Author
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Vogt, James |
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Submitted to: Environmental Entomology
Publication Type: Peer Reviewed Journal Publication Acceptance Date: 2/17/2004 Publication Date: 8/20/2004 Citation: Vogt, J.T. Quantifying imported fire ant (Hymenoptera: Formicidae) mounds with airborne digital imagery. Environmental Entomology 33: 1045-1054. 2004. Interpretive Summary: Detecting and quantifying imported fire ant mounds over large areas can present problems in terms of access to areas, sampling, and person-hours. State-of-the-art airborne digital imagery may provide an alternative to tedious and expensive work on the ground. A multispectral, airborne remote sensing system was used to obtain "true color" and "false color infrared" images (0.25 m resolution) of a large (approx. 650 acre) test site in northeastern Mississippi. Images were viewed on computer, and Global Positioning Systems information embedded into the images allowed researchers to accurately associate any point in the images with the corresponding point on the ground. Mounds in test plots on the ground were measured, and the location of each mound was logged with a GPS unit accurate to less than 3 feet. Approximately 70% of fire ant mounds in plots within the test area were detected in the images. Ongoing research is aimed toward examining seasonal effects on mound detection, and cost / benefit analyses of using higher resolution (0.1 m) imagery. Technical Abstract: Airborne multispectral digital imagery was used to detect imported fire ant mounds in northeast Mississippi pasture. Images were acquired using a GeoVantage¿ GeoScanner® camera system, flown at an altitude of 610 m for resolution of 0.25 m. Analysis of "true color" and "false color infrared" images using different color band combinations indicated that up to 83% of mounds were visible. Approximately 70% of mounds were detected analyzing near infrared images without prior knowledge of mound locations. Mound size (range approximately 0.05 to 0.9 m2) and vegetation cover influenced visibility of mounds; mounds with more vegetation cover were more difficult to see. Mounds with less vegetation cover appeared as dark or light spots surrounded by a dark green halo (true color images) or a reddish halo (near infrared images). |
