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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Differential parasitism and ash tree volatile organic chemicals

By Tyler Wist  

The ash leaf cone roller, Caloptilia fraxinella (Ely) (Lepidoptera: Gracillaridae) (Fig. 1) started to get noticed in the cities of the Western Canadian prairies in 1998, well, in Saskatoon, SK at least. I know this because that summer the green ash, Fraxinus pennsylvanica (Oleaceae), in my front yard was covered in cone rolled leaflets and had not been prior to that year. I had just started working for the City of Saskatoon’s Pest Management Program that year and one of our mandates was urban forest insects…not that there was any budget to control them, but it piqued my interest in urban forest entomology.

Fig. 1 The ash leaf coneroller, Caloptilia fraxinella (Ely) (Lepidoptera: Gracillaridae) adult, pupal exuvium and cocoon.

Fig. 1 – The ash leaf coneroller, Caloptilia fraxinella (Ely) (Lepidoptera: Gracillaridae) adult, pupal exuvium and cocoon.

The following year, Chris Saunders with the City of Edmonton’s Pest Management Program, contacted us in Pest Management and asked if we had seen this cone roller on our ash trees because they had just noticed it on the ash trees in Edmonton. Greg Pohl had identified this leaf miner/leaf roller that year on all species of horticultural Fraxinus in Edmonton and published the identification and some life history of the moth in a 2004 paper (Pohl et al. 2004) along with a brief identification of several parasitoids that were reared from larvae and pupae. The lone braconid, identified to the genus Apanteles and found to be all one species by Darryl Williams of the Canadian Forest Service in Edmonton seemed to be the dominant parasitoid in this complex, but without a species designation not much else about the wasp could be gleaned from the literature.

Chris Saunders suggested that I study the ash leaf cone roller as a master’s project but I digressed from urban forest entomology for a few years into pollination of a nutraceutical/agricultural crop. By this time, the ash leaf cone roller had spread to every ash tree in both cities and often rolled 100% of the leaflets on a single tree. I finally followed Chris’ advice and started a PhD project in Maya Evenden’s lab at the University of Alberta, which was the only lab in Canada that was working on the ash leaf cone roller problem (Evenden 2009). The Apanteles sp. was still the dominant parasitoid and so, along with studies on the chemical ecology of the moth (Wist et al. 2014), I also studied the third trophic level in this system (Wist and Evenden 2013). Of course, I couldn’t go through my studies without knowing what the species designation was for the dominant parasitoid wasp. Fortunately, Jose Fernandez-Triana had just begun his study of the genus Apanteles at the CNC in Ottawa and once Henri Goulet passed along the Apanteles specimens that I had sent for identification he quickly determined that this parasitoid was Apanteles polychrosidis Viereck (Hymenopetra: Braconidae) (Fig. 2).

Fig. 2 Female Apanteles polychrosidis Viereck (Hymenopetra: Braconidae)

Fig. 2  – Female Apanteles polychrosidis Viereck (Hymenopetra: Braconidae)

Apanteles polychrosidis kills the ash leaf cone roller larvae before they can chew their emergence “window” that they use to escape the cone rolled leaflet as adults. This behaviour gives a fairly reliable visual cue that a cone rolled leaflet without a “window” has been parasitized by A. polychrosidis because the other parasitoids in the complex emerge after the cone roller has pupated and created its escape route “window”. Unrolling the leaflet confirms the presence of A. polychrosidis if its telltale “hammock-like” cocoon is present (Fig. 3). This type of cocoon is thought to be a defense against hyper-parasitism but as we found (Wist and Evenden 2013) it doesn’t always work out for A. polychrosidis!

Fig. 3 Apanteles polychrosidis Viereck (Hymenopetra: Braconidae) adult above its cocoon and beside the leaflet cone rolled by Caloptilia fraxinella (Ely) (Lepidoptera: Gracillaridae). Note the emergence hole in the side of the leaflet that the wasp chewed to escape.

Fig. 3 – Apanteles polychrosidis Viereck (Hymenopetra: Braconidae) adult above its cocoon and beside the leaflet cone rolled by Caloptilia fraxinella (Ely) (Lepidoptera: Gracillaridae). Note the emergence hole in the side of the leaflet that the wasp chewed to escape.

To assess the percentage of parasitism by this dominant parasitoid I adapted a method that Chris Saunders and I had discussed years earlier for assessing the parasitism of Apanteles sp. on individual trees. For the initial experiment in our paper (Wist et al. 2015) I sampled leaflets to estimate the density of cone rollers on the tree and estimated the percentage of parasitism by A. polychrosidis on two of the common urban species of ash in Edmonton. Apanteles polychrosidis parasitism was higher on black ash, F. nigra, at all sites than it was on green ash, F. pennsylvanica, which can be called differential parasitism and it seems to be common when host larvae develop on two or more host plants, but had not been well studied on trees. When host density and parasitism were graphed, the relationship of parasitism to host density could be visualized by the slope of the regression line, and on black ash, parasitism was independent of host density on black ash, but was negatively density dependent on green ash. In other words, on black ash parasitism is always high but on green ash, parasitism declines as the density of C. fraxinella increases. I ran the same experiment on green and black ash trees in Saskatoon with the same results but we chose to leave them out of the final version of the manuscript.

I was already studying the chemical ecology of C. fraxinella so this was where we looked for an answer to the differential parasitism in the field. I ran a y-tube olfactometer experiment with black and green ash plant material as the attractive source of volatile organic chemicals (VOCs) and this turned out to be rather tricky. I had three treatments that I wanted to test; undamaged leaflets, leaflets damaged by C. fraxinella and leaflets that were mechanically damaged.

First, I tried to bag small seedlings as the source of the plant smell but I couldn’t seal the system well enough to get reliable airflow through the y tube chamber. I had to switch to using leaflets alone which raises the issue of the smell of the leaflets changing once they have been removed from the tree which could be a problem especially in the “undamaged” treatment. I also needed enough female A. polychrosidis hunting for hosts to give me a decent sample size so I had to collect and emerge as many “un-windowed” cone-rolled leaflets as I could in the summer, and hope that they would actually mate and want to oviposit into host larvae at this point in their lives. Another issue was that I couldn’t coax my summer emerged C. fraxinella to lay eggs on ash seedlings to create leaf-mined treatments. Fortunately, a subset of the local population of C. fraxinella had developed a second generation on the new ash leaves that a dying ash tree puts out in July in an effort to save itself. These leaflets became my leaf-mined treatment. Over two seasons with a lot of juggling and timing of three species I was able to gather enough experimental data with the olfactometer to discover that female A. polychrosidis were differentially attracted to the volatile odour cues from each ash species. In green ash tests, they were attracted to the smell of green ash alone but in black ash tests, they were not attracted unless the leaflets were attacked by its host. The “icing on the manuscript cake” was the GC-EAD results by co-authour Regine Gries that showed that 13 compounds in the volatile profile of ash could be sensed by the antennae of A. polychrosidis, and some of them are known to increase in response to herbivore damage.

I’d say that this manuscript is a starting point for further studies on this interesting parasitism system and could accommodate projects from chemical ecology and landscape ecology perspectives at the very least. In fact, Danielle Hoefele and Sarah McPike have already begun projects in Maya’s lab on the FraxinusCaloptilia-Apanteles system. In case you’d like to know more, here is the link to our manuscript published in Arthropod-Plant Interactions.

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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.

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Emerald Ash Borer – marking 10 years of research

Emerald Ash Borer. Credit Debbie Miller, USDA Forest Service. Bugwood.org

Emerald Ash Borer (Agrilus planipennis). Credit: Debbie Miller USDA Forest Service, Bugwood.org.

To mark the publication of the Emerald Ash Borer special issue from The Canadian Entomologist, guest editors Chris MacQuarrie and Krista Ryall from Natural Resources Canada have co-authored this blog post about the issue.

In 2002, residents of Detroit, Michigan noticed something was killing their ash trees. Ash trees in North America are susceptible to some diseases that can result in decline and mortality, so a forest disease specialist was dispatched to investigate why these trees were dying. It was soon determined that the culprit was not a disease, but an insect: a shiny, metallic-green, buprestid beetle not previously known from Michigan, or anywhere else in North America. Authorities in Michigan notified their Canadian counterparts who soon discovered numerous ash trees dying in Windsor, Ontario from damage caused by the same beetle. Eventually, with the help of a European systematist the insect was determined to be the previously described (and previously rare) Agrilus planipennis. Today, this insect is better known by its common name:  the emerald ash borer.

To commemorate the discovery of emerald ash borer in North America, we organized a symposium and workshop at the 2013 Entomological Society of Canada’s and Ontario’s Joint Meeting in Guelph, Ontario. The timing and location of this workshop seemed appropriate because 2013 marked 10 years of research on the emerald ash borer and Guelph is located only a few 100 kilometres from where emerald ash borer was first found, and is now well within the insect’s Canadian range. Our goal with this symposium was to review the state of knowledge on emerald ash borer after ten years of research, and look ahead to the questions that researchers will be asking as the infestation continues to grow and spread. We were fortunate that many of the researchers who have contributed so much of what we know about emerald ash borer were able to participate.

We were quite pleased with how well the symposium turned out. However, information presented in a symposium is ephemeral and fades away as soon as the last talk is over. To prevent this, we imposed upon our presenters to also prepare written versions of their presentations. It took some time, but now these papers are all complete, and have been put together to form a special issue of The Canadian Entomologist dedicated to the emerald ash borer.

Emerald Ash Borer

Emerald Ash Borer.  Image credit: Chris MacQuarrie

Ten years is a long time in research. We estimated that over 300 papers on emerald ash borer had been produced over that period, with more being produced every month. It is our hope that this special issue can serve as an entry point into this literature for researchers new to the field. We also hope that this issue can be valuable to more established researchers as well, to use as a resource and a touchstone in their own work. This special issue can also serve as a reminder of how much effort is required (in both research and by people) to understand a new pest. What we have learned about emerald ash borer over the past ten years (well, 13 years now) is immense. There is still much to learn though.”

The Emerald Ash Borer special issue is the free sample issue of The Canadian Entomologist for 2015.

Access the special issue for free until 1st January 2016 here.

Main image credit: Debbie Miller, USDA Forest Service, Bugwood.org

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Decoding the love songs of mate-seeking male bark beetles

—–By Amanda Lindeman, PhD Candidate, Carleton University—–

A male red turpentine beetle over the sound wave of a train of its interrupted chirps.

A male red turpentine beetle over the sound wave of a train of its interrupted chirps.

In April 2015, I coauthored a paper on what bark beetles are trying to say to each other when they interact with potential mates (1). No one knew for sure – since bark beetles, as their name implies, live under the bark, males could simply be announcing their presence as they wander the surface of the bark trying to join a mate in her gallery below, they could be advertising their species identity to make appropriate mate pairings or to say “Hey! I’m not a predator, let me in!” But the thing that always struck me is that many of the 5000+ species of bark beetles produce sounds, and their sounds are complex — they produce more than one kind of sound, and they can be multi-component. For a group of animals that already produces intricate attraction pheromones, why produce sound at all? Is it just for the sake of redundancy?

Image 2 Galleries

An elm bark beetle gallery located along the inner bark of an elm tree. The female digs the central (vertical) gallery and waits at the entrance of the gallery for a male to join her. Eventually, she will lay her eggs along the sides of the gallery and as the larvae hatch they will tunnel out causing the radiating (horizontal) galleries.

Before I go too far, perhaps I should go waayyyy back, and explain why I find insect sounds to be so interesting in the first place. I think that animal communication has always captured human attention and imagination as we consider both the beauty in animal sounds and what they mean. The dawn choir of birds; the roar of a lion; the squeak of a mouse. But, as Frank E. Lutz (1924) said: “probably the first definite sounds made by land-animals on this earth were made by insects. Before ever birds sang or even frogs croaked”. Insects led the way. Indeed, many insects have beautiful songs appreciated by people since antiquity when crickets were kept as domestic pets in ancient China (3) and cicadas were kept in cages in Greece and Rome (4), not unlike how we would keep a pet bird today. Apart from those musically talented insects, however, we need to remember that even in “the lowest insect tribes, many a rough, rasping note, though awakening no particular delight in us, serves as great a purpose as the more pleasant sounds” – F. C. Clark (1875). The trouble in research often comes down to finding out what that purpose is.

No group embodies this sentiment more than the beetles, an order with more ways of producing sound than any other, and yet with a very poor and widely neglected understanding of the purpose of those sounds (5). Bark beetles are an incredibly interesting group of beetles, who likely first caught our interest because of their destructiveness. The members of the genus Dendroctonus in particular have been hailed by forest entomologists as being “the most destructive enemies of the coniferous forests of North America” (6) and “the greatest tree killers known”(7).

One species in the genus that is no stranger to Canadians is the mountain pine beetle, and to put things in perspective, this beetle has impacted over 18 million hectares of forest in BC, and killed about 50% of the total volume of commercial lodgepole pine in only two decades. And, as I mentioned above, I personally find them particularly interesting because of their complex sounds which many of them invariably make as they approach the gallery of a potential mate and try to enter.

A male red turpentine beetle at the entrance to a female’s gallery. Female is visible blocking the gallery entrance.

A male red turpentine beetle at the entrance to a female’s gallery. The female is visible blocking the gallery entrance.

So, getting back on point, what do these sounds mean? In one species of the destructive Dendroctonus genus, the red turpentine beetle, I found that many aspects of a male’s courtship song correlated to his size. Since male size is linked to his ability to produce more offspring, this means that the male might be using his chirping as a way to honestly tell the female how fit he is. One important chirp variable related to size was the number of components per chirp. Chirps with just one component are termed “simple” while chirps with more than one component are termed “interrupted” and sound like a stutter in the chirp to the human ear. It turns out larger males have more components in their chirps. Also, and importantly, females always admitted a male into her gallery if he made interrupted chirps, while if he only made simple chirps, or was experimentally muted to produce no sound at all, he would only be successfully accepted approximately 60% of the time.

Even though I find the question of why an animal produces sound to be inherently interesting, someone who has unfortunately been a bark beetle victim and has seen local communities and businesses devastated by these insects might not care so much about the why and instead wonder what next? Now that we know that sounds may be important to the life history of bark beetles and that their chances of successful mating might depend to some extent on these signals, can this help us manage them? Probably! Acoustic technologies have helped control pest insects by using the sounds the pests rely on against them (8). This can mean anything ranging from detecting their presence to manipulating their behaviour. These kinds of technologies have not yet been applied in bark beetle management because we haven’t known enough about their sounds to develop strategies. Hopefully, as we begin to understand more about the purpose of their sounds, we can use acoustic technology to develop new targeted solutions to this serious problem.

Amanda Lindeman with a funnel trap (baited with pheromones and host tree kairomones to attract bark beetles) – photo credit: Michael Connolly.

Amanda Lindeman with a funnel trap (baited with pheromones and host tree kairomones to attract bark beetles) – photo credit: Michael Connolly.

References

(1) Lindeman, A.L. & Yack, J.E. (2015) What is the password? Female bark beetles (Scolytinae) grant males access to their galleries based on courtship song. Behav. Proc. 115:123-131

(2) Lutz, F.E. (1924) Insect sounds. Am. Mus. Nat. Hist. 50:333-372.

(3) Laufer, B. (1927) Insect Musicians and Cricket Champions of China. Field Museum of Natural History Leaflet

(4) Clark, F.C. (1875) The song of the cicada. Nat. 90(2):70-74.

(5) Wessel, A. (2005) Stridulation in the Coleoptera – An overview. Insect Sounds and Communication. 397-430

(6) Hopkins, A.D. (1909) Practical information on the Scolytid beetles of North American forests. I. Bark beetles of the genus USDA Bur. Entomol. Bull. 83. 169 pp.

(7) Wood, S.L. (1963) A revision of the bark beetle genus Dendroctonus Erichson (Coleoptera: Scolytidae). Great Basin Nat. 23:1-116.

(8) Mankin, R.W. et al. (2011) Perspective and promise: a century of insect acoustic detection and monitoring. Ent. 57(1):30-44.

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Costly colouration in a forest moth: the tale of a ten-year research project

As part of the Canadian Entomology Research roundup (the first two posts can be found here and here), we will be sharing more detailed posts from the grad students involved in the published research.

Below is a post from Jessica Ethier, sharing her research experience that spanned an undergraduate and PhD degree.


I just published a paper in Entomologia Experimentalis et Applicata. From start to finish, the work only took a decade.

Ten years ago, in the summer of 2005, I had just finished my first year as an undergraduate student at Concordia University. I had no plans yet for what I would do after graduating; really, I was just glad I’d survived that first year. But across the country, unbeknownst to me, traps were being set, insects were being collected, and by the time I was starting my second year of university here in Montreal, a student at the University of Alberta was busy pulling the wings off a bunch of dead moths.

A horrific sight to innocent insect passers-by.

A horrific sight to innocent insect passers-by.

That student was Kevin Lake. He was doing his undergraduate research project on the effects of population density on wing size and colour in the Malacosoma disstria moth with Maya Evenden and Brad Jones. Fast-forward one year to the fall semester of 2006, and I had now transformed (one might say, metamorphosed) into a seasoned third year undergrad dabbling in research for the very first time. In Emma Despland’s lab, I had a freezer-ful of more dead moths just waiting to be de-winged and studied, and (thanks to Maya and Emma) the protocols Kevin used for wing removal and colour scoring. One thing led to another, and before I knew it, it was 2009 and I had just fast-tracked to a PhD from a Master’s for my research on colour polymorphism and wing melanization in the M. disstria moth.

One of the aims of my graduate research as a whole was to try and figure out why there was always so much individual variation in colour within the genetically-based phenotypes. Emma and I developed an experiment for spring of 2010 to see if limiting dietary protein in the larval stage limited the expression of colour in the adult moth. I even had my very own undergraduate student for the project, Michael Gasse, to rear the insects, process the wings, and collect the colour data. But it wasn’t all rainbows and puppies and pulling wings off dead moths. First we had to get the insects from somewhere.

As luck would have it, there was a forest tent caterpillar outbreak about an hour away from the city that year (for some reason, the landowners – maple syrup producers – were not nearly as gleeful about this infestation of their sugar maple forests as all the members of the Despland lab were). So off we trooped in the middle of February, tree clippers, binoculars, and plastic lunchboxes in hand, to go collect as many egg masses as we could get our mitts on.

You thought the lunchboxes were for lunches? Photo by Alison Loader

You thought the lunchboxes were for lunches? Photo by Alison Loader

Then it was back to school, to spend most of April, May, and June in the sub-basement dungeon lab, slaves to the needs of the exponentially-growing, insatiable eating and pooping machines that we called our experimental subjects.

First instar M. disstria colonies in 30mL hatching cups with artificial diet. Those cups are basically the little plastic shot glasses you see at dollar stores. By the time they reach the final instar, the caterpillars are typically longer than those cups are tall. Photo by Alison Loader.

First instar M. disstria colonies in 30mL hatching cups with artificial diet. Those cups are basically the little plastic shot glasses you see at dollar stores. By the time they reach the final instar, the caterpillars are typically longer than those cups are tall. Photo by Alison Loader.

We all survived another research season, and Mike moved on to wing-pulling and colour scoring a few hundred moths. Time flew by, as time will do, but in 2012 I finally finished and submitted my article on nitrogen availability and wing melanization in the Malacosoma disstria moth!

It was rejected.

Undeterred, I chose another journal and submitted again. And again. And again. After the fourth or fifth rejection, I stopped resubmitting. Not because I was giving up, but because I had to write my thesis and graduate. Once that little matter was taken care of, I went back to my pesky paper. Looking at it with fresh eyes, I realized that the two sections I had divided my paper into just did not complement each other, despite being based on the same experiment. Then I had an epiphany. One of the reasons for forest tent caterpillars to suffer nitrogen limitation in real life is high population density.

And the rest, as they say, is history.

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Editor’s Pick: Resins, exotic woodwasps and how a study species picks a researcher.

by Christopher Buddle, McGill University

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As the Editor-in-Chief of The Canadian Entomologist, I have the pleasure of seeing all papers move through the publication process, from first submission to approval of the final proof.  This places me in a position to fully appreciate the incredible entomological research occurring around the world.  As one way to promote some of the great papers within TCE, I have decided to start a series of blog posts titled « Editor’s Pick » – these are papers that stand out as being high quality research, and research that has broad interest to the entomological community.  I will pick one paper from each issue, and write a short piece to profile the paper.

For the first issue of the current volume (145), I’ve picked the paper by Kathleen Ryan and colleagues, titled « Seasonal occurrence and spatial distribution of resinosis, a symptom of Sirex noctilio (Hymenoptera: Siricidae) injury, on boles of Pinus sylvestris (Pinaceae)« .   Sirex noctilio is a recently introduced species in Canada, and is a woodwasp that we need to pay attention to.   As Kathleen writes, « unlike our native species of woodwasps, it attacks and kills living pines » and because of this, we must strive to find effective ways to monitor the species.  One potential approach is to look for signs of resinosis, or ‘excessive’ outflow of tree sap and resins from conifers.  The goal of this work was to specifically assess « the spatial and temporal distribution of resin symptoms of attack to optimise sampling« .  The work involved Kathleen spending a LOT of time in the field, observing evidence of damage to trees, and assessing timing of resinosis relative to other damage to pine trees as related to woodwasps.  In the end, Kathleen was able to confirm that in most infested trees, the appearance of resin was a meaningful detection method.  This is a very practical paper, and very useful towards finding the best methods to detect this exotic species.

Sirex noctilio female - Photo by K. Ryan

Sirex noctilio female – Photo by K. Ryan

I asked Kathleen a few questions about this paper and the context of the work.

Q: Kathleen, what first got you interested in this area of research?

A: I became interested in studying Sirex’s interaction with other subcortical insects. Sirex was recently detected in North America at the time and we didn’t know much about it here including how, where and when to find it  – all of which were essential in planning research about insect interactions. So this study was my starting point – my “getting to know Sirex” study.

Q:  What do you hope will be the lasting impact of this paper?

A: This paper is the result of the many hours of field observations that helped me to become more familiar with Sirex. Since its really basic research, I hope that this paper might be a useful starting point for other people beginning to work with Sirex.

Q:  Where will your next line of research on this topic take you?  

A: Currently, I’m studying another invasive wood-borer, but I’d like to work with Sirex again – it’s a really interesting and unique insect biologically and ecologically. I’m especially interested in studying Sirex community ecology in its native, European, range to see how it compares to North America.

This is truly an important area of study, and I do look forward to seeing more of Kathleen’s papers in TCE.

Finally, I asked Kathleen about any amusing anecdotes about the research, and she shared this wonderful story with me:

The first day we worked together, my PhD advisor Peter de Groot, dropped me off at a forest site with instructions to only observe and collect absolutely no data. I had been in the forest for only a few moments, when a female Sirex landed right in front of me. So being an entomologist, naturally I caught her. A couple of hours later, still holding her, I met back up with Peter and sheepishly admitted that I had caught some “data”. Thinking it fantastic, from that point forward he told everyone that Sirex had picked me as her project.

Looking for wood wasps - Photo by K. Ryan

Looking for woodwasps – Photo by K. Ryan

I believe that these kinds of stories behind the research make Entomology more accessible and real, and help us appreciate the human element of scientific research.

As a final note, the entomological community was very saddened by Peter de Groot’s death in 2010.  His legacy to Canadian Entomology is still very strong.

A special thanks to Kathleen for answering a few questions, and sharing insights into the first ‘Editor’s pick’ for The Canadian Entomologist

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Reference:  Ryan, K, P. de Groot, S.M. Smith and J. J. Turgeon.  Seasonal occurrence and spatial distribution of resinosis, a symptom of Sirex noctilio (Hymenoptera: Siricidae) injury on boles of Pinus sylvestris (Pinaceae). The Canadian Entomologist 145: 117-122. Link.

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The trouble with common names

By Dr. Staffan Lindgren, University of Northern British Columbia

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When teaching Invertebrate zoology, entomology or forest entomology, I am regularly asked by students if they can use common names. Mostly this request is precipitated by the perceived difficulty of memorizing, let alone pronouncing, Latin names. I am fairly relaxed about these things, particularly with forestry students, who are quite unlikely to become entomologists no matter how you define that term.  It should be clarified that forest entomology is taught within a Disturbance Ecology and Forest Health course at my institution (UNBC), with diagnostics in half of a separate lab course. My stock answer is thus that they may use common names as long as the name clearly defines the species they are referring to.

Foresters are prone to colloquial terms, whether with respect to insects, trees or other organisms. For example, subalpine fir (Abies lasiocarpa) is called balsam by many, if not most foresters in BC, even though it is a distinct species from balsam fir (Abies balsamea) of eastern North America. Similarly, Pissodes strobi, the white pine weevil, is called spruce weevil (a legacy of the days when this weevil was considered three separate species, two of which primarily infest different spruce species in the west) or simply leader weevil.  The reason, supposedly, is that it is the wood quality that matters in terms of trees, and the type of damage with respect to insects. The consequences of being a bit loose with the taxonomy of a particular species may therefore seem fairly inconsequential in forestry.

Incidentally, our forestry students have even more to worry about when it comes to pathology, which they have to learn at the same time, as the same biological organism often has two completely different Latin names (including genera) depending on whether it is the sexual or asexual form (why this remains an accepted practice is beyond me), and they often do not have common names. Add the fact that fungal species seem to change name more often than I change vehicles (I was going to write ‘shirt’, but didn’t want to gross anyone out making you think that I wear the same shirt for years), and it becomes rather a nightmarish proposition for the poor students.

When it comes to entomology in general, however, common names are most commonly used in casual conversation, particularly with members of the public. For entomologists this is usually not a problem, but for non-entomologists it can be very confusing.  For example, colloquial use of ‘bug’ is pretty much anything that is small and crawls or flies around. Taxonomically it is quite specific (Hemiptera: Heteroptera). Ladybugs (Coleoptera: Coccinellidae) are perhaps the most recognizable insects to people in general, but they are clearly not bugs. Plant lice (Aphidoidea and Phylloxeroidea), bark lice (Psocoptera) and body lice (Phthiraptera) represent three vastly different taxonomic groups. In addition, if the non-louse groups above were to be correctly written to show that they are not Phthirapterans, there should be no space – however for these common names that principle is never applied as far as I can tell. It is to differentiate dragonflies, damselflies, stoneflies, mayflies, whiteflies etc. from the true flies. For example, a dragon fly, if there were such a thing (and probably there is somewhere – perhaps a decapitating fly (Phoridae) comes close enough to earn that epithet!) would be a dipteran, whereas a dragonfly is not. How is a non-entomologist supposed to know that (assuming that it is important to anyone except us entomophiles)? Then we can go on to more obvious misnomers such as ‘white ants’, which aren’t ants (Hymenoptera: Formicidae) at all, but termites (Isoptera).

Going back to forest entomology, one can have all kinds of fun with some common names, the origin of some could serve as fodder for endless speculation. For example, when discussing the problems with common names, I ask my students what they think a sequoia pitch moth (Synanthedon sequoiae)(Lepidoptera: Sesiidae) would attack. The correct answer is naturally “mostly lodgepole pine, but not sequoia”. Similarly, the Douglas-fir pitch moth (Synanthedon novaroensis) commonly breeds in lodgepole pine, but as far as I know not in Douglas-fir. I then go on to western spruce budworm, which as the name does not imply primarily attacks Douglas-fir.

Myrmica brevispinosa, the short-spined ant

Myrmica brevispinosa, the short-spined ant

Clearly one cannot expect members of the public to keep track of Latin names of insects, so common names are here to stay. I was interested to find in a book I recently purchased (Ellison et al. 2012) that the authors had invented common names for every species by essentially translating the Latin species epithet. That creates an interesting situation vis-à-vis the attempt of entomological societies to standardize common names (http://www.esc-sec.ca/ee/index.php/cndb; http://www.entsoc.org/common-names). Nevertheless, some ants simply retained their genus name, e.g., Harpagoxenus canadenis became “The Canadian Harpagoxenus” (not sure why, as they named the genus “The robber guest ants”), Formica hewitti became “Hewitt’s ant”,  Myrmica brevispinosa (the species in the photo accompanying this article) is called “The short-spined ant”, and perhaps my favourite Lasius subglaber was named “The somewhat hairy fuzzy ant”. Common names aren’t generally that innovative, but Latin names certainly can be.

Many years ago May Berenbaum (1993) wrote a column on this topic. If students would all read Dr. Berenbaum’s eminently humorous take on how insects get named, they would without a doubt get a new appreciation for both Latin names and their creators, and perhaps feel less trepidation about memorizing them. Then not only true blue entomologists would be tempted to buy a bumper sticker that read “Sona si Latine loqueris” (Honk if you speak Latin) (Unverified from http://www.latinsayings.info/).

Berenbaum, M. 1993. “Apis, Apis, Bobapis….”, American Entomologist 39: 133-134.

Ellison, A.M., N.J. Gotelli, E.J. Farnsworth, and G.D. Alpert. 2012. A field guide to the ants of New England. Yale University Press, New Haven and London, 398 pp.