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. 

Honey bee with 'pollen pants' on hind tibia (ATTTA ©, 2024)

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.

Honey bee foraging wild blueberry flower (ATTTA ©, 2024)

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

Connecting with ATTTA Specialists

If you’d like to connect with ATTTA specialists or learn more about our program, you can:

visit our website at https://www.perennia.ca/portfolio-items/honey-bees/

Email attta@perennia.ca

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.

Honey bees rely on more than just good nutrition to stay healthy, but also depend on a stable and diverse gut microbiome. This internal community of microbes supports digestion, strengthens immunity and helps honey bees resist disease. But parasites like Nosema spp. can invade the gut and disrupt their microbiome, threatening colony health.

Bee Alert: Attack of the Microsporidia

Nosema spp. are a microsporidian parasite that attacks the midgut of adult honey bees¹. The genus is being reviewed as Vairimorpha.  It is a spore-forming organism that is phylogenetically related to fungi ². Three types of microsporidia are known to infect honey bees Nosema apis, Nosema ceranae, and Nosema neumanni ³. Of these, N. apis and N. ceranae are the most common and widespread. The size of N. apis is about 6x3 μm, and N. ceranae are around 4.7 x 2.7 μm ³.  Transmission occurs when bees ingest spores through contaminated food or during grooming ³. Once inside the digestive tract, the spores attack the gut lining, damaging the tissue and can potentially spread to the hemolymph, which may cause septicemia ³.

Nosema ceranae specifically targets the midgut epithelium, which is the tissue responsible for nutrient absorption ⁴. As infection occurs, the bee’s ability to digest and absorb nutrients declines. This damage may lead to dysentery and weakened immunity. Dysentery is more common in N. apis ³ with the dominant species being N. ceranae. While most beekeepers might assume that increased sucrose consumption is a sign of healthy, active bees, infected bees often consume more sucrose and are less likely to share food with their colony, which can disrupt social dynamics due to behavioural changes and impact the whole colony ⁴.

Figure 1: Nosema Spores (circled) Viewed Under a Microscope (400X) (ATTTA©2020)

Beyond damaging the gut lining, Nosema spp. also disrupts the balance of beneficial microbes that live in the bee’s digestive system. Core bacteria like Snodgrassella alvi play a crucial role in maintaining gut health. Snodgrassella consumes oxygen in the ileum, creating an anaerobic environment for beneficial microbes ⁶. It also forms biofilms that protect the gut lining and has been shown to reduce spore loads of N. ceranae in infected bees ¹. These microbes are essential in stabilizing the gut environment and supporting immune function.

However, the effectiveness of microbial defense against pathogens can be influenced by diet. A recent study has shown that nutritional stress can accelerate the reproduction of N. ceranae, especially in early stages of infection ⁵. Bees fed low-quality pollen, such as Eucalyptus grandis, which lacks essential proteins, lipids, and the amino acid isoleucine, tend to carry higher spore loads than those fed diverse, polyfloral pollen ⁵. This highlights the importance of a nutritionally rich diet in maintaining gut health and resisting infection.

Figure 2: Healthy Bees (ATTTA©, 2024)

Poor nutrition does not just affect the spore loads of Nosema but also alters the composition of the gut microbiome. From studies, it has also been found that poor diets can have a reduction in bacteria like Lactobacillus and Bifidobacterium, which are both core gut bacteria in honey bees ⁵. Bifidobacteria, for example, are involved in producing hormones and signal molecules that may influence immunity and development in the gut ⁶. When these microbes decline, bees may become more vulnerable to infections like Nosemosis, as their immune defenses are compromised ⁷. This disruption in the microbiome can have broader implications for colony health, like reduced longevity and overwintering success.

The honey bee gut is not just a site of digestion but also an important ecosystem that is vital for defending against pathogens and supporting proper health. When parasites like Nosema spp. damage the midgut, they disrupt nutrient absorption and the balance of beneficial microbes, making bees more vulnerable to disease. Beekeepers should regularly monitor for Nosema to help protect colony health. The Atlantic Tech Transfer Team of Apiculture offers Nosema testing to help detect this disease. Supporting gut health through good nutrition and monitoring to identify when treatment is necessary helps maintain strong and healthy hives!

Written by Kaitlyn Newton, ATTTA Seasonal Apiculturist 

Connecting with ATTTA Specialists

If you’d like to connect with ATTTA specialists or learn more about our program, you can:

visit our website at https://www.perennia.ca/portfolio-items/honey-bees/

Email attta@perennia.ca

References:

1    Motta, E.V. and Moran, N.A., 2024. The honeybee microbiota and its impact on health and disease. Nature Reviews Microbiology, 22(3), pp.122-137.

2.     Zhang, Y., Su, M., Wang, L., Huang, S., Su, S. and Huang, W.F., 2021. Vairimorpha (Nosema) ceranae infection alters honey bee microbiota composition and sustains the survival of adult honey bees. Biology, 10(9), p.905.

3.     Galajda, R., Valenčáková, A., Sučik, M. and Kandráčová, P., 2021. Nosema disease of European honey bees. Journal of Fungi, 7(9), p.714.

4.     Lau, E., Maccaro, J., McFrederick, Q.S. and Nieh, J.C., 2024. Exploring the interactions between Nosema ceranae infection and the honey bee gut microbiome. Scientific Reports, 14(1), p.20037

5.     Castelli, L., Branchiccela, B., Garrido, M., Invernizzi, C., Porrini, M., Romero, H., Santos, E., Zunino, P. and Antúnez, K., 2020. Impact of nutritional stress on honeybee gut microbiota, immunity, and Nosema ceranae infection. Microbial ecology, 80, pp.908-919.

6.     Bonilla-Rosso, G. and Engel, P., 2018. Functional roles and metabolic niches in the honey bee gut microbiota. Current opinion in microbiology, 43, pp.69-76.

7.     Meehan, D.E. and O’Toole, P.W., 2025. A Review of Diet and Foraged Pollen Interactions with the Honeybee Gut Microbiome. Microbial Ecology, 88(1), pp.1-14.