Month: November 2012

Fear factor: spider silk reduces plant damage

/ Chris Buddle / 8 Comments

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

Strategies for teaching a field biology course

/ Chris Buddle / 3 Comments

…Part 2 from a series of posts about the value of field biology courses

I previously wrote about the value of field courses in undergraduate University programs, and promised to follow up with a post focused on the ‘how’. It’s also timely since my field biology course from this term is wrapping up, so it’s a good opportunity to reflect on the past term. It is important to write about some practical strategies for instructing field biology courses because I sometimes hear from my colleagues (and some University administrators) that field biology courses are too expensive, only possible with small class sizes, impractical for introductory classes, and otherwise difficult to successfully integrate into an Academic program. I have been teaching field biology for a number of years, and believe that most of these criticisms are not valid. I hope this post can dispel some myths about field biology courses, and convince more people to offer outdoor experiences and experiential learning as part of University curriculum.

Sampling pond invertebrates, five minutes from campus

1. Think global, act local. Field biology classes do not need to go to exotic locations to be successful. Many people associate field biology with traveling to a Caribbean Island, a rainforest, or the desert - true, these are prime locations for field courses, but it’s not necessary to travel far to teach field biology. Our own backyards are ideal locations to study. In fact, our own backyards are highly relevant to field biology since they are habitats that can be most relevant to our own well-being! A trip to a local agricultural field will firmly implant the importance of food security and the relationship between food production and global food markets. A trip to a urban park can be an opportunity to discuss and learn about introduced species and how they are affecting our local biota (European starlings, anyone?). A trip to a roadside ditch can illustrate how local dispersal plays a role in governing the population dynamics of aquatic macroinvertebrates. All of these concepts can be illustrated by habitats found within walking distances of many University campuses. No flights required.

2. The yellow school bus. Without a doubt, transportation is expensive, and even local trips can be costly. However, it’s important to remember that ALL courses are expensive, and the fees associated with a yellow school bus are analogous to fees for chemicals, glassware and other consumables associated with a wet chemistry laboratory. Unfortunately, my experience has been that Administrators do not see outdoors labs through the same lens as indoor labs. Although indoor ‘lab fees’ are often within Departmental or Faculty budgets, renting buses is often an expense that is not accounted for in the same way. This can be a key reason for the impression that field biology courses are expensive. I urge you to work within your own systems to find a way to make the yellow school bus as important as all other fees associated with delivering any University course. Until this institutional shift is made, you will need to come up with creative solutions to the transportation issue. For example, I often work with my colleagues to find a way to share busses, or do some laboratories within walking distance of our campus. It may also be possible to have students take public transit to a designated field site.

3. Group work! A few years ago I was faced with increased enrolment in my field biology course and this presented a challenge. Suddenly ‘in the field’ lectures and discussions would be impossible (how do you speak to 60 students outside, in a gale-force wind?). Discussing strategies with colleagues was informative, and I learned that many field biology courses were capped to avoid taking too many students outside. I didn’t like this - and I could not cap my course without good reason, especially since my course was a requirement for the program. The solution? Group work and student-led learning! For most of my laboratories, I have designed specific activities that don’t require any formal ‘outdoor lectures’ (which, by the way, are generally useless). Upon getting off a bus, students are often put into groups (sometimes predetermined, sometimes not) and they rotate through different activities. Here are some examples:

(i) In a lab about agroecosystems this term, groups of students walked separately through different field crops at the local horticultural centre, and were asked to observe various aspects of the small-scale agriculture system. The instructor and the TA walked among the groups and took part in the discussions as necessary. The students were asked to ask questions, make observations, and then meet at a designated time to discuss their questions with the head of the horticultural centre.

(ii) In an earlier offering of my course, students were put into groups at a local forest, and were asked to move around to different locations where they were met by instructors or TAs, and at those locations they took part in small activities related to studying biodiversity in the forest - invertebrates at one location, bird calls at another, plant identification at a third, etc.

(iii) I have sometimes sent all groups off to do the same activity (e.g., measuring soil types in a forest or agroecosystem) and then bring the data back to a classroom and their data provided the content for a lecture about variability in nature and bias in observation.

(iv) As a final example, in one laboratory to a wetland conservation area, individual students were asked, ahead of time, to research specific species that we would see while visiting a field site. The students became the experts and they were asked to share their knowledge with their peers (i.e., when they were in groups, in the field). The students became the instructors, and nothing reinforces concepts and content like having to teach it!

….Fundamentally, field biology with a larger class size must embrace the idea of doing group work.

Students, working in groups

4. Bring in the experts. Field biology is complex to teach in part because of nature’s variability and because an instructor cannot be the expert in all things. I use the approach of inviting my colleagues (and graduate students) to take part in (and lead) specific activities related to their own expertise. By in large, I have found my colleagues to be very open to this idea, and provided I do not ask them for help every year, they are most willing to take part. For many of my colleagues who do not teach in field biology courses regularly, this is a nice opportunity to get outdoors and take part in a different style of teaching. It’s also a big advantage to students as they are able to appreciate different teaching styles, and gain a recognition for various levels of expertise by instructors. In fact, this week I am inviting a geologist to take my students on a walk around Mont Royal in Montreal. Understanding the geological foundations to our local ecosystems is only possible in this class because of the generous involvement from my colleague. In sum - a field biology course can be improved by bringing in additional help.

5. Set-up your lab with a lecture: I have found it immensely useful to set up a field biology laboratory with some kind of content in advance of the trip. This allows for ‘setting the stage’ so the unfamiliar can be a little more familiar. To relate this back to my geology field-laboratory, earlier in the term the same colleague came and gave a (indoor) lecture on the geology of the greater Montreal area. The students therefore have had exposure to the topic in advance of the lab, and were asked to do some readings prior to the laboratory. This avoids that problem of tying to deliver lectures outside. Trying to combine experiential learning, in the field, with learning content and concepts, can be difficult. Use an earlier lecture slot as a means to set up the field activities and laboratories. Sometimes this will mean unique scheduling options for your course. For example, I have timetabled my course by doing a one-hour lecture each Tuesday an one four-hour field lab each Thursday - the Tuesday lecture can be used to cover some content and allows me to devote the entire field laboratory to field activities.

Field Biology in the winter - why not?

6. Embrace the unpredictable: Taking students out in a rainstorm, or when it’s -15C, is part of the field biology experience. Nature can be unpredictable, and we need to embrace this instead of shy away from it. In the Montreal area, seasonability is a driving force in all our ecosystems, yet field biology courses tend to be focused in ‘nice weather’ seasons. My colleague Murray Humphries is always telling me that our students must realize that winter ecology is as important as what happens in the summer! He’s right! (Murray, by the way, does take students out on winter trips in his mammalogy course, and they do winter tracking and other activities relate to cold-weather science). We can see and do a lot of field biology in all seasons, and must change the mindset of associating field biology with the warm months. And, as an anecdote, of all the camping trips that I did with my father when I was (much) younger, I remember vividly the ones with rain, sleet, snow and wind storms. Nice weather is boring.

In sum, field biology courses are doable, providing the instructor can be creative and embrace alternative approaches to teaching.

What are your own strategies? Please share…

Plain-language summary of research results: Mites, rotten wood, and forests

/ Chris Buddle / 14 Comments

Last week I wrote a post that outlined a proposal to require plain-language summaries of all research papers. I decided that I would start to do this with my own papers to see how difficult it might be, and also to see if this could help to make the research more accessible to a broad audience.

So… here it goes. This is a summary of paper written with my former MSc student Andrea Dechene, about mites, forests and fallen logs:

Mites are small animals, closely related to ticks and spiders. They are so small that it is very difficult to see them without the help of a magnifying glass or microscope. There are many kinds of mites, and they are found almost everywhere, including forests. Mites are important in forests because they can affect how leaves and rotten wood decompose on the forest floor.

In this research, we studied whether certain kinds of mites were associated with logs that were decomposing on the forest floor, and we did this work in north-western Quebec. We collected mites living in the wood, on the ground near the wood, and on the forest floor about 1 m away from logs. Mites were collected by taking a handful of soil, leaves or rotten wood, putting this in a zip-lock bag, and then the samples were taken to a laboratory. In the lab, these handfuls of soil, leaves and wood were placed on a bench below a light. Mites do not like bright lights and they try to get away by moving away from the light - in this case, they move downward where they think it is safe. The samples are on a screen, however, and the mites fall through the screen and into a jar that contains a liquid that will kill them. These jars are taken to a different lab where the mites are inspected with the help of a microscope. With the help of books and other resources, we could figure out all the different kinds of mites and sort them into their different varieties. Some kinds had names while other ones did not

We discovered 80 different kinds of mites and over 15,000 mites, in total, fell into the jars. That means a lot of mites live in forests! We also discovered that different kinds of mites live in the rotten wood compared to the forest floor and compared to the leaves. We found that the most different kinds of mites actually lived in the leaves that were over top of very, very rotten wood. This is an exciting result because nobody figured this out before, and it means that long after wood decomposes, there are still animals that ‘remember’ the wood was there and are using it as a suitable place to live. Lots of scientists have worked on rotten wood and it is well known that wood is very important for many animals and plants in a forest. Our work is different because we looked at some of the tiny animals in forests and they are also telling us that rotten wood is a good place to live. Next time you see a fallen tree, remember that many kinds of mites depend on that tree and you should leave it where it is.

Mites live here.

Phew.

By the way, here is the actual Abstract from that paper:

The removal of timber during harvesting substantially reduces important invertebrate habitat, most noticeably microhabitats associated with fallen trees. Oribatid mite diversity in downed woody material (DWM) using species-level data has not been well studied. We investigated the influence of decaying logs on the spatial distribution of oribatid mites on the forest floor at the sylviculture et aménagement forestiers écosystémique (SAFE) research station in the Abitibi region in NW Québec. In June 2006, six aspen logs were selected for study, and samples were taken at three distances for each log: directly on top of the log (ON), directly beside the log (ADJ) and at least one metre away from the log and any other fallen wood (AWAY). Samples ON logs consisted of a litter layer sample, an upper wood sample and an inner wood sample. Samples at the ADJ and AWAY distances consisted of litter samples and soil cores. The highest species richness was collected ON logs, and logs harboured a distinct oribatid species composition compared to nearby forest floor. There were species-specific changes in abundance with increasing distance away from DWM, which indicates an influence of DWM in structuring oribatid assemblages on the forest floor. Additionally, each layer (litter, wood and soil) exhibited a unique species composition and hosted a different diversity of oribatid mites. This study further highlights the importance of DWM to forest biodiversity by creating habitat for unique assemblages of oribatid mites.

The Extractor - getting mites from the samples

Thoughts? -I kind of like the plain-language summary.

The plain language summary was not easy to write and it took a lot of words to explain certain things. Despite the challenge, I’m convinced it was a worthwhile use of time. Please consider doing this with your own papers!

Reference:

Dechene, A. and C. M. Buddle. 2010. Decomposing logs increase oribatid mite assemblage diversity in mixedwood boreal forest. Biodiv. Cons. 19: 237-256. http://www.springerlink.com/content/r3681l0185620311/

Science outreach: plain-language summaries for all research papers

/ Chris Buddle / 56 Comments

1) Scientists do really interesting things.

2) Scientists have a responsibility to disseminate their results.

3) Scientists do not publish in an accessible format.

This is a really, really big problem.

Scientific research is largely funded by public money, and it can be argued that scientists have a responsibility to make their work accessible to the public (and scientists are particularly well suited for outreach activities!). The main platform for disseminating research results is the peer-reviewed journal paper and this is not ideal. Let’s be honest - these kinds of publications are often very specialized, full of jargon, and unreadable to most (even other scientists). Many papers are also behind pay-walls, making them even less accessible to people outside of certain institutions.

Earlier this week I attended a scientific conference (the annual meeting of the Entomological Society of Canada) and as part of this conference I was invited to speak in a symposium that was about social media in science. It was a great session and some of my favourite social media mentors were also speaking at the symposium, including Adrian Thysse, macromite, the Bug Geek, and Biodiversity in Focus. As I was preparing that talk the week before, I was also madly finishing a grant application, and in that application I was require to write a plain-language summary of my proposed research. The granting agency uses this ‘summary for public release’ as a way to communicate research to the public. Taxpayers fund the research and they might want to know where their money is going; the granting agency has found one way to communicate this information in a clever and effective manner.

…………………………..Eureka!

Here is the proposal: Every scientific paper published in a peer-reviewed journal must be accompanied by a short, plain-language summary of the work.

This summary would be placed on-line, free for everyone to read. It would be concise, clear, free of jargon, and highlight why the work was done, how it was done, and what was discovered.

Here are some examples of how these plain-language summaries could be used:

1. Media: Media offices at Universities are constantly interested in promoting fantastic work by their Professors. This work, however, is often not accessible and it can be a lengthy process to put together a press release (how easy is it to track down a researcher?). A plain-language summary written by the researcher would be readable, clear, accessible, and an easy way to start the process of promoting research activities occurring at Universities.

2. Blogging: I am a regular blogger, and always happy to promote the research occurring within my laboratory, the laboratories of colleagues, or just discussing interesting scientific papers that I have read. If I had plain-language summaries to access, it would make the process that much easier, and help facilitate timely communication with the public about recently published work. Other science bloggers could also pick up on these summaries for their own writing.

3. Publishers & Editors: As an editor-in-chief for a scientific journal, I sometimes look for ways to promote great papers, and promote the journal to a larger audience. If I was able to peruse the summaries for public release, this would make the process much easier. Publishers could also take text from these summaries, put together a press release or blog post, and also promote research results from their journals based on particularly interesting papers and findings.

4. For Everyone: In my experience, people outside my area of expertise are always keen to hear about research activities. It’s sometimes a challenge for me to explain my research results, and if I was always doing plain-language summaries, this would get easier. The audience for research results can be as big as you can imagine: high school students, friends, family, colleagues, Departmental chairs, graduate students, journalists, libraries, etc… Finally, the Bug Geek has a great post about the challenges of talking science to 10-year olds: it is hard to do, but important. We need practice. These summaries will help.

The procedure for getting plain language summaries could be quite simple. When an author submits the final revisions on a scientific publication, they would be required to write a short plain-language summary. I would like to think that publishers would be willing to incorporate this (simple) step into the on-line systems for manuscript processing, and be willing to post these, as open-access, on their websites, possibly paired with Abstracts. These summaries would not diminish the value of the actual peer-reviewed papers - it would probably help increase readership since these summaries would help people find the work they are actually looking for, and give them a doorway into the scientific literature.

Let’s make this happen.

It will be an effective way to do science outreach.

Please comment, share the idea, and let’s see this idea grow.