Dung Beetles Adapt to Climate Change by Burying Eggs Deeper
Rising temperatures are prompting temperate rainbow scarabs (Phanaeus vindex) to bury their dung‑ball nests deeper, creating a cooler micro‑environment for developing larvae. Ecologist Kimberly Sheldon presented this finding on Jan 6 at the Society for Integrative and Comparative Biology meeting in Portland, Oregon.
How the experiment was conducted
Sheldon’s team placed “greenhouses”—plastic cones with a vented tip—over soil‑filled buckets in a field. The cones amplified solar heating by about 2 °C, while the vent allowed weather fluctuations. Beetles under the cones dug their dung balls an average of five centimetres deeper, reaching roughly 21 cm below the surface and lowering incubation temperature by about 1 °C.
Repeat test in 2023
When the experiment was repeated in 2023, the deeper‑buried larvae emerged as adults at the same rate as those from shallower nests, despite the added heat.
Did You Know? The deeper burial shifted the nest depth from the surface to about 21 cm underground, a change that reduced the temperature experienced by the eggs by roughly 1 °C.
Contrast with tropical relatives
In parallel trials with the tropical cousin Oyxternon silenus in Ecuador, the beetles did not adjust burial depth under simulated warming, leaving it unclear how their eggs fared.
Expert Insight: Samantha Carter notes that the temperate scarab’s ability to modify nesting depth could buffer populations against climate stress, whereas the lack of such flexibility in tropical species may heighten their risk of decline, potentially disrupting dung‑decomposition services critical to ecosystem health.
Why this matters
Behavioral plasticity in insects can influence survival as global temperatures climb. Species that can fine‑tune nesting or foraging habits may maintain reproductive success, while those without such options could suffer population losses, altering nutrient cycles and soil health.
What could happen next
If temperate dung beetles continue to deepen their nests, they may sustain their numbers despite warming, preserving their ecological role. Conversely, tropical dung beetles lacking depth‑adjustment ability could experience reduced hatch rates, leading to declines that cascade through food webs. Researchers may monitor these trends and explore whether other insects develop similar adaptive behaviors.
Frequently Asked Questions
What did the “greenhouse” experiment reveal about rainbow scarabs?
The experiment showed that scarabs buried their dung balls about five centimetres deeper under warmer conditions, lowering the incubation temperature by roughly 1 °C.
Did the deeper burial affect the survival of the larvae?
In the 2023 repeat, the number of larvae that emerged as adults was unchanged, indicating that deeper burial helped maintain survival despite higher ambient temperatures.
How did the tropical beetles respond to simulated warming?
The tropical species Oyxternon silenus did not change burial depth when subjected to the same warming treatment, and the impact on their eggs remains unknown.
What do you think about insects adapting to climate change?