Precision glycerine jelly swab for removing pollen from small and fragile insect specimens

Historical datasets can establish a critical baseline of plant-animal
interactions for understanding contemporary interactions in the context of
global change. Pollen is often incidentally preserved on animals in
natural history collections. Techniques for removing pollen from insects
have largely been developed for fresh insect specimens or historical
specimens with large amounts of pollen on specialised structures. However,
many key pollinating insects do not have these specialised structures and
thus, there is a need for a method to extract pollen from these small, and
fragile insects. Here, we propose a precision glycerine jelly swab tool to
allow for the precise removal of pollen from old, small, and fragile
insect specimens. We use this tool to remove pollen from five families of
insects collected in the late 1970s. Additionally, we compare our method
with four previously published techniques for removing pollen from pinned
contemporary specimens. We show the functionality of the precision
glycerine jelly swab for removing small quantities of pollen across insect
families. We found that across the five methods, all removed pollen; yet,
it was clear that some are better suited for fragile specimens. In
particular, the traditional glycerine jelly swab and the precision
glycerine jelly swabs both performed well for removing pollen from bee
faces. The shaking wash resulted in specimen fracture and residue left
behind, the ethanol rinses left setae matted, and the glycerol swabbing
left residue on the specimen. Additionally, we present photographs
documenting the effects of these methods on pinned honey bee specimens.
The precision glycerine jelly swab opens up opportunities to sample pollen
from a variety of insects in natural history collections. These pollen
samples can be incorporated into downstream analyses for pollen
identification either via microscopy or DNA sequencing, and the resulting
plant-insect interaction data can establish historical baselines for
contemporary comparison. Beyond our application of this method to pollen
on insects, this precision glycerine jelly swab tool could be used to
explore pollen placement specialisation or to sample bryophyte, fungal,
and tree fern spores dispersing on animals.