Graduation date: 2007
New species introductions have been associated with the movement of
people for thousands of years. For instance, horses were introduced into North
America by Spanish explorers, while pigs were introduced by the Polynesians
into many Pacific islands long before the establishment of permanent
European settlements. Both of these species introductions resulted in
significant changes in both the biological and cultural composition of these
places. However, during the past century, the amount of material transported
by people has greatly increased due to the globalization of the economy and
breakthroughs in material handling technology. These breakthroughs, such
as the steel shipping container and the wooden pallet, allow goods to be
moved rapidly in a protected environment. This protected environment
prevents goods from being damaged while in transit, but it has also improved
the ability of pests to survive transit and resulted in invasive species
introductions. The volume of goods being transported has steadily increased
during the past 50 years and, thus, the number of species introductions has
increased as well, resulting in a number of high profile pest introductions. For
instance, the introduction of the Asian long horned beetle into Chicago and
New York cost millions of dollars to eradicate and resulted in the loss of
hardwood trees that previously lined the streets of these cities. In response to
the Asian long-horned beetle and the introduction of the pine wood nematode
into Europe, the Food and Agriculture Organization of the United Nations
drafted and approved International Standard for Phytosanitary Measures
Number 15. This measure recognizes solid wood packaging materials as an
invasive species pathway and recommends sanitization through heat
treatment or fumigation with methyl bromide. However, heat treatment or
fumigation are imperfect mitigation tools. Thus, researchers continue to
search for alternative methods.
Wood preservatives have long been formulated to prevent insect and
fungal attack of wood products exposed to warm humid climates, but the
ability of these chemicals to eliminate existing insect and fungal colonies has
not been investigated. In this study, a number wood preservative systems
were investigated to determine if these chemical formulations can be used for
this application and to determine if wood preservatives, in general, are suited
for use in phytosanitary applications.
A method for detecting the presence of wood boring insects through
acoustic emissions was investigated. It was thought that a system of
microphones and accelerometers could be used to detect wood boring insect
presence and activity within a particular wood sample. These assumptions
were based on earlier work conducted with termites. This system was to be
used to determine if a sample contained wood boring insects prior to using it in
the main study. However, acoustic emissions were not useful for this
application, since feeding of the wood boring insects was sporadic, unlike
termites which feed constantly.
Determining the feasibility of using wood preservatives in phytosanitary
applications was addressed in three trials: the ability of preservatives to
penetrate insect galleries, the ability of the insect larvae and pupae to
penetrate a treated barrier and the ability of established wood boring insect
populations to complete their life cycle under field conditions in wood pressure
treated with preservatives
Preservatives completely penetrated between 80-100% of all insect
galleries in western redcedar treated with ammoniacal copper quaternary
compound, disodium octaborate tetrahydrate, or imidacloprid. However,
barriers containing any of these three chemicals failed to prevent larvae from
exiting the treated material, even in instances where the barrier was more than
6mm thick. The wood boring insects were unable to complete their life cycle
under field conditions in pressure treated wood, while a large number of new
house borer adults emerged from the untreated controls.
The wood preservatives investigated act more as insecticides than
larvacides. However, vacuum pressure impregnation of solid wood packaging
materials with the appropriate chemicals could provide lasting protection
against invasive species introductions, allowing for the rapid, yet safe
transportation of goods around the world.