ARACHNOLOGY

Warm temperatures disrupt spider sex-changing bacteria in dwarf-spiders across generations

The Hebrew University of Jerusalem

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Mermessus fradeorum female

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A new study reveals that exposing dwarf spiders to a brief period of warm temperatures can disrupt a phenomenon where internal bacteria normally force genetic males to develop as females. Surprisingly, this reproductive disruption skips the directly heated spiders and hits their children and grandchildren instead, leading to a sudden comeback of male offspring. The temporary heat scrambles the spiders' internal microscopic ecosystem, allowing a rival bacterium to surge ahead and block the feminizing bacteria from taking over.

 A single brief spell of warm weather can ripple across generations, altering the internal bacterial ecosystems of spiders and disrupting their reproduction, according to a study from Israeli and American researchers.

The research, published in Molecular Ecology, was led by Prof. Yuval Gottlieb-Dror and the PhD student Virginija Mackevicius-Dubickaja from the Koret School of Veterinary Medicine at the Hebrew University of Jerusalem, alongside collaborators, Prof. Jen White from the University of Kentucky and Prof. Matt Duremos from the University of Illinois. The team investigated the dwarf spider (Mermessus fradeorum), an arthropod that naturally carries up to five different types of maternally transmitted bacteria inside its body.

One of these bacteria, a strain of Wolbachia, forces genetic male spiders to develop as females—a phenomenon known as feminization. This strategy allows the bacteria to spread rapidly, since they are passed down directly from mothers to their offspring. However, in nature, these feminizing bacteria only exist at intermediate frequencies, prompting scientists to investigate what constrains their spread.

To test the impact of temperature, the researchers exposed young spiders to elevated conditions mimicking warm summer daytime surface temperatures (27°C to 28°C) for just one generation. While the heat-exposed spiders themselves grew up into females as expected, a delayed effect occurred when they laid eggs back in a standard, cool environment (20°C).

Their children and grandchildren, who never directly experienced the heat, exhibited a disrupted feminization process, resulting in a sudden return of male offspring.

The scientists discovered that the temporary heat exposure triggered a transgenerational shift in the spiders' internal microbial dynamics. While the feminizing Wolbachia initially increased in titre under the heat, its ability to transmit successfully into the next generation declined. Concurrently, another resident bacterium called Tisiphia was completely lost from the lineage.

These shifts coincided with a surge in a rival bacterium, Rickettsiella, in the subsequent generation. The data demonstrated that a high relative abundance of Rickettsiella is negatively associated with feminization, suggesting it acts as an antagonist that suppresses Wolbachia.

"Our findings demonstrate how an organism's environmental history shapes the evolutionary stability of its microbial communities and their induced phenotypes," said the researchers. "A brief period of elevated temperatures disrupts the delicate competitive balance between these symbionts. We observed that Rickettsiella appears to inhibit the feminization process, showing that reproductive manipulation requires not just the presence of Wolbachia, but its relative dominance within the microbial community."

The study also found that spiders carrying multiple strains of Wolbachia (strains 1, 2, and 3) were much more resilient, maintaining stable symbiont relative abundances and recovering their female-heavy sex ratios faster than those with fewer strains. This indicates that co-infection enhances the stability of symbiont dynamics under thermal stress.

The results offer a real-time observation of how environmental conditions destabilize natural microbial communities within a live host. In natural populations experiencing daily and seasonal thermal fluctuations, environmentally driven shifts in symbiont communities likely influence transmission efficiency and host population structure. By occasionally reducing feminization rates, thermal stress may act as an important mechanism for maintaining males within the population and avoiding a demographic collapse.

Mermessus fradeorum female on a one dime coin

Credit

Jen White, University of Kentucky

 

Mermessus fradeorum spiderlings hatching from an egg sac.

Credit

Courtesy of Rebecca Robertson, University of Kentucky

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Journal

Molecular Ecology

DOI

10.1111/mec.70371 

Method of Research

Experimental study

Subject of Research

Not applicable

Article Title

Elevated Temperatures Disrupt Wolbachia-Induced Feminisation and Reshape Microbial Community Dynamics Across Generations in a Spider Host

BIVALVES

They’re here: Biologists identify first established colonies of invasive clam in Northeastern US

Team led by UMass Amherst in collaboration with MIT Sea Grant and Center for Coastal Studies find reproducing populations of Manila clam in Cape Cod and Boston Harbor

University of Massachusetts Amherst

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Aly Putnam holding a baby Manila clam, much smaller than a thumbnail. Newly born clams are evidence that the species has established itself.

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Credit: Aly Putnam

AMHERST, Mass. — A collaborative team of biologists led by the University of Massachusetts Amherst, MIT Sea Grant at the Massachusetts Institute of Technology and the Center for Coastal Studies has discovered that the invasive Manila clam, Ruditapes philippinarum, has established itself along the northwestern Atlantic coastline — the last place in the northern hemisphere to have remained Manila-clam free. The team’s findings, published in Biological Invasions, document an exceedingly rare moment when an invasive species first takes hold in a new environment and begins to spread.

The home range of the Manila clam is from the coast of Russia’s Sakhalin Islands through Japan and southern China, but since at least the early 20th century they have been spreading to coastlines throughout the northern hemisphere. This is because they were introduced accidentally and intentionally to the American Pacific coast and to Europe. They are a delicious clam, prized in many cultures’ cuisines, and now represent a $7 billion per year industry. However, the clams can also outcompete native shellfish, hybridize with similar species and, in colonies dense enough, affect the local ecological community.

But it’s not all bad. Aside from their marketability, they can also be a rich food source for seabirds, crabs and other animals, like racoons, that feed on shellfish.

“Given that Manila clams are everywhere else in the northern hemisphere, it was only a matter of time before they showed up here, and we’ve been keeping an eye out for them,” says marine scientist, Aly Putnam, who is a postdoctoral researcher at UMass Amherst and lecturer at Smith College, as well as the paper’s lead author.

As it turns out, the Manila clam has now reached the final major gap in its Northern Hemisphere distribution: the coastlines of the Northeastern U.S. We owe this new information to a simple text message.

In the summer of 2025, Putnam, who was leading a mini workshop on intertidal biodiversity on Spectacle Island in Boston Harbor, received a text from El Fernekees Hartshorn, a recent undergraduate student from the University of Rhode Island, who had worked alongside Putnam through regional Rapid Assessment Surveys for marine invasive species. Fernekees Hartshorn, also one of the paper’s co-authors, had texted Putnam a picture of a clam and suggested it might be a Manila clam. Putnam’s co-investigator Carolina Bastidas, research scientist with MIT Sea Grant, was also along on the trip to Spectacle Island, and the two decided to keep an eye out for Manila clam shells—which they found in abundance.

Unbeknownst to Putnam and Bastidas, another research group, led by the Center for Coastal Studies’ Owen Nichols, had also begun hearing reports from local clammers in 2023 of “weird clams” in Provincetown, at the northern tip of Cape Cod, and other sites around the Cape.

The two groups would have continued researching along parallel tracks were it not for James T. Carlton, emeritus professor of marine sciences at Williams College and one of the world’s foremost authorities on marine invasive species, who brought the Boston Harbor and Cape Cod groups together. When Carlton heard of the shells on Spectacle Island, he told Putnam and Bastidas to make sure they weren’t just the remains of someone’s dinner or discarded bait shells. “Find me living clams,” he told the group—especially baby clams and clams that showed evidence of having reproduced.

It didn’t take long for Putnam and Bastidas to do just that—the team spent hours digging at Squantum in Quincy and Calf Pasture Park in Boston. Using sieve-based sampling, they yielded dozens of tiny, live specimens, confirming recent reproduction and recruitment.

 And then, when Nichols’s team investigated the weird clams on Cape Cod, they found female Manila clams that showed evidence of having reproduced.

 “When I learned about what each group was working on,” Carlton says, “I realized that this was a golden opportunity to not only combine forces but also to catch a detailed snapshot of the moment a new invasive species establishes itself.”

“As a marine biologist, I have worked with invasive species and with Rapid Assessment Surveys from the Northeast Aquatic Nuisance Species (NEANS) Panel for 11 years now,” says Bastidas. “Collaboration is invaluable for these sorts of efforts, and the fact we had already a network of people looking into Manila clams, means that we could catch them at the moment they established themselves.”

It’s not clear how the clams arrived in the northwestern Atlantic, nor is it clear what the future holds for the Northeastern U.S.’s waters now that they’re here. Bastidas says, “We do need more research to understand the Manila clam’s potential effects on the shellfishing industry and ecological communities. On the positive side, because Manila clams can become a source of food for other animals, they can relieve pressure on native species—for example, the predatory pressure of green crabs on softshell clams. So, there could also be positive impacts.”

 “Discoveries like this remind us how much there is still a lot to learn about our coastal ecosystems,” said Putnam. “Finding the species is only the beginning. Now we are working to understand its distribution, if these populations are expanding and how these clams interact with other species in New England coastal systems. This research will help us determine whether this newcomer becomes a minor addition to the ecosystem or a more influential player in the years ahead.”

Researchers at the Northeastern University, Massachusetts Bays National Estuary Partnership, Massachusetts Office of Coastal Zone Management, Fisheries and Oceans Canada and Cape Cod Cooperative Extension Woods Hole Oceanographic Institution Sea Grant; and Salem Sound Coastwatch also contributed to this study.

A media kit with photos and all caption and credit information is available here.

 

Contacts: Aly Putnam, aputnam@umass.edu

                 Carolina Bastidas, bastidas@mit.edu

                 Daegan Miller, drmiller@umass.edu

 

About the University of Massachusetts Amherst 

The flagship of the commonwealth, the University of Massachusetts Amherst is a nationally ranked public land-grant research university that seeks to expand educational access, fuel innovation and creativity and share and use its knowledge for the common good. Founded in 1863, UMass Amherst sits on nearly 1,450-acres in scenic Western Massachusetts and boasts state-of-the-art facilities for teaching, research, scholarship and creative activity. The institution advances a diverse, equitable, and inclusive community where everyone feels connected and valued—and thrives, and offers a full range of undergraduate, graduate and professional degrees across 10 schools and colleges and 100 undergraduate majors.  

 

About MIT Sea Grant

Based at the Massachusetts Institute of Technology, MIT Sea Grant is a federal-institute partnership with NOAA that promotes the conservation and sustainable development of coastal and marine resources through research, education, and outreach. MIT Sea Grant works across four focus areas: Healthy Coastal Ecosystems; Environmental Literacy and Workforce Development; Resilient Communities and Economies; and Sustainable Fisheries and Aquaculture.

  

Empty Manila clam shells blanketing the intertidal zone in Boston Harbor’s Spectacle Island.

Credit

Aly Putnam

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Journal

Biological Invasions

DOI

10.1007/s10530-026-03861-z 

Article Title

Completing the journey in the global north: the Manila clam (Ruditapes philippinarum) (Bivalvia: Veneridae) arrives in the Northwest Atlantic Ocean

SPAGYRIC HERBALISM

Homegrown catnip lotion proves to be an effective mosquito repellent in rural Uganda

Society for Experimental Biology

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Field trial technicians preparing for human landing catch trials

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Credit: Cardiff University and CEMPOP

Plant researchers from Wales and Uganda have collaborated on a community enterprise project in rural Uganda, becoming the first to create affordable and highly effective mosquito repellent distilled from locally grown catnip plants. Laboratory and field experiments reveal that the catnip-based repellent skin lotion is just as effective as DEET and offers a much cheaper alternative for preventative action against mosquito-borne diseases in malaria-endemic regions, while also providing new economic opportunities for local Ugandans.

Nepetalactone is a chemical found in the essential oil of catnip, Nepeta cataria, and is the chemical responsible for causing feelings of euphoria in cats. Nepetalactone is also a potent natural insect repellent and is very effective at repelling mosquitoes, which are responsible for the transmission of malaria and other vector-borne diseases in Sub-Saharan Africa.

The insect-repelling properties of nepetalactone have been known for a long time, but it has never been commercialised or adopted by pharmaceutical companies since it cannot be patented. This project, presented at the Society for Experimental Biology conference in Florence, Italy, demonstrates the validation of nepetalactone as an effective and locally available mosquito repellent.

“There is a real need to reduce the reliance on malaria medicines because malaria can develop resistance to drugs,” says Dr Simon Scofield, a senior lecturer at Cardiff University. “Mosquito repellents represent one of the primary measures used to reduce the risk of malaria by reducing mosquito landing and biting events.”

Currently, DEET is the most widely used active ingredient in commercial insect repellents and works by disrupting insect sensors to prevent them from landing on human skin, but DEET products can be very expensive to import into Uganda.

“DEET is out of the price bracket for most rural Ugandan subsistence farmers, so buying commercially available mosquito repellents is just not practicable,” says Dr Scofield. “We wanted to make a repellent, which is highly efficacious, but also allows local people to be involved in the production cycle so that it costs a minimal amount of money.”

As well as being more affordable, the other benefits of using nepetalactone over DEET are that catnip is widely cultivatable in rural Uganda, the oil is easy to extract, it’s safe to use and users report that it smells a lot more pleasant than DEET.

To test the efficacy of the catnip oil as a repellent, Dr Scofield and his colleagues created a insect-repelling hand lotion containing the catnip oil, called DSK lotion, and conducted both laboratory and field trials that compared how mosquitoes were attracted to human skin with different repellent treatments.

The laboratory experiments used a Y-tube olfactometer to test if mosquitoes were more attracted to repellent-treated skin or skin without repellent under controlled conditions. The field trials used a “human landing catch assay” to measure how many wild mosquitoes landed on human skin treated with a different repellent treatments and controls.

“We found that a 6% catnip oil was just as effective as DEET, and the 2% catnip oil was only marginally less effective than that,” says Dr Scofield.

As a community enterprise project, this project has employed workers and volunteers from the local area in all aspects of the lotion’s production. DSK Lotion, named for local community leader Dison Stephen Kalebo, has been distributed for free in local trials thanks to external grant funding, but the next stage of the project will involve up-scaling production and selling the lotion for a small price to provide a sustainable income to the local workers involved in the project.

“Once we know that we can sell and distribute the repellent at a low-cost, that should generate a self-sustaining system where the money is flowing back to everybody at each stage in the development,” says Dr Scofield.

Dr Scofield adds that there may even be scope for expansion of the project’s scope across Africa and into the global north, since the repellent also works well on other biting insects such as midges and ticks.

Dr Scofield and his team at Cardiff University are working closely with researchers from Makerere University, Ugandan government officials and malaria clinic workers in the Budaka district of Eastern Uganda to facilitate the trialling and distribution of the repellent. The project is being led by a local organisation called CEMPOP Uganda Limited, which stands for Community Enterprise Model for Plant Oil Production.

 

Catnip oil insect repellent

A field trial participant engaged in collecting a landing mosquito.

Team members talking to school pupils.

Credit

Cardiff University and CEMPOP

 

Babies’ brains respond to music by three months of age – while moving to it begins by their first birthday

A study suggests babies’ brains recognize music from as young as three months of age, while spontaneous movements to music emerge by their first birthday and their ability to match movements to it develops later

eLife

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An overview of the experimental design and conditions (top), and participant sample (below) for the eLife study by Nguyen et al. Infants sat in front of a screen that showed slowly blossoming flowers to attract their attention, while speakers on each side played music. The dots on the images represent the body parts of which movements were tracked using video-based analysis.

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Credit: Nguyen et al. (CC BY 4.0)

Researchers have discovered that music begins to shape how we move within the first year of life.

Their study, published previously as a Reviewed Preprint in eLife and appearing today as the final Version of Record, provides insights into how the developing brain gradually transforms music into spontaneous movements. It suggests that while our brains are able to process music early in infancy, spontaneous movements to music increase only towards the end of the first year, and coordinating these movements in time with the beat develops later still. eLife’s editors describe the work as important, with compelling results that will be of significant interest to researchers studying music processing and how perception translates into action.

Musicality – our penchant for perceiving, appreciating, and producing music – is increasingly recognized as a fundamental aspect of human nature. At the heart of musicality is our engagement with music, which can be broken down into two components of neurocognitive development: a sensory component – the ability to perceive and recognise music – and a motor component – the ability to move (in time) to music. But when and how we develop musicality as infants remains largely unknown.

“This lack of knowledge is partly due to the fact that few to no studies have explored brain activity and spontaneous movements in response to music at the same time,” explains lead author Trinh Nguyen, Affiliated Researcher in the Neuroscience of Perception and Action Lab at the Istituto Italiano di Tecnologia (Italian Institute of Technology; IIT), Rome, Italy, and Senior Research Fellow at the University of Vienna, Austria. “Studying both the sensory and motor components of musicality in infants would give us a better understanding of how we learn to transform the perception of music into movement.”

To address this gap, Nguyen and colleagues played music to infants – 79 in total, aged three, six and 12 months old – and took EEG recordings and movement measurements to understand their neural (auditory) and motor responses, respectively. The music included instrumental refrains of children’s songs (referred to simply as ‘music’), shuffled versions of the same songs (‘shuffled music’), and high and low-pitched versions of the songs, as pitch may play a role in auditory-motor engagement in infancy.

From the infants’ EEG recordings, the team extracted event-related potentials (ERPs) – an averaging of the infants’ neural responses to pinpoint the precise timing of the brain’s response to each tone in the music – and auditory steady state responses (ASSRs) – a measure of how the brain responds to continuous sounds. 

When they compared ERPs that were elicited by ‘music’ to those elicited by ‘shuffled music’, they found that all age groups had an enhanced auditory response to ‘music’, indicating that music processing starts early in development. This finding is in line with one of their hypotheses: that auditory responses would be enhanced when triggered by music compared to shuffled music. This is based on the notion that musical structure, which was disrupted in the shuffled music, is essential to attract infants’ attention towards predictable events.

The researchers then estimated and compared the infants’ spontaneous movements in response to the music types using automated video-based motion-tracking, specifically open-source software called DeepLabCut. Applying a dimensionality reduction technique called principal component analysis, they categorised these movements into 10 principal movements (PMs) including: front-back rocking, side sway, proto-clapping, leg-kicking, up-down rocking, arm-pedalling, feet-kicking, whole-body wiggling, feet-shuffling, and feet-pedalling.

A data modelling technique highlighted a significant interaction between the type of music and age group, showing that only 12-month-olds exhibited higher quantities of movement in response to ‘music’ compared to ‘shuffled music’ across all PMs. When the team explored these movements further, they found that this response involved mostly movements of the upper body and/or upper limbs – specifically front-back rocking, side sway, proto-clapping, up-down rocking, and arm pedalling.

In comparison, infants aged three and six months old did not exhibit significantly different quantities of movement in response to ‘music’ vs ‘shuffled music’ in any of the PMs. These results were unchanged across all age groups when the researchers compared their movements in response to the high and low-pitched versions of the music.

“Across the first year of life, infants seem to consistently move their lower body while slowly increasing their capacity for more complex upper-body and whole-body movements while seated, as we saw in the 12-month-olds,” Nguyen explains. “We believe this increasing complexity is linked to the gradual maturation of the dorsal auditory stream in the brain, a pathway that has previously been suggested to play a crucial role in rhythmic entrainment and beat perception.”

Notably, the team also found there was no evidence that infants of any age coordinated their movements in time with the music. This points to a gradual refinement of human motor control: the system first develops the capacity to control individual muscles, while the capacity for more coordinated, whole-body movements follows later.

“We’ve shown that, much like the auditory encoding of music, moving to music emerges early in development. This may reflect a biological or early-developing predisposition that eventually leads to dance-like behaviours, although these motor responses remain underdeveloped before 12 months of age,” concludes senior author Giacomo Novembre, Principal Investigator in the Neuroscience of Perception and Action Lab at IIT. “This work provides initial insights into how the developing brain gradually transforms music into spontaneous movements. Future research is now needed to extend our characterisation of music-driven movement beyond the first year of life and explore what continues to be its mysterious functional significance.”

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Journal

eLife

DOI

10.7554/eLife.107088.4 

Method of Research

Experimental study

Subject of Research

People

Article Title

Development of auditory and spontaneous movement responses to music over the first postnatal year

Article Publication Date

7-Jul-2026