Direct relationship between evapotranspiration rate (ET_O) and vertebrate decomposition rate

Area of Science:

• Forensic Science
• Ecology
• Entomology

Background:

• Vertebrate scavenging significantly impacts carrion decomposition.
• Evapotranspiration Rate (ET_o) integrates key climatic factors influencing decomposition.
• Insect activity, particularly from maggots, is a critical factor in carrion decomposition.

Purpose of the Study:

• To investigate the relationship between Evapotranspiration Rate (ET_o) and vertebrate carrion decomposition rates.
• To assess the role of maggot activity as a predictor of decomposition.
• To explore the utility of ET_o in forensic entomology for Postmortem Interval (PMI) determination.

Main Methods:

• Conducted four decomposition experiments using pig carrion (Sus scrofa domesticus) over two years in Davis, California.
• Utilized Evapotranspiration Rate (ET_o), incorporating wind, temperature, humidity, solar radiation, and altitude, as the primary variable.
• Measured maggot weight and maggot mass temperature (using FLIR imagery) to quantify insect activity.

Main Results:

• A strong predictive relationship (R² = 0.98) was found between ET_o and carrion decomposition rate.
• Maggot activity, indicated by maggot mass temperature, was a significant predictor (p < 0.0001) of decomposition rate.
• Maggot weight was not a significant predictor (p > 0.1) of decomposition rate.

Conclusions:

• ET_o is a highly accurate predictor of vertebrate carrion decomposition rates when scavenging is excluded.
• Maggot mass temperature provides a reliable measure of insect activity influencing decomposition.
• Incorporating ET_o into decomposition studies can enhance the accuracy of Postmortem Interval (PMI) estimations in forensic investigations.