A foraging insect has the potential to be a good pollinator, but not all foragers pollinate crops effectively. This could be due to foragers that are also flower eaters, foragers that are known as cheaters, or foragers that do not have the most efficient foraging physiology. The goal of using managed insects in a fruit crop, such as wild blueberries, is to find a foraging insect that will make the most efficient and effective pollination unit. Bees, such as honey bees, bumblebees, and alfalfa leafcutter bees, are the only managed pollinators that are used to pollinate wild blueberry crops in Atlantic Canada. Bees have many anatomical features that aid in foraging, and this is why bees are typically considered the most effective and efficient pollinators.
Bee Foraging Physiology
The most efficient pollinator is the right shape and size, relative to the shape and size of the flowers they visit. This is because some parts of the pollinator’s body should be very close to or touching the anther of the flower to passively collect pollen during foraging activities [6]. The pollen that is actively collected is typically used by bees, so it is the passively collected pollen that gets transferred to the stigma of another flower for pollination. Flowers accumulate a negative charge and flying insects accumulate a positive charge, which allows these foragers to passively pick up pollen, through electroreception, as their body moves past anthers of a flower and carries it to another [1].
Pollen best adheres to fur or hair on a forager. If the surface of the forager is shiny, waxy, or contains chemicals then the pollen may not adhere to the forager or pollen could potentially be damaged, resulting in poor pollination [6]. Some bees, such as honey bees and bumblebees, can collect pollen on their corbiculae, which is a protrusion on the posterior of the hind tibia, also known as ‘pollen pants’. These bees collect pollen grains scattered on their bodies through different methods of grooming and pollen packing [8]. The methods used to groom and pack pollen by honey bees can damage pollen and reduce efficacy of pollination, unlike bumblebees. This is why passive pollen collection is important for successful pollination when using honey bees as pollinators. Bees may visit many flowers before returning to their hive, potentially pollinating flowers with the loose pollen on their body.
Bees have two pairs of wings which are connected to work as a single pair of wings. These wings are attached by V-shaped hooks, called hamuli [5]. The hamuli are flexible, durable, and help increase surface area. These traits aid with flight, which helps the bees create additional lift when the bee is heavier with foraging resources and needs to travel long distances or avoid predators [9].
Honey bees are generalist foragers, meaning they collect pollen and nectar from many different floral sources. To be able to forage nectar with differing concentrations of sugar, bees can either suck or lap, depending on the viscosity of the nectar [11]. The fluid intake rate for sucking becomes more efficient than lapping at sugar concentrations lower than 30% [6]. Honey bees also have a crop, or honey stomach, to temporarily store honey to bring back to the hive, which can make up to a third of the bee’s weight [4,7]. Therefore, honey bees can travel from flower to flower, collecting a lot of nectar before going back home and this will also help with pollination efforts.
Insects of the Hymenoptera order, containing bee species, possess two to three times the number of genes for olfactory receptors than insects of the Diptera order, containing fly species [2]. Gene expression for olfactory receptors occurs in the bee’s information-gathering sense organ, the antenna [3]. Honey bees’ antennae are used to detect and respond to vibrations, electrical charges, and changes in temperature, humidity, and air quality, such as levels of carbon dioxide [1,6]. Bees also use the Organ of Johnston to detect sound and speed of movement, through changes in vibration [10]. This helps bees to adjust the pitch of their body and reduce drag while flying as well as detecting dances of other bees to find foraging resources.
Bees are typically considered the best pollinator due to the many anatomical traits they have to help with foraging. There are also many behavioral traits that bees have, to help with foraging, both on an individual and colony level. Please read the upcoming blog for more information on bee foraging behavior.
Written by John MacDonald, ATTTA Seasonal Apiculturist
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References:
[1] Clarke, D., Morley, E., Robert, D. 2017. ‘The bee, the flower, and the electric field: electric ecology and aerial electroreception’, Journal of Comparative Physiology A, 203:737-748.
[2] De Bruyne, M., Baker, T.C., 2008. ‘Odor detection in insects: volatile codes’, Journal of Chemical Ecology, 34 (7):882–897.
[3] Fialho, M.Q., Guss-Matiello, C.P., Zanuncio, J.C., Campos, L.O., Serrão, J.E., 2015. ‘A comparative study of the antennal sensilla in corbiculate bees’, Journal of Apiculture Research, 53 (3):392–403.
[4] Harano, K.I., Mitsuhata-Asai, A., Konishi, T., Suzuki, T., Sasaki, M., 2013. ‘Honeybee foragers adjust crop contents before leaving the hive’, Behavioral Ecology and Sociobiology, 67 (7):1169–1178.
[5] Ma, Y., Ren, H., Ning, J., Gorb, S., 2022. ‘The combination of structure and material distribution ensures functionality of the honeybee wing-coupling mechanism’, Soft Matter 18 (5):956–963.
[6] Nearman, A., vanEngelsdorp, D. 2024. ‘Chapter 2 - Honey bee adaptations for foraging’, The Foraging Behavior of the Honey Bee (Apis mellifera)’, 45-64.
[7] Nicolson, S.W., Human, H., 2008. ‘Bees get a head start on honey production’, Biology Letters, 4:299–301.
[8] Parker, J.A., Tran, J.L., Ison, J.L., Bai, J.D., Weis, A.E., Thomson, J.D. 2015. ‘Pollen packing affects the function of pollen on corbiculate bees but not non-corbiculate bees’, Arthropod-Plant Interactions, 9:197-203.
[9] Sudo, S., Tsuyuki, K., Ito, Y., Tani, J., Wada, H., 2001. ‘The wing apparatus and flapping behavior of Hymenoptera’, JSME International Journal Series C: Mechanical Systems, Machine Elements and Manufacturing, 44 (4):1103–1110.
[10] Taylor, G.J., Luu, T., Ball, D., Srinivasan, M.V., 2013. ‘Vision and air flow combine to streamline flying honeybees’, Scientific Reports, 3.
[11] Wei, J., Huo, Z., Gorb, S.N., Rico-Guevara, A., Wu, Z., Wu, J., 2020. ‘Sucking or lapping: facultative feeding mechanisms in honeybees (Apis mellifera)’, Biology Letters, 16 (8):20200449.