Please use this identifier to cite or link to this item: https://hdl.handle.net/11681/6408
Title: Large-Scale Operations Management Test (LSOMT) of insects and pathogens for control of waterhyacinth in Louisiana. Volume II : Results for 1982-1983
Authors: Large-Scale Operations Management Test (LSOMT).
United States. Army. Corps of Engineers. New Orleans District.
Aquatic Plant Control Research Program (U.S.)
Sanders, Dana R.
Theriot, Edwin A.
Keywords: Aquatic plant control
Biological control
Biocontrol
Insects
Fungi
Plant pathogens
Louisiana
Waterhyacinth
Publisher: Environmental Laboratory (U.S.)
Engineer Research and Development Center (U.S.)
Description: Technical Report
Abstract: During 1979-1983, a Large-Scale Operations Management Test (LSOMT) was conducted to determine the potential for biological control of waterhyacinth in Louisiana using insects and plant pathogens. This report (Volume II) docume nts LSOMT results for 1982-1983 and presents final conclusions. Biocontrol agents were found to be a viable, long-term, low-cost alternative for waterhyacinth control. Primarily due to biocontrol agent activity , the waterhyacinth population in Louisiana decreased from an average of 1,250,000 acres in 1974-1978 to 305,000 acres in 1980. This decrease was attributed principally to effects produced by the mottled waterhyacinth weevil (Neochetina eichhorniae Warner). By 1983, the plant population had increased to 657,000 acres. This increase was attributed to a decline in the Neochetina population following the 1980 reduction in the waterhyacinth population. An increase in the waterhyacinth population had been anticipated, due to the greater reproductive potential of waterhyacinth than of Neochetina. However, the 1983 waterhyacinth population was still approximately 50 percent less than the 1974-1978 average , which led to the conclusion that Neochetina was still significantly impacting the water hyacinth population. The 1983 increase in the Neochetina population led to a suggestion that the waterhyacinth population might experience another decline during 1984 or 1985. Such a decline would provide evidence of the development of a cyclical relationship between waterhyacinth and Neochetina populations, in which the waterhyacinth population declines in the presence of large Neochetina populations, redevelops as Neochetina populations decline, and then declines as Neochetina populations redevelop. Other conclusions of the LSOMT were: (A.) The threshold population level for significant Neochetina impacts on waterhyacinth was 3.0 individuals (combined larvae and adults) per plant, followed by a sustained population level of 1.0 individual per plant for 6 months or longer. (B.) The waterhyacinth leaf spot fungus ( Cercospora rodmanii Conway) impacted waterhyacinth at one study area, but failed to become established at another study area. Cercospora in the formulation used in the latter case was viable, but not infectious. (C.) The Argentine waterhyacinth moth (Sameodes albiguttalis Warren) became successfully established at three of four release sites and rapidly dispersed throughout a large portion of southern Louisiana. Its 1983 distribution encompassed a 6,100-sq-mile area, and included all or portions of 13 parishes (counties). (D.) Long-term effectiveness of Sameodes as a biocontrol agent was not determined because the population was still in the dispersal phase. However, Sameodes was observed to produce locally significant impacts on waterhyacinth populations.
URI: http://hdl.handle.net/11681/6408
Appears in Collections:Technical Report

Files in This Item:
File Description SizeFormat 
TR-A-85-1-Volume-2.pdf18.97 MBAdobe PDFThumbnail
View/Open