Article: EAB Update in the Local Paper

DeWitte, Diane K. 2011. "A Destructive Pest: An Update on the Emerald Ash Borer." The Mankato Free Press. November 30.


Last month, as I worked for complete my prospectus for this class, I found an article in the local paper, The Mankato Free Press. Written by a U of M Extension educator, Diane K. DeWitte, the article provides the area with an update on what the ash borer is, what threat it presents, and what can be done to prevent it from moving. She mentions the reason for the update: the upcoming 10 year anniversary of EAB's discovery in Michigan in 2002.
She provides a timeline of EAB in Minnesota, from its discovery in Ramsey County in 2009, then Hennepin County and Houston County, and two years later another in Ramsey and more in Houston and the city of Winona.


To protect homeowner trees, DeWitte mentions the usual scouting for "D" shaped holes and woodpecker activity. She also states that insecticide should not be applied if the tree is "out of the likely range of emerald ash borer," and that "unnecessary insecticide application is a waste of money." Ashes are only at risk, she says, if EAB is found within a 10-15 mile radius. Probably due to limited word count for the article, she provides an excellent short synopsis of the EAB life cycle. 


This article was easy to understand for anyone interested in trees. It appeared on the front page of the Home and Garden section with three large, color images. The only downside is that it has no local angle, no opportunity for readers in Mankato to connect in a local way with the author.


I want to follow up with these three things mentioned at the end of the article:

1. There are three wasps being studied by the department of agriculture. What are they?
2. There are new requirements for heat-treating wooden shipping pallets. What are those requirements?
3. The Minnesota Tree Care Advisors will put out a communication plan in 2012. What will it be and who are those advisors?

Article: A New Exotic Pest

Hacket, Robert A.,  Eduard Jendek, Houping Liu, Kenneth R. Marchant, Toby R. Petrice, Therese M. Poland, and Hui Ye. 2002. "The emerald ash borer: a new exotic forest pest in North America." Newsletter. Michigan Entomology Society: (47) 3&4. September.


This newsletter brought some bad news to the United States. The authors, collaborators from America, Canada, Slovakia, and China, worked together to identify a new insect found in Michigan in June of 2002. When researchers observed some ash trees were declining, they noticed the "D"-shaped holes in the bark and the cambium-killing larvae tunnels. 


Quickly identifying the beetle was not possible. There are more than 2,000 species in the Agrilus family, so it wasn't until July 9th, when the specimens where shipped to Eduard Jendek, a specialist in Asian Agrilus, that the bug was positively identified at Agrilus planipennis Fairmaire (2). Shortly after, the Michigan Department of Agriculture started enforcing quarantines in infested counties. Meanwhile, Canadian authorities had found a similar beetle, it wasn't until August 7th that it too was confirmed as the same insect (2). At this point, researchers estimated the insect had been established for five years (4)!!!


This article provided great insight on the process of determining a new species in an environment. When an animal breaks through to a new boundary or region, it can easily be identified. Not so with small insects who come from wide families and get carried on shipping containers. 


When the insect was identified, the researches took votes on what to call it. They wanted to make sure the media didn't name the insect (1). Oregon Department of Agriculture's Richard Wescott and Natalia Vandenburg of the USDA suggested the name Emerald Ash Borer (EAB). Votes were tallied and a new acronym was born (1). 


The taxonomy section mentioned that the beetle goes by other names as well.  

Agrilus planipennis Fairmaire (1888; type China) has several synonyms, including A. marcopoli Obenberger (1930; type China), A. marcopoli ulmi Kurosawa (1956; type Japan), and A. feretrius Obenberger (1936; type Taiwan) (Jendek 1994).  EAB is referred to as A. marcopoli in much of the Chinese literature and as A. marcopoli ulmi in Japan.  Based on the morphology of the scutellum, deep pronotal medial sulcus, and robust body, A. planipennis appears most closely related to the Asian species A. auristermum Obenberger, A. cyaneoniger Saunders, and A. lubopetri Jendek (2).

I didn't know this was allowed in the world of entomology—it certainly makes things confusing. But I can understand why it would be very difficult to streamline names across cultures, especially when one culture has completely adapted a name. I wonder then, do other countries refer to EAB by these other names still? Or has the new concern in the West changed the way people refer to it? I looked at Eduard Jendek's website later and found nearly 100 varieties of insects named after him.


EAB, though new, is not alone as an foreign Agrilus. The authors list six other exotic members of the Agrilus family established in the United States (4).


The native habitat is described as Northeastern China, Far Eastern Russia, and Taiwan. The authors say only two Asian research articles were found on the bug, one from 1986, one from 1992 (2). Hacket, et al. provide a synopsis of these studies and describe other upcoming studies from Michigan (2). Significant early timetables provide a step-by-step retelling of the early infestation and where the beetles in the same family had been found at points of entry, although it was implied the ships were from China and Japan, the authors show it needed more study (4).


To conclude, the authors warn readers with a level-headed use of emotional language. Resources are said to be "at risk," because the wherever the insect moved, it "successfully attacked." The result could be "considerable economic and environmental damage." Therefore, "A vigorous research and management program along with harmonized quarantine actions are urgently needed to contain this new exotic tree pest" (5). 

Article: Insect Invasions and Management

Brockerhoff, Eckehard G., Andrew M. Liebhold, and Herve Jactel. 2006. "The ecology of forest insect invasions and advances in their management." Canadian Journal of Forestry Research. Vol. 36. 2006. 263-268.


The authors wrote this paper to "enhance the sharing of information" between scientists studying invasive species management (Brockerhoff 2006, 263). It was originally presented at the International Union of Forest Research Organizations Conference on Forest Diversity and Resistance to Native and Exotic Pest Insects in New Zealand. 


I found this paper to be a good culmination of four specific areas of research. The theme of management relates to my research because management demonstrates the need for agencies to present consistent information internally and to the public. Management cannot progress on this issue without consistent information.


The authors, from New Zealand, Morgantown, WV, and France, respectively, share information about four subjects relevant to invasive species management

1. The role of global trade; 
2. biogeographical effects; 
3. biodiversity; 
4. and advances in "detection, monitoring, and management of invasive species and native pests" (264).

Although this report mentions several different insects, the authors describe the emerald ash borer along with the Asian long horned beetle, Anoplophora glabripennis, the great spruce bark beetle, Dendroctonus micans, and the red turpentine beetle, Dendroctonus valens, as cases receiving "much attention because they represent a significant threat to the health of forests and urban trees" (264). They cite an early study done by Haack et al. in 2002, which I will read soon. The rest of the report maintains a macro-view to all the problems of invasive species.


The research done on the role of global trade in invasive species movement shows a need for government action. Studies prove a relationship between "interception frequency and probability of establishment" (264). It also shows a need for more research from the agencies responsible for inspecting shipping containers (264).


Biogeography is the study of plant distribution, such as how forests move over time, and where nurseries develop new plant stocks. Phylogeny deals with the development and diversification of different animals or insects. These two areas of study interweave when researching pests in forests. Research has found that invasive bugs spread for these three reasons:

1. The plants lack a natural defense;
2. few or no natural enemies exist;
3. few or no natural competitors exist (265).

However, the factors leading to the phylogenic introduction of the invasive species can be complex and closely related to the movement of plant species by human benefactors. The authors note, "a reliance on exotic trees in forestry increases the need to exclude pest introductions" (265). 

I imagine this can be a revolving problem. Invasive species prey on native trees and kill them, so new species are introduced, but with them come other invasive species. I'll bet large nurseries have to tackle this problem every year.

Although I have always heard that diversified forests (and urban forests) are less susceptible to invasive species, the authors show that only some research finds this to be true. In other research (from Jactel et al. 2005), some "mixed forests have greater levels of attack than forests with less tree species richness" (265). However, they don't offer too many citations for this information. They agree that many cases exist showing the opposite. In the end, they call for more research (266).

DNA testing and pheromone traps provide two new methods for detecting invasive species. The DNA testing showed 100 percent accuracy in tests (Ball and Armstrong 2006)! Inspectors can sample any part of insect or larvae to find a match and identify a pest. However, a full database needs establishing first. This could be a "standardized tool for biosecurity managers around the world" (266). Pheromone traps prove successful, but studies have shown need for caution when interpreting the data because the number caught does not always relate to the population quantity in the area (Bentz 2006). Other control studies include the simple introduction of a native predator or fungus and confusing the pests by spraying sex pheromones (266).

The authors do note that an "eradication campaign" was "successful" in com patting two pests in New Zealand. The campaign incorporated trapping, spraying a fungus, and releasing sterilized males (267). I wonder what they mean by successful though. Is it a manageable amount of pests or did they eradicate them?

The authors conclude by noting these three things:

1. Invasions will only increase with increased trade;
2. Increased communication will be needed between agencies and scientists; 
3. While some programs to decrease established pests can work, the "primary goal" should be a reduction of the pests becoming established in non-native environments (267). In other words, stop them on the ships!

Other Works Cited

Ball and Armstrong. 2006. "A universal DNA-based identification system for insect pests: a test case with the Lymantriidae (Lepidoptera). Canadian Journal of Forestry Research.

Bentz. 2006. "Mountain Pine Beetle population sampling: inferences from Lindgren pheromone traps and tree emergence cages." Canadian Journal of Forestry Research.

Other Work to Explore

Hacket et al. "The emerald ash borer: a new exotic forest pest in North America. Newsletter. Michigan Entomology Society (47)

Graphic: MN Quarantine Map

http://www.mda.state.mn.us/plants/pestmanagement/~/media/Images/plants/eab/eabquarantinemap.ashx

Article: Previous Research on the Pest

Wang, Xiao-Yi, Zhong-Qi Yang, Juli R. Gould, Yi-Nan Zhang, Gui-Jun Liu, and EnShan Liu. “The Biology and Ecology of the Emerald Ash Borer, Agrilus planipennis, in China.” Journal of Insect Science 10.128 (2010): 1-23. Web. 10 Mar. 2011 

In the similar environment on the other side of the world, scientists in China recognized a potential problem in the 1960s. In Northeastern China, many non-native ash trees (from the United States) were planted. The trees were similar to other ashes in Asia, and were planted widely in residential areas. Soon after, however, outbreaks of EAB followed. Little was known about the insect because most of its life cycle was hidden under the tree’s bark. EAB remained “only sometimes an important pest in certain areas in China,” and didn’t pose a large-scale threat (Wang 2).

The hidden life cycle of the EAB was studied by Chinese entomologists Xiao-Yi Wang, Zhong-Qi Yang, Juli R. Gould, Yi-Nan Zhang, Gui-Jun Liu, and EnShan Liu in Journal of Insect Science article, “The Biology and Ecology of the Emerald Ash Borer, Agrilus planipennis, in China.” They conducted a study on the velvet ash in Guangang Forest Park, Dagang District, Tianjin Municipality, China, where “most forests are monoculture ash plantings” (2).

They found that the beginning of the problem was the most difficult to detect.

There were rarely any clear symptoms on the surface of the bark during the initial infestation … It was more difficult to detect an early stage of infestation for those trees with rough or thick bark (6).

But once EAB has entered a tree, the tree’s life span is cut short. To study these life cycles, Wang al. et. cut down infected trees and studied them in two environments, the laboratory (where each pair of EAB were caged with a log) and in the outdoor environment. They cut the logs and sealed the ends with wax (so the bugs had to enter through the bark). 

Wang al. et. report that EAB deposit eggs under the bark and upon hatching from the egg, the larvae burrow deeper into the bark and into the cambium, then into the xylem for hibernation around the beginning or middle of September. From June to April they are in larval stage, around 300 days. They become pupae stage and eat through the cambium for 20 days to emerge in May (in China). After a week, they mate, lay eggs and die (Wang 3-18).

Narrative: The Start of a Crisis, Crossing the Mississippi

In early April, 2009, officials confirmed some bad news for Minnesota's ash trees. The news originated in Victory, Wisconsin, just across the Mississippi River from Minnesota's Houston County. 


A stand of ash trees in Victory were dying for no apparent reason. When inspected, thousands of little tunnels were revealed under the bark of the trees. These tunnels signaled a new turn of events in the battle for many forests and urban trees near the Mississippi River.


Many small green bugs created the tunnels. As they grew from a larvae stage, the bugs chewed through the phloem, the life-veins of the trees, and emerged out of the bark as full-grown flying beetles with brilliant green wings.  During their short life span they mate and burrow back into the bark to reproduce and die. 


But while their life cycle continues, the tree they call home slowly withers, unable to get the resources needed through its phloem. Within a three years, its foliage is completely gone and its bark, dry and brittle, peels off.


So for Houston County, bordered by Iowa to the south and the Mississippi River to the east, trouble was at the doorstep. Reporters carried the broadcast to every major city in the state. People hundreds of miles north, in Ely, Grand Marais, International Falls, winced at the news. The Emerald Ash Borer had nearly arrived.


The Minnesota Department of Agriculture moved quickly to carry the messages about not moving firewood, and they set a quarantine on any logging or movement of hardwoods in Houston county. County meetings were called and the MDA discussed their future plans to search for the bug in the vicinity. But it took another full year until infected ash trees were found in the county. The MDA gave confirmation of the infestation on April 29th, 2010. 


By then, the flying bug already migrated 175 miles northwest—to the Twin Cities. 




“Forest Protection Reserve Appropriation.” Minnesota Department of Agriculture. 15 Oct. 2009. PDF. <http://www.mda.state.mn.us/news/government/~/media/Files/news/govrelations/fpr-firstquarter2010.ashx>

“MDA Confirms Emerald Ash Borer Infestation In Houston County.” MDA.state.mn.us. Minnesota Department of Agriculture. 29 April 2010. Web. 26 Sept. 2011.