Spencer Whitford, Christopher Langevin, Janelly Torres, and Allison Burke

Abstract

In 2008, the Asian Longhorned Beetle (ALB) outbreak in Worcester, MA led to an eradication effort that left the local area barren, as trees were cut down. The ALB is an invasive insect originally from Asia that has spread throughout the world through infected wood packaging material. This burrowing beetle causes stress to forest ecosystems and the only effective eradication method can lead to the loss of thousands of trees. This chapter examines the dangers ALB poses, the damaging effects of the eradication effort, and the potential for a new outbreak leading to ecological and economic problems.

“Inspectors checking NY trees for Asian Longhorned Beetle“, CBSNewYork.com, Terms of use

Introduction

What is an Invasive Species?

Invasive species are the second leading cause of endangerment and extinction in the United States (Doherty, 2016). An alien-invasive species can be considered any non-native species in an ecosystem that successfully reproduces, reaches high density, and spreads further (Devin & Beisel, 2006). Alien-invasive species can disturb the natural balance of an ecosystem and lead to many problems, such as a loss of biodiversity and an imbalance of naturally occurring resources.

What is the Asian Longhorned Beetle?

The Asian Longhorned Beetle (Anoplophora Glabripennis) (ALB) is an invasive beetle native to China and Southeast Asia (Dodds, 2011). This invasive insect spends nine months of its year-long lifespan in the pupa stages buried in the trunks of hardwood trees. Upon reaching adulthood, the beetle tunnels to the surface and continues to feed on the trees. The ALB consumes essential portions of a host tree including the phloem, cambial tissue, xylem, and bark. This weakens the physical structure of the tree, as well as its essential cardiovascular system, and can result in its death (Stefan et al., 2014). After the local ALB population has depleted its host tree of resources and the tree dies, the ALB moves on to find a new host (Teng et al. 2013). Eradication efforts aimed at preventing the ALB from spreading further have resulted in the culling of many host trees by humans. This has led to a dramatic shift in the make up of forests in which the ALB has been present (Dodds, 2011). The ALB has appeared across the globe including multiple European countries such as Austria and France as well as several outbreaks across North America, more specifically the Northeast area (Dodds, 2011).

The Guiding Issue

Using a 2008 outbreak of ALB in Worcester, Massachusetts as our guiding case study, this project examines and lays out the problems associated with this invasive pest and suggests potentially improved eradication methods. Our guiding research questions for this project are: How is ALB spreading and why is it still a concern after eradication? What are the direct and indirect impacts of the insect on surrounding forests in the Northeast of the United States? This includes the damage the beetle incurs on trees directly as well as the loss of trees due to the eradication efforts. When ALB is found within a stand of trees, the most effective eradication method involves cutting down all current and potential host trees, this leads to the loss of thousands of trees. If the beetle is left alone, however, the same result occurs except the beetle remains and continues to be destructive. This loss of trees, particularly maple trees, has a drastic effect on the ecosystem, the maple industry, and the local human populations. All of these consequences will be discussed in further detail later in this chapter.

Research Methods

We began this project with a focus on the detrimental impacts of invasive land species on biodiversity and natural resources. Our research began by looking into scholarly sources and articles acquired through the WPI Gordon Library and it was quickly realized we needed to narrow down our scope. A team member familiar with the Worcester Area, Christopher Langevin, assisted with his personal experience dealing with ALB to re re-define our research scope. As a group, we began using scholarly articles and journal entries related to ALB within the Northeast as well as ALB in its native habitat.  In addition to compiling data from these journal articles, we reached out to various professionals in the field. We were able to interview Dr. Kevin Dodds, a key researcher on the Worcester outbreak in 2008. Dr. Kevin J. Dodds is a member of the USDA Forest Service who has also co-authored a paper on the invasive nature of ALB within Northeastern Forests and its impact in the Worcester Area between 2011 and 2012. Although Dr. Dodds has not worked specifically with ALB since the publication of these papers, his insights into the problem were invaluable to our research. We used local news reports to supplement our research and supply first hands accounts on how local areas were handling ALB outbreaks. Using all of the information gathered from scholarly sources, interviews, and firsthand news accounts, we compiled our findings in this chapter.

Intellectual Merit

This research considers and uses multiple disciplines to examine our research questions. Our research can potentially contribute to disciplines such as forestry, ecology, agricultural sciences, biology, and chemistry. Our research will contribute to each of these fields as it consolidates a significant portion of information regarding the impacts of the Asian Longhorned Beetle into a singular location to be referenced by multiple fields of study.

ALB in Worcester

While the entire Northeast is at risk due to this invasive species, one of the most notable outbreaks was in Worcester, Massachusetts. This 2008 outbreak was the first where the insect had spread out of the urban area and into the surrounding forest areas of the city. This in itself caused stress to the local ecosystem in the area on a bigger scale (Dodds, 2011).

During our interview with Dr. Kevin J. Dodds, we learned that it would be difficult to assess the spread of the ALB in the northeast over the near future (5 years). The researched populations of the 2008 Worcester outbreak, have been effectively eradicated making the spread from these populations unlikely. Worcester had an ideal ecosystem for the ALB to inhabit, as it had a large tree population. Places such as New York or New Jersey would not have sufficed as livable areas for the beetle. Should the ALB make a return to the Northeast, it would be difficult to detect it immediately, allowing it to spread. While losing a large population of maple trees was not ideal for the Worcester Area ecosystem, it did allow other species of plants and vegetation to flourish with the newfound space.

Before the Asian Longhorned Beetle was introduced to the Massachusetts forest, in the 1860’s there was a release of gypsy moths that spread through much of the Northeastern forests (Dodds, 2011). Looking back at this occurrence it acted almost the same as how the ALB spread in Worcester in 2008. Both of these species have changed how the forest looks, killing much of the same species of tree for each infestation. With the loss of these species of trees comes a large effect on the economy and the residential areas in the city of Worcester.

Twelve years after the initial outbreak of ALB in the Worcester area, the outbreak is no longer a persistent problem, however, it has had a lasting effect on the local area. According to Dr. Dodds, the Worcester area has seen a massive decrease in maple trees which has led to a shift in the balance of the ecosystem. This loss is mostly due to the currently most effective method of eradication involving cutting down thousands of trees. Many parts of the city are left lacking trees (Doyle, 2020). As will be discussed later in this chapter, the potential for reintroduction remains a problem, even if ALB is currently eradicated in the Worcester area. As a result it is a problem that must be addressed.

Current Eradication Methods

As the Asian Longhorned Beetle has been around in Worcester for over 10 years there have been multiple eradication methods and steps to ensure the demolition of the beetle. The beetle is known for “killing trees it lives in” by laying its eggs inside the tree (USDA APHIS, 2020). The larva eventually tunnels through the tree spending most of their life eating the tissue of the tree, specifically the maple tree. In order to stop the invasive insect, cities began to take action by cutting down the trees that host the ALB.

The ALB made it to places along the northeast region of the United States, specifically places like New York, Worcester, Mass, and New Jersey. It is said to have the potential to cause more damage than chestnut blight and gypsy moths destroying millions of trees in America’s national forest and even backyards (USDA APHIS, 2020). Due to the outbreak of the ALB many cities that have found signs of the beetle take part in eradication efforts in order to get rid of the insect. These places have decided to cut down trees infected with the beetle following a specific procedure that ensures the beetle is gone. The eradication strategy includes establishing a quarantine zone that keeps the beetle from spreading any further. Then the stressed host trees are cut down and removed. Even though this eradication strategy was one of the most effective to date, the removal of the trees is expensive, which leads to serious economic threats for cities (Nowak et al., 2001). Cutting down these trees also decreases the land value.

Although costly, these eradication efforts have been successful in many cities along the northeastern coast. Places like Illinois and New Jersey have seen massive decreases in the ALB population (Stefan et al., 2014). In order for the eradication of the beetle to work there needs to be strong stakeholder support and sufficient resources that will help carry out the eradication efforts ( Stefan et al., 2014).

Programs used to eradicate the beetle are also set in place to help fight the invasive insect. The USDA APHIS has created two goals for the program, to prevent more outbreaks of the ALB and to eradicate current ALB outbreaks. Without these eradication efforts, it is estimated that 45% of trees in the eastern parts of the U.S will be at risk for ALB infestation (Stefan et al., 2014). Proving the eradication efforts to be important and beneficial in saving the trees of the national forest. Although some can be costly and destructive it is the currently most effective way to eradicate the beetle as soon as possible.

Threat to the Maple Industry

Although eradication efforts have been very successful in multiple areas in the Northeast, it is extremely costly and destructive to the forest. The beetle itself poses economic threats to major cities, attacking and killing host trees impacting the people and industries. The ALB infestation has caused 30.3% tree mortality (1.2 billion trees) and a value loss of $669 billion (Nowak et al., 2001). The maple tree, being the most common host for the ALB, has caused maple industries to lose profit.

For years people have been tapping maple trees for sap to make syrup, which is now being threatened by the spread of the ALB. Through eradication efforts, many maple trees are being cut down, impacting property owners and posing a huge threat to the maple syrup industries (Greenwood, PR Newswire 2012). The beetle infestation has occurred in multiple maple-syrup-producing states, causing many industries to have economic issues. Along with the loss in property value, industries will lose around $1 to $10 million 30 years after the introduction of the pest (USDA APHIS, 2020). The ALB has caused there to be a drastic change in profit for maple syrup industries due to the infestation of maple trees.

Since the pest can’t move on its own, industries have found that the best way to stop the spread would be to not move any firewood from its original area. Not only are industries encouraging the “Don’t Move Firewood” campaign.  They also believe a good way to stop the spread of the beetle is to educate people unaware of the issue and bring awareness to the problem (Chapeskie, PR Newswire 2012). Many people may not know what’s going on in their surrounding area. By educating them it can push them to buy locally harvested wood and contribute to the protection of the trees (Greenwood, PR Newswire 2012). Although eradication efforts can be expensive, industries have realized that the potential loss from the ALB will exceed the cost of prevention (Chapeskie, PR Newswire 2012).

Potential for Reintroduction

In most major outbreaks of ALB, the eradication methods of quarantining and felling trees is effective in preventing further spread from the host stand. This, however, does not prevent the potential reintroduction of ALB into an ecosystem from new Solid Wood Packaging Material or the transversal of ALB through accidental human movement (Macleod, 2002). In a study examining the potential threat of ALB to European communities, A. Macleod establishes a very clear fact that ALB can and will be introduced in multiple locations throughout the world. The wood-boring nature of this pest allows it to travel undetected across oceans contained within palettes and other transported wood. The ability for ALB to travel in this manner is what has allowed it to become an invasive species throughout Europe and North America (Macleod, 2002).

The risk assessment conducted by Macleod analyzed weather and climate data regarding the native ranges of ALB and compared this distribution of climate with potential invasive zones. The study assigned various locations an Ecoclimatic Index (EI). This value assesses how well ALB is predicted to survive in these locations, the higher the value, the better ALB will survive.

Within the figure, larger circles represent higher EIs and a cross represents an EI of zero.  Although the risk assessment focuses on the European Community, the software was also run in New York and Chicago, which had EIs of 45 and 47 respectively (Macleod, 2002). These values are higher than the mean value of the native range of 32.1 +/- 6.9.  The risk assessment concludes that the invasion of ALB into the European Community is a potential risk that should be taken seriously. Based on the similar trade tendencies China has with the United States and Europe, consisting of billions of dollars of trade and goods shipped in SWPM that has the potential to transfer ALB, and the high EI values of Northeastern cities such as New York suggests the Northeast is also at risk of consistent introduction of ALB (Macleod, 2002). The high risk of ALB introduction is still prevalent and this leads to multiple distinct outbreaks unrelated to one another. This pattern of reintroduction can be observed in the presence of outbreaks all across the Northeast, such as Worcester, Boston, New York City, Long Island, Ontario, and New Jersey (Dodds, 2012).

According to Dr. Kevin Dodds in the interview we conducted with him throughout our research process, this potential for reintroduction is one of the hardest problems to combat and track since “it really only takes one shipment that gets through inspection and has solid wood packing material that was not treated properly to start an infestation.” This becomes a problem when, even after a local area has been quarantined and properly eradicated, such as the outbreak in the Worcester area, there is still the potential for ALB to begin its invasion nearby with no relation to the current outbreak. Most recently, the USDA has begun an eradication effort in South Carolina (USDA APHIS, 2020). This outbreak is clearly not connected to the various outbreaks found across Massachusetts and is a prime example of how ALB can be introduced to a multitude of locations and wreak havoc on ecosystems as independent populations.

There is also a danger of accidental transfer of ALB through firewood. Just as it would burrow into SWPM, ALB can just as easily pass undetected within firewood across county and state lines. Organizations such as the Don’t Move Firewood Organization in Massachusetts attempt to bring awareness to this issue and how easily ALB and other pests can be hidden. With the movement of firewood, ALB can easily establish a new population many miles away from the initial host tree and create a new distinct problem (Campbell, 2020).

Potential New Eradication Methods

Our group has explored a multitude of new solutions to solve the eradication of the Asian Longhorned Beetle. The two central solutions we focused on are 1) the introduction of predatory species into ALB affected areas, and 2) the introduction of insecticides to ALB affected areas.

Predators of the beetle include toads, wasps, and woodpeckers. Introducing a new species into an environment may limit the growth and spread of the ALB, but there will also be some negative side effects. Introducing a new species to an environment may negatively affect some of the other (non-ALB) species, similar to what the Asian Longhorned Beetle did to tree species in the northeast.

Rather than targeting adult ALB’s, our group researched methods on how to eradicate the beetle during its larvae stages. Nematodes have been discovered to prey on larvae stage ALB. These nematodes were used in China during the original ALB outbreak, prior to its spread to North America. For this specific predator, we suggest following in the footsteps of the Chinese environmental agencies, by stapling the nematode (which will sit on a moist sponge) to trees throughout the area. The nematodes are then able to locate and attack the host larvae within 30 centimeters of the initial entry point of the tree (Solter, 2017).

Our other targeted solution is the introduction of insecticides. Insecticides can decrease the number of beetles in an area and help trees from becoming infected. Insecticides might help contain the spread of the beetle in currently infested areas and will kill off the beetle so that it is not able to infest new areas. Insecticides are used only on trees that are not known to be infested. The insecticide itself can be applied either directly into the trunk of the tree or directly into the soil beneath it. The tree’s vascular system will then pull the insecticide up and throughout the tree so that all parts receive the insecticide.

Imidacloprid is a tested insecticide. Historically, imidacloprid has been shown to be effective against other insects such as termites, cockroaches, and flies (USDA, 2017). Imidacloprid is also used for tick and flea prevention in domestic pets and has been sold commercially in the US for over 25 years.

Our team suggests treating only specific types of trees with the Imidacloprid insecticide. These types of trees include -but are not limited to- maple, birch, buckeye, willow, and boxelder. In order to maximize the effectiveness we suggest treating all host trees in an area, so that we are able to see the effectiveness of the insecticide of an entire area. The application of the Imidacloprid insecticide should take place only during specific seasons. Ideally, the insecticide will be applied during the spring or the early summer, which will be prior to the adult emergence of the Asian Longhorned Beetle. The aforementioned tree injection can take 1-3 weeks to be fully effective throughout the tree, and the soil injection can take up to 3 months. These time frames are dependent on the size, age, and overall health of the tree.

While our group has high expectations for the effectiveness of the insecticide, we recognize that it will not rid any tree entirely of the Asian Longhorned Beetle, only limit the spread. The entire removal of trees remains the only effective method of entirely ridding a stand of the ALB.

Conclusion

Ultimately our findings show ALB is never going to be a contained problem. Even after the eradication of a local population ALB can still be introduced to a location and cause harm to the local ecosystem. Our findings have shown the detriment this and the accompanied eradication methods can have on local ecosystems and humans. Our research found that it is almost always human intervention that spreads ALB. As a result, we, as humans, have an ethical duty to attempt to correct this impact we have had on ecosystems. This duty has come with eradication methods which often have just as much effect on the ecosystem. This is why our research has made an effort to develop and suggest new eradication methods, such as insecticides, that will not be damaging to the ecosystem while still solving the problem. Our findings can also be felt economically. ALB’s specific targeting of maple trees has the potential to be devastating to the maple industry. In order to not experience a greater drop in this industry, ALB must be monitored and effectively eradicated when present. In addition to the ethical and economic implications, socially our research has also shown the effects of ALB on urban forests.

The loss of trees throughout cities has led to an imbalance of access to trees and nature within underprivileged neighborhoods throughout Worcester and other cities. Preventing the spread of ALB will prevent these losses from becoming greater than they already are. Our research has led us to suggest the usage of safe insecticides in place of the current eradication method, a better monitoring of the movement of SWPM as well as firewood that could contain ALB, and the continued monitoring of Northeastern forests for potential reintroduction. We believe it is essential to continue to monitor forests and recognize an infestation early and eradicate the local population in the least harmful way possible. We also recognize research into other potential eradication methods or preventative measures can be beneficial for the future of our forests.

The Asian Longhorned Beetle has had a major impact on Worcester forests and their surrounding areas. The species has impacted Worcester County for the past twelve years and the lasting results show even after eradication in the lack of trees. In the hope to stop the spread of this invasive species, the eradication methods that were mentioned above have started to become implemented to help stop the spread in order to save the forest. With this being said, there is a high chance for the maple industry in the surrounding area to economically be saved and for the maple industry to begin to rebuild itself. With the current eradication method in place, even if this is successful, however, there is a chance that there can be a reintroduction of the Asian Longhorned Beetle. With this, there has been more research of the current eradication methods being executed in the locations with the most substantial outbreaks, and new methods of eradication are being implemented into this current outbreak. Overall, if the new eradication methods are successful, the forests will begin to flourish once again, saving the oak and maple trees that have been affected for over ten years, and the maple industry will become positively economically impacted.

Acknowledgments

We would like to acknowledge Dr. Kevin Dodds of the USDA for helping us with our research. Dr. Dodds was kind enough to conduct an interview with us over email.

We would also like to acknowledge Professors Bakermans and San Martín of WPI for their guidance as well as Anxhelo Ripa, our Peer Learning Assistant who helped us develop our project.

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