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United States Department of Agriculture

Agricultural Research Service

Title: Increased Mortality of Coptotermes Formosanus (Isoptera: Rhinotermitidae) Exposed to Eicosanoid Formation Inhibitors and Serratia Marcescens (Eubacteriales: Enterobacteriaceae)

Authors
item Connick Jr, William
item Osbrink, Weste
item Wright, Maureen
item Williams, Kelley
item Daigle, Donald
item Boykin, Deborah
item Lax, Alan

Submitted to: Environmental Entomology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: December 8, 2000
Publication Date: N/A

Interpretive Summary: The ability to kill Formosan termites by using microorganisms that are their natural enemies is made difficult by their effective immune systems and by the defensive behavior of these social insects. It has been shown that some chemicals commonly used in human medicine can weaken the termites' immune system so that high concentrations of a bacteria can kill them more readily. If perfected, this concept could lead to new termite control procedures. This research will benefit the pest control companies.

Technical Abstract: The biological control of termites may be facilitated if their highly- evolved immune systems can be suppressed. Eicosanoids are C20 polyunsaturated acids that are of widespread biochemical importance, including their role in protecting insects from bacterial infection. In laboratory experiments, the eicosanoid formation inhibitors dexamethasone, ibuprofen, and ibuprofen sodium salt were each provided along with a red-pigmented isolate of Serratia marcescens Bizio, a bacterial pathogen, to the Formosan subterranean termite, Coptotermes formosanus Shiraki, by means of treated filter paper. The increased mortality that resulted with dexamethasone and ibuprofen supported, but alone was insufficient to prove, the hypothesis that the termites' immune systems were suppressed by these compounds making the insects more vulnerable to infection by S. marcescens. This effect on mortality was noted only at 3.4 X 10 to 10th colony-forming units per milliliter, a high treatment level. A significant amount of the infection and subsequent mortality may have resulted from direct contact with the bacterium and the remainder from its ingestion. Water-soluble ibuprofen sodium salt demonstrated a protective effect.

Last Modified: 10/20/2014
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