Typically, monitoring fungi in rice fields involves disturbing the soil, swabbing plant surfaces, or using air filters. These methods might miss what travels through the air, but a new study suggests that living fungi caught in spiderwebs offer a simple way to detect and study this hidden diversity.
A team in Thailand decided to investigate what spiderwebs collect. Across three provinces, they scraped off web contents, cultured them, and discovered living fungi, including some previously unclassified by science. The findings are detailed in the Biodiversity Data Journal.
Spider silk is engineered to capture and hold. Its sticky fibers trap dust, pollen, and anything else drifting by. These webs present inexpensive, readily available samples. One previous study even managed to extract DNA from them to track nearby wildlife.
While DNA can confirm an animal’s passage through an area, it doesn’t indicate if the animal is still alive. Of all the things known to be caught in webs, fungi have received the least attention.
Tanakorn Inta from Thammasat University aimed to change this. He wanted to know what living organisms might be present in spiderwebs and if they could be successfully cultivated.
The research focused on the Cyclosa mulmeinensis orb-weaver, a thumb-nail-sized spider found in South and Southeast Asia. Female spiders construct flat, circular webs smaller than a dinner plate, adorning them in a unique fashion.
Along one silk strand, the spider creates a “trash line” – clumps of plant matter, insect exoskeletons, shed skins, and other debris. This decoration aids in camouflage and prey capture, and it might also provide more surfaces for airborne particles to adhere to.
This combination of exposed silk and densely packed debris forms a rough, sticky surface in the open air. Fungal spores are ubiquitous, dispersed through soil, plants, and the atmosphere, making such a web an easy landing spot.
Careful handling was required to collect the webs without contamination. The team placed sterile Petri dishes over each web and sealed them without touching the silk, then kept the samples cool during transport.
At the National Center for Genetic Engineering and Biotechnology, researchers washed the trapped material from the silk into a saline solution. They then spread this mixture onto Petri dishes containing nutrient agar, to which an antibiotic was added to suppress bacteria. After that, they waited.
Within days, colonies began to appear on the Petri dishes – fuzzy, colorful patches, each grown from something captured by the webs in rice fields across three Thai provinces. They sampled one web from each location.
These Petri dishes revealed 112 viable fungal colonies. Sorted by appearance and then by DNA, they were classified into 23 distinct types across six broad groups – these are molds, common in soil and air globally.
The sheer number found was not the biggest surprise. What was remarkable was that the fungi were alive – growing on the Petri dishes, ready for study, rather than existing as mere genetic traces.
Previously, web-based fungal studies had relied exclusively on DNA detection. While fungi could be identified, they could not be successfully cultured.
“We were particularly amazed that many fungi recovered from the webs remained viable and could be cultured,” Inta stated.
A living culture can be grown, named, and studied for its functions. DNA sequences alone cannot achieve this.
Some colonies resisted matching any existing data. When checked against global databases, only a few occupied their own unique branch on the tree of life.
They were close to known species but did not match any precisely.
Most of these unknown types belonged to two groups. Cladosporium, a mold so common it’s found in outdoor air almost everywhere, was the most diverse among them, with several of its types never officially named. Another group belonged to Talaromyces.
This fits into a larger context. Science has described over 120,000 fungal species, but this represents only a fraction of the estimated millions. Such hidden fungal diversity often goes unnoticed, even within well-studied groups.
A live culture is something researchers can work with. They can grow it, observe its behavior, test its products, and preserve it for future study. Some of these mold species impact both crops and human health.
The precise origin of the fungi remains an open question. A network of airborne dispersal, nearby plants, and soil is formed along the way, and the study did not attempt to disentangle these sources or determine their individual contributions.
The scope of the investigation was intentionally limited – three webs, one from each site, were treated as an initial proof-of-concept rather than a comprehensive survey.
Differences observed between these webs are considered clues rather than conclusions, a point the team made clear.
The study’s core finding is straightforward: spiderwebs harbor living fungi that can be collected, cultivated, and identified, with some potentially representing species yet to be cataloged.
This offers biologists a new sampling opportunity they lacked before. It’s inexpensive, harmless to the spider, and available for sampling whenever a web is regenerated. For monitoring fungi in agricultural settings, it’s a valuable option.
The same approach can now be applied to different spiders, environments, and seasons, potentially unlocking questions previously difficult to investigate in this field.
The humble spiderweb can provide scientists access to living fungi, and sometimes, to those yet to be named.
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