May 9, 2013 by Chris Buddle

The case of the missing genitalia: copulation costs for male spiders

This post is written by Chris Buddle (Associate Professor, McGill University). This article was originally published in “The Canadian Arachnologist” – a newsletter about Arachnology in Canada (this newsletter is no longer being published).

Spider sex can be a dangerous and costly venture, the classic example being the (often) misunderstood act of sexual cannibalism (e.g., the black widow spider). However, many of the costs for males are not always so obvious: during copulation, the emboli of some male spiders may break off, which results in the male being unable to properly re-fill his palpal organ and mate again (Foelix 1996). Without this ability, the male’s future is essentially an early retirement. While sorting and identifying spiders for my dissertation research, I noticed that male Cybaeopsis euopla (a ‘hackledmesh’ weaver spider) seemed to frequently be missing one or both of their pedipalps. Could this be another example of a copulation cost?

Looking to the literature, missing pedipalps are documented with some species – tiny males from the sexually dimorphic genus Tidarren (Theridiidae) will remove their own palps and this increases their running speed considerably (Ramos et al. 2004). Working with the same genus, Knofach and van Harten (2001) observed that females remove one of the male’s palps ‘after achieving genitalia coupling’. The female then proceeds to eat the male, while the detached palp acts as both a mating plug and continues to inseminate the female! Something similar happens with the species Nephilengys malabarensis and this fascinating biology was reported by science bloggers such as Ed Yong. In the wolf spider (Lycosidae) Pardosa milvina, frequent palpal losses were observed and effects on courtship and mating were studied by Lynam et al. (2006). Perhaps not surprisingly, these authors report that ‘intact males were less likely to be cannibalized and suffered fewer predatory attacks by females than autotomized males’.

With that background, I began counting the frequency of missing pedipalps for a sub-sample of the specimens of C. euopla. The objective was to assess the percentage of males were missing right, left, or both pedipalps and see if this related to phenology or other life-history events.

The samples came from a mixed-wood forest at the George Lake Field Station, located about 75 km NW of Edmonton, Alberta. This mature mixed-wood forest is dominated by trembling aspen and balsam poplar. Samples were collected using standard pitfall traps, and were part of several other projects on spider assemblages in mixed-wood boreal forests (e.g., see Buddle 2001).

Cybaeopsis euopla – lovely little spiders! (Photo by C. Buddle)

Cybaeopis euopla (Amaurobiidae) (formerly Callioplus euoplus) is widespread in Canada, ranging from the Maritimes to the far north-west (Leech 1972). Males are about 3.5 to 5 mm in length, and are pale orange to light brown in colour. Specimens are typically collected from the leaf-litter of closed-canopy deciduous forests (Leech 1972; Buddle et al. 2000). From a sample of 653 male C. euopla, I found a total of 309 (or 47%) to be missing either one or both pedipalps. This is an impressive number, and essentially means that about half the males in the population are missing the very parts of their bodies that are required for reproduction. Of the 309 that were missing pedipalps, 124 were missing the left pedipalp, 97 were missing the right pedipalp, and 88 were missing both. In virtually all cases, the pedipalp was severed at the trochanter-femur joint. So the most plausible explanations for missing pedipalps are:

Pedipalp autotomy occurs during the act of copulation
The female may remove the pedipalps before, during or after copulation
C. euopla males may use their pedipalps in antagonistic courtship behaviours
Perhaps pedipalps are frequently used to grapple with aggressive prey, and are thus damaged.

It would be difficult to relate missing pedipalps to the act of copulation without detailed studies of courtship and copulation in C. euopla. However, the fate of pedipalps could be determined indirectly if the frequency of missing pedipalps increased during the reproductive period. The period of reproduction for ground-dwelling spiders, such as C. euopla, can be assessed from the peak activity period for male and female spiders, inferred from a passive sampling technique such as pitfall trapping. Using a larger data-set for male and female C. euopla collected by pitfall traps set at the George Lake Field Station, it is evident that males are most active early in the season (early May through the end of June) (Figure 1). Females were found throughout the spring and summer months over two years, with a slight increase in late June (Figure 1). These results generally agree with Leech (1972), who suggests May and June are the main periods of activity for C. euopla. Thus, it is inferred that this species will mate primarily in the spring in central Alberta.

The next step is to ask whether the frequency of missing pedipalps is related to the hypothesized mating period. This was done by calculating the average percentage of males with missing pedipalps as a function of sampling date (Figure 2). In both sampling years, the percentage of males with missing pedipalps increased as the season progressed (Figure 2). Although the sample size for July samples was low (12 individuals), the average number missing pedipalps was over 80%. Furthermore, the earliest sampling date in 1999 (6 May), which collected over 200 individuals, had the lowest average percentage of males with missing pedipalps (< 20%). These results indirectly suggest that as the season progresses, and the spiders mate, males begin to lose their pedipalps. I can therefore likely exclude the possibility that palpal loss is related to aggressive prey, and the explanation is likely related to courtship or copulation.

This small study has raised as many questions as it has answered, and there are certainly other explanations that I have failed to mention. I invite fellow Arachnologists to comment on the phenomenon of missing pedipalps in C. euopla, and in other species. I suspect pedipalp loss is widespread, but seriously understudied. Given this importance of palps to the fitness of spiders, future research is certainly warranted.

References:

Buddle, C. (2001). Spiders (Araneae) associated with downed woody material in a deciduous forest in central Alberta, Canada Agricultural and Forest Entomology, 3 (4), 241-251 DOI: 10.1046/j.1461-9555.2001.00103.x

Buddle, C., Spence, J., & Langor, D. (2000). Succession of boreal forest spider assemblages following wildfire and harvesting Ecography, 23 (4), 424-436 DOI: 10.1034/j.1600-0587.2000.230405.x

Foelix, R.M. 1996. The Biology of Spiders. Oxford University Press.

Knoflach, B., & van Harten, A. (2001). Tidarren argo sp. nov. (Araneae: Theridiidae) and its exceptional copulatory behaviour: emasculation, male palpal organ as a mating plug and sexual cannibalism Journal of Zoology, 254 (4), 449-459 DOI: 10.1017/S0952836901000954

Leech, R. 1972. A revision of the nearctic Amaurobiidae (Arachnida: Araneida). Memoirs of the Entomological Society of Canada 84: 1-182.

Lynam, E., Owens, J., & Persons, M. (2006). The Influence of Pedipalp Autotomy on the Courtship and Mating Behavior of Pardosa milvina (Araneae: Lycosidae) Journal of Insect Behavior, 19 (1), 63-75 DOI: 10.1007/s10905-005-9008-x

Ramos, M. (2004). Overcoming an evolutionary conflict: Removal of a reproductive organ greatly increases locomotor performance Proceedings of the National Academy of Sciences, 101 (14), 4883-4887 DOI: 10.1073/pnas.0400324101

April 26, 2013 by Chris Buddle

Kids Like Bugs: entomology outreach in elementary schools (Part 2)

On Wednesday, Chris Buddle and Paul Manning posted the first of a two-part series on outreach activities in elementary schools. That post focused on the ‘why’ - this one (also written by Chris and Paul) is about the ‘how’.

How to talk to kids about bugs:

First thing about talking to elementary school kids is stay calm and don’t worry! If you have any University-level training in Entomology, you are qualified – Now, this doesn’t mean you have to be able to speak about all aspects of entomology: play to your strengths! If you are a taxonomists working on Syrphidae flies, bring in your flies and talk about them these magnificent animals. If your experience is broader and less specialized, browse some notes, look on-line, or peek at a textbook: do a short overview of the main Orders of insects and their characteristics. Although most kids get some entomology in elementary schools, it’s not usually very much (although ALL kids do seem to learn about monarch butterflies!).

One great way to speak to kids about bugs is to make the session thematic. In addition to bringing in a drawer or two of insects, link the specimens to biology. For example, one of us (Paul) has recently used ‘metamorphosis’ as a focal point for discussion. The transition from larvae to adult is a biological wonder, and acts as an excellent focal point for discussion. It brings together different facets of biology, from hormones, to physiological development, behavioural adaptations, through to discussion about life history strategies. Paul brought galls into the classroom, and demonstrated that there were larvae living inside. The students screamed with excitement when they saw the larvae living within the gall. One student described it as a ‘cute white blob‘. Several students asked if they could bring the larvae home (wouldn’t Mom and Dad just LOVE that!).

Kids like bugs. And they like to draw them.

Don’t be afraid to say “I don’t know”. In fact, kids find it refreshing to hear that an ‘expert’ doesn’t know all the answers. Turn it around to illustrate that the world of entomology is so vast that there are a lot of unknowns out there, and many questions still to be answered.

Have patience. With younger grades, asking kids questions, or having them answer questions, can quickly turn into ‘stories’ from young, enthusiastic students. For example:

Q: Does anyone know what kind of insect a ladybug is?

[Hand shoots into the air...]

A (from a 6 year old): Um, yes, I know a lot about those things. Once, when I was 4, I remember that I saw a beautiful bug flying by my garden – it was really big and black and I think it was a ladybug and my granddad told me about how ones like that eat trees and kill the trees and that makes me sad because we have a big tree in our front yard that I really like but sometimes my little bratty brother hides behind it and scares me when I am walking by. But I really like all bugs especially ladybug ones that are red but they smell funny sometimes and my mom said they can bite – will they bite me if I play with them? why do they smell funny? why are there so many spots on them? do their spots get bigger when they grow….

Give kids a chance to tell you these stories, but know that it will take patience…. but heck, if bugs get them talking and excited, that can’t be a bad thing!

(as an aside, most elementary school teachers will typically coach students so that they will ask/answer question instead of tell stories)

Bring a few props: If you can do an event outdoors, try to bring a few sweep nets and vials. We will often bring extra vials from the lab and give students the vials to keep (heck, plastic vials cost very little!). For MONTHS afterwards, parents will often tell us about how their child packed that vial full of insects and carried it around obsessively for weeks. That’s a great way to inspire entomology.

Beetle galleries are easily found in wood, and can be a great prop to bring to an entomology session with school kids.

If you are doing an indoor talk, make sure to have a lot of photographs of interesting insects, and whenever possible, discuss/show or use examples from your local fauna – this will allow kids to connect to things they have seen on the playground or in their own yards – this connection between the content you are discussing and the insects they are seeing on their own, is very powerful. With a smaller group, you can certainly bring in a few drawers of insects – if you don’t have any, this becomes a great excuse to make a little synoptic collection of your own to use for educational purposes. Or, ask your local entomology museum, or local naturalist club, about borrowing some specimens.

Whenever possible, bring a few ‘real’ field guides. One of us (CB) ran a biodiversity challenge at an elementary school and managed to convince the school to buy a couple of sets of field guides. The kids LOVE the look and feel of real field guides and will thumb through them with delight. Part of our own passion about natural history can be traced back to field guides in our houses when we were young.

A field guide to insects – suitable for all ages!

Don’t dumb down the material: Too often we think kids need to be talked down to, but nothing is further from the truth. As mentioned above, kids are sponges for information and in our experience they want to hear the details. You will want to avoid jargon, but other than that, provide the details whenever you can. Again, doing a ‘thematic’ talk with school kids becomes quite important because you just won’t have time to cover anything in-depth if you try to cover too much.

Finally, and most importantly, be passionate and enthusiastic. Kids will feel your positive energy and love of entomology; they will feed off of this, take it home with them; they will start asking more questions, start to dream, and fall further in love with the world around them. Spending a bit of time in a classroom is perhaps one of the most important kinds of outreach activities to do.

April 23, 2013 by Chris Buddle

Kids Like Bugs: entomology outreach in elementary schools (Part 1)

Written by Chris Buddle and Paul Manning.

Spending time talking to kids about Entomology is ALWAYS worth it. If ever invited to speak at an elementary school about insects, always say “yes”, and in this post, we’ll expand on why it’s worth your time. In a second post on this topic, we’ll provide some tips on how to talk to kids about bugs. Although these posts are focused primarily at elementary school events, the ideas and tips could be expanded to community nature walks, events at an ‘earth day’ celebration, hosting a bug day in your backyard, etc.

Part 1: Why talk to kids about bugs?

Most kids aren’t afraid of nature. In our experience, elementary school kids (especially the younger grades) still have a fascination with entomology and are still curious and excited by ‘bugs’. Later in life, it seems that many kids will follow one of several paths: (a) disinterest, (b) disgust, or (c) delight. As entomologists, in a field that is so important, getting kids to be delighted is very important.

Kids like bugs.

Kids already know a lot but they like an expert to verify their findings and support their interests. In our experience, kids can get especially excited about insects because they see them all the time – they have played with them in their yards, tasted them (perhaps), and probably spend time trying to burn them with a magnifying glass. Bugs are accessible, small, curious, and catchable, and thus kids learn about them – an entomologist can keep facilitating this learning.

Kids are truly amazed that you can ‘get a job‘ studying insects. This is unfathomable to them, since they don’t typically get much exposure to biologists. They are exposed to limited career options (“I want to play in the NHL“, “I want to be a doctor“, “I want to be a firefighter“) in part because our school systems often exclude the cool jobs like “stream ecologist”, “geologist”, or “entomologist”. The idea that you can spend time (as an adult!) collecting and curating insects (i.e., FUN STUFF) can be quite extraordinary. In our experiences, it’s so painfully obvious that working outdoors with insects is simply not noticed as a real job by many people; entomologists must work to correct this. Giving kids exposure to wonderful careers (like entomology) can help encourage future scientists that there are truly enjoyable careers that involve getting ones hands dirty, and spending time outside.

Entomologists have a responsibility to dispel myths about arthropods, and this should start at an early age. Invariably, we get statements from kids such as “My Dad told me to stay away from spiders ’cause they will bite you“, or “My aunt told me that earwigs go into your ear, so I hate them“, or “I am allergic to bees because my cousin is allergic“, etc. We can bring clarity to these kinds of statements, and by offering an ‘expert opinion’ on these topics, can help kids understand the real facts about entomology.

Kids are sponges: it is satisfying to speak to an audience who is fully engaged and willing to soak up as much as you can provide. Bugs are a very exciting topic for kids, and they will remain interested, excited and enthused if you continue to provide good content.

Kids ask great questions. As an example, one of us (PM) recently talked about insects to an elementary school class. The class was asked to guess what was living within a gall, and to make guesses as to what they thought the gall was, and how it was formed. After one student quickly suggested that an insect was living within the gall, a flurry of wonderful questions began. Students asked questions like:

How did the insect get inside the gall?
How does the insect survive the winter?
What does the insect eat when inside the plant?
Why doesn’t the insect kill the plant?

All of these questions prompt interesting, and relevant discussions that fit well within learning objectives in science curriculum. Providing a concrete example that is applicable to students, might also result in a better understanding of the concept.

Finally, it’s nice to talk to kids about bugs because they genuinely appreciate it. Being thanked for spending time doing this kind of outreach is really, really nice. And, sometimes you might receive some nice thank-you cards or posters to put up on your wall. To us, these are as important as a diploma on your wall, or a favourite butterfly poster. Thank-you notes from kids are some of the most wonderful things to read, and they often include delightful, creative, and colourful drawings.

March 5, 2013 by Chris Buddle

Ten fun facts about Daddy Longlegs

Animals with many names: Harvestmen, Daddy longlegs, Shepherd Spiders, Grandfather Greybeard, Phalangids, Opiliones.

Cousins of other Arachnids, but an Order all to their own. Over the past 11 months, I’ve been on a journal of discovery about these amazing creatures.

After nearly 300 tweets, and over 600 pages of text in Pinto-da-Rocha et al.’s book on Harvestmen, the Opiliones Project (in the way it was originally conceived) is over. To recap – this was a twitter-based project in which I shared content from that weighty textbook with anyone who cared to follow along (using the hashtag #OpilionesProject). Many folks followed along, notably my twitter friends Derek Hennen, Jaden Walker, Matthew Cobb, and many, many others…

A lovely Harvestmen – photo by B. Valentine, reproduced here with permission

I learned a lot along the way – and will take this opportunity to highlight ten fun facts about Harvestmen – all of these were part of the Opiliones Project.

Did you know that…

1. Salvador Dali featured Harvestmen in his work! It’s true – check it out: “Daddy Longlegs of the Evening”

2. Harvestmen can breath through their legs! Spiracles in harvestmen are located just posterior to the coxae of the 4th pair of legs and this supply of oxygen to Harvestmen legs (e.g., after they are removed) contributes to the duration of twitching

3. Harvestmen have been around for at least 400 million years! Phenominal! And Harvestmen from the Rynie chert have an extensive tracheal system – the oldest record of such tubes of ANY arthropod

4. Harvestmen are NOT venomous! They don’t have venom glands! A common urban myth.

5. Over 60 chemical compounds have been isolated from Harvestmen secretions (e.g., the secretions that are often used in chemical defense)

6. At least a dozen species of Harvestmen are known to be parthenogenetic (females lay eggs that produce only females)!

7. Harvestmen often show aggregation behavior, and the largest aggregation recorded is 70,000 individuals on a candelabrum cactus!

8. Unlike other Arachnids, Harvestmen males have a penis!

9. In some Harvestmen species, males use their chelicerae to offer oral secretion to female – a type of nuptial gift!

10. In some species, Harvestment moult even after they are have reached adulthood!

So there you have it. Many fascinating and fun facts about Harvestmen (and there are many, many more) – you can access all the tweets from the Opiliones Project here (all 24 pages of them).

There were some other notable Harvestmen events over the past year, and it was fortunate this project coincided with these events. For example, the Taxonomy Hulk burst onto the scene, and highlighted an article depicting a mix-up between a spider and a Harvestmen (a common mistake…). Also, a truly HUGE harvestmen species was discovered – this sucker had a 13 inch legspan. As May Berenbaum said over twitter…that’s a Daddy Loooooonglegs!

So, to finish – a big THANK YOU to everyone who followed along. I hope this project was a fun for you as it was for me.

Another lovely Harvestmen, photo by B. Valentine, reproduced here with permission.

A special thanks to Brian Valentine for permission to use his Harvestmen photos on this blog!

February 20, 2013 by Chris Buddle

The greatness of pseudoscorpions

As you know, I’m quite passionate about Arachnology, from spiders, to harvestmen and Pseudoscorpions. These are all some of the creatures that fall into the category of the ‘obscure and amazing‘. On the topic of pseudoscorpions, a few very fun and interesting things have happened recently, and enough to warrant a short blog post. I also promised that I would post a few more videos related to some research activities on the hunt for pseudoscorpions in the Yukon.

1. Just look at this SEM of a pseudoscorpion!

A little while ago, my Arachnid friends and colleagues from Alberta, Heather Proctor and Dave Walter, forwarded me a stunning image of a pseudoscorpion taken with a scanning electron microscope (SEM). Dave was kind enough to give me permission to share it here:

SEM of a pseudoscorpion (Chernetidae) – copyright D. Walter (reproduced here with permission)

There really is something lovely about getting up close and personal with these little Arachnids. I don’t know this species, but it’s definitely in the family Chernetidae – a relatively diverse family, quite common across Canada. My favourite Yukon species, Wyochernes asiaticus, is also a Chernetid. Dave Walter really does some magic with his SEM images, and you are encouraged to check out is macromite blog (his home bug garden blog is also worth a peek!).

2. Just look at these videos about collecting pseudoscropions in the wild!

Speaking of my favourite Yukon species, I took a lot of videos of field work in the Yukon last summer and I wanted to share a few with you, here. Although our larger purpose for the trip was to complete some follow-up field work for the Northern Biodiversity Program, I also wanted to collect additional specimens of a wonderful pseudoscorpion species. The first video provides some context to the work, and gives you a bit of a flavour of the landscape up near the Yukon – Northwest Territory border in Canada:

Typically, pseudoscorpions are not that commonly encountered. In my experience, when they are encountered, you tend to see one or two. What is truly amazing is the sheer abundance of this species found under rocks in creek/river beds in the Yukon. Furthermore, you can see and collect multiple life stages, including females with eggs. This short video gives a taste for this abundance.

The third and final video is a big goofy, and highlight the ‘collecting gear’ and appropriate field attire for becoming a “pseudoscorpion hunter“. I am continually on a crusade to help generate enthusiasm for Arachnids, whether it is dispelling myths, or trying to inspire others to become Arachnologists (you know, we do need Arachnologists in Canada!).

One important caveat: you may NOT simply run to the Yukon and flip rocks to collect pseudoscorpions – many parts of the world, including the Yukon, have strict guidelines about what you can collect. Permits are required, and be sure to check into this before you plan on becoming an Arachnologist!

3. Just look at this pseudoscorpion necklace!

To further illustrate my rather quirky obsession, I managed to find a wonderful person on Etsy who was able to make me a pendant with a pseudoscorpion design:

The pseudoscorpion necklace. You want one.

Not only that, this design is actually from a photography I took a few years ago, and is an accurate depiction of the cosmopoliton species Chelifer cancroides.

Chelifer cancroides – my photo which was used to design the pendant

I KNOW you want to get yourself one of these… start a conversation with Lynn. Get yourself one of these necklaces and stand proud with other pseudoscorpionologists!

In sum, I do hope you find this post interesting, hopefully fun, and has whetted your appetite from more information about curious critters.

Stay tuned… I will continue to post more about Arachnids…

January 24, 2013 by Chris Buddle

Where did all the spiderlings go? A story about egg-sac parasitism in Arctic wolf spiders

This week we are in a deep freeze in the Montreal area, so it seems somewhat fitting to discuss Arctic spiders. I’ve discussed the life-history of Arctic wolf spiders (Lycosidae) before, specifically in the context of high densities of wolf spiders on the tundra. Much of this work was done with my former PhD student Joseph Bowden. The latest paper from his work was published last autumn, and was titled ‘Egg sac parasitism of Arctic wolf spiders (Araneae: Lycosidae) from northwestern North America‘. In this work we document the rates of egg sac parasitism by Ichneumonidae wasps in the genus Gelis. These wasps are fascinating, and we have found them to be very common on the tundra. There are often multiple wasps in a single egg sac, and as is typical with Gelis, they leave nothing behind: all eggs within an egg sac are consumed. After fully developed, the adult wasps pop out of the egg sac; the Gelis adults we encountered had both winged forms and wingless females, the latter superficially resembling ants.

A Gelis emerging from a wolf spider egg sac. Photo by Crystal Ernst, reproduced here with permission.

The rates of parasitism of Pardosa egg sacs (by Gelis) were, at some sites, extremely high. In some cases over 50% of the wolf spider egg sacs were parasitized. Stated another way, half of all the females encountered with egg sacs had zero fecundity because the female was carrying around wasps within the egg sac instead of spider eggs.

It’s quite interesting to think about these wingless Gelis females: after emerging from egg sacs, they end up wandering around the tundra in search of hosts. Spiders with egg sacs must be encountered frequently enough for the wasps to grab on to a passing wolf spider in order to parasitize the egg sac. Recall, densities of wolf spiders can be very high in the Arctic (4,000 per hectare, at least). Hmmm…. this is all starting to fit… high densities of wolf spiders support high rates of egg parasitism and these wasps can ‘afford’ to be wingless since their hosts are frequently encountered: an interesting feedback loop! We can also speculate about large-scale gradients in diversity – many Ichneudmonidae show high diversity in northern regions. Within Gelis, it’s a good bet that they will find many suitable spider hosts in these environments.

Looking down the microscope – all those Gelis!

So, how extreme are these rates of egg parasitism? Looking at some of the literature, there are certainly a number of papers about wasps that parasitize spider egg sacs. Cobb & Cobb (2004) studied two Pardosa species in Idaho, and recorded a egg parasitism rate of about 15% (by Gelis wasps and wasps in the genus Baeus [Sceleonidae]). Van Baarlen et al (1994) studied egg parasitism in European Linyphiidae spiders and their maximum rates of parasitism were about 30%. Finch (2005) did a detailed study of four spiders species (non-Lycosidae) and rates of egg parasitism varied between 5% up to as high as 60% in an Agroeca species.

Our documented parasitism rates for Arctic wolf spiders are certainly quite high (for Lycosidae), but not out of the range of other published studies for non-Lycosidae. I do wonder whether we will continue to find high egg parasitism rates if more species were examined in detail – certainly a fertile area of study. Related to this, what are the population-level consequences of this interaction? What is the relationship between spider densities and parasitism rates? Although Joe and I did try to speculate on this, our data are preliminary – again, a key area for future research.

In the Arctic context, we will continue to uncover fascinating food-web dynamics. Our research group has already been thinking seriously about this – Crystal Ernst has written a nice post about the idea of an ‘inverse trophic web’ (i.e., predator-dominated) in the Arctic, and a fair amount of my future research will pursue this avenue of research.

Pique your interest…? Why not think about graduate school in my lab, and study Arctic arthropod biodiversity?

References:

Bowden, J., & Buddle, C. (2012). Egg sac parasitism of Arctic wolf spiders (Araneae: Lycosidae) from northwestern North America Journal of Arachnology, 40 (3), 348-350 DOI: 10.1636/P11-50.1

Cobb, LM & Cobb VA (2004). Occurrence of parasitoid wasps, Baeus sp and Gelis sp., in the egg sacs of the wolf spiders Pardosa moesta and Pardosa sternalis (Araneae: Lycosidae) in southeastern Idaho. Canadian Field Naturalist 118(1); 122-123.

Baarlen, P., Sunderland, K., & Topping, C. (1994). Eggsac parasitism of money spiders (Araneae, Linyphiidae) in cereals, with a simple method for estimating percentage parasitism of spp. eggsacs by Hymenoptera Journal of Applied Entomology, 118 (1-5), 217-223 DOI: 10.1111/j.1439-0418.1994.tb00797.x

Finch, O. (2005). The parasitoid complex and parasitoid-induced mortality of spiders (Araneae) in a Central European woodland Journal of Natural History, 39 (25), 2339-2354 DOI: 10.1080/00222930500101720

January 15, 2013 by Chris Buddle

We need the Taxonomy Hulk

The Taxonomy Hulk burst onto twitter yesterday. We need superheroes like Taxonomy Hulk. As his/her alter ego, s/he surfs the internet, working away as a taxonomist, doing things that taxonomists do – describing species, inferring their evolutionary relationships, discovering their natural history. However, if s/he spots a taxonomic mistake on a website, news story, scientific article, or blog – LOOK OUT. The Hulk goes through an impressive metamophosis. S/he gets mad and gets even. If you make a taxonomic mistake, you will be shamed. Message: DON’T MAKE A #TAXONOMYFAIL. Taxonomy Hulk points out misidentifications in images (e.g., see this website with a Harvestmen instead of a spider.. oops [although a common mistake]).

Taxonomy Hulk reminds us to use Latin names, not common names.

Taxonomy Hulk is also funny. We need humour – every day.

On a slightly more serious note: correct taxonomy is critically important. Other posts (e.g., see here or here) have pointed out taxonomic failures – and I especially like Bug Girl’s Flickr set!. One letter difference in Miridae (a family of plant bugs) gets you to Muridae (rodents and their relatives) – yeah those two are just a bit different. As an ecologist (although one with envy of taxonomists, and one in awe of the work taxonomists do!), I admit that I am perhaps not as careful as I should be when it comes to checking nomenclature, or ensuring spelling is always correct. I try – but given that my training is not in taxonomy, I surely make mistakes. I fear that some ecologists appreciate the importance of sound taxonomy even less than I do, and we need a watchdog. Reminders about correct taxonomy are a good idea. Taxonomy Hulk reminds us that we must be clear in what we are saying, whether it be in science journalism, writing a blog post, or working on a scientific paper.

Taxonomy Hulk is a concept not a person and this is a good thing: the humour and fun and ‘alter ego’ perspective is non-threatening, and allows taxonomic issues to be brought into the open easily and effectively. We can fix our mistakes, smile about it, and move forward.

Thank you Taxonomy Hulk. (and yes, you should follow Taxonomy Hulk on twitter)

I finish by stating that Taxonomy Hulk’s ‘regular’ persona (the Bruce Banner) is known to some of us (and s/he’s an incredibly competent taxonomist!, and a super-nice person).

But I’ll keep it quiet – it’s better that way.

January 10, 2013 by Chris Buddle

Natural History: unknown.

I sometimes see this statement in taxonomic papers that describe a new species:

Natural History: Unknown

Think about this… specimens have been collected, somewhere, sometime. Perhaps these specimens sat in an Entomology museum for decades until a MSc student took them out and started a revision. Perhaps the specimen was recently sorted from a bulk malaise trap sample from the Amazon basin, and sent to a taxonomic expert for identification. S/he recognized it was something different and later, while doing a taxonomic revision, included it, measured it, did a line drawing, extracted some DNA, wrote a description, gave it a name. However, when writing what is known about its natural history and biology had to write “unknown“. (by the way, discussions about defining natural history can be found here and here).

An unknown weevil with unknown natural history.

I recognize why nothing is known, but when trying to get some sense of why a particular species might be found in a particular habitat, having no information about natural history and biology can be frustrating. This is especially true for ecologists, whose research might benefit immensely from ANY natural history information. In my own work, after I key out a species of wolf spider, for example, I immediately flip to the description, and scan down to the notes about the biology of the species – these notes can confirm details about the species (hey look, I found it under rocks on a shoreline, and that is where it is reported, also!; or, indeed, it makes sense that I found that egg sac in late summer – that species is known to mate in mid-summer).

Natural history is important, as is so elegantly stated in many papers (e.g., see Greene’s 2005 paper) and the impending extinction of natural history was written about over 10 years ago by Wilcove & Eisner. The world needs natural history information, and although I recognize that having a name is clearly very important, it is also essential to have some natural history information. Such information can lead to additional research on the species, or allow others to document the species in new locations around the globe. Having some information will help future graduate students figure out when during the growing season they should find specimens, and perhaps what host plants they should look on.

So, I ask these questions, and I look forward to responses, especially from taxonomists:

Should taxonomists wait to describe a species until there are some details known about its natural history? (this will, of course, take more specimens and more time…)

and,

Under what conditions is it acceptable to state “Natural History: unknown”?

Caveats: I am coming from this question as an ecologist with an appreciation for taxonomy, but not as someone trained in taxonomy. I am, therefore, biased in my views. I also recognize that in many cases, taxonomists only have one specimen and a label to work with, and data on the label itself may be lacking, hence the need to state “natural history: unknown”. My questions are meant to be more general, and I am hoping to gain insights into whether seeking additional natural history information about species (when it is described) is a losing battle… and whether this task should be in the hands of the individuals who describe species.

References

Greene, H.W. (2005). Organisms in nature as a central focus for biology Trends in Ecology and Evolution, 20 (1), 23-27 DOI: 10.1016/j.tree.2004.11.005

Wilcove, D. and Eisner, T. (2000) The impending extinction of natural history. Chron. Higher Ed. Sept. 15, B24. Available here.

November 28, 2012 by Chris Buddle

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

October 29, 2012 by Chris Buddle

The transformative power of social media: blogs and tweets in a university course

As part of my field biology course this term, groups of students are working on research projects related to observing species in their natural setting – a ‘Natural History‘ project. Students are working in groups of 4-6, and each group is doing a focused project about a particular species (or group of species) including the following: American beech trees, sugar maple trees, hemlock trees, shelf fungi, aquatic macroinvertebrates, litter-dwelling arthropods, small mammals, the American crow and chickadees.

The first part of this project involves providing an overview of the natural history of their study species, and this overview is being released in the form of a scientific blog post. Starting today, and for the next three weeks, the nine blog posts will be released on the following site. (Today’s release is all about American beech Trees).

ENVB222 – the first post

I have opted to use blog posts, as one form of social media, as a direct communication tool in this undergraduate course. This opens the work up to the broadest audience possible, and students have a lot more people to write for than just their instructors. I believe this will increase the quality of the writing since the stakes are quite high: experts on their topics will be able to read and comment on their posts. The students are encouraged to connect with the broader scientific community and seek input on their study species. Another reason to use social media is to allow the classroom work to move outside the walls of Academia. Students have told me that they are inspired by the idea of taking what they are learning and seeing how it is valued outside the (typically) insular classroom activities.

The use of social media in the classroom would not be complete without Twitter! The groups have set up twitter accounts, and within 48 hours of their posts going live, they will be tweeting a series of facts related to their study species! This is another informative, collaborative and fun way to seek input into their projects, and a way to bring what they have learned out to the broader community of biologists. Follow along! You can simply use the hashtag #ENVB222 to track the tweets related to the project. (by the way, you can follow the Beech tee group @BBDteam ). Here are a couple of examples of other tweets:

A tweet from the litter dwellers…

The Crow group’s tweet

Students have already started to connect with scientists from other institutions – they are already feeling part of something bigger. For example, students in a field biology course at the University of Hull in the UK have connected with McGill students – the students from the two institutions can share connect, collaborate and share their experiences. This can be done easily through #hashtags:

A re-tweet to Hull Students, from their Professor (Graham Scott)

So far this social media experiment in the classroom is inspiring, exciting, and leveraging real tools as a way to take the teaching and learning experience to a new level. However, it will only work if their blogs are read, critiqued, and discussed with the broader community. So, I encourage you to follow along and take part in this activity. You are all invited.

Community. Sharing. Collaboration. Outreach. Communication.

This is the power of social media.

Arthropod Ecology

Writings about arthropod ecology, arachnids & academia at McGill University

Category Archives: Natural History