Tag Archives: scent

How Pollution Alters Ant Scent, Leading to Attacks on Nestmates

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Harvester ants and the impact of ozone pollution

Harvester Ants and Scent Recognition

Credit: JorgeOrtiz_1976/Shutterstock

Common air pollutants like ozone and nitric oxide can alter the scent of ants, triggering aggressive behavior from nestmates who perceive them as intruders.

Ants rely on scent for social recognition, and when they encounter individuals with unfamiliar scents, they often react with aggression—biting or even killing the perceived invader. Notably, ozone—a greenhouse gas emitted from vehicle exhaust and industrial processes—can impact the chemical makeup of alkenes, compounds important to the unique scent profile of their colony.

Markus Knaden and researchers at the Max Planck Institute for Chemical Ecology in Jena, Germany, previously noted that ozone-induced changes in alkenes can disrupt insect communication, leading to phenomena such as fruit flies mating with inappropriate partners or pollinators like the tobacco moth losing interest in flowers. But how does ozone affect ant behavior?

To explore this, Knaden’s team established artificial colonies of six ant species, exposing them to glass chambers with varied ozone concentrations, mirroring summer levels recorded in Jena. Upon their return, the subjected ants faced attacks from their colony members.

“I honestly didn’t expect this outcome,” Knaden remarked. “We anticipated the ozone might alter just a small fraction—2 to 5 percent—of the overall scent blend.”

In natural settings, such aggressive behavior can hinder colony efficiency, even without any fatalities among the ants, though it is complex to design experiments that effectively measure these impacts.

Daniel Cronauer, a professor at Rockefeller University in New York, commented that the aggression observed is not surprising given the crucial role alkenes play in identifying nestmates.

Alkenes also facilitate other vital ant behaviors, including tracking via footprints and communication between larvae and adults. This study indicates that ozone exposure may lead clonal ant adults (Oseraea Billoi) to neglect their larvae, suggesting that these changes could disrupt various facets of ant life and potentially affect broader ecosystem dynamics.

“In most terrestrial ecosystems, the removal of ants would likely lead to catastrophic consequences,” Cronauer stated. Ants are pivotal for dispersing seeds, aerating soil, and fostering symbiotic relationships with other species.

With global insect populations in decline, this research adds to a growing body of evidence linking air pollution to these declines. Knaden asserts that while current ozone levels may not pose immediate dangers to humans, “we must acknowledge the unseen consequences of our actions.”

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Source: www.newscientist.com

Cats Can Identify Their Owner’s Scent, Researchers Find

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Across the globe, people coexist with cats, engaging in various social behaviors with their furry companions. While olfaction is one of cats’ most crucial sensory abilities, its specific role in identifying humans remains unclear. A recent study conducted by researchers at Tokyo University of Agriculture examined how domestic cats use their sense of smell to differentiate between familiar and unfamiliar humans.

Miyairi et al. Ferris Catus’ behavioral response to human olfactory stimuli was explained. They suggest that cats use their sense of smell to recognize humans. Moreover, the olfactory exploration behaviors of cats are linked to their personality traits, indicating a lateralization in odor detection between the left and right nostrils. Image credits: Sci.news / makieni777 / rise-a-mui / alexas_fotos / dorothe / vaclav zavada / artem makarov / daga roszkowska / birgit / pasi mammela.

“Dogs (Canis Familiaris) and cats (Felis Catus) present unique social interactions,” said Dr. Yutaro Miyairi, the lead author of the study.

“Prior research has largely focused on how these animals bond with their owners.”

“For instance, dogs are adept at recognizing human emotional expressions through facial cues and vocal tones, demonstrating their ability to process social information from humans.”

“Cats, too, possess remarkable social cognitive skills that have piqued the interest of researchers.”

“However, studies on cat-human interactions have not progressed to the extent seen in canine research.”

In this study, the team aimed to determine whether cats can distinguish between familiar and unfamiliar individuals using olfactory cues alone.

The researchers tested 30 cats by presenting them with plastic tubes containing swabs that had been rubbed under the armpits, behind the ears, and between the toes of their owners and unfamiliar humans.

Cats exhibited a significantly longer interest in unfamiliar scents compared to those from their owners or empty tubes.

Interestingly, the scientists observed that cats initially preferred using their right nostrils to smell unknown odors, later switching to their left nostrils as they became acquainted with the scents.

Cat owners were asked to complete an online survey to evaluate the relationship between their cats’ personalities and their ownership experiences.

Male cats with anxious temperaments tended to repeatedly sniff each tube, whereas those with more relaxed personalities approached the tubes in a calmer manner.

In contrast, there was no observable personality influence on the behaviors of female cats during the experiment.

The findings suggest that pet cats can differentiate between familiar and unfamiliar humans based on scent alone, though it remains uncertain if they can identify a specific individual based solely on smell.

Additionally, the preference for investigating new scents with the right nostril implies a potential lateralization in brain function, a phenomenon also documented in other animals like dogs, fish, and birds.

“Our findings further support the idea that cats utilize their olfactory sense to recognize humans,” the authors stated.

“This also reinforces the significance of rubbing behavior that follows sniffing, which may suggest an exploratory phase that precedes scent marking.”

“This relationship calls for further exploration, particularly regarding whether cats can recognize specific individuals using olfactory signals.”

The study was published online in the journal PLOS ONE.

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Y. Miyairi et al. 2025. The behavioral response of pet cats to human odor. PLOS ONE 20(5): E0324016; doi: 10.1371/journal.pone.0324016

Source: www.sci.news

Rare Titan Arum blooms in Kew Gardens emitting scent of rotten flesh

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June 18th, Corpse Flowers at Kew Gardens

Sebstian Kettley/RBG Cue

This gorgeous, but smelly, corpse flower bloomed on June 18th. Royal Botanic Gardens, KewIn London however it tends to be only for a short period, lasting only 24 to 36 hours.

Corpse Flower (Amorphophallus titanium) also known as Titan Aramgets its name from the foul smell it gives off, resembling rotting meat, which is so strong it can be heard for hundreds of metres. The smell is produced to attract rare pollinating insects, such as flesh flies and carrion beetles, to the short-lived flowers, and must be strong enough to do its job during the short period the plant is in flower, because the plant may not flower again for many years.

Strictly speaking, this up to 3 metre tall plant isn’t one flower, but many. The inner inflorescence, or spadix, emerges from a purple, pleated collar called a bract and looks like a yellow obelisk. The inflorescence, or cluster of flowers, lies in the protected area between the bract and the spadix.

If you happen to see and smell it, the smell may not be what you expect: it can change during the flower’s short lifespan and can smell like rotting flesh, as well as pleasant excrement or warm garbage.

This rare plant is endemic to the rainforests of the Indonesian island of Sumatra, but is cultivated in many botanical gardens around the world for its beauty and the crowds it attracts when it blooms. The first time it is known to flower outside of Sumatra was in 1889 at Kew Botanical Gardens.

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Source: www.newscientist.com

The scent of flowers is altered by air pollution, confusing insects

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Hawk moths are less likely to visit flowers if air pollution changes their smell.

Image courtesy of Floris van Brugel

Insects may have a hard time finding flowers because air pollutants are breaking down the chemicals responsible for the flowers' attractive scent.

“In recent years, there has been increasing interest in 'sensory pollution,'” he says. Jeff Riffel at the University of Washington in Seattle. This pollution resulting from human activities can change wild animal behavior by changing or introducing new stimuli, he says.

For example, we know that noise pollution affects bird songs and may be linked to an increase in whale strandings. Light pollution, on the other hand, can disorient a variety of animals, including migratory birds and sea turtles.

However, little is known about how human activities affect animals' sense of smell. Riffel and colleagues therefore investigated the effects of anthropogenic pollutants on plant pollinators.

They focused on ozone and nitric acid radicals, which are pollutants produced by the interaction of vehicle exhaust and gases in the atmosphere. Both are known to react with compounds emitted by flowers to change their scent.

The research team discovered pale evening primrose (evening primrose), a desert flower found in North America. Both pollutants degraded aroma compounds, but nitrate radicals did so more completely.

To study whether this led to changes in the behavior of the flowers' main pollinators, the researchers exposed species of hawk moths, including the hawk-moth sphinx.Hyles Lineata), flowers that emit a natural floral scent, or flowers that have been engineered to emit a degraded scent.

Primroses that emitted degraded scents were visited 70% less frequently than flowers that emitted naturally delivered scents. This decline in visitors could affect the hawkmoth's health, Riffel said. Researchers estimate that reduced moth visitation could reduce the amount of fruit plants produce by 28 percent, potentially having ripple effects on the broader ecosystem.

The researchers' models show that since the Industrial Revolution, the distance at which hawk moths can detect flowers has shrunk from about two kilometers to just a few hundred meters.

“This is another reason why we need to switch to energy sources that do not involve combustion,” say team members. Joel Thornton, also at the University of Washington. “Reducing nitrogen oxide emissions would be a win not only for air quality, but also for ecosystem function and agriculture.”

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Source: www.newscientist.com

The transformation of seedlings into super plants through a rare chemical scent

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plants by exposing them to certain chemicals at seed can affect subsequent growth. Researchers found that treating seeds with ethylene gas improved both growth and stress tolerance. This finding includes enhanced photosynthesis. Carbohydrate production in plants has the potential to be a breakthrough in improving crop yields and resilience to environmental stressors. Like other living things, plants can be stressed. Usually the conditions are as follows heat and drought. That can lead to stress, and when stressed, the plant may not grow as much or produce less. This can be a problem for farmers, so many scientists have tried genetically modified plants to make it more elastic. However, plants modified to obtain higher crop yields are low stress tolerance. This is because they put more energy into growing than protecting them from stress. Similarly, as plants improve their ability to withstand stress, production often decreases because they spend more energy protecting than growing. This brainteaser makes it possible It is difficult to improve crop yields. I was studying How the plant hormone ethylene regulates plant growth and stress responses. In Research to be published in July 2023, my lab made an unexpected and provocative observation. We found that when seeds that are normally underground germinate in the dark, adding ethylene improves both growth and stress tolerance. Ethylene is a plant hormone Because plants cannot move around, they cannot avoid stressful environmental conditions such as heat or drought. They receive various signals from their environment, such as light and temperature, which shape their growth, development, and how they respond to stressful situations. As part of this regulation, plants make various hormones They are part of a regulatory network that allows them to adapt to environmental conditions. Ethylene was first discovered as a gaseous plant hormone over 100 years ago. Since then, research has shown that all land plants studied produce ethylene. In addition to controlling growth and responding to stress, they are also involved in other processes, such as turning leaves in autumn and promoting fruit ripening. Ethylene as a way to “prime” plants My lab focuses on how plants and bacteria sense ethylene and how ethylene interacts with other hormonal pathways to regulate plant development. While conducting this research, my group accidental discovery. We were experimenting with germinating seeds in a dark room. Seed germination is a critical period in a plant’s life when seeds transition from dormancy to seedlings under favorable conditions. In this experiment, Seeds exposed to ethylene gas Continue this for a few days to see what effect it has. The ethylene was then removed. Normally, the experiment should end here. However, after collecting data on these seedlings, we transferred them to lightweight carts. This is not something we normally do, but we wanted to grow the plants to adulthood so we could have seeds for future experiments. After a few days of placing the seedlings under light, some lab members made the unexpected and surprising observation that the plants briefly gassed with ethylene. it was much bigger. These plants had larger leaves and longer and more complex root systems than plants not exposed to ethylene. These plants continued to grow at a faster rate throughout their lives. The plant on the left was not primed with ethylene, while the plant on the right was primed with ethylene. Both plants are the same age. Credit: Binder Lab, University of Tennessee, Knoxville My colleagues and I wanted to know if plants are diverse seed Exposure to ethylene during seed germination showed growth stimulation. We discovered it the answer is yes. We tested the effects of short-term ethylene treatment on germinating tomato, cucumber, wheat, and arugula seeds, all of which grew significantly. However, what made this observation unusual and exciting is that short ethylene treatments also Increased tolerance to various stresses salinity stress, high temperature, hypoxic conditions, etc. The long-term effects of short-term exposure to a stimulus on growth and stress tolerance are often referred to as priming effects. This can be thought of as pump priming priming allows the pump to start easier and faster. There are studies that investigated how plants grow after priming at different ages and developmental stages. but Seed priming Methods using various chemicals and stress are probably the most studied because they are easy to implement and, if successful, can be…

Source: scitechdaily.com