Globalization is a phenomenon that has allowed insects to travel across the world and into different environments. A United States Forest Service Research Entomologist, Andrew Liebhold, firmly believes that the increasing pest problems, which we have all been hearing about on the news is a result of globalization. This line of thought seems reasonable since there have been numerous cases in which nonnative insects traveled across the ocean by cargo ship only to arrive in a different continent. Although many experts agree that our ecosystems are in danger from rapid global travel, this is not the only reason as to why we are seeing more and more damaging non native insects in the US. Of course, the process of global warming is playing a part in mass invasive insect migration as well.
Back during the roaring ‘20’s hemlock trees from Japan were shipped to America for landscaping purposes. Unfortunately, many of the trees that were shipped to the US from Japan were likely riddled with spiders known as the hemlock woolly adelgids (HWA). As soon as the 1980’s rolled around, it became clear that the HWA’s were destroying numerous hemlock trees at rapid rates.
Unfortunately, destroying hemlock trees results in undesirable environmental consequences. Even after a hemlock tree dies it can still have a negative impact on the ecosystem. For example, ninety bird species, forty five mammal species, and a plethora of aquatic life all use the hemlock tree for shelter. Once hemlock trees die as a result of the HWA’s tinkering, many of the above mentioned classes of animals will perish from lack of shelter.
Many different species of bird also inhabit the hemlock tree. Although the birds are lucky enough not to die while the HWA’s are destroying the tree, the birds are still forced to migrate elsewhere. An abrupt change in bird migrations can also have unexpected negative consequences on the ecosystem, as well as on other animal species living within the same environmental conditions.
Scientists have tried combating the invasive HWA insects by employing a variety of different methods. One method had researchers bring the HWA’s natural predatory enemies into the HWA’s habitat. Another method involved releasing parasites that seek the HWA as an ideal host. These two different species of organism were imported from Japan, which is also the HWA’s home country. Currently public health professionals are attempting to halt the migration of insects via human travel by restricting what types of cargo passengers can carry onto a plane or a cargo ship. Anything that could attract invasive insects may soon be prohibited in airports and train stations. For example, wood packing material, such as wooden crates and pallets, may soon be prohibited since the HWA insect loves hitching rides on old slabs of musty wood. Instead these particularly types of wood will be outlawed at many airports around the world. Instead TSA officials will start to allow for manufactured wood, such as plywood or composite wood, which the HWA’s find repellent.
Pests like the HWA’s cause four billion dollars in damage annually, and that is in the US alone. Unfortunately, these costs are often pushed onto homeowners. Scientists are currently considering the use of strategically placed surveillance systems, so that hemlock tree smugglers can be caught before their criminality destroys the environment.
Could the HWA become eradicated after releasing the HWA’s natural predator into the HWA’s environment? Could releasing another nonnative predatory insect from Japan cause the same environmental problems that the HWA insect has caused already in the United States?