A protocol for analysing thermal stress in insects using infrared thermography

Area of Science:

• * Entomology
• * Thermal Physiology
• * Non-invasive Measurement Techniques

Background:

• * Existing insect thermal stress studies lack standardized protocols, hindering result comparison.
• * Cold-blooded organisms like insects require precise temperature monitoring.
• * Infrared thermography offers a non-invasive method for continuous temperature measurement.

Purpose of the Study:

• * To develop and validate a standardized infrared thermography protocol for insect thermal stress assays.
• * To analyze both physiological (body temperature) and behavioral responses to thermal stress.
• * To apply advanced statistical methods (partial least squares regression) suitable for rare species.

Main Methods:

• * Development of a working protocol using infrared thermography for cold and heat stress assessment.
• * Continuous, non-invasive body temperature measurements of insects.
• * Analysis of behavioral responses alongside temperature data.
• * Application of partial least squares regression for statistical analysis.

Main Results:

• * The protocol generated five variables for cold stress response and twelve for heat stress response.
• * Infrared thermography successfully discriminated between two closely related, flightless dung beetle species (Jekelius hernandezi and Jekelius punctatolineatus).
• * Jekelius hernandezi exhibited a faster cooling rate and lower critical temperatures for stupor and freezing compared to J. punctatolineatus.
• * Both species showed similar thermoregulation capacities within their non-lethal heat stress ranges.

Conclusions:

• * Infrared thermography is a highly sensitive and suitable method for assessing insect thermal responses.
• * The developed protocol standardizes thermal assays, enabling better inter-study comparisons.
• * This methodology can differentiate even closely related insect species based on their thermal tolerance and response.
• * The study highlights the utility of non-invasive techniques in entomological research, particularly for rare species.