Global temperatures are rising by 0.2 °C every decade and climate change is one of the biggest and most frightening challenges that we face this century. We have already witnessed many extreme weather events and natural disasters across the world in the last couple of decades from Tsunamis in the Far East to devastating bush fires in Australia. In 2023, lives were lost through severe flooding in the UK which also caused widespread havoc and economic damage. And it goes on; it seems like whenever we turn on the news there are flooding and mudslides somewhere in the world. This last winter and spring in Scotland have been exceptionally long, wet, and changeable with a lovely warm May for nectar secretion and honey-making, and the coldest wettest June on record, I think. Beekeepers have been feeding their bees and experienced beekeepers have noticed queens have stopped laying in some colonies.
Expectations.
We have already been warned that severe weather events will be relentless and ongoing and that climate change will always be with us. We can expect to experience ongoing problems when glaciers retreat further and the Arctic regions melt increasing melt-water, and raising sea levels. Changing rainfall patterns will cause flooding and soil erosion washing away nutrients from many areas. Encroaching deserts will further decrease fertile agricultural land and reduce food production in dry regions. Soil erosion and dispersal in gales will add to reduced fertility of land in arid regions. Water shortages will cause human strife and conflict and it will become increasingly harder to live in many parts of the world. Food security will become one of the biggest challenges and will beekeeping still be viable in a few decades time?
Locally Adapted Bees.
A gloomy forecast indeed but we can face reality and do what we can now to mitigate some of the issues and adapt to work with the climate we have as best we can. How will the changing climate affect beekeeping? We cannot know the true impact on beekeeping in years to come, but we can plan as far as possible to reduce the risks and mitigate the damage. We know that our Western honey bee (Apis mellifera) originated in Northern Europe and then diversified in Southeastern Europe and expanded into Asia Minor. This species evolved into around 25 subspecies that adapted to the areas of habitation where each is best suited. We can better support beekeeping now by keeping bees and rearing queens from locally adapted bees that prosper and thrive in the regions that they have acclimatised to. This will be harder for bee farmers to do because they need to requeen every year and in North America they tend to buy in queens from the south where it is warmer and queen rearing is possible early in the season.
Species Move North.
As our climate warms, non-native and other species will continue to move north in increasing numbers. We have already experienced the Asian hornet becoming established in the UK in 2023. Species like the Ivy bee, Colletes hederae, and Tree bumble bee, Bombus hypnorum, have moved north to Scotland over the past decade. We might find Tropilaelaps spp. and small hive beetle moving to the UK. Australia has already experienced the arrival of Varroa destructor in 2022 and their latest unwanted arrival is the red dwarf honey bee, Apis florea, which is an Asian honey bee and is host to another varroa mite, Euvarroa sinhai, which is not a known parasite of the western honey bee but it could be according to research studies1. It carries the serious parasite Tropilaelaps clareae which does affect the western honey bee, and the red dwarf bee is capable of carrying brood diseases and viruses too.
Non-Native Plants.
The same applies to plants and beekeepers should know that non-native plants can easily out-compete local species and that we can support local forage by restoring local plants and planting up areas with native trees and plants. This also means not buying and supporting non-native species. Changes in the distribution of plants geographically and can disrupt pollinator and plant interactions. We can shade apiaries by planting trees to protect colonies from the sun as summers warm.
Forage Impacted.
As crops fail in extreme weather events, honey bee forage will be at risk. Competition will increase across all bee species as seasonal shifts affect plant blooming times. Some plants will bloom earlier but the temperatures might still not be high enough for them to secrete nectar. This is true of oil seed rape which needs at least 15°C for sustained nectar secretion. Where I live in the Scottish Highlands some years it might be so cold in the early part of May that for half the time the crop is flowering, the bees cannot utilise it. Perhaps farmers might alter their planting schedules in future. They want these crops pollinated by honey bees because the seeds are larger and better set as a result.
We already know that heat-stressed bees forage less and plant nectar yields decrease when temperatures rise2 (Bauer et al.2023). In a study of honey bees pollinating scarlet runner beans (Phaseolus coccineus) in a green house, scientists raised the ambient air temperature of one greenhouse to 35°C. The bees in this greenhouse foraged on fewer flowers and also took a longer time on each flower than in the control greenhouse which was kept at 22°C. The bees stopped visiting the flowers after a few days as nectar yield fell.
Beekeepers can mitigate forage competition by reducing the numbers of managed honey bee colonies and keeping just enough to provide honey on a small scale, unless they are making a living from beekeeping. We can plant more forage including native trees and shrubs to increase available pollen and nectar. Keeping fewer colonies is my own personal strategy and I do find that I get better yields from a few strong colonies that are in tip top condition. But I am not trying to make a living from bees and this might become harder to do for bee farmers of the future.
Honey Bee Health & Dynamics Affected.
Beekeepers of the future will need more education around the dynamics of climate change and honey bee management. We already know that malnourished honey bees have reduced immunity and the ability to detoxify harmful substances like pesticides in their systems. The increased stress that this causes impacts health and increases vulnerability to pathogens and viruses. Honey bee nutritional supplementation and feeding might become the norm for all managed colonies.
Seasonal shifts will mean shorter brood-free periods in some areas, or no brood breaks as is the norm currently in the tropics. This means that pests like varroa will flourish, and more foragers will be competing for nectar and pollen.
Scientific Work.
What are the scientists doing at the moment to help us plan for the future? Well climate change is an emerging area of study and they don’t know enough to predict precise outcomes, but there is work going on now which we can draw on.
Rajagopalan et al3. have just published a paper looking at the effects of warm autumns and winters on honey bees in the northwest US Pacific region. They studied colony losses and investigated cold storage of honey bee colonies over winter as a strategy to mitigate the negative effects of colonies foraging later in the season in temperate climates.
What is wrong with colonies foraging later into the season? Does this not mean they collect more winter stores? Well, no, it is not a good thing because it messes up the colony dynamics and winter bee production. There are more older foragers that will die before spring so the new season will start with fewer available foragers. Precocious foragers will be recruited before their normal in-hive age-related duties finish, but it is a fact that these precocious foragers have shortened lives in the field.
The scientists used colony modelling to simulate outcomes of warmer winters. Interestingly, but perhaps not surprisingly, warmer summers and winters correlated to higher winter losses. There was earlier brood rearing at a time when there was more brood than forage available and varroa increased. The experiment involved cold-storage of colonies from October 15th to Jan 31st and this kept the adult populations stable regarding size and the normal age distribution because there was no late foraging to upset the balance.
This paper reinforced the Allee effect (https://en.wikipedia.org/wiki/Allee_effect) and the message is to keep strong colonies to combat climate change because one of the main features of social insects is that large colonies rear increasing numbers of brood and thrive, whereas small colonies tend to rear progressively less brood and ultimately fail.
What I found especially interesting, from the US perspective, was that because honey-bees are not native to the US there is only a small amount of genetic diversity among their populations compared with the countries where bees originated in. Also, the potential for managed colonies to adapt to new conditions in the US is going to be limited because of the needs of commercial beekeepers to buy in queens from other geographical regions which doesn’t promote adaption to the new areas where they must live.
Just to throw a cat among the pigeons, the cold-storage concept is at odds with Dr Derek Mitchell’s findings4 that honey bee clustering in winter is not a normal biological response, but rather the winter cluster is a stressful heat sink and not an insulation strategy. It is clear that we need more evidence to work from, and we will probably not be needing cold-storage over winter in the northern hemisphere in our lifetimes.
To end on a more positive note, the good things about warmer weather are that drone flight activity is increased and they will leave the hives more frequently on mating flights which is going to impact queen activity and mating behaviour5. Hygienic behaviour will increase because environmental conditions affect the gene expression for this.
Keep a look out for more information of climate change and beekeeping in the journals as this becomes a hotter topic.
References,
1 Quigley. A.2024. Red dwarf bees and euvarroa in Australia. The Beekeepers Quarterly. Number 156. June 2024.
2 Bauer, B., L. Morawetz, A. Ribarits, R. Wüest, and H.W. Krenn, 2023 Impact of heat stress on flower visitation and pollination of Phaseolus coccineus by honey bees (Apis mellifera) Journal of Apicultural Research, 2023•Taylor & Francis
3Rajagopalan, K., G. DeGrandi‑Hoffman, M. Pruett, V. P. Jones, V. Corby‑Harris, J. Pireaud , R. Curry, B. Hopkins, & T. D. Northfield. Warmer autumns and winters could reduce honey bee overwintering survival with potential risks for pollination services.
www.nature.com/scientificreports
4 Mitchell, D. 2023 Honeybee cluster—not insulation but stressful heat sink. J. R. Soc. Interface 20: 20230488. https://doi.org/10.1098/rsif.2023.0488
5 Neumann, P. & L. Straub (2023) Beekeeping under climate change, Journal of Apicultural Research, 62:5, 963-968, DOI: 10.1080/00218839.2023.2247115 To link to this article: https://doi.org/10.1080/00218839.2023.2247115
Interesting article, Ann. The erratic swings in conditions seem to be getting more extreme and more regular, so the thing that any creature must adapt to is continual change. I suppose, for bees, it makes little difference whether a lack of pollen and/or nectar is caused by cool conditions or heat/drought. Luckily our honey bees have beekeepers to step in when needed – so the pressure is on for beekeepers to adapt too. Best wishes, Steve.
Hello, Steve. Thank you for commenting and I am glad that you liked to article. The erratic swings got me thinking about this problem. I think that the next thing to solve is honey bee nutrition and to find out what they actually need in terms of supplements, rather than what the supply companies currently think we should buy.We probably need to encourage more young people to be scientists? Best wishes, Ann
Great thought provoking piece Ann, following on from the debunking of the Isle of Wight disease last week.
We find locally adapted bees react sensibly to changes in weather and nectar flows, often wrong-footing beekeepers. Openly mated queens, with many drones, have the breadth of genetics to adapt to climate changes and happily exist across climate zones from the tropics to sub arctic. We doubt this is true of narrowly bred, instrumentally inseminated queens, which are produced for mass sale rather than fitness.
With beekeepers now able to learn about selecting for varroa resistant traits, this hygienic behaviour of honey bees should alleviate the worries of mite growth during warmer autumns.
Hello Steve. Glad you liked the piece. Thank you for your reassuring comments based on experiences. Best wishes, Ann. PS. The lovely raspberry bush likes its new setting.