Pollen report: Quantitative review of pollen crude protein concentrations offered by bee pollinated flowers in agricultural and non-agricultural landscapes

Abstract

To ease nutritional stress on managed as well as native bee populations in agricultural habitats, agro-environmental protection schemes aim to provide alternative nutritional resources for bee populations during times of need. However, such efforts have so far focused on quantity (supply of flowering plants) and timing (flower-scarce periods) while ignoring the quality of the two main bee relevant flower-derived resources (pollen and nectar). As a first step to address this issue we have compiled a geographically explicit dataset focusing on pollen crude protein concentration, one measurement traditionally associated with pollen quality for bees. We attempt to provide a robust baseline for protein levels bees can collect in- (crop and weed species) and off-field (wild) in agricultural habitats around the globe. Using this database we identify crop genera which provide sub-optimal pollen resources in terms of crude protein concentration for bees and suggest potential plant genera that could serve as alternative resources for protein. This information could be used by scientists, regulators, bee keepers, NGOs and farmers to compare the pollen quality currently offered in alternative foraging habitats and identify opportunities to improve them. In the long run we hope that additional markers of pollen quality will be added to the database in order to get a more complete picture of flower resources offered to bees and foster a data-informed discussion about pollinator conservation in modern agricultural landscapes.

Are honeybees suitable surrogates for use in pesticide risk assessment for non‐Apisbees?

“…The fundamental nature of scaling laws also influences toxicology with the sensitivity of organisms towards a range of xenobiotics exhibiting compound‐specific scaling relationships . A conserved scaling relationship for the acute toxicity (LD 50 ) of bees towards the acetylcholinesterase‐inhibiting insecticides (organophosphorus and carbamate classes) has also been suggested with A. mellifera as a sensitive bee species on a per bee and even more so on a per weight bee basis, even when compared with the smallest bees of the data set, Brazilian stingless bees (Tribe Meliponini) . In this case, the LD 50 values for these acetylcholinesterase inhibitors scaled proportionally with body weight (i.e.…”

How much pollen do solitary bee larvae consume? : Or establishing realistic exposure estimates of solitary bee larvae via pollen for the use in risk assessment

“…Because pollinator exposure assessment is based on the provisioned pollen and the expected or measured PPP residues within it we rescaled the protein prediction model (Equation 2), assuming a median pollen protein concentration of 29.1% (Pamminger, Becker et al 2019), to directly predict the corresponding amount of pollen [mg] likely provisioned by a generalist SB based on their body weight. …”

“…SBs often provide their offspring with a single provision of unprocessed pollen of known host plant origin (Westrich 2018, Danforth, Minckley et al 2019), which makes it possible to extrapolate their pollen needs directly from their protein requirements whenever the pollen protein concentration of the host plant(s) is known (Pamminger, Becker et al 2019). In this case our pollen provision model is based on the median protein concentration found in the pollen of bee pollinated flowers which is likely a good approximation for pollen generalist bees.…”

“…In contrast to the majority of bees A. mellifera is highly social (Danforth, Minckley et al 2019), which can have important consequences for the RA in particular for the expected exposure of different developmental stages and scenarios as they do not directly provide pollen to their offspring (Boyle, Pitts-Singer et al 2019). While the currently implemented A. mellifera centered pollinator RA schemes are likely protective for solitary bees (SB) as well (Boyle, Pitts-Singer et al 2019, Thompson and Pamminger 2019) it is unclear if this also extends to exposure routs not directly addressed in current pollinator risk assessments (Boyle, Pitts-Singer et al 2019). One of these alternative exposure routes is related to developing SB, which in contrast to honeybees often feed on a single provision of unprocessed, and potentially PPP contaminated pollen mixed with varying degrees of nectar (Boyle, Pitts-Singer et al 2019).…”

Establishing realistic exposure estimates of solitary bee larvae via pollen for use in risk assessment

“…SB often provide their offspring with a single provision of unprocessed pollen of known host plant origin (Danforth et al, 2019;Westrich, 2018), which makes it possible to extrapolate their pollen needs directly from their protein requirements whenever the pollen protein concentration of the host plant(s) is known (Pamminger et al, 2019). In this case our pollen provision model is based on the median protein concentration found in the pollen of bee-pollinated flowers, which seems acceptable as a starting point to predict the needs of pollen generalist bees such as O. bicornis (Westrich, Using this model, we were able to predict the pollen needs of the known pollen generalist O. bicornis (Westrich, 2018), supporting the validity of the model as an extrapolation starting point for O. bicornis pollen needs (see Figure 3).…”