A Hot Plant’s Irresistible Signal Makes Beetles Its Pollinators

Ancient cycads lure insects with a warm, infrared “come hither” cue

Researchers have uncovered a striking new twist in the reproductive strategy of cycads, the prehistoric plant group that has survived since the age of dinosaurs. The study shows that these “living fossils” emit a subtle pulse of infrared radiation, effectively turning up the heat to attract specific beetles that act as their pollinators.

“It’s as if the plants are whispering ‘come hither’ in a language only heat‑sensing insects can hear,” said Dr. Lina Ortega, lead author of the paper published in Nature Ecology & Evolution. “The infrared signal is invisible to the human eye, but beetles equipped with thermoreceptors can detect it from a distance and are drawn to the source.

Field observations in tropical rainforests revealed that beetles of the family Dynastidae consistently visited the cones of several cycad species during the early morning hours, when the ambient temperature was lowest. Thermal imaging confirmed that the cones were a few degrees warmer than the surrounding foliage, creating a thermal hotspot that guided the insects straight to the plant’s reproductive structures.

The discovery sheds light on a long‑standing mystery: how non‑flowering plants like cycads achieve effective pollination without the colorful petals and sweet scents typical of angiosperms. By exploiting the beetles’ innate preference for warm surfaces—often a cue for food or mates—cycads have evolved a low‑tech but highly efficient signaling system.

Beyond its ecological intrigue, the finding may have practical implications. Understanding the thermal cues that drive insect behavior could inspire new, pesticide‑free methods for managing pollinator services in agriculture, especially in regions where beetles play a key role.

As climate change continues to alter temperature regimes worldwide, scientists warn that the delicate balance between cycads and their beetle partners could be disrupted. “If the thermal gradient disappears, the beetles may no longer find the plants,” Ortega cautioned, “potentially threatening the survival of these ancient lineages.”