Evaluation of time-average dispersion models for estimating pheromone concentration in a deciduous forest

Area of Science:

• Atmospheric science and entomology
• Chemical ecology and environmental modeling

Background:

• Atmospheric dispersion models like Sutton and Gaussian plume are used to predict chemical concentrations.
• Understanding pheromone dispersal is crucial for insect behavior studies, particularly for pest management like the gypsy moth (Lymantria dispar).

Purpose of the Study:

• To evaluate the accuracy of atmospheric dispersion models in predicting downwind pheromone concentrations in a forest environment.
• To compare model predictions with observed behavioral responses of male gypsy moths to pheromones.

Main Methods:

• Utilized Sutton and Gaussian plume models for atmospheric dispersion simulations.
• Recorded wind data using bivane anemometers and emitted pheromone from a point source.
• Monitored male gypsy moth wing-fanning response at various downwind sites as an indicator of pheromone detection.

Main Results:

• Gaussian-type models frequently predicted pheromone concentrations orders of magnitude lower than behavioral thresholds.
• Probit analyses revealed no correlation between predicted pheromone doses and observed moth responses.
• Discrepancies arise because models provide time-averaged concentrations, exceeding the short intervals required for behavioral responses.

Conclusions:

• Standard time-averaged atmospheric dispersion models are inadequate for predicting pheromone-mediated insect behavior.
• The temporal resolution of dispersion models needs improvement to align with insect sensory and behavioral timescales.
• Further research should focus on developing more dynamic models for accurate chemical communication assessment in ecological studies.