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  • Writer's pictureJohn Mackay

'Gimme a Feeder of Joe'


Bees like caffeine … who knew?

By John Mackay

New Zealand’s rapid adoption of the coffee culture must be unparalleled. It doesn’t seem so long ago that if you wanted coffee, your options were ‘black or white’. ‘Single shot Americano with hot water on the side’ seemed the realm of films (we laughed at the LA Story coffee piece* in the early 90s, but didn’t know why... or, maybe that was just me?).

Well, it turns out that we’re not the only ones who enjoy caffeine! In the last decade, various reports have shown caffeine to be attractive to bees, with the foragers actively seeking out plants with low levels of caffeine in their nectar and pollen, over those without. Yes, coffee plants, but also others such as citrus.

Memory, learning behaviours and foraging activities are all increased in honey bees upon ingesting caffeine, not always to their benefit if they target low-value (but caffeinated!) nectars. Viruses like Deformed Wing Virus (aka Hive Killer 1) can be mitigated by the prior boosting of immune-related genes thanks to caffeine. Not only viruses, but also nosemas (now called vairimorpha) can be reduced in spore numbers.

In a current study (Motta et al. 2023) they are looking at the effects of caffeine in protecting against a bacterial pathogen called Serratia marcescens – a bacteria found in high levels in dead bees from hives lost over winter – as well as associated varroa. The authors looked at whether various concentrations of caffeine in the bees’ syrup affected their gut microbes, before feeding the bees caffeine, plus the Serratia pathogen. They showed that the pathogen – as expected – shortened the bees’ lifespan with no or low caffeine. However, when higher concentrations of caffeine were fed to the bees, the pathogen had little effect on the bees’ lifespan, compared to the control bees without the pathogen (and regardless, whether or not the non-pathogen control bees were fed caffeine).

No studies have been done to see whether we have this pathogen in New Zealand – and while it may prove beneficial against other bacterial pathogens (as it does for viruses and nosemas/vairimorpha) further work is needed to see whether brood diseases (often caused by bacteria) can be helped by metabolites such as caffeine.

But how much caffeine are we talking about? I’m not suggesting to try this, but the caffeine concentration that showed positive effects works out to be approximately a 50% espresso solution…. or roughly all your instant coffee brew!

*For those wondering about the LA Story reference, the film is from 1991 with Steve Martin – the coffee piece is here:

John Mackay is a molecular biologist and the technical director of Gisborne-based lab dnature diagnostics and logistics, as well as a hobby beekeeper.

Reference: Motta EVS, Arnott RLW, Moran NA. 2023. Caffeine Consumption Helps Honey Bees Fight a Bacterial Pathogen. Microbiol Spectr.


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