This is a guest post by a student in my graduate course.
Wood-boring beetles can be found cozied up in trees, lumber, furniture and other sources of wood worldwide, posing both ecological and economic concerns. These beetles lay their eggs beneath the bark of trees, where their larvae hatch and feast on the tree’s nutrients before developing into adults, tunneling their way out of the tree, and continuing on to infest new trees. These beetles have classically been restricted to the environments from which they originate, but the influx of international trading has allowed for “alien” species of wood-boring beetles to infest new lands. Although protocols are in place to stop the spread of wood-boring beetles, larvae of these bugs are able to remain undetected in wood that is used for packaging during international shipping, allowing them to hatch, reproduce, and spread upon arrival. These invasive beetles are especially problematic in their new environments because they frequently do not face the same ecological constraints that they would in their natural ecosystem, such as risk of predation or lack of suitable host trees to infest. While wood-boring beetles are rarely able to reach populations large enough to pose a risk in their native environments, they are often able to flourish in new ecosystems, spreading rapidly, destroying tree populations.
One example that you may be familiar with is the Emerald Ash Borer . It originates from Asia, where it is only a minor pest, as populations can rarely grow dense enough to kill healthy trees. However, after arriving in packaging material during the 1990s the emerald ash borer has thrived in North America, spreading rapidly while leaving a trail of decimated Ash trees in its wake. For over a decade, North Americans have struggled to limit the spread of the Emerald Ash Borer, with no easy solution in sight. It is apparent that wood-boring beetles must be further studied in order to track and limit their dispersion.
In order to improve the efficiency and cost effectiveness of measures to prevent the arrival and dispersion of invasive wood-boring beetles, the Italian researchers Davide Rassati, Massimo Faccoli, Edoardo Petrucco Toffolo, Andrea Battisti, and Lorenzo Marini investigated the factors that influence the arrival and establishment these beetles. As trading ports are considered the most likely point of entry for alien wood-boring beetles, the researchers selected fifteen Italian trading ports and surrounding forests to set up traps that were specially designed to attract and capture wood-boring beetles. Over 150 days the traps caught fourteen alien species, four of which had not been seen in Italy before. The more imports a port received, the more beetles that were found in the port and the surrounding forests. As these invasive beetles feed on broadleaf trees, they heavily preferred broadleaf forests, taking little time to infest their preferred host species. Upon arrival, the beetles quickly established themselves in the surrounding forests; more beetles were found in the forests than the ports they originated from. As it is desirable to stop the spread of beetles to the forests once they have entered a port, the researchers argued that that an early detection system is necessary to quickly catch and eradicate any invasive wood-boring beetles. They recommend that ports that receive high volumes of commodities, especially those surrounded by broadleaf forests, should be actively tapped and monitored for invasive beetles.
I agree with the researchers that the early detection of invasive wood-boring beetles is important to stopping them from spreading; however I believe that the emphasis should be placed on developing shipping practices that prevent the transport of invasive species, rather than hoping to detect and eliminate invasive species once they have arrived. By the time wood-boring beetles are detected, it is likely that they have already dispersed, requiring a long, costly cleanup, such as the Asian Long horned Beetle infestation Toronto suffered in the last decade. To prevent the spread of invasive wood-boring beetles, manufacturers must either use packaging materials that cannot be infested by the beetles, or more carefully treat their wood before shipping, both of which would come at increased international shipping costs. One must then ask: is it worth compromising the integrity of our ecosystems in the name of globalization?
Rassati D, Faccoli M, Petrucco Toffolo E, Battisti A, Marini L (2014) Improving the early detection of alien wood-boring beetles in ports and surrounding forests. Journal of Applied Ecology, online in advance of print.
Rassati D, Faccoli M, Petrucco Toffolo E, Battisti A, Marini L (2014) Data from: Improving the early detection of alien wood-boring beetles in ports and surrounding forests. Dryad Digital Repository.