Evaluation of Vetiver Oil and Alate Biology as Preventative Measures against Formosan Subterranean Termites, Coptotermes Formosanus Shiraki (Isoptera:Rhinotermitidae)
The Formosan subterranean termite, Coptotermes formosanus Shiraki, is responsible for over $1 billion in property damage, repairs, and control in the United States. Presently, control of this exotic pest depends mainly on chemical methods. There is an increasing interest in using natural products in pest control because of their low mammalian toxicity and environmental safety.
Chemical components of the roots of vetiver grass, Vetiveria zizanioides (L.) Nash, have shown to be effective repellents and toxicants to Formosan subterranean termites. Objectives of this research were to evaluate: 1) vetiver grass root growth and its oil distribution; 2) vetiver oil, nootkatone, and tetrahydronootkatone as wood treatments; and 3) understanding alate flight biology as preventative measures against Formosan subterranean termites.
The amount of vetiver oil present in the root system increased as root weight increased at each sampling date. At the final sampling period, mean root weight increased 520% from the previous sampling period. The highest vetiver root mulch to sand ratio tested was effective against Formosan subterranean termites by decreasing tunneling activity and increasing termite mortality, thus decreasing wood consumption.
In field and laboratory studies, wood samples treated with 5% nootkatone or 5% tetrahydronootkatone solutions showed good potential as possible wood treatment options. These studies indicated significantly less consumption of treated wood samples verses untreated controls. Significantly higher termite mortality was observed with treated wood samples as opposed to untreated controls in the laboratory evaluation.
Analysis of annual flights of the Formosan subterranean termite monitored for 16 years in New Orleans, Louisiana, indicated the timing of peak flights was non-random, suggesting a mechanism, either external or internal to the colony, triggers peak alate flights. No relationship was observed between any of the extrinsic factors tested in relation to the largest flight of the year. A degree day model was constructed to aid in predicting each years largest Formosan subterranean termite flight, which indicated peak flights did not occur before an average of 2611 heat units had accumulated.
Advisor:Seth Johnson; Gregg Henderson; Roger A. Laine
School:Louisiana State University in Shreveport
School Location:USA - Louisiana
Source Type:Master's Thesis
Date of Publication:11/08/2005