Extreme heat waves disrupt honey bee thermoregulation and threaten colony survival
Although honey bees have the ability to regulate hive temperatures, new research published in Ecological and Evolutionary Physiology shows that extreme summer heat can overwhelm these critical pollinators' cooling systems, leading to significant colony population declines.
The research in “Negative Effects of Excessive Heat on Colony Thermoregulation and Population Dynamics in Honey Bees,” conducted during a hot Arizona summer, monitored nine honey bee colonies through three months of temperatures that frequently exceeded 40°C (104°F). The results indicate that intensifying heat waves worldwide represent a significant threat to honey bees and the pollination services they provide.
"Honey bee colonies have well-documented mechanisms to cope with heat exposure," write authors Jun Chen, Adrian Fisher II, Gloria DeGrandi-Hoffman, Cahit Ozturk, Brian H. Smith, Jennifer H. Fewell, Yun Kang, Kylie Maxwell, Kynadi Overcash, Keerut Chahal, and Jon F. Harrison. "However, there have been no studies to date that have assessed the limits of such thermoregulation or how natural heat waves affect the capacity of honey bees colonies to thermoregulate and grow."
The research team discovered that while colonies maintained average brood temperatures within the optimal 34-36°C range necessary for healthy development, significant daily temperature fluctuations still occurred. Developing bees in the brood center experienced nearly 1.7 hours below optimal temperatures and 1.6 hours above them each day. Conditions were even more extreme at the brood edges, where young bees spent almost 8 hours per day outside the optimal range.
These temperature swings had measurable consequences. Higher maximum air temperatures and greater temperature fluctuations within hives led to population declines. The study found that "excessive heat, with maximal temperatures exceeding 40°C, can reduce colony populations by impairing the thermoregulation of brood or by exposing adults to temperatures that shorten their lifespans."
Colony size emerged as a critical factor in thermal protection. Larger colonies maintained more stable internal temperatures, with the smallest hives experiencing daily temperature swings of up to 11°C at the outer edges compared to 6°C in the largest colonies. This enhanced stability meant that developing bees and adult workers in larger colonies spent far less time exposed to potentially harmful temperature extremes.
Beyond Arizona, "Climate projections indicate that global average temperatures could rise by approximately 2.7°C by the end of the century, with potential increases up to 4°C under higher emission scenarios," the authors note. Such warming would intensify heat wave frequency and severity worldwide. Additionally, high humidity may compound these challenges in many regions. The authors note that "high humidity significantly reduces the effectiveness of evaporative cooling—the primary mechanism honey bees use to regulate hive temperatures—potentially making thermoregulation even more difficult."
The research has practical implications for beekeepers and agricultural systems that depend on honey bee pollination. The authors suggest that implementing effective management strategies, such as supplemental water provision, shading of hives, improved hive structure and materials that provide greater insulation, and ensuring high-quality forage will become increasingly important to mitigate impacts of high temperatures and maintain colony stability in a warming climate.
Ecological and Evolutionary Physiology primarily publishes original research examining fundamental questions about how the ecological environment and/or evolutionary history interact with physiological function, as well as the ways physiology may constrain behavior. For EEP, physiology denotes the study of function in the broadest sense, across levels of organization from molecules to morphology to organismal performance and on behavior and life history traits.
Journal
Ecological and Evolutionary Physiology
Article Title
Negative Effects of Excessive Heat on Colony Thermoregulation and Population Dynamics in Honeybees
INDIA
‘Save Last Honey Bee Before Human Existence Inches Toward Extinction’
The forests, once resonating with the music of chirping birds, rustling leaves, humming of insects and animal steps, have gone silent.
Forests are disappearing fast, rivers drying up, the homes of millions of species are in total jeopardy, to say the least. In the altar of development, these are being sacrificed for over a century. Every tree felled is just not wood lost, but a feather of heritage being plucked.
None other than, perhaps, scientist Albert Einstein predicted that with the end of the last honey bee from Earth, human existence too would come to an end.
Although this quote from Einstein remains unconfirmed, going by a post from USDA published in Natural Resources Defense Council. However, the threat to insects is seemingly growing faster than ever thought, as in all the spheres of the Earth, insects are on rapid decline. Both the creeper and the feathered species.
Amid all this lies a question: why are the homes of bees being taken away, and how can they escape extinction?
While the real-time numbers vary, Odisha has thousands of beekeepers, with significant efforts by bodies like the Odisha Khadi Board and the Council for Scientific & Industrial Research (CSIR) training hundreds of farmers, and pioneers, such as Bikash Patra, empowering over 30,000 rural individuals, showing a growing, but still developing, beekeeping sector focused on tribal and rural livelihoods.
In late 2025, CSIR-NBRI trained 78 farmers in Koraput and Sambalpur and distributed 350 hives, notes a Facebook post from CSIR & National Botanical Research Institute (NBRI).
The Odisha Khadi Board and CYSD supported 60 farmers with training and equipment in Keonjhar, with plans to reach 600 farmers.
Tribal Focus
Traditional tribal communities in Odisha have long collected honey, and efforts now focus on integrating modern techniques for better income, as detailed by The New Indian Express.
The most notable beekeepers in Odisha include Dr. Patra, a scientist leading the stingless bee revolution, and farmer-entrepreneurs like Bijay Kumar Bir, known for his successful Minibala Beekeeping Unit and training initiatives, and Rajesh Biswal (Mahua Mitu), a young guide in honeybee cultivation, all championing sustainable, profitable apiculture
Modern technology and monoculture have destroyed 75% of the world's biodiversity. The number of beneficial bees is decreasing rapidly. Einstein warned the people, "When the last bee disappears, there will be no human society “.
Biologists have identified one million species of insects on the planet. Insects are the most abundant in the Kranti (turmoil) region. Because they get more food there. Their number may be 10 times more than scientists have calculated. Amid the destruction going on for the past 100 years in the name of development, these tiny creatures are being sacrificed in large numbers.
Insects and moths play a significant role in the balance of biodiversity. Moths are more or less found all over the world. Scientists have realised that their protection is essential for the well-being of mankind and the protection of nature.
India is one of the 12 biomes on the planet. Some species of these insects and moths help in the reproduction of fruits and seeds of plants. This process of reproduction is called pollination.
Birds, butterflies, bees, flies, bats, moths, small and large insect species do pollination. The fruits or seeds of plants can be pollinated in two ways. Pollination and angiosperm. Some species like cassava, potato, yam and banana are propagated by the vegetative process.
There are two types of pollination -- self-pollination and cross-pollination. Rice, wheat, maize, barley, oats, millet, and small grains reproduce by self-pollination. About 85% of the fruits and seeds of plants are produced by cross-pollination. Most fruits or seeds of flowering plants are produced by pollination. This work is done by insects like bees, bats, butterflies, and moths. Botany experts say that about 2% of plant reproduction is done by wind. As much as 73% pollination of cultivated or wild plants is done by bees. Isn’t this enough to understand the miracle of honey bees?
Simply put, the disappearance of bees would be devastating – from a biological, societal and economic standpoint. If we lose bees, we lose far more than honey; our crops, ecosystems and food systems all depend on their pollination. There is no species on earth, including us, that can do their job.
“When bees fly from flower to flower and suck honey, pollen sticks on their legs, hair and wings. The male carries pollen from the flower and sits on the female flower and collects honey, while the pollen gets stuck on the stigma of the flower. There is a tube from stigma to the stigma. When the pollen reaches the uterus through the tube, it becomes fertilised. The uterus then swells and produces fruits and seeds. Bees collect honey from about 700,000 species of plants that have been identified. There are about 60,000 species of bees in the world” Natabar Sarangi, a veteran botanical researcher and nature lover., told this writer.
We know that wild bees or tiger bees (wild bees), seven-horned, stinging, scorpion, and cored bees are some species. No bee is predatory. When some creatures like humans, bears, and foxes eat honey from the honeycomb, the bees become restless. Some of sting in self-defense. Engineer Amit Godse, founder of the Baskot Foundation in Mumbai, holds a tiger bee honeycomb in his hand and takes care of them. "We are afraid of bees without understanding them," he says. "We set fire to them to get honey. They attack us and sting us", he adds. Humans need to revisit the world of bees.
What Humans Must Learn From Bees
The Odisha Khadi Board is doing beekeeping promotion and propagation work. If you see the work of bees up close, you will be amazed. What an architect, craftsperson, an engineer is each of them! The way they make foam from wax, build cells is amazing.
All the cells are the same. Perfect measurement. Each has a queen bee, who is 2/3 times bigger than the worker bee. The humpback moves like an elephant. Thousands of worker bees guard it. Bees are a beautiful creation of nature. A bee can collect 100,000 times its weight in honey in a year. For this, three lakh flowers are required. They fly long distances and return to their hives with honey and pollen. Timeliness, discipline, and team spirit should be learned from them.
Why is the number of bees decreasing so rapidly? Why do hundreds of pumpkin flowers or lotus flowers bloom but no fruit remains? Why do farmers go to war with seed sellers? Answer: Chemical agriculture, green revolution and pesticides.
Diminishing Honey bees
In many parts of the world the decrease in the honey bee population can be simply attributed to the modern methods for better yield of produces, be it fruits, vegetable, grains, flowers and many other things.
Honey bee populations globally face significant threats, with alarming losses reported, averaging around 40% annually in the US, though numbers fluctuate, and some regions see concerning drops, like a potential 70% loss in 2025 predicted by some researchers, alongside regional declines in Asian honeybees and threats to native species.
Overall trends point to unsustainable losses driven by mites, pesticides, habitat loss, and climate change, impacting food security and biodiversity.
There are significant figures showing honey bee declines in many Asian countries, especially for the native Apis cerana (a native honey bee specie), with some reports indicating over 50% decreases in occupied hives and honey production in regions of Nepal, and widespread severe losses in countries like Thailand, South Korea, Pakistan, and Afghanistan, though some Asian nations like China and India have somehow managed bee populations increase due to commercial beekeeping.
“Also figures on honey bee decline in Odisha exist, with a significant 2017 study in Koraput and Rayagada districts showing four out of five native bee species declined by up to 90%, highlighting severe losses impacting crops like mustard, brinjal, and cucumbers, though precise state-wide, recent numbers remain difficult to pinpoint due to data gaps, emphasising impacts from pesticides, habitat loss, and climate change”, says S N Patra, a botanist.
Until 1840, indigenous farming was done on the Earth, with ploughs. land was fertilised by applying manure and fertilisers. Farmers used to sow indigenous seeds and harvest crops. In 1840, John von Liebig invented chemical fertilisers. Farmers in Europe and America poured fertiliser instead of manure on the land. Soon pests and diseases started destroying crops. Pesticides were sprayed on the land. The bees, too, began to die in the process. In 1934, Swiss chemist Hermann Muller invented DDT, which helped control pests in crops”, but also affected bees, laments Sarangi.
The writer is a freelance journalist based in Odisha with over 40 years’ experience in the profession.
