A recent study has discovered that two types of harmful fungi surprisingly share their insect victims with one another instead of competing for them.
Entomologists from the University of Maryland have found an unusual partnership between two fungal species known for their proficiency in invading and killing insects. Instead of competing with hostility, these fungi cooperate peacefully and share their insect prey.
The research, which appeared in the journal Public Library of Science (PLOS) Pathogens on November 7, 2024, sheds light on some significant evolutionary achievements in nature, according to study co-authors Raymond St. Leger, who is a Distinguished University Professor of Entomology, and Huiyu Sheng, a Ph.D. candidate in entomology.
“This isn’t just about survival of the fittest as we commonly perceive it. Sometimes, those who can coexist are the ones that thrive,” St. Leger remarked. “Instead of obliterating each other, these fungi seem to have developed advanced methods of living together — and we are just starting to grasp that equilibrium.”
The research centered on two species from the genus Metarhizium, which is found in soils across the globe. These fungi help shield plants from detrimental environmental stresses (like drought or nutrient deficiency) and harmful insects.
“These microorganisms are recognized as keystone species due to their vital roles in maintaining plant health and managing natural insect populations,” St. Leger stated. “Our results may clarify their remarkable success in ecosystems worldwide.”
The scientists utilized advanced imaging techniques combined with fluorescent proteins that made the fungi emit red or green light to monitor their interactions as they colonized (infected, spread throughout, and ultimately killed) insects. Instead of one strain overpowering the other, the team noticed that the fungi skillfully divided their territory between themselves — quite literally.
When infecting their insect hosts, the two fungal strains demonstrated a remarkable ability to partition their prey. One strain typically invaded the front segments of the insect, while the other took over the back segments, with a strikingly clear boundary separating their territories. This behavior was consistent regardless of whether the insect was a ten-gram caterpillar or a tiny fly weighing less than a milligram.
“The vivid distinction between where one fungus begins and the other ends is quite strange,” St. Leger observed. “The separation between their segments is remarkably well-defined.”
But why do these fungi operate in this collaborative manner? The researchers suggest that over time, each strain adapted to develop its own unique specializations and niches, allowing them to share limited resources.
“It’s becoming increasingly evident that sometimes, the secret to evolutionary success lies in cooperation rather than outcompeting your adversaries,” St. Leger remarked.
However, the exact mechanisms by which these fungi position themselves within their hosts and communicate their territorial arrangements remain unanswered questions. The researchers aim to explore how these host-sharing strategies work and potentially pave the way for new research avenues that could enhance food security and biodiversity on Earth.
Understanding the interactions between different fungal species might assist scientists and agriculturalists in creating improved biological pest control methods and promoting plant growth. St. Leger highlighted that these fungi already show remarkable potential in safeguarding plants against mercury toxicity, boosting crop growth, and eliminating insects that spread diseases.
“These fungi have proven to be incredibly adaptable,” he said. “They have been evolving their sophisticated techniques for a long time, and they are also relatively easy to genetically modify, which means their applications are only confined by our imagination.”
