Evaluation of four different methods for assessing bee diversity as ecological indicators of agro-ecosystems

Krahner, André; Schmidt, Juliane; Maixner, Michael; Porten, M.; Schmitt, Thomas

doi:10.1016/j.ecolind.2021.107573

Cited by 25 publications

(29 citation statements)

References 51 publications

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“…We confirm the results of previous work showing that individual survey methods are biased towards different components of pollinator communities (O'Connor et al, 2019; Westphal et al, 2008), with the relative effectiveness of survey methods differing according to taxon (Prendergast et al, 2020). Our results concur with the results of a recent assessment of the performance of different methods to sample wild bees in a single and different crop (vineyards) habitat (Krahner et al, 2021). As in our study, there was evidence of an effect of body size and guild on the capacity of survey methods to sample bee pollinators.…”

Section: Discussionsupporting

confidence: 92%

“…Whilst monitoring schemes for pollinator communities are emerging (Carvell et al, 2017; Potts et al, 2021), a specific emphasis on crop pollinators in agricultural settings is vital to safeguard crop production (Garibaldi et al, 2020). Whilst several studies have compared wild bee sampling methods, they are rarely carried out in crop areas, or consider multiple different crops (Krahner et al, 2021 and references therein). Furthermore, where studies have been carried out in crop habitats (O'Connor et al, 2019; Westphal et al, 2008) they have included the entire bee species community, and thus likely many non‐crop pollinating bee species.…”

Section: Discussionmentioning

confidence: 99%

“…Whilst many studies have evaluated different sampling techniques, results can be conflicting, and may be contingent upon the study system being tested. For example, pollinator size and trap colour may influence the efficacy of different sampling methods (Krahner et al, 2021). Furthermore, assessments of sampling techniques are predominantly carried out in non-crop areas (McCravy, 2018), or do not focus specifically on crop habitats, nor account for the impacts of crop type on results.…”

Section: Introductionmentioning

confidence: 99%

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Inventorying and monitoring crop pollinating bees: Evaluating the effectiveness of common sampling methods

Hutchinson

Oliver

Breeze

et al. 2021

Insect Conserv Diversity

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1. Wild bees provide a critical ecosystem service by pollinating globally important crops. Documented bee declines, notably in agricultural landscapes, therefore threaten future food security. Yet, evaluations of methods to inventory bees are rarely carried out in different crops or focus specifically upon crop pollinating species.2. We utilise standardised field datasets to elucidate differences in the capacity of transect walks, observation plots and pan traps to sample wild bee pollinator communities in four contrasting crops. Our results indicate that individual survey methods detect different components of crop pollinator communities, with guild and body size potentially important causal factors behind these differences.3. Transects detected half or less of the total potential pollinator community in three of our four study crops. Whilst transects were the most efficient method for sampling bumblebees, they often missed smaller solitary species, which were most efficiently sampled by yellow pan traps.4. Crop type is likely an important determinant of the most suitable survey methods to sample bee pollinator communities. Whilst transects alone are sufficient in crops pollinated predominantly by bumblebees, pan traps, and potentially observation plots, may be an important addition in some crops where smaller solitary bee species are potentially important pollinators. 5. Our results indicate that the most efficient methods to sample bee species in agricultural landscapes are dependent upon crop type and pollinator community composition. We use our findings to make a set of recommendations on the inventorying and monitoring of bee pollinator crop communities that can inform regional and national monitoring programmes.

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Section: Discussionsupporting

confidence: 92%

Section: Discussionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Inventorying and monitoring crop pollinating bees: Evaluating the effectiveness of common sampling methods

Hutchinson

Oliver

Breeze

et al. 2021

Insect Conserv Diversity

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“…Several investigations compared the efficiency of different methods in sampling hoverflies and especially bees [ 53 , 56 , 57 , 58 ]. Pan traps and entomological nets along transects proved to be the most efficient methods, though not fully exhaustive.…”

Section: Discussionmentioning

confidence: 99%

“…Both hoverflies and bees were sampled by coloured pantraps: white, blue, and yellow, as suggested in current literature [ 53 , 54 , 55 ]. Pan traps and active netting along transects are considered the most suitable methods to sample bees for their efficiency, repeatability, and standardization [ 53 , 56 , 57 , 58 ]. We decided to use pan traps instead of entomological nets in order to avoid a potential sampling bias due to the collector; furthermore, given the high climate variability over time along the gradient, we preferred a sampling method that would reduce the field time.…”

Section: Methodsmentioning

confidence: 99%

Different Distribution Patterns of Hoverflies (Diptera: Syrphidae) and Bees (Hymenoptera: Anthophila) Along Altitudinal Gradients in Dolomiti Bellunesi National Park (Italy)

Sommaggio

Zanotelli

Vettorazzo³

et al. 2022

Insects

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Hoverflies (Diptera: Syrphidae) and bees (Hymenoptera: Anthophila) are two key taxa for plant pollination. In the present research, the altitudinal distribution of these taxa was studied along two gradients (elevation range: 780–2130 m) in the Dolomiti Bellunesi National Park (Northeastern Italy). Pan traps were used as a sampling device to collect both hoverflies and bees. Other than altitude, the effect of landscape complexity and plant diversity were considered as potential predictors of hoverfly and bee richness and abundance along the two gradients. A total of 68 species of hoverflies and 67 of bees were collected during one sampling year, confirming the efficacy of pan traps as a sampling device to study these taxa. Altitude was the main variable affecting both hoverfly and bee distribution. The two taxa show different distribution patterns: hoverflies have a unimodal distribution (richness and abundance) with peak at middle altitude (1500 m), while bees have a monotonic decline (richness and abundance) with increasing altitude. Both hoverfly and bee populations change with the increasing altitude, but the change in hoverflies is more pronounced than in bees. Species turnover dominates the β-diversity both for hoverflies and bees; therefore, the hoverfly and bee communities at higher altitudes are not subsamples of species at lower altitude but are characterized by different species. This poses important conservation consequences. Some rare species, typical of an alpine habitat were recorded; the present research represents important baseline data to plan a monitoring scheme aimed at evaluating the effect of climate change on pollinators in these fragile habitats.

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Fewer bowl traps and more hand netting can increase effective number of bee species and reduce excessive captures

Larson,

Pennarola,

Leone

et al. 2024

Ecology and Evolution

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Reports increasingly point to substantial declines in wild bee abundance and diversity, yet there is uncertainty about how best to measure these attributes in wild bee populations. Two commonly used methods are passive trapping with bee bowls or active netting of bees on flowers, but each of these has drawbacks. Comparing the outcomes of the two methods is complicated by their uncomparable units of effort. The abundance distribution of bee species is also typically highly skewed, making it difficult to accurately assess diversity when rarer species are unlikely to be caught. The effective number of species, or Hill numbers, provides a way forward by basing the response metric on the number of equally abundant species. Our goal is to compare the effective number of bee species captured between hand netting and bowl trapping in wheatgrass prairie in South Dakota and tallgrass prairie in Minnesota, USA. Species overlap between the two methods ranged from ~40% to ~60%. Emphasis placed on rare species was important, so that 95% confidence limits overlapped between the two methods for species richness but netting exceeded trapping for Shannon's and Simpson's diversities. Netting always captured more bee species with fewer bee individuals than trapping. In most cases, the number of bees captured in bowl traps indicated substantial over‐sampling, with little increase in bee species detected. Correlations between bee and floral abundance, richness, and diversity differed between netted and trapped samples. We conclude that netting and trapping together produce a more complete account of species richness, but shifting sampling emphasis from trapping to netting will result in fewer bees, but more bee species captured. Due to the different relationships between bee and floral diversities that depended on sampling method, it is unwise to compare habitat associations determined by netting with those determined by trapping.

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Evaluation of four different methods for assessing bee diversity as ecological indicators of agro-ecosystems

Cited by 25 publications

References 51 publications

Inventorying and monitoring crop pollinating bees: Evaluating the effectiveness of common sampling methods

Inventorying and monitoring crop pollinating bees: Evaluating the effectiveness of common sampling methods

Different Distribution Patterns of Hoverflies (Diptera: Syrphidae) and Bees (Hymenoptera: Anthophila) Along Altitudinal Gradients in Dolomiti Bellunesi National Park (Italy)

Fewer bowl traps and more hand netting can increase effective number of bee species and reduce excessive captures

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