Behavioral thermoregulation in a small herbivore avoids direct UVB damage

Area of Science:

• Ecology
• Environmental Science
• Animal Behavior

Background:

• Stratospheric ozone depletion increases solar ultraviolet-B (UVB) radiation, posing risks to organisms.
• Ectotherms may use behavioral thermoregulation to avoid direct UVB exposure, but the timing and triggers are unclear.

Purpose of the Study:

• To investigate if sunlight-avoidance behavior in English grain aphids (Sitobion avenae) is driven by heat stress or UVB radiation.
• To determine if behavioral thermoregulation in shaded microhabitats reduces direct UVB damage.

Main Methods:

• Observational study of Sitobion avenae habitat selection on leaf surfaces in Mongolia during May and June.
• Comparison of temperatures between sun-exposed and shaded leaf surfaces.
• Assessment of aphid behavior in relation to ambient heat and UVB levels.

Main Results:

• Sitobion avenae shifted from sun-exposed to shaded leaf surfaces between May and June, indicating sunlight avoidance.
• Heat exposure, not UVB, was the primary driver of this avoidance behavior.
• Shaded microhabitats offered significantly lower temperatures, confirming behavioral thermoregulation.

Conclusions:

• Aphid sunlight-avoidance behavior is primarily thermoregulatory, occurring before UVB levels become harmful.
• Behavioral thermoregulation inadvertently provides protection against direct UVB damage.
• This response may be crucial for ectotherm survival under combined climate warming and increased UVB radiation.