Tag Archives: pollen

It’s official. Climate change is making the pollen season much worse

Climate change is making pollen seasons start earlier, last longer and have more pollen, which essentially means more days of runny noses, according to a new study. Researchers looked at pollen trends across the United States and Canada between 1990 and 2018 and used climate models to understand the link with climate change.

Image credit: Flickr / Clare Black

Pollen is one of the most common triggers of allergies. It’s a very fine powder produced by trees, flowers, grasses, and weeds that causes an adverse immune response on some people who breathe it. The immune system mistakenly identifies pollen as an intruder and produces chemicals to fight it, a process known as an allergic reaction. The result can range from a minor inconvenience to serious conditions.

Some people have pollen allergies year-round, while others only have them during certain times of the year, especially in spring, summer, and fall – when plants release pollen to fertilize other plants. Grasses are the most common cause of allergy, especially ragweed. Other sources include sagebrush, pigweed, and tumbleweed, among others.

The prevalence of allergies among US citizens has skyrocketed in just a few decades. In 1970, about one in ten Americans suffered from hay fever, which is caused by airborne allergens, such as pollen. By 2000, three in ten did, which represents 20 million on the adult population, according to research by the Asthma and Allergy Foundation of America. A part of that increase may be caused by climate change.

William Anderegg of the University of Utah School of Biological Sciences and a group of researchers wanted to further understand the link between pollen and climate change. While previous studies had looked at the link between pollen and climate change, no studies had been done before on pollen trends at a continental scale or to calculate the likely contribution of climate change

“A number of smaller-scale studies – usually in greenhouse settings on small plants – had indicated strong links between temperature and pollen,” Anderegg, the study lead, said in a statement. “This study reveals that connection at continental scales and explicitly links pollen trends to human-caused climate change. It’s a crystal clear example of how climate change is already affecting people’s health.”

The researchers collected measurements between 1990 and 2018 from 60 pollen count stations across the US and Canada, which are run by the National Allergy Bureau. The stations collect airborne pollen and mold samples, which are then hand-counted by certified counters. Most of the stations are in the US, with just two in the cities of London and Ontario in Canada.

The amount of nationwide pollen increased by around 21% over the study period, the findings showed. The greatest increases were recorded in Texas and the Midwest. At the same time, the researchers found that pollen season currently starts 20 days earlier than in 1990. This suggests that global warming is changing the internal timing of plants, known as phenology, to start producing pollen earlier.

The researchers also applied statistical methods to the pollen trends in conjunction with nearly two dozen climate models. They found that climate change alone could account for around half of the pollen season lengthening and around 8% of the pollen amount increasing. They divided the study years into two periods and found climate change’s contribution to the increasing amount of pollen is accelerating.

The findings are in line with a research brief by Climate Central from 2019, which showed global warming is extending the freeze-free season – giving plants more time to grow, flower, and produce pollen. At the same time, as CO2 levels rise, some plants that produce allergenic pollen produce even more of it, lab experiments showed.

The study was published in the journal PNAS.

Soap bubbles are quite good pollinators, a new paper shows

New research from the Japan Advanced Institute of Science and Technology plans to fertilize fruit-bearing plants with soap bubbles.

Image via Pixabay.

Whimsical? Yes. But researchers in Nomi, Japan, suggest soap bubbles as a low-tech approach to support robotic pollination. Such processes are becoming more important as bees and other insect pollinators struggle under climate change and environmental degradation.

Bubble business

“It sounds somewhat like fantasy, but the functional soap bubble allows effective pollination and assures that the quality of fruits is the same as with conventional hand pollination,” says senior author Eijiro Miyako, an associate professor in the School of Materials Science at the Japan Advanced Institute of Science and Technology.

“In comparison with other types of remote pollination, functional soap bubbles have innovative potentiality and unique properties, such as effective and convenient delivery of pollen grains to targeted flowers and high flexibility to avoid damaging them.”

Some of the team’s previous work included using tiny, toy drones to pollinate flowers. While efficient, that approach very often destroyed the blossoms whey were trying to reach. Bubbles, Miyako observed one afternoon in the park with his son, could work as an alternative.

After confirming in the lab that they could carry grains of pollen around, the team tested five commercially-available surfactants (compounds that can produce bubbles with water) for their ability to create bubbles and their effect on the pollen. They settled on lauramidopropyl betain (A-20AB), as it had a positive effect on the grains after deposition on flowers.

In the end, they settled on pear pollen grains in a 0.4% A-20AB bubble solution, with some other compounds thrown in to stabilize its pH and provide needed ions (such as calcium) for germination.

The authors then loaded the solution into a bubble gun and used it to apply the pollen in a pear orchard. It was very successful, and pears grew merrily. The authors report that every bubble carries around 2,000 grains of pollen directly to the targeted flower. The last step was to install a bubble-producing device on an autonomous drone. This setup had a 90% success rate from a height of two meters and at a drone velocity of two meters per second (meaning the bubbles can be applied while the drone is in transit).

One other advantage of the bubble method is that the solution which carries the grains of pollen can be used to support its activity. Pollen activity mediated through the soap bubbles remained steady three hours after pollination, the team explains, while the grains applied through other methods such as through powder or solution became less effective.

For now the findings are definitely exciting, but it will take more refinement to make it usable on large scales in the field. Another thing to note is that the bubbles can only be applied during mild weather, as raindrops can wash away the pollen from flowers and winds can blow the bubbles away entirely. In the immediate future, the team plans to focus on increasing the efficiency of the system, as the prototype device still wastes pollen (which lands on the ground, not the flowers).

The paper “Soap Bubble Pollination” has been published in the journal iScience.

Beetle trapped in amber pushes back insect pollination by 50 million years

Paleontologists in China and the US have documented the earliest case of insect pollination thanks to a 99-million-year-old beetle preserved in amber. The pristine fossil contains traces of pollen showing that the evolution of plants and animals during this time period were closely intertwined.

Illustration of A. burmitina. Credit: Ding-hau Yang.

David Dilcher, an emeritus professor at the Department of Earth and Atmospheric Science at the Indiana University, performed a morphological review of the 62 grains of pollen found in the amber, which came from a mine in northern Myanmar. Dilcher is one of the world’s foremost experts in amber fossilization, who also has a lot of experience studying the earliest flowering plants.

The pollen was not easy to find. To the untrained eye, the tiny granules don’t look like anything important. However, the researchers analyzed the beetle’s body hairs under a confocal laser microscope, which made the pollen grains glow, contrasting strongly with the darkness of the insect’s shell.

This is the earliest known physical evidence of insect pollination. Credit: Nanjing Institute of Geology and Palaeontology.

The shape and structure of the pollen — particularly the pollen’s size, “ornamentation” and clumping ability — show that it evolved to spread through contact with insects.  The analysis showed that the pollen came from a flower species in the group eudicots, which is one of the most common types of flowering plant species.

As for the beetle trapped in the amber, it belongs to a new species that the researchers named Angimordella burmitina. Using X-ray microcomputed tomography (micro-CT), Dilcher and colleagues could study the insect’s shape and physical features in minute detail without having to disturb or damage the fossil in any way whatsoever. Armed with a 3-D digital model of the beetle, the researchers could clearly see several specialized body parts signaling the insect’s role as a pollinator, including the shape of the body itself and pollen-feeding mouthparts.

A close up of A. burmitina in amber. Credit: Nanjing Institute of Geology and Palaeontology.

Researchers determined the age of the amber fossil from the age of other known fossils retrieved from the same location. At nearly 100 million years old — during a time when pterodactyls were still alive, roaming the sky — the discovery pushes back the earliest documented instance of insect pollination to about 50 million years earlier.

“It’s exceedingly rare to find a specimen where both the insect and the pollen are preserved in a single fossil,” said Dilcher. “Aside from the significance as earliest known direct evidence of insect pollination of flowering plants, this specimen perfectly illustrates the cooperative evolution of plants and animals during this time period, during which a true exposition of flowering plants occurred.”

The findings appeared in the journal Proceedings of the National Academy of Sciences.

Pollen clouds cover south-east USA causing allergy spikes

Nothing reminds you that spring is here quite like the sight of blossoming plants, the warming weather, and the nasty allergies. This week, pollen counts have increased across the US, which may mean that about 50 million Americans will suffer from some combination of a runny nose, watery, itchy eyes, and sneezing as their allergy symptoms ramp up.

Pollen season typically lasts from early to late spring. Pollen is a fine powdery substance, typically yellow, consisting of microscopic grains discharged from plants, trees, and grass. Being extremely lightweight, pollen is easily swept away by the wind which can transport the irritating substance miles away from its source.

While pollen is not actually sperm per se, pollen grains contain cells necessary to transfer the male half of the plant’s DNA to a compatible plant’s female counterparts (like the pistil and female cones). So, in a way, you could say that pollen is plant sperm powder.

In some parts of the US, such as the Midwest and Northeast, the amount of pollen discharged by plants was so great that the sky became covered in a yellow haze.

To get an idea of how much pollen trees can produce at the height of allergy season, watch this viral video showing what happens when a backhoe nudges a pine tree.


Something similar was caught on camera this week when a falling tree in Hixson, Tennessee, sent billions of pollen particles flying into the air.

During the thick of pollen season, doctors recommend people who are vulnerable to allergies to avoid being outside in the first half of the morning and later in the afternoon. After being outside, people with pollen allergies should shower and wash their hair and clothes. Over-the-counter medications like nasal sprays, antihistamines, and eye drops can also offer some relief.


Insecticides and low floral diversity are driving bumblebees into the ground

Bumblebee queens are finding it harder and harder to cope — and, as they go, so do their colonies.


Image credits Tim Hill.

It’s not easy being royalty, at least not if you’re a bumblebee. Every year after emerging from hibernation, bumblebee queens must prepare the nest, lay eggs, and rear larvae — all on their own. Needless to say, it’s a highly demanding job. And, if they fail to live up to it, there won’t be any colony. New research worryingly shows that we might be putting more on the plate of these single moms than they can shoulder.

Queen of an empty castle

The research team at the University of California Riverside reports that exposure to widely-used insecticide substances, along with poorer diets caused by reduced availability of flowers, are taking a toll on the queens. Since each must get the colony up and running by herself, the team is worried this effect will have drastic consequences on the bumblebees — a critical pollinator that’s already wavering.

Bumblebees play a key role in both natural and agricultural settings. They’re fuzzy and fast, meaning they can carry quite a lot of pollen around. They’re not picky, meaning they’ll pollinate virtually every flower they can get to. A lot of our crops today — from tomatoes to blueberries — heavily depend on bumblebees as the main pollinator species. However, unlike honey bees, bumblebee colonies need to be reset each year, starting from a single queen — making the species incredibly vulnerable during this phase.

“Queens are probably already a bottleneck for bumblebee population dynamics,” said Hollis Woodard, an assistant professor of entomology at the University of California Riverside and paper first author.

“If a queen dies because of exposure to humanmade stressors, then a nest full of hundreds of important pollinators simply won’t exist.”

Previous research has linked insecticide use — including neonicotinoids, one of the most widely-used of such compounds — with a decline in pollinator numbers. Neonicotinoids are usually applied to seeds, the team writes, but they can seep into the soil. And that’s where bumblebee queens hibernate. The compounds can also accumulate in the mature plant’s tissues, including its pollen and nectar.

Another factor that’s impacting bumblebees is declining floral diversity. This is mostly due to the use of land for agriculture and broader global changes that affect ecosystem integrity, such as climate change. According to the team, bumblebees “collect pollen from a wide variety of plant species,” and there is evidence that they need a mixed diet. Dining on pollen from a single species just doesn’t cut it for the fuzzy insects.

The team tested the effects of temporary and sustained exposure to imidacloprid — a neonicotinoid — on a queen’s mortality, activity, and ability to set-up a healthy nest. They also ran the test to see what effect a single source of pollen would have on those factors.

Their results showed that queens were significantly less active and six times more likely to die after sustained exposure to the pesticide (37 days). A shorter exposure (17 days) somewhat reduced these effects. More worryingly, even if the queens survived, they produced only a third of the eggs and a quarter of the larvae of untreated queens.

Monofloral pollen didn’t have such drastic effects, but it still noticeably influenced a queen’s activity levels and the size of its brood.

“Ours is the first study to explore the impact of multiple stressors on bumblebee queens during an understudied but important phase of their lives. It joins a small but growing body of research suggesting there are unique effects on queens that can have dramatic consequences for future generations,” Woodard said.

Woodard believes the findings are grounds for U.S. policymakers to reconsider the use of neonicotinoids. The EU has already set a ban on the use of these substances, to come into effect by the end of 2018.

Since bumblebees and pollinators on a whole are so immensely valuable to humanity, I hope Woodard’s warning is heeded.

The paper “Effects of neonicotinoid insecticide exposure and monofloral diet on nest-founding bumblebee queens” has been published in the journal Proceedings of the Royal Society B: Biological Sciences.


Sick bees take care of themselves by eating better quality food

Sick bees will actively select for better food, study shows.


Image via Pixabay.

Being sick as an adult is quite a depressing experience. Not only do you feel horrible, but you have to call all sorts of people to let them know you won’t be coming in to work today, or that you’ll be paying them a visit at the clinic, respectively. You have to go get your own meds, make sure you’re staying hydrated — all in all, it’s a hassle, and often, we can’t really afford to take that sick leave. So we bear and power through it.

Bees, however, take good care of themselves when sick. A team led by Dr. Lori Lach, Senior Lecturer at JCU, reports that the black-and-yellow critters will actually select better food when sick, to get an extra energy boost.

For the study, the team worked with some healthy bees (as controls), others infected with the gut parasite Nosema ceranae, and compared their feeding habits. Nosema ceranae is one of the most widespread parasites of adult honey bees in the world, and its effects on the host bee’s physiology has been studied at length. However, this is “the first study we’re aware of to investigate effects on floral choice,” said Dr. Lach.

“The question then was — when the bees had the opportunity to select their own food, would they choose what was good for them?” said Jade Ferguson, the student who conducted the project for her Honours degree.

The team gave the bees artificial flowers to forage from, which housed either high-quality pollen (which was more nutritious and had a higher calorie count), low-quality pollen, or sugary water. Overall, the researchers report that healthy bees showed no preference for either type of pollen. However, twice as many infected bees picked the higher quality pollen over the lower quality one.

To their surprise, the team found that sick bees lived longer than healthy ones when they had access to the more nutritious pollen — even though it also increased the parasite count in their guts. This suggests that their preference for the higher-quality pollen stems from a bid to counteract the negative effects of the parasites.

It’s still unclear how the bees distinguish between pollens of different quality. However, the team believes that the bees’ preferences will affect what native and crop flowers the insects visit, as they can vary greatly in the quality of pollen offered. Since plants often compete for pollinators, the findings can be used to estimate which plants (both crops and wild) will be visited by a given colony. Parasite presence, the team reports, seems to be the only factor that influences which flowers are visited.


The paper “Honey Bee (Apis mellifera) Pollen Foraging Reflects Benefits Dependent on Individual Infection Status” has been published in the journal Microbial Ecology.

Bees prefer rural flowers to urban ones, new study indicates

When given the choice, bees tend to opt for blossoms in the rural areas, forgoing those in urban sites.

Carniolan honey bee (Apis mellifera carnica). Image via Wiki Commons.

A team from Ohio State University positioned several honey bee colonies in a central Ohio cemetery smack in the middle of where urban residential development transitions into farmland. They were careful to place the hives in an area that would make it equally accessible for both urban and rural plants and then, they simply left the bees on their own, to fend for themselves, studying which flowers the bees opted for.

The bees always seemed to prefer the rural flowers and at one point, flowers opted for rural polen 96% of the time. Rather interestingly, they did so regardless of the flower diversity that was presented to them.

“Honey bees didn’t seem to care that much what the floral diversity was. What they wanted was large patches of their favorite stuff,” said Sponsler, who now works at Penn State University.

What’s interesting about this study is that it challenges the classic belief that farmlands don’t do anything to help the bees. While the agricultural plants themselves are of no interest to bees, the countryside generally features wide swaths of unmowed wild plants (which we commonly know as weeds) on the side of fields and roads. These weeds can feed the bees much better than urban options — at least that’s what the bees themselves seem to think.

“When the bees have a choice, they go to the farmland. We’ve had trouble keeping our urban colonies alive, so this makes a lot of sense to us,” Johnson said. There’s this popular perception that urban places are better for bees because of the diversity of plants. This is showing that, at least in Ohio, the agricultural areas are actually superior and that’s despite the pesticide use that’s out there,” he said.”Apparently, farmland isn’t desolate at all — at least not for honey bees.”

Goldenrod, often regarded as a common weed, can be a trove of nectar for honeybees. Image credits: Rooster613 / Wikipedia.

In order to reach this conclusion, researchers first tracked the tell-tale dance patterns of bees returning from foraging. These dances can give a good indication of the direction in which the bees were foraging, as well as the distance from the hive. In other words, you can get a pretty good idea where the bee was foraging without actually following it.

“These things can be pretty easily decoded by the human observer, thankfully. You can map the locations that are being referred to in the dance,” Sponsler said.

Secondly, they carried out a more direct analysis. Namely, they looked through the bees’ collection. Whenever the bees would return from some scouting or foraging, they would walk through a screen that allowed their body to pass through but scraped some of the pollen. The researchers carefully collected this pollen and analyzed it to see what plant it comes from. As it turns out, Goldenrod was the most popular plant in the area – again, a plant that commonly grows on wild fields or on the side of the road.

The research offers some valuable indication for urban bee growers. Bee populations worldwide are dwindling, and especially in urban areas, the insects are highly threatened. The takeaway is pretty simple: if you want to keep a healthy beehive, you should supplement their diet. Planting certain trees, for instance, can produce very high amounts of nectar, as can flowers. After all, there’s no reason why we shouldn’t have some flowers on our fields, is there?

“There’s no reason why our urban landscapes cannot be full of flowers. It’s just that we’ve inherited a certain preference toward things that look like golf courses rather than things that look like prairies.”

Journal Reference: Douglas B. Sponsler, Emma G. Matcham, Chia-Hua Lin, Jessie L. Lanterman, Reed M. Johnson. Spatial and taxonomic patterns of honey bee foraging: A choice test between urban and agricultural landscapes. Journal of Urban Ecology, 2017; 3 (1) DOI: 10.1093/jue/juw008

Pollen may actually influence weather

Spring – for some people it’s the most beautiful time of the year, when the snows melt, the sun shines brighter and hotter and everything turns green, while for others, it’s hell on Earth. For people with allergies, especially pollen allergies, spring is sneeze season. But as some researchers found, pollen does more than trigger a nasty allergy – it can actually influence the weather.

Pollen is a fine to coarse powder containing the microgametophytes of seed plants; if pollen lands on a compatible female cone, it germinates. However, if it lands inside your nose, it can irritate you and trigger serious allergies. Now, researchers from Texas A&M and the University of Michigan are suggesting that these tiny particles can not only influence your health, but they can influence the weather – especially rain.

The study, published on Monday in Geophysical Research Letters, explains that regular pollen is too heavy to influence the weather, but airborne pollen grains can burst when wet, splitting into subpollen particles. These smaller, subpollen particles can seed clouds and thus lead to increased rain formation.

“What we found is when pollen gets wet, it can rupture very easily in seconds or minutes and make lots of smaller particles that can act as cloud condensation nuclei, or collectors for water,” University of Michigan associate professor Allison Steiner said.

Contrary to popular belief, that all pollen grains break into smaller particles when they come in contact with water, she showed that subpollen particles actually absorb water vapour, encouraging further cloud formation.

They tested for this by getting pollen from several known allergic plants that included pecan, cedar, pine trees, oak, birch, and ragweed. They extracted two grams of pollen and soaked them in water for an hour, after which they made a pollen fragment spray with an atomizer, and sprayed it into a cloud-making chamber. The different types of pollen exhibited a similar behaviour, encouraging cloud formation.

This has significant effects not only for weather patterns, but for the estimated 20% of people with pollen allergies. Additionally, researchers are beginning to think that trees released pollen so rain can come around more often to help trees and plants grow, and this phenomenon can also significantly influence drought spells.

Journal Reference: Allison L. Steiner, Sarah D. Brooks, Chunhua Deng, Daniel C.O. Thornton, Michael Pendleton,
Vaughn Bryant. Pollen as atmospheric cloud condensation nuclei. DOI: 10.1002/2015GL064060


Amber fossil shows early reproduction in flowering plants

  • A cluster of 18 flowering plants from the Cretaceous (100 million years ago) has been found preserved in amber
  • Among the flowers, one shows the earliest reproduction of flowering plants
  • Based on microscopic imaging, paleontologists conclude that the pollination mechanism has remained virtually unchanged

Flowers of Micropetasos burmensis in a 100-million-year-old piece of amber. Image credit: Oregon State University.

Amber is fossilized tree resin, valued as a gem since prehistoric times. It is also used as an ingredient in perfumes, as a healing agent in folk medicine, but it’s even more valuable for scientists. Sometimes, mosquitoes, bugs, or even plants can get trapped inside the resin and fossilize alongside it, being preserved incredibly well by the amber, providing valuable clues as to how life was millions of years ago.

Such is the case with this 100 million year old fossil, dating from the Cretaceous. This is the oldest evidence of sexual reproduction in a flowering plant — a cluster of 18 tiny flowers, with one of them caught in the process of making some new seeds for the next generation.

The scene itself is perfectly preserved; it’s as if a painter was observing the scene and immortalized it to the smallest detail to capture its beauty for eternity. In the mid Cretaceous, flowering plants were in the process of changing the face of the Earth forever, adding biodiversity, food, and beauty to a relatively monotonous world.

“The evolution of flowering plants caused an enormous change in the biodiversity of life on Earth, especially in the tropics and subtropics,” said dr. George Poinar, Jr., a professor emeritus in the Department of Integrative Biology at the OSU College of Science. New associations between these small flowering plants and various types of insects and other animal life resulted in the successful distribution and evolution of these plants through most of the world today.”

Microscopic imaging revealed pollen tubes growing out of two grains of pollen and penetrating the flower’s stigma, the receptive part of the female reproductive system. This would basically start the egg fertilization process, which in turn would generate seed formation… had the reproductive act been completed.

“In Cretaceous flowers we’ve never before seen a fossil that shows the pollen tube actually entering the stigma,” Poinar said. “This is the beauty of amber fossils. They are preserved so rapidly after entering the resin that structures such as pollen grains and tubes can be detected with a microscope.”

But they were able to find out even more about this scene: the pollen appears to be sticky, which suggests it was carried around by a pollinating insect, adding further insights into the biodiversity and biology of life in the Cretaceous. At the time, the dominating plants were conifers, ferns, mosses, and cycads. Towards the end of the era mammals, birds, and flowering plants were gaining ground, but dinosaurs still pretty much dominated the planet. It’s fascinating to see that the biological mechanism has remained virtually unchanged for such a huge period of time.

“It’s interesting that the mechanisms for reproduction that are still with us today had already been established some 100 million years ago.”, Poinar concluded.

However, the bad news is that the seeds can’t actually be grown. DNA has a half life of about 500 years and it’s estimated that even if perfectly preserved anything older than 6.8 million years wouldn’t germinate.

Story Source:

The above story is based on materials provided by Oregon State University.