Humidity-tolerant rate-dependent capillary viscous adhesion of bee-collected pollen fluids

Abstract

We report a two-phase adhesive fluid recovered from pollen, which displays remarkable rate tunability and humidity stabilization at microscopic and macroscopic scales. These natural materials provide a previously-unknown model for bioinspired humidity-stable and dynamically-tunable adhesive materials. In particular, two immiscible liquid phases are identified in bioadhesive fluid extracted from dandelion pollen taken from honey bees: a sugary adhesive aqueous phase similar to bee nectar and an oily phase consistent with plant pollenkitt. Here we show that the aqueous phase exhibits a rate-dependent capillary adhesion attributed to hydrodynamic forces above a critical separation rate. However, the performance of this adhesive phase alone is very sensitive to humidity due to water loss or uptake. Interestingly, the oily phase contributes scarcely to the wet adhesion. Rather, it spreads over the aqueous phase and functions as a barrier to water vapor that tempers the effects of humidity changes and stabilizes the capillary adhesion.

Overview of Bee Pollination and Its Economic Value for Crop Production

“…The mutualistic relationship between plants and honey bees results from the exchange of nectar and pollen. Bees play a vital role in the pollination of plants [40], and plants secrete a rich liquid sugar similar to nectar from their glands to attract pollinators to their flowers so that the pollen can adhere to bee-collected pollen grains [42]. Researchers have found that honey bees (A. mellifera L.) appear to prefer crops rich with nectar and pollen in order to store large quantities of food, thus sustaining the colony growth and improving foraging performance [43,44].…”

Biomechanics of pollen pellet removal by the honey bee

“…They could also use adhesion tests with varying approach speeds to measure the pollen pellet's adhesion energy with the corbicula, such as with an AFM. Such techniques have previously been used for measuring pollen adhesion [36][37][38].…”

Bio-based and bio-inspired adhesives from animals and plants for biomedical applications

“… common name species family glue function Ref. barley hordeum vulgare poaceae attachment with hulls [ 47 ] chia salvia hispanica lamiaceae protection of germ [ 48 ] orchid phalaenopsis aphrodite orchidaceae pollen spreading [ 49 ] philodendron syngonium podophyllum araceae attachment [ 50 ] arabidopsis arabidopsis thaliana brassicales germination [ 51 ] tropical milkweed asclepias curassavica apocynaceae pollen spreading [ 52 ] dandelion taraxacum officinale asteraceae pollen spreading [ 53 ] fly bush roridula gorgonias roridulaceae prey capture [ 54 , 55 ] sundew drosera capensis drosera glanduligera drosophyllum lusitanicum droseraceae drosophyllaceae prey capture [ 42 , 56 , 57 ] ivy hedera helix parthenocissus tricuspidate araliaceae vitaceae attachment [ 37 , 38 ] aloe vera aloe barbadensis Miller asphodelaceae storage, protection from desiccation [...…”