Category Archives: Laboratory News

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It’s a wrap! How about a thesis on Arctic spiders? How about two of them…?

This week I am thrilled to report that two of my MSc students have successfully completed their degrees! Both the projects are part of the collaborative Northern Biodiversity Program – a project aimed to quantify and understand ecological change with Arthropods from Canada’s north.

A BIG congratulations to Sarah Loboda and Katie Sim  - they are both tremendously talented students, excellent Arachnologists, and wonderful people to know.  Last night we had our annual Lab BBQ – and at that event, I was pleased to give Sarah and Katie a small token of appreciation.  Here’s a photo showing them both with their wolf spider photographs (photos by the incredible Thomas Shahan):

Katie Sim (l) and Sarah Loboda (r) - successful MSc students!

Katie Sim (left) and Sarah Loboda (right) – successful (& happy) MSc students!

Sarah Loboda’s thesis is titled Multi-scale patterns of ground-dwelling spider (Araneae) diversity in northern Canada. Her research focused on broad diversity patterns of ground-dwelling spiders collected from our 12 study sites, spread across Canada’s north. Our project spanned 30 degrees of latitude and 80 degrees of longitude –> yes that is a lot of land area! Sarah identified over 300 spider species from 14 families, and over 23,000 individuals.  Publications are forthcoming so I won’t give details here, except to say that we can learn a lot about diversity patterns over broad spatial scales using a study taxon such as spiders.

Here's where the Northern Biodiversity Program took our field teams!

Here’s where the Northern Biodiversity Program took our field teams.

Katie’s work (co-supervised by Prof. Terry Wheeler) had a different slant, but was still on Arctic spiders. Her thesis is titled:  Genetic analysis of Pardosa wolf spiders (Araneae: Lycosidae) across the northern Nearctic. The first part of Katie’s thesis was about understanding the phylogeographic history of the Arctic spider Pardosa glacialis, with particular attention to post-glacial dispersal patterns, as inferred by population genetics. The second part of her thesis was focused on whether or not there is enough evidence to suggest two northern Pardosa species should remain as separate species, or be merged into one – based on both molecular and morphological characters.  Let’s just say that Katie had to be a ‘field genius‘, ‘lab genius‘ and ‘spider genitalia genius‘.  Here’s an example of what she looked at, a lot:

The epigynum of a wolf spider species, (part of) the topic of Katie's research.

The epigynum of a wolf spider species, (part of) the topic of Katie’s research.

In sum, I am thrilled to see Sarah and Katie finish up their work, although their success also comes with a touch of sadness, as I will miss their daily presence in the laboratory.  Stay tuned… we shall soon report all the details from their research.

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An indoor field trip: visiting Canada’s national spider collection

Last week I traveled up to Ottawa with two of my students – our goal was to visit the Arachnid collection at the Canadian National Collection of Insects (CNCI) (and Arachnids and Nematodes). The spider collection is housed on the fourth floor of the Neatby building, in a room that seldom has its lights turned on.  Canada’s National Spider collection has been without a curator since the 1990s, when Dr. Charles Dondale retired. In fact, his name is still on the door.

Dr. Dondale

The spider collection has historically been one of the finest, world-wide. It contains numerous type specimens, and houses thousands upon thousands of vials, all within stand-up cabinets. These vials contain rich biological information – they contain a spider with a species name, where it was found, who collected it, and when. These kinds of museum data are absolutely vital as we try to understand our biodiversity, and how it might be changing in the face of environmental stresses. Museum data form the basis of taxonomic revisions, and museum specimens (identified to species, by experts) are an important way for someone to learn taxonomy (that is how I did it!).

Our goal in the spider collection was to data-base some specimens – this means taking what is written on (old) labels, and entering data into a data-base (one that will eventually go on-line). On this trip, we were looking for some records of purse-web spiders in North America, and for northern black widow spider records. We also worked to database the jumping spiders (Salticidae), with a particular focus on those species occurring in Canada.

The task of data-basing.

The task of data-basing.

You might wonder why we would take time away from our own (busy) laboratory in Montreal to drive up to Ottawa to enter data; surely there are better uses of that precious resource of time (and money)?  Nope: A visit to the CNCI is always worth it.  Here’s why:

1. Label data are useful data! I have quite a few projects ongoing this summer, including a better understanding of the distribution of jumping spiders in Quebec. There’s no better way to find certain species than going to where they have been found before.  How do you know where they have been found before? Although much can be gleaned from publications, there are hundreds of specimens that have been collected and stored at the CNCI, but whose data has never been used in a publication. Looking at vials and reading labels is a good place to start, and while doing this, it only makes sense to enter the information into a data-base. It’s not exciting work, but having data digitally accessible allows my own research interests to move forward more effectively.

Treasures in the cabinet.

Treasures in the cabinet.

2. I’m an Arachnologist in Canada, and as such, I feel a responsibility to use the collection in Ottawa. The spider room at the CNCI is where (historically) Canada become a global leader in spider taxonomy. Charlie Dondale and others (notably James Redner) wrote some of the most important papers and books about spiders in North America, and their (free!) books remain a critical resource for Arachnologists throughout North America.  The hallowed grounds of the spider room are where much of this work occurred. It’s a special place, and one that is worth visiting.

3. If you don’t use it, you’ll lose it. The future is not bright for this spider collection. Surprisingly, a replacement for Charlie has not be hired. We need an Arachnologist in Ottawa (I’ve written about this before). I worry deeply for this collection, and even a few visits per year are better than none at all – it shows there is still broader interest in the spider collection, and that it remains an important resource for people from other regions of Canada. Showing continual use and interest in the collection is a great way to show its value.

4. If it’s lost, let’s hope the data are not. Time for thinking about ‘worst case scenarios‘:  every time I am at the CNCI I see evidence of further degradation of the spider collection. Spiders are stored in ethanol, long-term, and without  curation the ethanol degrades, discolours, the specimens get brittle or break apart, the labels fade or become unreadable, or perhaps a vial or two break.  The spider collection has not receive high consistent curation for a very long time. At the very least, we better have the data from those specimens, and that requires data-basing.

Trouble in the collection: A vial with a cracked glass lip.

Trouble in the collection: A vial with a cracked glass lip.

In sum, the spider room at the CNCI is a national treasure and it was really great to be there. We didn’t get much done (only about a hundred specimens databased – and, truthfully, I did very little of the hard work – my students did all the heavy lifting).  But it was a start, and means that we’ll need to come back. I sincerely look forward to the next visit!

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Seasonality of Arctic Beetles

I’m excited to report on paper written by Crystal Ernst, PhD student in my lab, and well known as the “Bug Geek“. This paper is a product of the Northern Biodiversity Program (yes, it sure is great that the papers from this project are starting to appear!), and will be one of Crystal’s PhD thesis chapters. The paper is titled Seasonal patterns in the structure of epigeic beetle (Coleoptera) assemblages in two subarctic habitats in Nunavut, Canada

A very nice Arctic beetle! (photo by C. Ernst, reproduced here with permission)

A very nice Arctic beetle! (photo by C. Ernst, reproduced here with permission)

Here’s a plain-language summary of the work:

Although we often think of Arctic systems as cold and lifeless, Canada’s tundra habitats are home to a high diversity of arthropods (insects, spiders and their relatives). Beetles are important insects on the tundra – filling ecological roles as predators (feeding on other insects), herbivores (feeding on plants), mycophages (feeding on fungi), and necrophages (feeding on dead or decaying animals). In this research, we wanted to find out what happens to ground-dwelling Arctic beetles as a function of seasonality. We were curious about whether different species occurred at different times during the short Arctic summer, and whether the functions of the beetles changes over the summer. This is an important area of study because beetles perform important ecological functions, and knowing how these functions change over time may have broader implications for northern ecosystems. This is especially relevant in the Arctic since these systems have a short ‘active season’, and climate change is disproportionally affecting northern latitudes. If climate change alters an already short summer, what might happen to the beetles?

This research was done as part of the Northern Biodiversity Program (NBP) – a broad, integrative project about the diversity of insects and spiders across northern Canada. The NBP involved collecting samples at 12 sites in the Arctic, but at one of these sites (Kugluktuk, in Nunavut) we had an opportunity to do a more detailed collection over the entire summer of 2010. This involved setting out traps for the entire active season, from June through to August. These traps were plastic containers sunk into the ground – beetles that wander along the tundra fall unawares into these traps, which contain preservatives, and are trapped until a researcher collects the samples. Traps were placed in wet and (relatively) dry habitats so that we could compare the two habitats. After the collections were returned to our laboratory, the beetles were identified to species, counted, and the biomass of the beetles was estimated – biomass lets us determine what happens to the ‘amount of beetles’ on the tundra in addition to figuring out ‘how many’ (abundance) and ‘what kind’ (species) were in the traps. The beetles were also classified into their key ecological roles. The data were then compared as a function of when traps were serviced to let us assess what happens to beetles as a function of seasonality.

We collected over 2500 beetles, representing 50 different species – remarkably, 17 of these species represented new Territorial records. This means that 17 of the species that were identified had never before been recorded in all of Nunavut! Although many ecological functions were represented by the beetles we collected, most were predators. We documented that wet habitats had different kinds of beetle species than the drier tundra habitats, even though the actual number of species between the habitats did not differ. We also uncovered a seasonal affect on the functions of beetles in the system – as the season progressed, the beetles tended to be represented more by predators compared to earlier in the season, which was dominated by beetles representing a diversity of functions. The mean daily temperature also related to the seasonal change that was observed in the beetles.

PhD student Crystal Ernst, happily working on the Arctic tundra.

PhD student Crystal Ernst, happily working on the Arctic tundra.

This work is one of the first to carefully quantify how beetles change during short Arctic summers. We found a diverse assemblage of beetles, filling a range of ecological roles. These ecological roles, however, do not stay the same all summer long, and the shifts in the beetles were related to mean daily temperature. Given that Arctic systems will be significantly affected by climate change, this is worrisome – if temperatures increase, or become more variable, this may affect ecosystem functions that are mediated by beetles. This is more evidence supporting the need to track climate change in the Arctic, and play close attention to the small animals of the tundra.

Reference:

Ernst, C., & Buddle, C. (2013). Seasonal patterns in the structure of epigeic beetle (Coleoptera) assemblages in two subarctic habitats in Nunavut, Canada The Canadian Entomologist, 145 (02), 171-183 DOI: 10.4039/tce.2012.111

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Assessing five decades of change in a high Arctic parasitoid community

As my colleague Terry Wheeler mentioned on his blog, our Northern Biodiversity Program team is thrilled to see post-doc Laura Timms‘s paper about Arctic parasitoid wasps published in Ecography!  Our team worked on Ellesmere Island, Nunavut, in 2010, and compared parasitoid wasps to historical collections from the same site that were made in 1961-65, 1980-82, and 1989-92. Parasitoid wasps are at the top of the insect food chain: they lay eggs inside or on top of other arthropods and the wasp larvae emerge after consuming their hosts – a gruesome but very common lifestyle for many types of wasps.  Species at higher trophic levels, such as these parasitoid wasps, are often the first to respond to new environmental pressures, including the climate change that is occurring rapidly in Arctic systems.

Laura identified a LOT of wasps, recorded the type of host attacked (e.g. plant-feeding hosts versus hosts that are predators), and the body size of two species of wasps that were commonly collected in all time periods.  We found no clear pattern of change in most aspects of the parasitoid wasp community on Ellesmere Island over past 50 years, even though temperature and precipitation have increased significantly during the same period. However, there were some signs that parasitoids of plant-feeding insects may be more affected more than other groups: one common parasitoid species that was abundant in 1960s hasn’t been collected since then, and the community in the 2010 study contained fewer parasitoids of plant-feeding insects than previous studies.

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Some members of the Northern Biodiversity Program working in the Yukon in 2012. (l-r, Chris Buddle, Laura Timms, Crystal Ernst and Katie Sim)

Laura takes it as a good sign that no major changes in the ecology of the high Arctic parasitoid community have been observed, but isn’t taking it for granted that the community will remain unaffected for long.  At 82°N, Ellesmere Island is relatively isolated, but other research has found that parasitoid communities further south are changing dramatically (Fernandez-Triana et al 2011).

Laura has the following comment about our work: “We hope that our findings will be used as baseline data for ongoing monitoring on Ellesmere Island”, said Timms.  “We know so little about these high Arctic insect communities, we should learn as much as possible about them while they are still intact.”

References

Timms, L., Bennett, A., Buddle, C., & Wheeler, T. (2013). Assessing five decades of change in a high Arctic parasitoid community Ecography DOI: 10.1111/j.1600-0587.2012.00278.x

Fernandez-Triana, J., Smith, M., Boudreault, C., Goulet, H., Hebert, P., Smith, A., & Roughley, R. (2011). A Poorly Known High-Latitude Parasitoid Wasp Community: Unexpected Diversity and Dramatic Changes through Time PLoS ONE, 6 (8) DOI: 10.1371/journal.pone.0023719

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WANTED: graduate students

Interested in arthropod ecology?

Interested in graduate school?

I’m seeking at least two graduate students.  One, at the MSc level, on a project related to pollinator diversity within an agroecology context.  This is a Quebec-based project, and bilingualism would be required. The second, at the PhD level, will be about Arctic arthropod biodiversity with a particular focus on temporal changes in community structure. The Arctic project will involve a combination of field and laboratory work, and will in part deal with historical specimens. Both projects will require a student with interests in both taxonomy and ecology.  In other words, significant time at a microscope as well as time doing quantitative ecology.  Start dates are negotiable, but there is potential for field work to commence in May/June 2013.  Required skills include excellent communication skills, ability to work in a large, dynamic laboratory, passion for arthropod ecology, and abilities/interest in quantitative ecology.  Experience in Entomology and/or Arachnology would be an asset.

Please do your homework:  read my blog, and do research about my research; try to assess if you think you’ll be a good fit within my laboratory group.

Interested candidates should e-mail me with a brief (<200 words) statement of interest, a brief (<200 words) statement that outlines relevant experience and skills, and a brief sentence or two about your expectations in the context of graduate school at McGill University.  Please submit these to me before the end of January 2013.

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Resolutions: from blogs to birds

Happy New Year!

End-of-year posts tend to be focused on reflections on the past year - now it is time to look forward and make some resolutions.  From a personal perspective, I’m not a big fan of New Year’s resolutions.  I’ll try to floss my teeth, exercise, and eat my veggies.  However, I will forget about these or feel guilty and annoyed by the time February hits.  I wonder if perhaps I can stick to my professional resolutions?  Will it help if I wrote a post about these and make them very public? Why not give it a try

… here are six resolutions:

1.  Keep blogging.  I think this will be an easy one to keep – I achieved 75 posts last year and I’ll work to equal or better that.  I’m motivated to write more posts: it’s fun, and provides immense value.   I thought that perhaps blogging would get tiresome and I would run out of ideas.  This is not the case.  I have a lot of ideas, and will soon write about spider parasitoids (including this one), share some videos related to field work from last summer, discuss the pros and cons of comprehensive exams in PhD programs, and discuss uses of technology in teaching (or not…back to chalk?).  I’ll also work to follow good advice for writing science posts.

2.  Finish the Opiliones Project.  For new followers, this was a project that uses twitter to share the information from a fabulous (but expensive) textbook about Harvestmen – fascinating cousins of spiders.  The project is about 3/4 of the way finished.  I will do my best to find a bit of time to wrap this up, archive it, and write a summary post… before winter’s end!

An Opiliones from Panama (with mites, too!)

An Opiliones from Panama (with mites, too!)

3.  Back to the Microscope.  It’s seldom I can find the time to use that magical tool – you know, that thing that you look into and it makes stuff big?  I really am going to try to rediscover my love of Arachnid taxonomy.  I’m thinking of starting with jumping spiders, and would like to work on a larger project about the local jumping spider fauna.

4. Manuscripts!  Quite a few of my graduate students will be finishing up this year – the Northern Biodiversity Program is coming to a close, and I hope to get manuscripts submitted for publication.  The work is very exciting, and that project has really been a catalyst of change – and the bulk of my research next year will have an Arctic focus.  However, I don’t feel a project is fully completed until all the manuscripts are submitted.

5. Get control of email.  I must be honest: this is the resolution that will be really tough to keep. E-mail is just so overwhelming, and I do a poor job of organizing it.  Typically I don’t delete anything, wait a few month and dump everything into an archive folder and rely on my email search function (or my memory – yikes!) to find things.  That system is not efficient and I frequently miss important tasks due to my lack of control over email.  I will try be more efficient, and hopefully more productive, by clearing and deleting unnecessary e-mail clutter daily (yeah, right.) –>Does anyone have good suggestions for managing e-mail??

#2013Birds - the beginning.

#2013Birds – the beginning.

6.  Become a (better) birder. This resolution reflects the fact that the line between my professional life and my personal life is pretty blurry.  I wish to be more knowledgable about birds because they are part of earth’s rich fabric that we call biodiversity and my research interests are about biodiversity.  I also think that birds are lovely and fun to watch.  Every year I try to be a better birder but it seems to fizzle out my mid-year.  This year will be different because I will give myself a goal.  I am quite obsessed with list-making, and by tracking all the bird species I see in a year provides me an opportunity to make another list, and will hopefully help me become a better birder.  Want to join the fun?  With twitter, use the hashtag #2013Birds.  I think I will also experiment with i-naturalist to track the species count. So far this year?  Blue jays, Chipping sparrows American tree sparrow, Black-eyed Juncos, American crows, and black-capped Chickadees (most of these in my own backyard).

Wish me luck!  (I’ll keep you posted about successes and failures!)

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Taxonomic sufficiency in biodiversity research: Is it always necessary to identify species?

It’s been a successful few weeks in the lab!  Two weeks ago I promoted an exciting paper about spider silk and herbivory and just after that paper come out, another publication from our lab was published, titled: “Does species-level resolution matter? Taxonomic sufficiency in terrestrial arthropod biodiversity studies“.  This paper evolved out of a past graduate-level class in Forest Entomology at McGill, and was re-worked and re-written by post-doc Laura Timms, former Phd student Joseph Bowden, and my colleague Keith Summerville.

Let me provide a plain language summary of this work and I will also touch upon some of the controversy that has arisen because of this paper:

Biodiversity science is about the discovery and description of all the different kinds (species) of organisms living on our planet.  It is a vitally important area of research because different species play important roles in our ecosystems, and as a consequence, are important to us.  The different number of species in an area can also inform us about how we might be harming or helping ecosystems.  This is an active area of study in the context of forestry, since some forest practices (for example, cutting all the trees down in an area) can cause changes in the number of species (and whether they are rare or common) and these changes can inform us about whether our forestry practices are harming our ecosystems.  All of this kind of work, however, depends on the ability of scientists to collect, sort, and identify different kinds of species.  Since most described species on the planet are Arthropods (e.g., spiders, insects, and their relatives), these animals are often used as a way to indicate how biodiversity might be affected by environmental change.  However, there is a problem: it takes a very long time to identify different arthropods, and it is costly and difficult – requiring highly specialized training, by people known as taxonomists.  In our research project, we asked whether not you always need to know the exact differences between insects and spiders  in order to tell if a disturbance is affecting biodiversity.  We did this by looking at a series of data-sets about beetles (Coleoptera), moths & butterflies (Lepidoptera), and spiders (Araneae). These data-sets were from past research projects about how forest disturbance affects biodiversity.

Here is how we did the work: Different kinds of organisms are classified using a two-part name:  the genus and the species.  There can be many different species within one genus.  You can then classify different genera (the plural of genus) into grouping called Families.  For example, all wolf spiders are in the Family Lycosidae.  A common genus within this family is Pardosa – there are dozens of species of Pardosa in Canada; Pardosa mackenziana, Pardosa moesta, Pardosa hyperborea, etc.  We first took our big data-sets and using the lowest level of naming (the species) we asked whether forest disturbance affected biodiversity.  We then grouped all our species into their respective genera -this meant that the data-sets got smaller (i.e., there are necessarily fewer genera than species).  We did the same analysis to see if we could still get a signal about the effects of disturbance on biodiversity, but now with the ‘reduced’ data.  We did this again at the family level.  We did this because we wanted to know if you could take a short-cut. Stated another way, if you don’t have the time or ability to figure out all the species in your research project, can you still see if there is an effect of forestry on biodiversity?

A wolf spider (Lycosidae)

A wolf spider – do you need to know its name?

Our results showed that in most cases, you do not need to know the species identity to see the effects of forestry practices on the biodiversity of spiders, beetles and moths & butterflies – you do not get as clear answers when things were grouped into Families, but the datasets with species grouped into genera were almost as good as when you group things into species.  This was surprising, because an assumption in biodiversity science is that species-level identifications are necessary and should be the ‘gold standard’ for this kind of research.  We showed that in many cases, you can get your answer by identifying arthropods to the generic level:  this can save you a lot of time (and money).   Some researchers (including taxonomists) may not be thrilled with this result as it might suggest that species are not important, and specialized taxonomic knowledge is not essential to complete biodiversity research.  This is certainly not the case, which leads me to the caveats:

1) Our results do not mean species are not important!  Instead, we are saying that if there are logistical and financial constraints, you might be able to answer your research question without having to identify all the species.   If you have a project about large-scale disturbance and are looking to see whether there are any broad affects on biodiversity, our approach might work.   However, you might miss some subtle effects, so this approach must be taken with caution.  Although our suggestion is a short-cut, it would still be important to save all the samples, and at a later time (as money and expertise permits) the species could be determined.

2) Our study is specifically geared towards research about insects and spiders in relation to large-scale forestry disturbances.  We are not saying that this will work in all situations and with all different kinds of organisms! The context is important.  Related to this, if an overarching research question is about species in an ecosystem, species-level identifications are essential.  Everything depends on the research question and the research context.

3) This general approach that we have discussed is highly dependent on what kind of organisms you are studying.  If you are working with a group of organisms that do not have too many different species within a genus, our approach may work.  If, however, there are many species within a single genus, our suggestion will not work as well.  Therefore, a researcher should look at the general relationship between the number of species per genus for their study organisms and use this ratio as a guide when thinking about taking the short-cut that we discussed in the research.

In sum, we are quite excited about this research – we think it will provide more opportunities for biodiversity projects to get done, and will help answer certain research questions when there are substantial constraints on time and money.  This is one way to be pragmatic about biodiversity research.

Please share your thoughts!

Reference:

Timms, L., Bowden, J., Summerville, K., & Buddle, C. (2012). Does species-level resolution matter? Taxonomic sufficiency in terrestrial arthropod biodiversity studies Insect Conservation and Diversity DOI: 10.1111/icad.12004

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Fear factor: spider silk reduces plant damage

Today I am excited to report on research published with Ann Rypstra, a most wonderful person and exceptional spider ecologist.  Here’s the take home message from our paper, titled  ”Spider silk reduces insect herbivory” (Rypstra & Buddle 2013):

In the presence of spider silk, insect herbivores eat less plant material  - and the spider doesn’t have to be around to see this effect!

A spider’s web, made with silk. Photo courtesy of M. Larrivee (reproduced here, with permission)

Here’s a plain-language summary of the research:

Spiders are important in agricultural systems because they eat many insect pests that in turn eat valuable crops.  Spiders also leave behind silk as they move through an agricultural field – sometimes this silk is there because it was part of a web that was constructed to catch prey, or sometimes spiders leave silk in the form of a ‘drag-line’ – a kind of silk that acts as a safety-line for a spider.  Whatever the means, the agricultural landscape contains plants, their insect pests, spiders and spider silk.  In this work, we wondered whether  silk, in the absence of a spider, would still cause the insect pests to be wary, and feed differently than if there was no spider silk in their environment.  

We used laboratory and field-based experiments for this research, and we used two pest species – the Japanese beetle and the Mexican bean beetle.  These pests were allowed to eat either leaflets or whole plants of bush-style snap beans.  The plants or leaflets were either left alone, or were adorned with five strands of spider silk or with five strands of silkworm silk.  We included the silkworm silk (i.e, produced from the silkworm moth) because we were curious about whether the beetles might respond to ANY silk instead of silk produced specifically by spiders.  To extract the spider silk, we allowed a long-jawed orb-web spider to hang from its drag-line, and we wound its silk around a stick as the spider bobbed up and down – in this way we could get enough silk for the experiments. We found that when spider silk was on the plants, the insects inflicted less damage compared to when there was no silk.  The silkworm silk also caused the insects to feed less, but the effect with silkworm silk was less than with spider silk.  We also wondered whether this response could just be because the silk got in the way of the beetles, and so we did some experiments with human hair, and a strand of kevlar – these are both ‘silk-like’ strands but since they did not come from an insect or spider, would only represent the physical nature of the silk rather than have any other chemicals or smells from the silk produced by a insect or spider.  This additional experiment showed us the same results: the insect pests still ate less when on plants containing silkworm silk or spider silk compared to those with the kevlar or human hair.  

All these experiments, combined, tell us that there is something very special about spider silk, and it causes pest insects to eat less plants.  In ecology this is dubbed an ‘indirect’ effect – the spiders do not have to eat a pest insect to cause it to change its behaviour! It is also called a ‘non-consumptive effect’ – meaning the effect of the spider on its prey is not through the act of eating the prey, but rather by changing prey behaviour by other means.  This work is fascinating because it shows that spiders have a much more important role in agricultural systems than we realized before: spiders do not have to be present to cause insects pests to eat less – as long as they were there, and produced silk as they moved through their environment, their potential prey will live in a ‘landscape of fear’.  Or, the insect pest is living in fear of spiders because of their silk. 

Here is a more technical summary, placed within a broader ecological context:

Tetragnatha – a long-jawed orb-web spider. Photo by Lee Jaszlics, reproduced here with permission

The pest insects (the beetles) in our study system recognize the silk is coming from a potential predator (the spider), and this means they alter their behaviour, or LIVE IN FEAR!  This work fits within the broader literature about the landscape of fear (e.g. see Laundré et al. 2012), or ecology of fear sensu Brown et al. (1999). The idea here is that prey are shifting their behaviours depending on predators, and so the prey’s overall ‘landscape’ is peaks and valleys related to the strength and type of interactions (direct or indirect) caused by the predator.  To anthropomophize this even more: fear induces behavioural changes in prey; they are scared and this fear has real and measurable effects.

Although a lot of this kind of research is with vertebrates, there are some interesting examples from the arthropod world.  One recent example is by Hawlena et al. (2012) – in this work, grasshoppers that were raised in an environment of fear (via continual exposure to spiders whose chelicerae were glued shut) had different Carbon:Nitrogen ratio in their bodies relative to controls, and this affected plant litter decomposition.  So, the ‘fear factor’ changed the elemental composition of grasshopper’s bodies and eventually this affected the decomposition process!  In Hlivko & Rypstra’s (2003) work, a leaf-eating beetle, when exposed to a range of cues produced by spiders (this included feces, silk and other chemicals) ate less plant biomass compared to controls, and the strongest effect was from cues of the largest spider.   Within the context of fear – the largest (and presumably the most feared) spider, can elicit a response in its prey which results in an affect on plant biomass.  Our paper is taking this one more level, and focuses on the silk as a key ‘cue’ that induces the behavioural change in the prey.

Our results show that insect pests that feed on plants in agroecosystems may be living in a landscape of fear that is brought on by one of the most common substances produced our eight-legged friends…the silk.  This silk acts as an important cue for the insect pests and they eat less plant material because of this.   This research also shows the added value of spiders in agroecosystems; conservation of spiders, or even habitat manipulations to encourage spiders to live in agroecosystems, could have many pay-offs.

The study species in our research: Tetragnatha (photo courtesy of M. Larrivee, reproduced here with permission)

Thanks to Max Larrivee and Lee Jaszlics for permission to use their wonderful photographs!

References:

Brown, J., Laundré, J., Gurung, M., & Laundre, J. (1999). The Ecology of Fear: Optimal Foraging, Game Theory, and Trophic Interactions Journal of Mammalogy, 80 (2) DOI: 10.2307/1383287

Hawlena, D., Strickland, M., Bradford, M., & Schmitz, O. (2012). Fear of Predation Slows Plant-Litter Decomposition Science, 336 (6087), 1434-1438 DOI: 10.1126/science.1220097

Hlivko, J., & Rypstra, A. (2003). Spiders Reduce Herbivory: Nonlethal Effects of Spiders on the Consumption of Soybean Leaves by Beetle Pests Annals of the Entomological Society of America, 96 (6), 914-919 DOI: 10.1603/0013-8746(2003)096[0914:SRHNEO]2.0.CO;2

Laundre, J., Hernandez, L., & Ripple, W. (2010). The Landscape of Fear: Ecological Implications of Being Afraid~!2009-09-09~!2009-11-16~!2010-02-02~! The Open Ecology Journal, 3 (3), 1-7 DOI: 10.2174/1874213001003030001

Rypstra, A., & Buddle, C.M. (2012). Spider silk reduces insect herbivory Biology Letters, 9 (1), 20120948-20120948 DOI: 10.1098/rsbl.2012.0948

ResearchBlogging.org

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Spider cakes!

My graduate students are a very talented bunch – they are intelligent, creative, and have a good sense of humour.  Some of our lab group celebrated birthdays recently, and in honour of this, we had two cakes earlier this week.  The first, made by MSc student Sarah Loboda, is the VERY BEST SPIDER CAKE I have ever seen (or eaten!).  Check this out:

Spider Cake!

Of course, let’s discuss how anatomically correct that cake is!  Two body parts, pedicel, eight legs (coming from the cephalothorax, of course), and a bunch of eyes.

Spider cake! (eyes0

As you may know, most spiders in Canada have eight eyes, but since some do have six, I find it quite acceptable that this spider has six eyes.  Furthermore, not all spider eyes are identical so it is appropriate to have two kinds represented on the cake.  Well done, Sarah.

And in case that STUNNING MASTERPIECE isn’t enough, another student (Dorothy Maguire)  made a cake that is a very good approximation for the female epigynum of wolf spiders in the genus Pardosa.

Pardosa epigynum

And not just any Pardosa:  this is diagnostically similar to one of the species that graduate student Katie Sim is working on!  Incredible!

….want some proof – look at this image, taken from Dondale & Redner’s text on the Lycosidae of Canada.  Enough said.

Pardosa concinna epigynum

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The laboratory mascot is growing older, just like me.

Time marches on.

In my laboratory, I can judge the years by the growth of our lab’s mascot, a Chilean Rose-hair tarantula named “Harriet” (but who also goes by the name of Grillonthosaur).  I was away last week, but when I returned to the laboratory on Monday morning, my students were excited to tell me that Harriet is a little bigger than before I left.  She moulted, and now has a shiny new coat.

Our lab mascot, with her shiny new coat!

The story of Harriet is kind of amazing.  Before Harriet was our laboratory’s mascot, she was the pet of an enthusiastic undergraduate student at McGill.  This student loved entomology, and did a project in my laboratory about four months after I started as a shiny-new tenure-track assistant professor.   When this student left Montreal, she gave Harriet to me since she could not take the spider with her at the time.  That was in the winter of 2003, and Harriet was already several years old then.  Harriet is, therefore at least 13 years old and shows no signs of slowing down.

Harriet’s old ‘skin’.

Harriet has seen a lot of changes, and been a passive observer of quite a few graduate student research projects.  I am also growing older – I just turned 40 this past weekend.  I am pleased to report that I don’t seem to be showing signs of slowing down either.

(by the way, the undergraduate student I referred to left McGill for a MSc in British Columbia followed by a PhD in Australia.  She, like Harriet, is doing very, very well!)