At the same time, plants unable to detect the molecular signature of the caterpillar’s saliva were largely ignored by the wasps. However, they were not completely defenseless. “There are other papers that show that if you eliminate all the immune signals, the caterpillars become twice as large—they become much larger,” says Steinbrenner. They suggest this indicates that the immune system had other ways to fend off herbivores such as caterpillars.
crop protection systems
While the team linked the broken inceptin receptor to a muted distress call, the exact downstream immune signaling pathways are not fully understood. The authors suspect that the highly specialized caterpillar detection they observed piggybacked on the plant’s normal wound response, potentially triggering a secondary internal alarm, known as a damage-associated molecular pattern, or DAMP. Exactly how initial receptor activation ultimately translates into the production of volatile organic compounds remains a puzzle.
Another caveat lies in the choice of attacker. Spodoptera exiguaKnown as the beet armyworm, it is a generalist herbivore, meaning it eats a wide variety of plants and is sensitive to plant defenses. Specialist herbivores that feed on specific plants probably evolved metabolic measures to bypass or otherwise detoxify their hosts’ chemical defenses. In the study, the researchers acknowledged that we are not yet sure whether a functional inceptin receptor provides broad-spectrum resistance, or whether particular insects can fool this alarm system.
Finally, in Oaxacan field trials, the team showed that predatory wasps use aerial distress signals to find their prey, but the relative importance of this indirect wasp recruitment versus direct leaf protection is unclear. Scientists want to investigate this in more detail in their future research. Still, the team hopes their work will help us better protect crops like bean plants from pests.
“Today, we do this with chemicals, with pesticides, but if we can use the best receptors and the best volatiles from different plants, maybe we might be able to provide immunity to most problematic pests or pathogens in a targeted way,” Steinbrenner says. “That’s the big picture, the goal of our lab in the long run. And I think doing this will mean understanding more of these types of receptors and volatiles.”
Science Advances, 2026. DOI: 10.1126/sciadv.aec3229
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