Diversity and Pollen Loads
In total 3352 insects were observed; of those 972 were Apis
mellifera (29%), 496 were other bees (15%), and 1884 were non-bee
flower visitors (56%) (Supplementary Table 1).
In addition, a total of 604 insects were collected and successfully
sequenced (GenBank Accessions OQ622469 – OQ623072). 515 of those were
non-bee visitors belonging to 4 orders, 29 families, 53 genera, 62
species (Table 2; Supplementary Table 2). Sequence read lengths ranged
from 359 to 658 bp, with an average of 644 bp. For pollen load
comparison 89 bee specimens were caught and successfully sequenced, 26
were assigned species level identification representing three families
containing 13 species (Table 2). For two genera (Nomada andSphecodes ) DNA barcodes did not provide consistent
identifications due to a poorly parameterized reference library on BOLD.
Consequently, both were excluded from pollen counts.
When considering only the data from collected specimens, the non-bee
families which contributed the most pollen (average pollen count x
abundance) were flies of the families Syrphidae, Polleniidae and
Anthomyiidae (Figure 1a). Overall, the species that carried the most
pollen (in the order of 10,000-70,000 pollen grains on average per
individual) were Eristalis tenax > Eristalis
similis > Halictus confusus >Lasioglossum pectorale > Ceratina mikmaqi
> Neocnemodon coxalis > Callirhytis
tumifica > Bombus impatiens (Figure 1b; Table 2).
Of the non-bee flower visitors, 30 of the 53 genera caught, had pollen
loads that were not significantly different in size from the genus of
bee (Halictus ) with the highest pollen count (Table 3).Eristalis was the only genus that carried more pollen thanHalictus (Figure 1b; Table 3). Variation in pollen load size was
substantial, even within a species group. For example, Eristalis
tenax individual loads ranged from 1,617- 316,300 pollen grains (Table
2).