A study published in the Journal of Animal Ecology by researchers from Bielefeld University reveals that certain plant compounds, from non-food plants that then affect the social behavior and lifespan of the turnip sawfly (Athalia rosae). Led by Dr. Pragya Singh, a postdoctoral researcher in the Collaborative Research Center (CRC) Transregio 212 in the Chemical Ecology group, the team investigated how the consumption of specific non-nutritional plant-derived chemicals, known as clerodanoids, alters social networks within sawfly populations while simultaneously shortening the insects’ lifespan. These findings provide valuable insights into plant-animal interactions and social networks in ecology.
Plants offer more to animals than just food. The study showed that sawflies specifically take up clerodanoids from plants like Ajuga reptans to gain advantages. These chemicals provide protection from predators and enhance reproductive success. “Interestingly, sawflies acquire these compounds not only directly from plants but also through social interactions with other sawflies that have accessed these plants. Such encounters often involve conflict, as the sawflies attempt to ‘nibble’ small amounts of the valuable chemicals from each other,” explains Dr. Pragya Singh, lead author of the study.
© Bielefeld University
In their research, the scientists examined wild populations of turnip sawflies and found that some individuals had high levels of clerodanoids, while others had none. This inequality directly influenced the social behavior of the sawflies in the laboratory. Those without access to clerodanoids were more frequently involved in conflict-driven interactions to obtain the valuable compounds from others.
Through detailed social network analysis, the researchers demonstrated that sawflies with access to clerodanoids exhibited significantly more social interactions, especially in groups where some individuals had clerodanoids and others did not. While these compounds offer defensive and reproductive benefits, they also come with costs. The study showed that sawflies with clerodanoids experienced shorter lifespans when in groups with sawflies lacking them. The frequent social interactions and aggressive attempts by others to obtain the chemicals may have led to the reduced lifespan for the carriers, even without visible injuries. “It was surprising to see how much these aggressive social interactions reduced the sawflies’ lifespans without any external signs of injury,” Dr. Pragya Singh explains. “The social costs of these conflicts may stem from increased metabolic stress, despite the absence of physical harm.”
New perspectives for research into social networks
The study not only provides novel insights into how plant chemicals influence animal behavior but also opens new avenues for research into social networks in ecological systems. “Our findings raise important questions about the long-term effects of non-nutritional plant-animal interactions on population structure,” Singh continues. “What role do these chemicals play in multi-species ecological networks, such as predator-prey or parasite-host relationships, over longer timescale?”
This research aligns with the overarching goals of CRC 212, which examines how individual traits shape ecological niches and influence social behavior. The study highlights how individual variation in clerodanoid uptake leads to different social behaviors, shaping the structure of social networks.
Original publication:
Pragya Singh, Leon Brueggemann, Steven Janz, Yasmina Saidi, Gaurav Baruah, Caroline Müller: Plant metabolites modulate social networks and lifespan in a sawfly. Journal of Animal Ecology. https://doi.org/10.1111/1365-2656.14189, published on September 22, 2024.