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Title: DIFFUSION OF INSECT PHEROMONES IN A FOREST CANOPY: CO-LOCATED TRACER/ELECTROANTENNOGRAM EXPERIMENTS.

Author
item SMITH, T - UNIV. OF MONTANA
item PETERSON, H. - UNIV. OF MONTANA
item Thorpe, Kevin
item TCHESLAVSKAIA, K. - VIRGINIA TECH
item THISTLE, H. - USDA,FOREST SERV.
item STRAND, T - WASHINGTON STATE UNIV
item LAMB, B. - WASH. STATE UNIV

Submitted to: American Society of Agricultural Engineers Meetings Papers
Publication Type: Proceedings
Publication Acceptance Date: 10/1/2003
Publication Date: 12/1/2004
Citation: Smith, T., Peterson, H., Thorpe, K.W., Tcheslavskaia, K., Thistle, H., Strand, T., Lamb, B. 2004. Diffusion of insect pheromones in a forest canopy: co-located tracer/electroantennogram experiments.. American Society of Agricultural Engineers Meetings Papers.

Interpretive Summary: Insect infestation is considered to be the leading cause of damage and mortality to trees in the United States. Mating disruption, a technique in which the insect's own sexual chemical attractants called pheromones are used to disrupt courtship and mating, is an environmentally friendly method of insect control that has been used successfully against some insect pests of forests. However, many uncertainties still exist about the concentration and distribution of pheromones within a forest canopy following their application as mating disruptants. The goal of this research was to improve current understanding of pheromone distribution and movement in forest canopies. Plastic strips containing the synthetic gypsy moth pheromone disparlure were placed in the center of a wooded area alongside a compressed gas cylinder releasing a mixture of air and sulfur hexafluoride (SF6), a gas used to mimic the movement of pheromones through the forest canopy. The presence of disparlure at various distances from the center was measured using a portable electroantennogram device (EAG) which detects electrical impulses from a severed gypsy moth antenna in response to the presence of pheromone. The SF6 gas was detected using a modified gas chromatograph to positively identify the gas. The EAG and the SF6 analyzer were located side by side. The results confirmed that the SF6 gas is a useful model to simulate the movement of an insect pheromone within a forest canopy. These results support the use of the SF6 system as a model for insect pheromones, since it is more sensitive and easier to use than working with actual pheromones. This information will benefit researchers seeking to improve and expand the use of mating disruption to control insect pests in forests.

Technical Abstract: Sulfur hexafluoride (SF6) is a tracer gas that has been widely used to simulate behavior of air pollutants in the atmosphere. In this study, however, tracer experiments were conducted to study diffusion of insect pheromone through a forest canopy. Experiments were performed during morning and afternoon hours in August of 2003 at a forested field site near Pellston, Michigan. An SF6 source was collocated with a gypsy moth pheromone source, and concentration data for both gases were collected downwind with near-instantaneous equipment at a source-to-receptor distance of 5 m. In addition, a sonic anemometer was used to measure turbulent changes in horizontal and vertical winds throughout the study. The results illustrate the use of SF6 as a surrogate for insect pheromone, and to evaluate the performance of a new, portable, electroantennogram (EAG) device.