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Title: ASSESSING BIOLOGICAL CONTROL DAMAGE OF GIANT SALVINIA USING REMOTE SENSING TECHNOLOGIES

Author
item FLORES, DANIEL - USDA-APHIS,EDINBURG,TX
item Everitt, James
item CARLSON, JASON - USDA-APHIS, EDINBURG,TX

Submitted to: Biannual Workshop in Color Photography and Videography in Resource
Publication Type: Proceedings
Publication Acceptance Date: 10/15/2006
Publication Date: 3/15/2006
Citation: Flores, D., Everitt, J.H., Carlson, J.W. 2006. Assessing biological control damage of giant salvinia using remote sensing technologies. In: Proceedings of the 20th Biennial Workshop on Aerial Photography, Videography, and High Resolution Digital Imagery for Resource Assessment, Bethesda, Maryland. 2006 CDROM.

Interpretive Summary: The invasion and spread of undesirable plant species in wetlands present a serious problem to resource managers. Giant salvinia is an invasive aquatic fern that has invaded and clogged waterways in many subtropical and tropical areas of the world. The salvinia weevil has been widely used to control giant salvinia. A study was conducted to evaluate remote sensing technology for assessing control of giant salvinia by the salvinia weevil. Field reflectance measurements were used to distinguish among giant salvinia plants suffering various degrees of salvinia weevil feeding damage. Color-infrared aerial photography remotely detected giant salvinia plants into three broad categories: healthy, moderately damaged, and severely damaged. Before and after aerial photographs were used to show an increase in feeding damage over time. These results should be of interest to wetland resource managers.

Technical Abstract: The use of the highly specific biological control agent, Cyrtobagous salviniae Calder and Sands, commonly known as the salvinia weevil, has long been recognized as the leading and most used control strategy in all areas of the world for the management of the rapidly proliferating aquatic fern giant salvinia, Salvinia molesta Mitchell. Field reflectance measurements were used to distinguish among giant salvinia plants suffering various degrees of salvinia weevil feeding damage. Color-infrared photography remotely detected giant salvinia plants damaged by the weevil in a small pond located in Bridge City, Texas. These results clearly indicated that through the use of reflectance measurements, salvinia plants could be grouped into three broad categories: healthy, moderately damaged, and severely damaged. Based on these categories, before and after images showed a 14% increase in damage between April 2004 and July 2004. The color-infrared aerial photography coupled with image processing procedures, can be used to discriminate among plants in these same categories over a larger spatial area as well as hard to access areas and can contribute to assessing biological control damage.