Novel Method of Specifying Low and High Threshold Temperatures Using Thermodynamic SSI Model of Insect Development

Area of Science:

• Ecology
• Evolutionary Biology
• Physiology

Background:

• Insect temperature tolerance is vital for physiological, ecological, and evolutionary processes.
• Current methods using empirical models for critical thermal thresholds may lack reliability.

Purpose of the Study:

• To review insect temperature tolerance in relation to development.
• To propose a novel, theoretically-based method for specifying low and high temperature thresholds.

Main Methods:

• Critically evaluate existing empirical models for insect thermal tolerance.
• Implement the Sharpe-Schoolfield-Ikemoto (SSI) model, a nonlinear theoretical model based on thermodynamics.
• Utilize the P2 function within the SSI model to define thermal thresholds based on enzyme activity probabilities.

Main Results:

• The Sharpe-Schoolfield-Ikemoto model offers a thermodynamically grounded alternative to empirical models.
• The P2 function within the SSI model identifies intrinsic optimum temperature (TΦ) and 50% activity/inactivity thresholds (TL50, TH50).
• The SSI model allows for the determination of thermal thresholds at any specified enzyme activity level (0

Conclusions:

• The Sharpe-Schoolfield-Ikemoto model provides a more robust framework for understanding insect thermal tolerance.
• This model enables precise determination of critical thermal thresholds relevant to insect's natural environments.
• The findings contribute to a better understanding of insect adaptation to varying temperatures.