Lead: Researchers report that cycads, 250-million-year-old seed plants, produce heat in their reproductive cones that attracts specialist beetles on dusk in a study published in Science on Dec. 11, 2025. The Zamia furfuracea cones warmed above ambient temperature and appeared to emit a signal detectable by Rhopalotria furfuracea beetles equipped with infrared-sensitive antennae, encouraging pollination. Harvard evolutionary biologist Wendy Valencia-Montoya, an author on the paper, framed the finding as evidence that non-visual, thermal cues played a role in early plant–animal communications. The work combines behavioral trials, thermal imaging and anatomical study to link cone heating with beetle orientation.
Key Takeaways
- Cycads like Zamia furfuracea can raise cone temperatures above ambient; some thermogenic plants elsewhere reach 60–90°F above surroundings, and cycads show measurable heating at dusk.
- Beetles Rhopalotria furfuracea respond to infrared cues: controlled tests indicate antennae detect warm cones and trigger approach behavior.
- The study was published in Science on Dec. 11, 2025, and includes field observations and lab experiments documenting heat-driven attraction.
- Authors include Wendy Valencia-Montoya of Harvard University; the research argues thermal signaling may be an ancient pollination channel dating back hundreds of millions of years.
- Thermogenesis in plants is already known in taxa such as lotus and titan arum; this paper links thermogenesis to active attraction via insect infrared sensing.
- Findings suggest a non-olfactory, non-visual modality—infrared emissions—can function as a pollination cue in tropical ecosystems.
Background
Cycads are an ancient lineage of seed plants with a fossil record stretching roughly 250 million years. They resemble palms or ferns but reproduce with large male and female cones rather than flowers. Historically, botanists emphasized color and scent as the primary mechanisms plants use to recruit animal pollinators, and thermogenesis was often interpreted as scent-amplifying or shelter-providing.
Thermogenic flowering—where floral structures heat significantly above ambient temperature—has been documented in several unrelated plant groups, sometimes reaching tens of degrees above surroundings. Prior work proposed that warming helps volatilize scent compounds or offers insect visitors a warm refuge when ambient temperatures are low, but direct evidence that animals sense and follow thermal cues remained limited.
Main Event
The new study focused on male cones of Zamia furfuracea and the beetle Rhopalotria furfuracea. Researchers used thermal imaging to record cone temperatures at dusk and compared beetle behavior toward warmed versus ambient artificial targets. In both field and lab settings, beetles showed a repeatable preference for warmer objects that matched cone surface temperatures.
Microscopic and anatomical analyses revealed specialized sensilla on the beetle antennae consistent with thermosensory function. Behavioral assays with manipulated antennae or blocked thermal gradients reduced approach rates, strengthening the causal link between heat perception and pollination visits. The authors emphasize that the response was specific: beetles did not simply move toward general light or scent cues but toward the warm surface itself.
Wendy Valencia-Montoya and colleagues situate these results within the broader dataset by noting parallel thermogenic strategies in other plants, such as the pink lotus and titan arum, that warm to boost scent emission by tens of degrees. The cycad–beetle pairing adds physiological and behavioral evidence that thermal emissions can act as an active attractant rather than a passive byproduct.
Analysis & Implications
The study broadens the palette of recognized plant signals beyond color and odor to include patterned thermal radiation as an ecological cue. If thermal signaling proved widespread among early seed plants, it could alter interpretations of how pollination syndromes evolved on a hotter, differently lit prehistoric Earth. The authors argue that infrared perception in insects may be an ancestral sensory channel co-opted by early plants.
Ecologically, thermal cues can be reliable at twilight when visual contrast declines and scent dispersal changes with temperature and humidity. For specialist beetles that forage at dusk, a warm cone offers both a directional cue and, potentially, an energetic reward—an advantage in cooler periods. That combination can strengthen mutual dependence, shaping coevolutionary trajectories between plant and pollinator.
From a conservation perspective, recognizing thermal cues adds a dimension to habitat suitability assessments: microclimate alterations due to habitat loss or climate change could disrupt thermally mediated interactions. If certain beetle species rely on precise temperature differentials to find cones, shifts in dusk temperature regimes might reduce effective pollination, affecting cycad reproduction rates.
Comparison & Data
| Plant/Group | Reported Temp Rise (above ambient) | Primary Hypothesized Function |
|---|---|---|
| Zamia furfuracea (cycad) | Measured warming at dusk (study-specific values) | Beetle attraction via infrared cues |
| Pink lotus | Up to tens of °F | Scent volatility and attraction |
| Titan arum | Up to 60–90°F | Scent dispersion and visitor warmth |
The table summarizes comparative examples; the cycad case adds behavioral tests and antennal morphology data that explicitly link warming to insect approach. While some thermogenic plants show extreme temperature spikes, the key functional variable is the detectability of the thermal gradient by the target pollinator rather than peak temperature alone.
Reactions & Quotes
Authors framed the finding as a window into ancient signaling systems.
If you think about how the ancient planet looked when plants and animals first started to communicate, there were other signals that were important.
Wendy Valencia-Montoya, Harvard University (study author)
Outside scientists noted the study strengthens the case for non-visual signals in pollination ecology and called for broader surveys across insect taxa.
The results provide compelling behavioral and anatomical evidence that thermal emissions can serve as a directed cue for pollinators.
Science (peer-reviewed journal summary)
Unconfirmed
- Whether thermal signaling in cycads represents the ancestral origin of all animal-mediated pollination remains unproven and is presented as a hypothesis by the authors.
- The prevalence of infrared-guided pollination across other cycad species and unrelated plant families is not yet quantified and requires broader sampling.
- Exact temperature differentials that trigger beetle approach behavior in varied field climates need more replication across seasons and locations.
Bottom Line
The study adds a rigorous case that warm reproductive organs can function as an active attractant, detected by infrared-sensitive beetles, and that thermal cues deserve a place alongside color and scent in pollination biology. By combining field observation, behavior experiments and anatomical study, the research gives a mechanistic explanation for beetle attraction to cycad cones at dusk.
Future work should map how common thermally mediated attraction is across plant and insect lineages and test vulnerability to climate-induced microclimate shifts. For conservationists and ecologists, the take-home is clear: preserving microclimates and considering thermal microhabitats may be essential to maintain certain ancient plant–pollinator relationships.