Do Bees Self Medicate on Plant Medicine?


This week in the @naturalmedicine contest, we have a very cool and unique contest. We’re invited to write about 1 to 3 plants, namely Basil, Elecampane and Plantain. Wow, how fun! Check it out!

I have had some thoughts running through my mind as I learn climate change statistics surrounding insects. It’s grim and we need to do something quickly lest populations of insects continue to decline in rapid numbers. I wrote more about some of these side effects yesterday in Unbelievable Stats about Climate Change.

Yet what I want to focus on today, especially concerning the variety of Basil I’ve chosen to write about, Holy Basil, is the effects that adaptogenic (more on this term soon) plants have on insect immunity.

What’s an Adaptogen?

Adaptogens are becoming widely known and more often used every day, which is fantastic news for humanity.

Adaptogens are stress‐response modifiers that increase an organism’s nonspecific resistance to stress by increasing its ability to adapt and survive. 

Understanding adaptogenic activity: specificity of the pharmacological action of adaptogens and other phytochemicals

It is frequently said that adaptogens help bring the body’s systems into balance and each day more research is coming out about these amazing plants. Our herb of focus today, Holy Basil, is a supreme adaptogen – one of the best!

Holy Basil

It is well documented that Holy Basil, Ocimum tenuiflorum, is beneficial for the human organism. It’s one of my favorite plants and we grow her every year (well she comes back reseeding with vigor!) each year. We’ve written previously about here, here, and here. And we also sell a tincture of Holy Basil through @homesteader’s coop in our shop.

Our love for her really is incomparable, which is name she often goes by- the incomparable one!

If you’re interested in learning a more in depth profile that is scientifically comprehensive and contains historical lore, I suggest reading this article, Tulsi Queen of Herbs.

Yet, my interest today goes beyond the human realm, where the amazing immune supportive and boosting, holistic system adapting effects of Holy Basil are well documented.

Today I want to learn some new things about insects and their relationships with plants and if through growing adaptogenic, medicinal and immune-boosting plants in my garden, I can help strengthen the immune systems & disease resistance of our insect neighbors.

The Research

I have been researching for an hour so far and the first article I’ve found referencing any organism benefitting from adaptogens is this article: Plant adaptogens increase lifespan and stress resistance in C. elegans.

The adaptogens studied in this article are Siberian Ginseng and Rhodiola and C. elegans is a common nematode found in compost and garden soils. The researchers did find that the adaptogens elongated the lifespan of the nematode. The researchers concluded:

Based on these observations, it is suggested that adaptogens are experienced as mild stressors at the lifespan-enhancing concentrations and thereby induce increased stress resistance and a longer lifespan.


Let’s see what we can find surrounding insects’ immunity related to adaptogens, if anything.

Plants do affect immunity of insects

The first research paper I found referencing insect health relating to the plant they were eating is this study, Host plant variation plastically impacts different traits of the immune system of a phytophagous insect.

Basically they took a species of moth larvae and fed it different types of grapes and charted their immune responses. This paragraph stood out to me.

Antibiotic chemicals in host plants may indirectly provide protection against microbial pathogens to herbivorous insects, which could then maintain higher levels of immune defence against a range of other pathogens.

While I mainly saw an enormous amount of bees, flies and other flying insects on the pollen of the Holy Basil – rarely does our Holy Basil have any pest issues on the leaves, this is hopeful news that the constituents in the host plants have the ability to change the immunomodulation of the insects they’re in relation with.

I think in order to have any direction in my research, I’m going to have to focus in on a specific insect relationship and thinking of Manuka honey, which is well known for its incredible potency due to the Manuka flowers the bees feast on, I’m inspired to focus on bees, their honey and nectar.

This honey is a superfood sought out by humans and it is well known that their pollen, nectar, propolis and royal jelly are beneficial for humans, but what about the health of the bees that are the “intermediaries” so to say?

My line of thinking started to head this way as I saw soooo many honeybees on our Tulsi plants flying around with bright reddish orange Tulsi pollen collected on their legs! We know honey and propolis are amazing for human health, but is this benefitting the bees?

Honeybees world round are facing a lot of diseases and threats from Colony Collapse Disorder and pest issues. Out of 5 healthy wild swarms that we caught last year, only 1 is still with us (2 absconded and the rest died for unknown reasons – most likely because of hive beetles and weak colonies.)

I am so concerned with this research because I have a hunch that by growing medicinal plants with potent nectar & pollen, we can help boost the immunity of our insect populations.

Pollinator habitats are all the rage – and that’s a great thing! Many of the popular high nectar and pollen plants that are on popular lists are medicinal as well.

Insect Immunity

Here’s what we know about insect immunity:

Insects have diverse mechanisms to combat infection by pathogens. Many insects are protected by a layer of antimicrobial secretions on their exterior, and by a gut environment that is hostile to pathogens. When pathogens move beyond these defences, the epithelium is often sufficient to stop further progress. Should pathogens defeat the morphological defences of insects, they are often met by efficient cellular and humoral immune defences. Insect immunity shows many parallels to the innate immune responses of humans and other vertebrates, involving a diverse set of actions including the secretion of antimicrobial peptides, phagocytosis, melanization and the enzymatic degradation of pathogens

Further, insect immune pathways share both an overall architecture and specific orthologous components with the innate immune system of vertebrates 

This suggests both a shared root for these immune pathways and selection to conserve many components over hundreds of millions of years. 

source(emphasis mine)

This similarity in our immune function bodes hopeful for my hypothesis.

Nectar used as Medicine by Bees

Goldmine! Jackpot! I didn’t know the scientific wording for the question I was asking. Turns out I needed to research: secondary metabolites can reduce bee disease.

The following studies confirm my hypothesis that medicinal nectar & pollen is medicinal for bees.

Nectar chemistry mediates the behavior of parasitized bees: consequences for plant fitness

These results suggest that pollinators may be able to use nectar chemistry to self-medicate in the wild.

Previous research has demonstrated that insect herbivores can self medicate, changing their foraging behavior when parasitized and resulting in an increased consumption of secondary metabolites (Singer et al. 2009, Abbott 2014). Combined with the discovery that consumption of catalpol can lower Crithidia infection of B. impatiens (Richardson et al. 2015), our results suggest the interesting possibility that bumble bees may self medicate with iridoid glycosides when challenged by natural enemies, increasing visitation to flowers with high iridoid glycosides in nectar relative to uninfected bees. This potential self-medication behavior is not unique to bumble bees. For example, honey bees (Apis mellifera L.) increase their collection of plant resins (propolis) with antibiotic function in response to nest pathogens (Simone-Finstrom and Spivak 2012), and have been shown to increase consumption of nectar secondary metabolites with antibiotic properties when parasitized (Gherman et al. 2014). Our foraging experiment suggests that parasitized bumble bees return to the nest with greater quantities of nectar iridoid glycosides than uninfected conspecifics, ingestion of which should lower their Crithidia parasite load (Richardson et al. 2015). Bumble bees are social insects and workers make foraging decisions based both on individual and colony needs; we could thus have underestimated the importance of parasites in shaping bee foraging behavior, since many individuals from infected colonies show no sign of infection themselves (Otterstatter and Thomson 2007).

Essentially there is abundant research noting that bees under various types of health threats seek out medicinal properties of plants!

Here are some other notable studies:

‘Bee’ healthy: NMSU researchers study medicinal benefits of oregano for bees

What’s wonderful about this study is that they’re promoting the distribution of Monarda fistulosa (Bee balm or wild oregano), a very popular pollinator AND beautiful plant! (Actually this study is still in process, but I will be following its progress here. And here is a video talking about their research. Right along my lines of thinking and own observation!!!

Bee Disease Reduced By Nature’s “Medicine Cabinet,” Dartmouth-Led Study Finds

Flower pharmacies help bees fight parasites
& Secondary metabolites in floral nectar reduce parasite infections in bumblebees
& Consumption of a nectar alkaloid reduces pathogen load in bumble bees

Medicinal value of sunflower pollen against bee pathogens

Increased Resin Collection after Parasite Challenge: A Case of Self-Medication in Honey Bees?

Pharmacophagy and pharmacophory: mechanisms of self-medication and disease prevention in the honeybee colony (Apis mellifera)

The Wrap-Up

Based on the findings that bees certainly seek out plants based on their qualities, I think there is good reason to assume that bees would benefit from the proven antimicrobial (Antimicrobial Activity of Tulsi (Ocimum tenuiflorum) Essential Oil and Their Major Constituents against Three Species of Bacteria) and various other health benefits from the nectar and pollen of Holy Basil. The camphor, eucalyptol and eugenol within Holy Basil are the likely components and many medicinal herbs share these benefits so it makes an even stronger case for widespread medicinal herb gardens!

In many studies, bees that were parasitized or had pest or disease threats to the colony sought out specific constituents in plant nectar and pollen which boosted their immunity. While this information isn’t surprising and fully confirms my hypothesis, it is great to have it confirmed by science. How exciting!!

Bees do self medicate!

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