Tag Archives: spiders

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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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Expiscor (20 May 2013)

This week’s Expiscor is coming to you on a holiday Monday across much of Canada. This is the day that many Canadians feel that the ‘warm season‘ has officially arrived. We can plant things in our garden without fear of frost; the lawn shall be mowed, the birds are busy, the butterflies are flying.

What is Expiscor? …it’s a weekly digest of discoveries from the world of entomology, biology, and so much more.

  • It seems that every week there’s a story about ‘dangerous spiders‘ – this week, Bug Girl wrote a post to help FIX THE INTERNET – in this case, to discuss a bogus spider poster.
  • On the topic of jumping spiders – they can make you look twice – WOW, WOW and WOW again. (thanks Alex Wild, for that photo, and permission to use it)

Screen Shot 2013-05-19 at 3.17.12 PM

  • Biodiversity under foot – great video about threats to soil biodiversity (thanks to my former MSc student, and recent PhD graduate, Zach for posting that link.
  • Fireflies: I always find the larvae of the Lampyridae beetles to be odd-looking, and I sometimes have trouble reconciling their habitus with adults.  This is a lot easer thanks to Derek Hennen for this lovely photo of an adult – check out that abdomen! (and thanks, Derek, for allowing me to use this photo)

Screen Shot 2013-05-19 at 3.33.34 PM

  • Scale it. This is VERY worth checking out. I personally like 10 to the power of -2.5
  • A worthy ordeal: Another great post from one of my heroes, Simon Leather – a terrific tradition in the British University system.
  • Lego geek-fest. Star Wars, LOTR, Arrested Development & so much more.
  • To finish, as usual, with some music. I’ve been a fan of Steve Earle for quite a long time, and his latest album (the Low Highway) does not disappoint. Here’s a video from one of the songs from that album. Worth a listen (and a good lesson in there, too)

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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)

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.

Fig 1

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.

Fig 2

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

ResearchBlogging.org

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Expiscor (6 May 2013)

Welcome to May! Expiscor is still going strong, and thanks to everyone for the continued support and interest. I’m certainly thrilled about this, and will continue to post weekly links about entomology, arachnology, natural history, biology and a dash of the curious and odd.

  • Silk farming and biotechnology: the future is here. This paper describes some things that I don’t fully understand, and I am partially fascinated by, and partially terrified about, the idea (anyone read Margaret Atwood‘s book, Oryx & Crake?).
  • On the death of a bug blog? Ted MacRae posts about waning interest by readers, and perhaps by him, with his fabulous Beetles in the Bush blog. Ted will keep posting (phew!) but less regularly. Actually, I have noticed that over the past six months or so quite a few bug blogs have been less active.  This saddens me – high quality entomology blogs are an important way for this discipline to reach a wide audience.  Come on, folks – keep them going!
  • Palpal action. and check out this stunning photo from Chthoniid!  Yes, Harvestmen are among the most lovely of the Arachnida.
A charming harvestmen. © Chthoniid, reproduced here with permission.

A charming harvestmen. © Chthoniid, reproduced here with permission.

  • Worried about the decline of bees and colony collapse disorder?  Read this –> an important message (thanks Bug Girl for posting this)
  • On-line reading – I have been enjoying Nautilus this past week. Here’s their motto: “Nautilus is a different kind of science magazine. We deliver big-picture science by reporting on a single monthly topic from multiple perspectives. Read a new chapter in the story every Thursday”.  Definitely one to follow. And it’s a lovely site to look at.
  • Avoid that mumbo-jumbo.  Here’s Alan Alda’s take on scientific jargon.  Here’s a great quote from him:  ”There’s no reason for the jargon when you’re trying to communicate the essence of the science to the public because you’re talking what amounts to gibberish to them“.  He’s right.
  • Think you’r a pretty big deal? What to think about your place in the Universe? Think again. (thanks Sam Heads for tweeting that link!)
  • Kids have an interesting fashion sense. Here’s a photo of my 9 year old, en route to school.  I wish we could all worry a little less about whether or not things might clash, and just be happy that we have clothes to wear and food to eat.
Fashion. That is all.

Fashion. That is all.

  • Unless you’ve been off the grid for months, you have probably heard of the great Canadian Chris Hadfield, up on the International Space Station. He and Barenaked Ladies frontman Ed Robertson teamed up a while ago to write and perform a song (yes, Chris was in SPACE during the recording). Well, this was all leading up to MUSIC MONDAY, which is today. A fabulous celebration about music – all the details are here.  And the video of the Hadfield/Robertson song is below. Worth a listen.
  • ….on a related note, Chris Hadfield has more twitter followers than Canada’s Prime Minster (and for good reason).
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Expiscor (29 April 2013)

As you may have noticed, the ‘weekly’ Expiscor missed last week! This is because I have opted to change to Mondays for this blog feature.  The start of the week just works better, for a whole suite of reasons that I won’t bore you with!  So, you can now look forward to starting your week with some odd discoveries, from arthropods to general biology and other geekery.

  • Most (many?) Arachnologists know of Emerton’s classic “The Common Spiders of the United States” written in 1902 – that book is now available on-line! Big WIN for spider enthusiasts.
  • Be still my heart.  Here’s a video showing the heartbeat of a spider after being captured and placed in a mud-dauber (wasp) nest.  Wasp finds spider. Paralyzes it. Returns it to its nest. Spider is still alive. A tasty feast for later on…. (thanks to Spider Joe for this video!)
  • Adrian Thysse always impresses me with his amazing photographs.  This one depicts one of the most lovely spiders in North America, Habronattus americanus.  Yes, it’s one of my most favourite spiders, here’s why:
Habronattus americanus - photography by A. Thysse (reproduced here, with permission)

Habronattus americanus - photography by A. Thysse (reproduced here, with permission)

  • If you don’t buy stuff on ETSY, you should – amazing on-line resource. Also, some lovely insects finds on ETSY, including this from GollyBard (thanks Cameron Webb for pointing me to this)
One of GollyBard's paintings - listing here. (reproduced here with permission)

One of GollyBard’s paintings – listing here. (reproduced here with permission)

  • Peeping peepers: I live on the outskirts of Montreal and over the past week, the spring peepers have been making some noise! (spring –> it’s here!)
  • Milk Cartons & Guitars: Two musical bits to wrap up.  First, I’m especially fond of bluegrass, old-time, trad., folk, indie…. My colleague and friend Elena Bennett pointed me to the “Milk Carton Kids” – what a talented duo.
  • And, to finish… talk about GEEKY!  Here’s the “Arthropod song“

“Baby you’re and arthropod. Shake that segmented bod”

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Expiscor (19 April 2013)

Here’s  Expiscor -some discoveries I stumbled upon this week… (past versions can be found here)

  • World’s Biggest Butterfly Collection.  This video explores the amazing collection at London’s Natural History Museum.
  • Spiders, spiders, lovely spiders.  How about this image of a spitting spider by Chris Ruijter – STUNNING (thanks Alex Wild for directing me to Chris’ photos…)
A spitting spider, photo by Chris Ruijter (reproduced here, with permission)

A spitting spider, photo by Chris Ruijter (reproduced here, with permission)

  • The trees are speaking… this story describes how scientists listen to ultrasonic noise made by bubbles forming inside water-stressed trees (thanks Carly Ziter for that link)
  • More on the links between Art and Science.  The debate about “E.O. Wilson versus Math” inspired a discussion in my ecology class, but coincidentally, a friend of mine also pointed me to this truly lovely writing about Mathematics and the Arts (starts on page 55), written by Marston Morse in1959. Here is a quote from that piece:

            “…mathematics is the sister as well as the servant of the arts and is touched by the same madness and genius. This must be known.”

  • A passion for beetles: a retired researcher from Germany’s Federal Center for Meat Research in Bavaria has a lovely collection of Coleoptera, 6,000 species at over 30,000 individuals. Now that’s a hobby! (thanks Bug Girl for the tweet about that story)
  • To finish, glad to see that Entomologists are out there correcting bad taxonomy.  Here, Ainsley Seago (aka @AmericanBeetles) does some fine work (and it was given a stamp of approval by Taxonomy Hulk – yes, we do need him, too!)

Screen Shot 2013-04-18 at 8.21.19 AM

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Expiscor (12 April 2013)

I am pleased to bring you the third edition of Expiscor – a weekly digest of discoveries and curiosities, from Arachnids, to natural history and beyond.  You can view previous postings here and here.

  • I’ve been editing work from two of my Master’s students who will soon be graduating – both on Arctic spiders – here are a couple of great quotes from their work, about spiders: “There are a recognized 43,244 species and sub-species of spider worldwide,  46% of which are described based on only one sex” and “18% of total linyphiid species in the world found north of 60°”  WOW – clearly much work is needed in Arachnology, and we ought to work in the North for some families.
A Solifugid - this stunning image is courtesy of Joe Lapp ("spider joe"), reproduced here with permission.

A Solifugid – this stunning image is courtesy of Joe Lapp (“spider joe”), reproduced here with permission.

  • Climate Change: it’s real.  It’s pervasive.  Not convinced?  Have a look at this – it’ll take you 26 seconds.
  • On a lighter note, do you like BRAINS?  Visit the Brain Museum….
  • And to finish, watch this if you need a laugh.  (Not for everybody, but this goofy, physical comedy with some biological realism made me chuckle out loud …and thanks CayBeach for tweeting about it)
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Where are all the Arachnologists? (and why you should care)

Canada is a big country, with an amazing diversity of habitats, from the temperate rainforests of Vancouver Island, to the polar deserts on Ellesmere Island.  We are a country that harbours thousands of Arachnid species (yes, our eight-legged friends!).  Some examples: the Yukon Territory hosts over 300 spider species and over 150 species of Oribatid mites; Quebec is home to well over 600 spider species.  The Alberta Biodiversity Monitoring Institute has documented over 200 species of Sarcoptiformes mites from a relatively few number of sites in Alberta, and their work is far from complete.  The Canadian National Collection of Insects and Arachnids in Ottawa has one of the best spider and mite collections, world-wide.

A beautiful jumping spider. Photo by C. Ernst, reproduced here with permission.

A beautiful jumping spider. Photo by C. Ernst, reproduced here with permission.

The general public is fascinating by Arachnids: my post titled ‘Spiders do Not Bite‘ continues to get hundreds of hits every week.  We link comic-books and superheroes to Arachnids (even if the anatomy of spiderman is all wrong…).  Spider silk is used to make dresses, violin strings, and has potential in pest control.  There are invasive spider species that go unnoticed, yet may affect native species – as Bednarski, et al (2010) have documented in Maine.  Spiders continually show up in grocery stores and cause alarm and fear (although mostly not warranted..).  People are often picking ticks off their pets, or hearing about lyme disease.

Everyone has a story to share about Arachnids.

Recently, the Class Arachnida was a lunchtime topic of discussion in the lab. This discussion was in part prompted by an email I received from Leslie Brunetta. She asked the question about how we can promote Arachnology in University education.  One way to do this would be for Arachnologists to agree to deliver guest lectures in organismal biology classes, and this got us into a discussion about how many people get paid to work on Arachnology in Canada.

I tried to estimate the number of people in Canada who spend a significant portion of their time getting paid to do things with Arachnids – and I consulted a lot of colleagues to get this done.  This would include academics with a research focus on Arachnids (from behavioural ecology to biodiversity science), and government scientists working on Arachnids (from systematics through to the use of mites as biological control agents).  This does not include graduate students, nor does it include people working on short-term contracts.  I estimate that fewer than 20 people are paid to work on Arachnids in this country. This is truly astounding and astonishing.  Arachnids include two Orders that are among the most diverse on the planet: combining the Acari (mites & ticks) and Araneae (spiders) gives you estimates of well over 85,000 described species, globally.  There are only a handful of Insect Orders that are higher.

Let’s revisit why EVERYONE should care about Arachnids and why Canada ought to have more Arachnologists: 

Spiders are key predators in agroecosystems (the classic paper by Riechert & Lockley 1984 is quite relevant!). Spiders eat mosquitoes, including those that can be vectors for malaria (Nelson & Jackson 2006) .  Spiders are key prey for highly valued vertebrates (Gunnarsson 2007).  Spiders can be medically important – their venom has remarkable potential for drug development (Rates et al. 2011).

Mites are everywhere – they play critical roles in decomposition of organic matter (Kampichler & Bruckner 2009). Plant-feeding mites are economically important for dozens of crops.  Follicle mites are in our heads (Elston 2010).

Ticks can transmit diseases that are very important for human health and well being (Sperling & Sperling 2012). Ticks can hurt our beloved pets (Blagburn & Dryden 2009).  Ticks can be harmful for wildlife populations (Addison et al. 1994).

Need more convincing?

Arachnids are stunningly beautiful; they are among the ‘small and obscure’ creatures most worthy of study. In addition to mites, ticks and spiders, we can’t forget about Opiliones, Pseudoscorpiones, Scorpiones and other Orders… Arachnids should adored as much as Pandas, or the Mona Lisa.

8 Oribatid mites scaled to a 12 pt Times Roman period (0.5 mm dia.). Photo by D. Walter, reproduced here, with permission. You should visit his blog.

8 Oribatid mites scaled to a 12 pt Times Roman period (0.5 mm dia.). Photo by D. Walter, reproduced here, with permission. You should visit his blog.

CANADA: THIS IS A CRISIS!  We must find a way to ensure Arachnologists get paid to do Arachnology in Canada.  The most obvious place to point is the CNC.  It is unacceptable that a spider taxonomists has yet to be hired to maintain that spider collection.  We should be embarrassed.  Taxonomists are needed in Canada, especially for dominant arthropod groups.  The Canadian Council of Academics makes this point quite clearly in their report on Canadian Taxonomy:

     Job openings in taxonomy have virtually ceased and research funding is stagnant.  Canada’s international contribution to new species descriptions has fallen from 6th in the 1980s to 14th in the 2000s. 

Oh Canada. Where are your Arachnologists?

Oh Canada. Where are your Arachnologists?

I realize that many other taxonomic groups remain understudied – However, I am discussing an entire Class of animals!  Could you imagine if I were discussing Mammalia, or Reptilia, or Insecta?  There would be an uproar.

Let us work to fix this.  Let’s train excellent Arachnology graduate students, let’s lobby Departmental Chair, Deans, Bureaucrats in Government, members of Parliament, and whoever else will listen.  MUST Listen.

Our eight-legged friends need our help.

References

Addison, E., McLaughlin, R., & Broadfoot, J. (1994). Growth of moose calves infested and uninfested with winter ticks Canadian Journal of Zoology, 72 (8), 1469-1476 DOI: 10.1139/z94-194

Blagburn BL, & Dryden MW (2009). Biology, treatment, and control of flea and tick infestations. The Veterinary clinics of North America. Small animal practice, 39 (6) PMID: 19932369

Danks VH and JA Downes. 1997. Insects of the Yukon. Biological Survey of Canada.

Gunnarsson, B. (2007). Bird Predation On Spiders: Ecological Mechanisms And Evolutionary Consequences Journal of Arachnology, 35 (3), 509-529 DOI: 10.1636/RT07-64.1

Elston, D. (2010). Demodex mites: Facts and controversies Clinics in Dermatology, 28 (5), 502-504 DOI: 10.1016/j.clindermatol.2010.03.006

Kampichler, C., & Bruckner, A. (2009). The role of microarthropods in terrestrial decomposition: a meta-analysis of 40 years of litterbag studies Biological Reviews, 84 (3), 375-389 DOI: 10.1111/j.1469-185X.2009.00078.x

Nelson, X., & Jackson, R. (2006). A Predator from East Africa that Chooses Malaria Vectors as Preferred Prey PLoS ONE, 1 (1) DOI: 10.1371/journal.pone.0000132

Rates B, Verano-Braga T, Santos DM, Nunes KP, Pimenta AM, & De Lima ME (2011). From the stretcher to the pharmacy’s shelf: drug leads from medically important brazilian venomous arachnid species. Inflammation & allergy drug targets, 10 (5), 411-9 PMID: 21824079

Paquin, P.  &  N. Dupérré 2006. The spiders of Québec: update, additions and corrections. Zootaxa 1133: 1-37.

Riechert, S., & Lockley, T. (1984). Spiders as Biological Control Agents Annual Review of Entomology, 29 (1), 299-320 DOI: 10.1146/annurev.en.29.010184.001503

Sperling, J., & Sperling, F. (2012). Lyme borreliosis in Canada: biological diversity and diagnostic complexity from an entomological perspective The Canadian Entomologist, 141 (06), 521-549 DOI: 10.4039/n08-CPA04

ResearchBlogging.org

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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.

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!

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.

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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

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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]).

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

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

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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.