Articles

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When should a non-aggressive exotic species be demoted to a harmless naturalized resident?

By Dr. Laurel Haavik, US Forest Service

Exotic species that establish, spread, and cause substantial damage are demonized as foreign invaders that charge with menacing force across the landscape. Rightly so; those pests threaten to displace or eliminate native species and alter ecosystem functions. Chestnut blight, emerald ash borer, and hemlock woolly adelgid are all excellent examples. What about invaders that aren’t so destructive? Or, at least don’t seem to be at the moment? At what point do we stop monitoring a seemingly innocuous invasive species, especially one that has proved itself a serious pest elsewhere? To make this decision, it’s helpful to know how much the species has affected its new habitat, and whether this impact already has or is likely to change over time. That is exactly what we set out to do with the European woodwasp, Sirex noctilio, in Ontario.

Nearly a decade after the woodwasp was first found in a trap near the Finger Lakes in New York (and then a year later across Lake Ontario in Sandbanks Provincial Park), it still hadn’t killed pines in noticeable numbers, either in the US or Canada. Native to Europe and Asia, this woodwasp has been introduced to several countries in the Southern Hemisphere, where it has been a serious pest in forests planted with exotic pines. By contrast, in North America, it seems that only the weakest trees, those that are already stressed by something else, are killed by the woodwasp. Would forests with many weakened trees allow populations of the woodwasp to build up enough that they could then kill healthy trees in well-maintained forests? Could we find any evidence that this had already happened or would likely happen in the future?

Our goal was to measure the impact the woodwasp has had in Ontario, and whether that has changed over time, by closely examining the same trees in pine forests every year. First, we had to find sites where the woodwasp could be found, which wasn’t every pine forest, and where landowners would allow us to work. We were not interested in sites that were well-managed, because research had already confirmed that the woodwasp was not present in those forests. We used records of positive woodwasp captures from the Ontario Ministry of Natural Resources trap survey as a guide. We visited 50 potential sites, and eventually selected eight for close scrutiny in our long-term study. These sites were areas where there was likely to be intense competition among trees for resources, with plenty of stressed trees for the woodwasp.

The European woodwasp was probably absent from a well-managed red pine forest (left), but likely to be found in an un-managed scots pine forest (right).

We visited all eight sites every fall from 2012 to 2016, after woodwasps had the opportunity to attack trees. Adult woodwasps mate and lay eggs, attacking trees in the process, in mid-summer. Attack was visible as distinctive resin beads scattered over the trunk. We recorded which trees had been attacked, and later (usually the following year) killed by the woodwasp.

The woodwasp population was considerable at some of our sites, having killed about one-third of the trees within five years. Though at other sites, the population was much smaller, having killed only a small percentage of trees. We’re not exactly sure what caused this variability. It’s possible that the woodwasp arrived at some of our sites years before it arrived at others, and the most vulnerable trees were long dead at the sites it invaded earlier. We have no record of time since woodwasp invasion at any of our sites. It’s also possible that local environmental conditions, which we did not measure, could in some way have affected tree resistance or the woodwasp population.

Most curious, though, was that over the five years many trees attacked by the woodwasp did not die – around 50 to 80%. At least half of these trees were attacked again and again in successive years. We had captured an interesting part of the woodwasp’s ecology, its way of essentially priming trees to become better habitat for its young. When laying eggs, female woodwasps also inject a self-made toxic venom along with a symbiotic fungus into the tree, to help kill it. If the tree is sufficiently resistant to attack, the female may not lay eggs, only the fungus and venom. The fungus and venom then work in concert to weaken (prime) the tree for re-attack – and hopefully successful colonization – in subsequent years.

Female woodwasps sometimes die while laying eggs. Survival of the fittest?

Two-thirds of trees that were attacked by the woodwasp at some point in our study (one or more times) did not die, which shows that most trees selected by the woodwasp as suitable habitat are at the moment resistant to its advances. This also shows, along with the variability in woodwasp impact among sites, that this invader is active in the forest. Should environmental conditions change (say, if a drought occurs), woodwasp populations could quickly rise to outbreak levels, which could kill large numbers of healthy pines. This has happened in other places.

Long-term study of these sites, and hopefully others, is needed so that we can be aware of changes that arise in woodwasp impact. This will allow us to be proactive about what steps to take to manage this invader, should it become a problem. It will also help us better understand and predict what causes exotic species to vacillate on the spectrum between aggressive invader and innocuous resident.

Want to read more? Check out the original article published in The Canadian Entomologist, which is freely available for reading & download until May 14, 2018.

Haavik, L.J., Dodds, K.J. & Allison, J.D. (2018) Sirex noctilio (Hymenoptera: Siricidae) in Ontario (Canada) pine forests: observations over five years. The Canadian Entomologist, 1–14. doi: 10.4039/tce.2018.18

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ESC Blog Classifieds – 2 Post-docs @ University of Alberta (Chemical Ecology & Ecophysiology)

Seeking Two Postdoctoral Fellows in Tree Responses to Insect Herbivores and Drought

Area of Research: Chemical Ecology & Ecophysiology

Location: Department of Renewable Resources, University of Alberta, Edmonton (Alberta, Canada)

Description of positions: The interdisciplinary project goal is to characterize the contributions that metabolomics and genomics-assisted tree breeding can play in comprehensive forest planning. Postdoctoral fellows (PDFs) sought for this project to assess the activities of tree defense and ecophysiological responses to insect herbivory and drought. The PDFs will characterize the secondary compounds, anatomy, and ecophysiology of two conifer species (lodgepole pine and white spruce) in response to insect herbivory and drought treatments in both greenhouse trials and associated progeny field trials in Alberta. The PDFs will be responsible for conducting and coordinating both lab and field investigations that include anatomical and chemical characterization of tree defenses, assessment of 13C, gas exchange, and chlorophyll fluorescence plant drought response, implementation of greenhouse and field experiments, data management, statistical analyses, writing reports and peer-reviewed journal manuscripts, and interact with industrial and government partners. The PDFs will also assist with supervision of full and part-time research assistants and undergraduate students. Even though each PDF will have his/her own research projects, it is expected that they work and collaborate together.

Salary: $50,000+ benefits per year, commensurate with experience.

Required qualifications: PhD in a relevant field is required. The ideal candidate should have background and experience in chemical ecology, ecophysiology, entomology, forest ecology, with strong analytical chemistry of plant secondary compounds (primarily terpenes and phenolics) using GC-MS and LC-MS, and writing skills. Suitable applicants with a primary background in one or more areas, plus interest in other research areas, are encouraged to apply.

Application instructions: All individuals interested in these positions must submit: (1) an updated CV; and (2) a cover letter explaining their qualities, including a list of 3 references along with their contact information (a maximum of 2 pages). Applications should be sent by email to Nadir Erbilgin (erbilgin@aulberta.ca) and Barb Thomas (bthomas@ualberta.ca) by the closing date. Please list “PDF application in Tree Responses to Insect Herbivores and Drought” in the subject heading.

Closing date: November 30, 2016.

Supervisors: Nadir Erbilgin (https://sites.ualberta.ca/~erbilgin/) and Barb Thomas (http://www.rr.ualberta.ca/StaffProfiles/AcademicStaff/Thomas.aspx)

Expected start date: January 2017 (with some flexibility)

Terms: 1-4 years (1st year initial appointment, with additional years subject to satisfactory performance).

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Entomologist Survey: Life & Living in Academia

This is a guest post by Dr. Laurel Haavik, post-doctoral researcher in the Department of Entomology at The Ohio State University.

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I am a post-doc. I’ve been one for nearly six years. Like many other post-docs, I have been working for over a decade towards my goal: a tenure-track position at a research-intensive academic institution. I enjoy research and teaching, and so a career including both seemed like a logical pursuit. I must be good enough to succeed in this pursuit, otherwise someone would have told me to opt for a different path by now. After all, only a small percentage of Ph.D.s actually become professors. I must be pretty close to achieving this goal, because lately I’ve had several interviews – no offers yet. By now, most of my peers have secured permanent positions, although some have gone on different paths. It must be my turn soon. I had faith in the system; confidence in myself.

Earlier this summer, I was invited to give a talk at a conference, in a session on women in science. I accepted willingly; the subject seemed challenging and relevant. As I began to prepare, I realized I knew nothing about it. So, I did what any scientist would do: I turned to the primary literature on women in science. What I found changed my whole perspective on academia, my career, and most importantly: my life.

I learned that the tenure system is outdated, and filters out many creative and talented people. It was established ca. 1940, when those entering academic careers were mostly men. Assistant professors were expected to live on campus, and work intensively, around-the-clock, on establishing themselves until achieving tenure. Sounds a lot like graduate school, or a post-doc, doesn’t it? There’s not much room in that scenario for having a life outside of this pursuit. It turns out that not much has changed about this in the intervening 70+ years. To make it worse, there are now few jobs and too many of us with graduate degrees competing to fill them. It turns out that women, more often than men, are willing to forgo their academic dreams because of this ridiculousness, in favor of something better – probably a happier life. It seems that there are two issues. One: is it even possible? Women are confronted with the complications of basic biology at the very same time as they would be embarking on a demanding academic career. Most of us are well into our thirties, near the end of our child-bearing years, by the time we’re on the job search. Two: they’re exhausted, wondering if an academic career is akin to never-ending graduate school. In the academic atmosphere, there is intense pressure to do more; for example, publish or perish, fund or famish. Talent and creativity that science badly needs is undoubtedly lost as women and men continue to opt out of this outdated system, and for very reasonable grounds.

I took a long, hard look at my career so far. I’m on my third post-doc. I’ve had two failed relationships and a third that might not make it if I have to move again. I’m not married. I don’t have children. I’m in my mid-thirties, meaning that if I want to have children, I better get situated and do it soon. Maybe academia isn’t for me after all, even though my interests, teaching and research, are so well-aligned with the academic mission. I realized that my adult life so far, 90% career and 10% life outside of work, is a direct product of what I like to call our broken academic system. We need to better understand and voice our discontent with the broken academic system, or it won’t change.

I wondered if others feel the same way. In my field, had others thought of leaving science? And if so, why? Has the disparity in numbers of women and men graduates vs. those occupying professional positions actually changed in recent decades? Most importantly, what allows people to cope with such a rigorous career? I’ve been lucky to have had some great mentors, support from my family, and support and encouragement from the scientific community in my field. Have others had the same kinds of emotional support systems?

My study pursues these questions among three related fields: Forestry, Entomology, and Forest Entomology. In all three of these fields women are not historically well-represented, but this has changed in recent years, especially in Entomology. There are still few women in Forestry. Forest Entomology is a small field with a very inter-connected community, which I hope will provide an interesting contrast to its two larger, sister fields.

Please follow the link below to participate in my study, by completing my survey.

I invite men and women at all stages in their careers, as well as those who are no longer in science, to participate. Please forward this invitation to anyone you know who is no longer in science, but completed graduate school (M.S. or Ph.D.). The results of this study will be published in the primary literature.

Please follow the link below to complete the brief, 28-question survey by September 30, 2015

https://www.surveymonkey.com/r/forestry-entomology

It may take 10-15 minutes to complete. I apologize for any cross-posting of this survey. No personal identifying information will be collected as part of the survey, and your participation will be completely anonymous. Answering questions in the survey will indicate consent. Participation is voluntary and you may withdraw at any time without penalty, and there are no incentives to participate. Participation will have no effect upon your relationship with the Entomological Society of Canada. This study has been determined Exempt from IRB review.

Please contact me if I can provide any additional information regarding the aims of or your participation in the survey (Laurel Haavik, 479-422-4997, haavik.1@osu.edu). For questions about your rights as a participant in this study or to discuss other study-related concerns or complaints with someone who is not part of the research team, you may contact Ms. Sandra Meadows in the Office of Responsible Research Practices at 1-800-678-6251 or hsconcerns@osu.edu.