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THE LOUISIANA AREA-WIDE MANAGEMENT PROGRAM FOR FORMOSAN SUBTERRANEAN TERMITE IN TREES

DENNIS R. RING AND GREGG R. HENDERSON
Louisiana State University Agricultural Center, Baton Rouge

  

  

Introduction

     The Formosan subterranean termite is thought to cause $1 billion/year in losses in the United States. Estimates of losses each year are $500 million in Louisiana with $300 million occurring in New Orleans. It is thought to be the most destructive insect in Louisiana, negatively affecting the economy and wealth of the state despite the fact that its presently known range mainly includes parishes south of Interstate 10 and 12 and it is not widely distributed in all of these parishes. 

   
     The Formosan subterranean termite is a very aggressive termite species. It eats the centers of creosote treated railroad ties, wharves and telephone poles. This insect goes through thin sheets of soft metal, mortar, PVC pipe, electric power lines, and telecommunications lines. The Formosan subterranean termite also infests live trees. The weakened trees are susceptible to being blown over in high-speed winds and possibly falling on homes, structures, cars, property, roads, or people.

  

Tree treating program 

     A task force was appointed by the governor of Louisiana to consider management of the Formosan subterranean termite. The task force appointed a scientific committee to investigate the cost of treating all structures with baits in the New Orleans and Lake Charles, Louisiana areas. These two areas are the most heavily infested with Formosan termites in Louisiana. This cost was estimated to be between $0.75 - $1.0 billion and deemed too expensive. Then, the cost of placing termite baits around blocks was investigated. This cost was also too high. The Louisiana Legislature appropriated $5.65 million in 1999 for management of the Formosan subterranean termite. Infested trees are reservoirs for termites to infest houses. Thus, the task force decided to drill and attempt to treat trees on public property in New Orleans and Lake Charles. The Louisiana Department of Agriculture and Forestry directed the program. 
   

     The tree treating program began in 2000. Treatment zones were designated in both cities. Teams (2 people per team) of pest control operators were trained to treat trees in New Orleans (90 teams) and Lake Charles (10 teams). The program provided drilling equipment, foaming machines, foam and insecticide to the pest control operators. 
   

     The trees were drilled and treated according to the following protocol. Trees were drilled using a inch diameter by 18" long drill bit and a gasoline powered drill. Holes penetrated a minimum of the diameter of the tree or to the length of the drill bit, but did not penetrate the entire diameter of the tree. The drill bit was dipped into a 10% household bleach solution before each hole was drilled to prevent the spread of pathogens. 
   

     The number of holes drilled in trees was dependent on the diameter of trees. Trees greater than 24 inches in diameter were drilled seven times. Four holes were drilled around the base of the tree 4 - 6 inches off the ground and at a slight downward angle directed towards the center of the tree. The other three holes were drilled (at approximately 90 degrees to each other) in areas of visible or suspected termite activity. If activity was not visible, the three holes were drilled approximately 90 degrees from each other spiraling up the tree trunk about one foot above the other. 
   
     Trees with diameters between 10 and 23 inches were drilled four times. The first hole was drilled around the base of the tree 4 - 6 inches off the ground and at a slight angle directed towards the center of the tree. The other three holes were drilled (at approximately 90 degrees to each other) in a spiral 12 inches higher up the trunk for each hole. Trees with diameters less than 10 inches were not drilled.
   

     Insecticide was foamed into drill holes of trees that would take foam. The insecticides used were imidachloprid or fipronil in New Orleans and imidachloprid in Lake Charles. These insecticides were believed to be non repellent at the rates they were applied. Thus, termites would be killed and not driven into nearby structures. The expansion ratio for the foam was 15:1, and the foam was applied at 20 p.s.i. A maximum of 5 gallons of liquid (75 gallons of foam) was applied to each tree. Equal amounts of termiticide foam were applied to each drill hole that accepted foam. Application ceased when foam exuded from natural openings. Upon completion of foam injection the holes were plugged.
   

     The program resulted in the drilling and attempted treatment of ninety thousand trees in 2000. thousand trees were treated in New Orleans, and trees were treated in Lake Charles.
   

Evaluation program
   
     The LSU AgCenter conducted an evaluation of the effectiveness of the tree treating program. Fifty termite infested trees were identified in zones to be treated with imidachloprid and fipronil in New Orleans and with imidachloprid in Lake Charles. A total of fifty termite infested trees to be treated with foam alone (controls) were identified in both locations. A minimum of three sites with active termites were required for a tree to be included in the evaluation program. Evaluation trees were inspected for visible signs of active termites before trees were treated. The positions of the active sites on the tree were recorded. Control trees were treated by LSU AgCenter personnel, while insecticide treated trees were treated by pest control operators. Termites and terminal buds with leaves were collected and curated from each evaluation tree as a voucher specimen of the termite and tree species included in the evaluation program. 
   

     Evaluation trees were inspected one and six months after treatment. These trees will be inspected again one year after treatment. The number and position of active sites of termites was recorded each time trees were inspected. Also, termites were collected each time they were found infesting trees.
   

     This program is the first area-wide treatment of trees for management of a termite in the United States. The program has not progressed far enough to provide conclusive results. Continued monitoring of the evaluation trees is needed to evaluate the effectiveness of the program.

  


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