Daily temperature extremes play an important role in predicting thermal effects

Area of Science:

• Ecology
• Environmental Science
• Climate Change Biology

Background:

• Organisms face daily temperature fluctuations, not constant temperatures.
• Previous studies often overlook the impact of diel temperature cycles, focusing on average or short-term heat stress.

Purpose of the Study:

• Investigate the effects of daily maximum temperatures on demographic parameters and fitness in the English grain aphid (Sitobion avenae).
• Compare observed effects with predictions based on constant temperature performance.

Main Methods:

• Exposed Sitobion avenae to varying daily maximum temperatures while keeping night-time temperatures constant.
• Assessed demographic parameters and fitness under different thermal regimes.

Main Results:

• Moderate daily maximum temperatures reduced aphid performance.
• Extreme daily maximum temperatures had severe negative impacts, even below critical thresholds.
• Constant temperature models inaccurately predicted aphid performance.

Conclusions:

• Daily maximum temperature is a critical factor influencing natural population dynamics.
• Accurate population predictions require considering both daily maximum and minimum temperatures.
• Findings are vital for understanding aphid population responses to increasing extreme temperatures due to climate change.