arable, i.e., row crops) in the surrounding landscape. As yet no study has tested the hypothesis that effectiveness declines in the most intensively managed landscapes ( > 99% cropland). In a system where all sites are set within highly heterogeneous landscapes ( < 40% arable cropland), neither local- nor landscape-scale factors explains crop visitation by native bees; rather, native bees are abundant throughout the entire system. 19 , 91 This is consistent with the hypothesis that in highly heterogeneous landscapes, bees are supported by the landscapes themselves and restoration is not required. In a system where the proportion of arable cropland in the landscape varies from 20–95%, bumble bee density in restored patches increases more than linearly with increasing arable crop cover. 248 Similarly, there is an interaction between bee species richness in organic versus conventional wheat fields and surrounding land cover, such that the organic/conventional difference increases with the proportion of arable croplands over a range of roughly 20–85%. 240 Last, the reproduction of a solitary bee species is similar on organic and conventional farms when both are near patches of seminatural habitat, but diverges on farms set within intensively agricultural landscapes. 158 Studies of nonbee taxa have also found that the benefit of organic farming is greatest in the most intensively agricultural landscapes. 249 , 250 These studies are broadly consistent with the work finding that the economic value of pollination services provided by natural habitat outweighs the value of land conversion only in the most degraded landscapes (see above). Restorations can also be accomplished by reducing the intensity of a single land use variable, in which case the biodiversity gains can be plotted against land use intensity as a bivariate relationship. The steepness of the resulting slope indicates where biodiversity gains are greatest for a given incremental change in land use intensity (Fig. 2). A study of plant species richness and nitrogen inputs (a proxy for land use intensity) shows that the benefits of reducing nitrogen inputs are greatest in the least intensive systems 54 —the opposite of the conclusion reached by the studies of organic farming and arable crop cover reviewed above. In reality, the optimal location for a restoration is determined not only by relative benefits, as in Figure 2 or the studies of organic farming above, but also by relative costs. This full cost-benefit approach has not yet been applied to the question of what landscape context offers the best restoration value. The cost-benefit approach has been used for a larger-scale question: whether biodiversity conservation and restoration should be focused on agricultural lands at all. In an influential paper, Green et al . 251 contrasted two approaches to biodiversity conservation: wildlife-friendly farming, which involves integrating conservation into agricultural landscapes through, for example, AES and Farm Bill restorations; and sparing land for nature, which en- tails concentrating agricultural production in high- intensity, low-biodiversity areas while protecting more natural areas elsewhere for biodiversity. Green et al . propose that the relative efficacy of these two approaches can be evaluated by considering how rapidly agricultural yield declines when wildlife- friendly farming is implemented—specifically, by plotting the density of a given species of conservation concern against agricultural yield. If this curve is concave, then wildlife-friendly farming is predicted to be the best conservation approach, because species declines are slower than yield increases as agricultural intensification increases (Fig. 3A). Conversely, if the curve is convex, then intensive agriculture combined with land sparing is predicted to be the best approach because species declines are rapid even when yields are low (Fig. 3B). Note that Green et al . 251 compare the shape of the biodiversity–yield relationship across entire study systems to identify the optimal system for conservation projects (Fig. 3), whereas Kleijn et al . 54 seek the optimal location for restoration within a given system by finding the area with the steepest slope (Fig. 2). If one assumes a fixed global need for food, as assumed by the model of Green et al ., 251 then greater yields will tautologically lead to less land area being used for agriculture because yield is defined as food production per unit area. However, on a per capita caloric basis enough food is already produced globally, which suggests that factors other than the need for food, such as distribution inequities, are driving agricultural land conversion. 252–254 Two ad- ditional factors make it difficult to evaluate the relative effectiveness of the wildlife-friendly farming and land sparing approaches. First, empirical density-yield relationships of the type shown hy- pothetically in Fig. 3 are not yet known for any species. 251 , 255 Although relationships are generally negative for the few taxa that have been investi- gated, 256 , 257 the shape of the relationship is not clear. In addition, the extent to which biodiversity- friendly agriculture reduces crop yields is controversial. Restorations that take land out of production presumably reduce yields, but the transition to organic farming can either reduce or increase yield. 254 Organic farming is, however, more expensive, which suggests that another variable—the cost of production—should be considered in the cost- benefit analysis. Second, there is as yet little evidence that using land for intensive agriculture leads to sparing land for nature elsewhere. 258 Yield and deforestation rates can be negatively correlated, 255 but this is not necessarily a causal relationship. At a local scale, both agricultural yields and the extent of land under production can be limited by the same factors— capitalization and technology—such that when limits on yield are removed, it becomes profitable for farmers to farm more land, not less. 259 Differences between developed temperate and developing tropical systems need to be kept in mind when comparing among approaches to conservation and restoration Agricultural expansion over the next few decades is predicted to occur largely in the developing world. 255 Yet what we know about bee restoration through AES-type approaches is based largely on northwest Europe, which is one of the most agriculturally developed areas of the world. 54 Tropical bees that have only recently encountered agriculture may be less robust to it and in greater need of land-sparing approaches, as compared to the bee fauna that persists in areas with a long history of agricultural land use. Last, in terms of global conservation planning it is important to keep in mind that the per area costs of conservation in USA and UK, including AES-type restorations, are among the highest in the world. 33 For pollinators specifically, several factors weigh in favor of focusing restoration on agricultural lands. First, significant funding for such restorations already exists, at least in the EU and USA, whereas less funding is currently available for nonagricultural restorations. Second, ecosystem services arguments for pollinator conservation are most relevant in agricultural areas. And third, agricultural systems have the potential to provide suitable habitat for at least some bee species. One study has quantita- tively evaluated how AES restorations might affect both bee biodiversity and crop yield. Based on a study of bees in winter wheat fields, an increase in organic farmland from 5% to 20% is predicted to increase the species richness of bees in fallow strips by 50%, and the abundance of solitary bees by 60% and of bumble bees by 150%. 241 These benefits can be compared to the 40% decrease in yield (kg/ha of wheat) incurred by changing from conventional to organic agriculture. 240 In this study, 100% of the bee species were polylectic, indicating that the dietary specialists, which may be in the greatest need of conservation, have likely been lost from the system already. 241 This serves as an important reminder that only a subset of bees, namely those found in agricultural settings, are benefitted by agricultural restorations. This is an important question about which we know surprisingly little. Restoration protocols that restore pollinator biodiversity may not restore ecosystem services, and vice versa, because a small subset of species commonly provide the majority of the ecosystem services ( e.g., Ref. 260). For example, single, common bumble bee species provided 49% of the pollination services to watermelon, out of 46 native bee species found pollinating the crop (Fig. 4; 19 ). It may be that agricultural habitat restoration programs, which tend to protect common species, 55 may be effective for the restoration of ecosystem services even if they are not effective for the conservation of biodiversity. It is striking, given the potential benefits of agricultural pollinator restorations to crop pollination, that no published study has inves- tigated this question using actual cropping systems. A study investigating the restoration of pollination services to crops as a function of habitat restoration has been in progress in California since 2006 but is not yet completed (C. Kremen, Unpublished data). Several studies have shown the potential for crop pollination benefits by monitoring potted phytometers or noncrop plants situated near pollinator restorations. Seed set is higher in AES versus control (conventional) hay meadows for 2 of 3 potted, noncrop plant species. 233 Seed set of potted phytometers 300 m from a pollinator restoration falls to 1/3 the levels found within 100 m of the restoration; however, the difference was not significant. 261 Given the fact that restorations generally focus on the vegetative community, yet ...
Citations
... Agroforestry ecosystem provides them suitable nesting sites and floral resources, enhancing their pollination services to crops at a landscape level (Sutter 2017;Kay et al. 2019). Bees are the primary pollinators and roughly cover 90% of world plant population (Winfree 2010). ...
The investigation study assesses the diversity of bees in Brinjal Solanum melongena L. and Ridge Gourd Luffa acutangula L. crop field from agroforestry ecosystem in South Kangsabati Forest Division, India. The study was carried out in May 2021 to May 2022 that based on transect, focal observation and pan trap samplings. A total of 1,085 individuals were identified during the field work, belonging to three family seven genera (Apis, Tetragonula, Xylocopa, Ceratina, Amegelia, Nomia, and Megachile) and seventeen species, the non Apis bees (63.78%) were most abundant than Apis bees (36.22%). In brinjal, Shannon diversity index of bees is 2.12 and Shannon evenness index is 0.35, whereas, Shannon diversity index in ridge gourd was 1.94 and Shannon evenness index is 0.3. The observations signify greater diversity and population of wild bees. The natural habitat close to agricultural land helps to sustain the diversity and population of wild bees, which enhance the crop quality and yield.
... Wild bees (monophyletic group Apiformes, clade Antophila, non-Apis bees) are a diverse group from a species-richness, phylogenetical and behavioral perspectives, and comprises around 18,000 species worldwide divided in seven different families (Michener, 2000;Winfree, 2010). This diversity has enabled wild bees to colonize a wide variety of ecosystems, being present in every continent of the planet, with the exception of Antarctica (Danforth, 2007). ...
... Although the negative effects of agrochemicals on plant biodiversity have been widely reported [55] [56], our comparison of plant species diversity between organic and conventional crops, shows no statistical effect of the farming system. Even if the lack of agrochemicals is known to increase wild bee diversity [57], there may other factors influencing the number of plants available for the pollinators, such as for instance, landscape complexity, which has known to have a positive effect on pollinator-plant interactions [58]. Therefore, the landscape homogeneity occurring in intensive agricultural areas, such as LTSER ZA Plaine & Val de Sèvre, would be affecting the pollination spectrum in both, organic and conventional crops. ...
Wild bees are known to be efficient pollinators of wild plants and cultivated crops and they are essential ecosystem service providers. However, wild bee populations have been suffering from significant declines in the last decades mainly due to the use of agrochemicals. Within this framework, we aimed to characterize wild bees pollination spectrum (i.e. the community of pollinated flowering plants) in intensive agroecosystems, and describe the environmental variables and wild bee species traits influencing the pollination. To do this, we conducted metabarcoding analyses of pollen loads from wild bees collected in sunflower crops in the French region of Nouvelle-Aquitaine. Our study revealed that wild bees visited flowering plants corresponding to 231 different Operational Taxonomic Units, classified in 38 families of which Asteraceae, Brassicaceae and Apiaceae were the most visited and more than 90% of the visited taxa turned out to be wild flowers. We also analysed the potential effect of environmental variables and wild bee species traits in governing their choice of pollinated plants. The community composition of pollinated plants varied depending on the flowering stages of the sunflower and the farming system. Our results also show that pollination niche breadth (alpha diversity) varied depending on the flowering stages of the sunflower but was not different between organic and conventional farming systems. Regarding wild bee species traits, the community composition of pollinated plants varied in relation to wild bees body sizes and, sociality levels. Our results are consistent with previous studies, suggesting that solitary bees are more specialists when it comes to flower selection than social bees, which are more generalist. The metabarcoding of pollen loads enabled us to draw a global picture of plant-wild bee interactions in an intensive agroecosystem. Our findings support the hypothesis that a higher diversity of weeds may increase wild bee diversity in intensive agroecosystems.
... Agri-environmental interventions for insect pollinator conservation typically focus on re-establishing floral resources [53], e.g., restoring species-rich grasslands, sowing field margins with nectar and pollen-rich mixes, and inclusion of flowering species such as legumes in rotations [54,55]. The use of sown flower strips in crops to provide resources for pollinators (mainly Hymenoptera: Apoidea and Diptera: Syrphidae) has been examined by several researchers [8,[56][57][58][59][60][61][62][63][64]. ...
Apples depend on insect pollination but intensification of agriculture jeopardizes pollination services in agroecosystems. Concerns about the dependency of crop pollination exclusively on honey bees increase the interest in agricultural practices that safeguard wild pollinators in agroecosystems. The purpose of the study was to assess the potential of floral resource provision in apple orchards to enhance the conservation of hymenopterous pollinating insects and potentially the pollination service to the crop. For this reason, flowering plant mixtures sown in patches inside apple orchards were tested against wild plant patches. Pollinator taxa recorded on the sown and wild plant patches were honey bees, wild bees (Andrena, Anthophora, Eucera, Halictus, Lasioglossum, Megachilidae on both; Systropha only on wild plants; Bombus, Hylaeus, Sphecodes, Nomada, Xylocopa only on sown mixture), syrphids, bee flies. The most abundant pollinator of apple was A. mellifera but wild bees were also recorded (Andrena, Anthophora, Bombus, Xylocopa, Lasioglossum, Megachilidae). The sown mixture attracted a more diverse taxa of pollinators and in greater numbers compared to the weed flora, but it did not have an effect on pollinators visiting apple flowers. Groundcover management with patches of suitable flowering mixtures can enhance pollinator conservation in apple orchards.
... A higher proportion of oligolectic bees and bee species were found at sites with higher flower abundance and proportion of uncultivated land at the landscape and lower woody cover. Taken together, these results may reflect, both directly and indirectly, variation in the availability of forage resources and the sensitivity of oligolectic bees to changes in land use [49][50][51]. As in many bee communities in agricultural landscapes, the distribution of sociality was skewed toward much higher proportion of solitary bees and bee species, so that the modeling of primitive eusocial bees could not be performed. ...
In agricultural landscapes, uncultivated habitat patches may have a focal role in supporting communities of ecosystem service providers. However, little is known on the variances among different types of uncultivated habitat patches in providing resources and maintaining populations of these beneficial organisms. We studied wild bee communities in natural and semi-natural uncultivated patches embedded in semi-arid Mediterranean agricultural landscapes. We investigated the effects of local- and landscape-scale land-use characteristics, as well as their interactions, on bee diversity, functional composition, and forage and nesting resources. Most bee community parameters were affected by both local- and landscape-scale characteristics, but no significant interactions were found among the scales. Local land-use effects were related primarily to overall plant cover, and to the abundance and richness of flowering plants. Landscape effects, mostly limited to a 400 m range, were varied. The abundance of focal crop pollinators varied considerably between patch type and pollinator species. The different types of uncultivated habitats maintain complementary bee and flower communities. Our findings show the important role of uncultivated habitat patches in providing floral and nesting resources for bees, and creating resource-landscapes that can support wild bee communities and crop pollination services in Mediterranean agricultural landscapes.
... Plant-pollinator interactions play a key role in plant reproductive success, animal survival and the functioning of terrestrial ecosystems (Fenster et al., 2004;Klein et al., 2007;Rosas-Guerrero et al., 2014). These interactions are important for more than 90% of flowering plants and more than 70% of crops used as food resources in the world (Klein et al., 2007;Winfree, 2010). However, this mutualism is being severely affected by diverse anthropogenic factors, mainly the loss and fragmentation of natural habitats (Hagen & Kraemer, 2010;Potts et al., 2010;Watanabe, 2013). ...
1. Plant‐pollinator interactions are fundamental to ecosystem functioning; however, the role that succession and phenology have on these interactions is poorly understood, particularly in endangered tropical ecosystems. In highly diverse ecosystems such as tropical dry forests (TDF), variation in water and food availability determines the life cycles of animal pollinators. Therefore, understanding patterns of flowering phenology and plant‐pollinator interactions across seasons in successional environments is key to maintaining and restoring TDF. 2. We analysed the functional dynamics of plant‐floral visitor interactions at the community level across a successional gradient in a Mexican TDF. We evaluated changes in the diversity of blooming plant species and floral visitors, phenological patterns, interaction network metrics, and beta diversity among early, intermediate, and late successional stages, between dry and rainy seasons. 3. We found a higher diversity of blooming plant species and a higher richness of animal species in the intermediate and late successional stages. Peak abundance of floral visitors overlapped with flowering peaks in the late successional stages, but this was not consistently the case in the early and intermediate stages. Plant‐floral visitors networks differed in structure according to successional stage and season, but specialisation metrics were higher in late successional stages. Interaction networks were more dissimilar between dry and rainy seasons within successional stages than within seasons between successional stages, suggesting connectivity across successional sites during each season. In addition, closely related plant species do not share the same pollination systems in any successional stage. 4. Synthesis. Our results showed that plant‐floral visitor interactions are dynamic and vary with flowering phenology and with successional changes in plant and animal diversity. Plant‐floral visitor interactions were more diverse and specialised in the late successional stages. In the rainy season, differences in network structure among successional stages are due to interaction rewiring, while in the dry season it is caused by species turnover. Our results demonstrate that seasonality plays a key role in community diversity and network structure and highlight the importance of conserving mature forests to ensure the maintenance of critical pollination interactions across all successional stages.
... Knowledge of the behaviour, nesting biology, floral preferences and chemical ecology of southern hemisphere colletids is far from complete, and detailed studies are few. This is not unexpected when the majority of bee species are ground nesters (Cane 2003;Antoine and Forrest 2021) and are much more difficult to study than cavity nesters (Winfree 2010). Consequently, generalisations about their nesting biology might be unreliable, and novel facts might yet emerge. ...
Trichocolletes orientalis is an Australian solitary, ground-nesting bee, reported to have some unusual aspects to its nesting biology. Prime among these, and a focus for the present study, is the production of copious amounts of oil by post-feeding pre-defaecating larvae. To better understand the mechanism of oil production, we examined the bee’s floral resources and larval provisions and compared the fatty acid profiles of the provision and larval oil exudate using gas chromatography. The study population was monolectic on the legume Hardenbergia comptoniana. Unusually for Neopasiphaeinae, larval provisions were liquid but contained no obvious free oil. Differences in the fatty acid composition of the provision and larval oil lead us to conclude that larvae must secrete the oil. Fully fed larvae prevented from curling produced a yellowish, non-oily liquid from the anus. The Malpighian tubules are implicated in the production of this liquid and perhaps the oil (which has not been reported for any other bee species). While likely preventing water loss from resting larvae, the oil contains some fatty acids with known antimicrobial and antifungal properties and might protect the larvae from pathogens. Additionally, we provide a complete life cycle calendar for the bee.
... Over the last two decades, there has been substantial interest in the status of pollinators (Allen-Wardell et al. 1998;Kevan and Phillips 2001;Marlin and LaBerge 2001;Biesmeijer et al. 2006;Berenbaum et al. 2007;Potts et al. 2010;Winfree 2010;Colla et al. 2012;Bartomeus et al. 2013;Lebuhn et al. 2013;Senapathi et al. 2015). With the possible exception of bumble bees (Cameron et al. 2011;Kerr et al. 2015), few wild bee taxa have been sufficiently well documented in North America to provide effective baseline data to reliably measure conservation status. ...
We record 392 species or morphospecies of bees (Hymenoptera: Apoidea) for Manitoba, Canada, which is 154 more species than reported in 2015 and includes five new generic records since 2015 ( Ashmeadiella , Brachymelecta , Eucera, Neolarra, and Triepeolus ). Thirteen new records reported here are new for Canada: Calliopsis ( Nomadopsis ) australior Cockerell, Perdita ( Perdita ) tridentata Stevens, Brachymelecta interrupta (Cresson), Diadasia ( Dasiapis ) ochracea (Cockerell), Melissodes bidentis Cockerell, Nomada crawfordi crawfordi Cockerell, Nomada fuscicincta Swenk, Nomada sphaerogaster Cockerell, Nomada xantholepis Cockerell, Triepeolus cf. grindeliae Cockerell, Dianthidium ( Dianthidium ) parvum (Cresson), Coelioxys ( Xerocoelioxys ) nodis Baker, and Megachile ( Megachiloides ) dakotensis Mitchell. We remove the following species from the list of Manitoba bees based on re-examination of voucher material: Andrena ( Ptilandrena ) geranii Robertson, Andrena ( Rhacandrena ) robertsonii Dalla Torre, Andrena ( Simandrena ) nasonii Robertson, Andrena ( Trachandrena ) ceanothi Viereck, Andrena ( Trachandrena ) quintilis Robertson, Lasioglossum ( Hemihalictus ) pectoraloides (Cockerell), Lasioglossum ( Lasioglossum ) forbesii (Robertson), and Dianthidium ( Dianthidium ) concinnum (Cresson). We propose that Nomada alpha paralpha Cockerell, 1921 and N. alpha dialpha Cockerell, 1921 are junior synonyms of N. alpha Cockerell, 1905. Nomada arenicola Swenk, 1912 is considered a junior synonym of N. fervida Smith, 1854. Protandrena albertensis (Cockerell) and Neolarra mallochi Michener are recognised as valid species. We provide additional notes on taxonomy, nomenclature, and behaviour for select species in the list.
... Wild (+): living in a state of nature and not tame or domesticated (Merriam-Webster 2022); uncontrolled, violent, or extreme (Cambridge, 2022); [bees] not managed by humans (Mallinger et al., 2017;Winfree, 2010). ...
Effectively promoting the stability and quality of ecosystem services involves the successful management of domesticated species and the control of introduced species. In the pollinator literature, interest and concern regarding pollinator species and pollinator health dramatically increased in recent years. Concurrently, the use of loaded terms when discussing domesticated and non-native species may have increased. As a result, pollinator ecology has inherited both the confusion associated with invasion biology’s lack of a standardized terminology to describe native, managed, or introduced species as well as loaded terms with very strong positive or negative connotations. The recent explosion of research on native bees and alternative pollinators, coupled with the use of loaded language, has led to a perceived divide between native bee and managed bee researchers. In comparison, the bird literature discusses the study of managed (poultry) and non-managed (all other birds) species without an apparent conflict with regard to the use of terms with strong connotations or sentiment. Here, we analyze word usage when discussing non-managed and managed bee and bird species in 3614 ecological and evolutionary biology papers published between 1990 and 2019. Using time series analyses, we demonstrate how the use of specific descriptor terms (such as wild, introduced, and exotic) changed over time. We then conducted co-citation network analyses to determine whether papers that share references have similar terminology and sentiment. We predicted a negative language bias towards introduced species and positive language bias towards native species. We found an association between the term invasive and bumble bees and we observed significant increases in the usage of more ambiguous terms to describe non-managed species, such as wild . We detected a negative sentiment associated with the research area of pathogen spillover in bumble bees, which corroborates the subjectivity that language carries. We recommend using terms that acknowledge the role of human activities on pathogen spillover and biological invasions. Avoiding the usage of loaded terms when discussing managed and non-managed species will advance our understanding and promote effective and productive communication across scientists, general public, policy makers and other stake holders in our society.
... These ecosystems have higher levels of bee abundance when compared to ecosystems dominated by anthropogenic activities and contain crucial habitats for bee communities (Figure 1) (Koh et al. 2016;Carril et al. 2018). Yet restoration strategies for pollinators have primarily been developed within agroecosystems as opposed to seminatural ecosystems (Winfree 2010 ...
Individual plant species play valuable roles in meeting restoration goals for pollinators. However, the selection of plant species for pollinator restoration is rarely informed using empirical evidence and is usually developed in agroecosystems, which experience frequent human interventions to ensure plant success as compared to seminatural ecosystems. We highlight concepts and future research needs to design planting mixes that fulfill the ecological requirements of pollinators in seminatural ecosystems. Native plants that are attractive to pollinators, increase the stability of pollination services, and provide consistent floral resources across the landscape and growing season should be prioritized in pollinator restoration projects in seminatural ecosystems. Furthermore, condensing criteria of desirable plant traits into a composite score can aid managers in selecting plant species that meet restoration goals. Developing restoration strategies for pollinators on seminatural lands is important for preserving organisms essential for biodiversity maintenance and ecosystem function.
... If not all of these resources are available in a single habitat, wild bees may complementarily use both habitats. For example, wild bees use food resources in open landscapes while using nesting resources in forests (Mandelik et al. 2012;Winfree 2010). Therefore, forest road verges may offer critical food resources not only to forest-associated species but also to ubiquitous species and species associated with open landscapes. ...
... Gathering information about the specific use of flowering resources within habitats is essential for conservation efforts for wild bees (Winfree 2010;Jha, Stefanovich, and Kremen 2013). In this study, we took a closer look at the pollen use of the common carder bee to illustrate its use of forest road verge resources and to clarify which resources are especially important for them. ...
Forests in Germany are occupied with roads, paths, and trails with a density of 5.03 km/km². Their construction and maintenance create a network of verges promoting flowering plants. Whether these verges are visited by bees, which factors are determining their abundance, diversity, and composition, and which flowering resources are used is unknown. We selected 13 verges in the Black Forest (Germany), sweep-netted wild bees along transects, calculated the flowering area of all herbs, and measured the area (hectares) of grassland within 1 km around the transects. To evaluate the resource use of a common bumblebee species, we analyzed the pollen load of common carder bees (Bombus pascuorum) using microscopes. The abundance and diversity of wild bees was positively related to flowering area. With an increasing area of grassland, the abundance of ubiquitous species increased. Wild bee community composition was driven by flowering area. Common carder bees collected pollen from several flower resources but mainly used few species, such as the common hemp nettle (Galeopsis tetrahit L.). As the flowering area influenced wild bee abundance, diversity, and composition, we suggest creating road verges that favor the occurrence of native flowering plants to support wild bees in forest ecosystems.
Study Implications: Forest road verges generally have higher light availability than the forest interior and therefore have higher availability of flowering plants. Although the importance of verges for wild bee conservation in agricultural landscapes is known, forest road verges are understudied. Our study demonstrates that forest road verges are important habitats for many ubiquitous bees and that the flowering area on these verges is the key determinant for the abundance and diversity of wild bees. Therefore, creating road verges that favor the occurrence of native flowering plants is key to support bees on these verges.
