Well-Nigh Wordless Wednesday: Net

The first year I taught the insect behavior lab at my school, I planned a dragonfly field trip so we could study territoriality.  We spent part of a morning at one of Tucson’s urban lakes, and at one point all I could see of any of my students was this:

Net

Dragonfly hunting

A few seconds later the student nearly flung himself into the lake trying to catch a darner.  Sadly, I didn’t get that on camera…  :)

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Unless otherwise stated, all text, images, and video are copyright © 2011 DragonflyWoman.wordpress.com

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Mites on Blue Orchard Bees

A few years ago, I had a job working as a scanning electron microscope (SEM) technician for some bee biologists.  They were looking at how well the blue orchard bee (Osmia lignaria) pollinated almond orchards in California.  At the time, colony collapse disorder (CCD) was starting to cause problems and the Almond Board of California was worried about the impacts the bee losses would have on their billion dollar a year crop.  That’s right – California almonds rake in over a billion dollars each year, and it’s all thanks to bees.  Honey bee colonies are shipped to California from all over the country to pollinate almonds, over a million hives in all.  In fact, nearly half of the commercial hives in the US participate in almond pollination in California!  Needless to say, increases in CCD worried almond growers because fewer bees meant lower yields and decreased profits.  The Almond Board was therefore very interested in using native bees to supplement honey bee pollination, and they funded the project I was involved in.  The goal: to determine if the blue orchard bee was an effective almond pollinator species so that they could supplement and/or replace honey bees in the event that CCD continued to decimate their populations.

My part of the project was to use the SEM to 1) determine how pollens from different almond varieties differed (i.e., the structure of the pollen) and 2) to determine whether the blue orchard bees were visiting more than one tree variety, apparently an essential component of almond pollination, by identifying the pollen types they carried.  I spent hundreds of hours looking at pollen from flowers of various almond tree types and bees that had been captured in almond orchards after being allowed to pollinate flowers.  Basically, I spent hundreds of hours looking at this, over and over again:

pollen

Almond pollen, Nonpareil variety. The pollen grain is the wrinkly thing in the middle. The little blobby things in the upper left are fungus or some other junk.

I’m not going to talk about the results at all here because they haven’t been published yet and the information belongs to the USDA, but I did want to talk about one thing I discovered during the project: mites!

There are mites associated with a lot of bees.  The varroa mite is likely involved in CCD in honey bees and causes all sorts of problems.  Other bees have other kinds of mites.  (Check out this fabulous website if you want to see just how many bee-associated mites there are!)  The blue orchard bees apparently have these:

mite

A mite on a blue orchard bee

I was so excited when I found these on the bees! Lots of the bees I looked at had mites on them.  And, if they had any mites at all, they typically had lots of mites:

mites

Mites on a blue orchard bee. There are 7 in this picture!

I looked into the mite-Osmia connection and discovered that these mites are almost surely Krombein’s hairy-footed mite, or Chaetodactylus krombeini.  This mite is really interesting!  First, the mites like the ones  I found on the blue orchard bees are a specialized stage found in some mites called the hypopus or deutonymph.  Because they are immature, they only have 6 legs, not the 8 legs typical of their arachnid brethren (they get the last pair when they become adults):

Mite

Mite on blue orchard bee, view of the bottom of the mite

The hypopus is a funky life stage in the mite groups that have it.  Hypopi don’t have definable heads and have no mouthparts, so they don’t feed.  However, they do have giant claws on their legs that are used to grab the hairs of the bees.  If you click on the photo above and look at the tips of the legs (four in the upper right of the photo and two curled up closer to the back), you’ll see the claws.  These claws are necessary because the mites hitch rides on the bees to move them from place to place!  (This lifestyle is called phoresy, and the hypopus is a phoretic stage in this mite.)  Without the claws, they wouldn’t be able to hold on very well.

The mites are hitchhikers as hypopi and generally do not harm the adult bees in this stage.  Once they are taken back to the nest, though, the mites climb off the bees and infest the nest cavities.  There, they feed on the eggs or larvae of the bees or the pollen store left for the bee larva by its mother.  In either case, these mites are a bit of a pest in this species and cause serious damage or death to immature bees.  However, they are also a native pest species and have been associated with these bees for a long time.  Considering the blue orchard bee is still around, the relationship seems to be working out so far!

So the mites are interesting biologically, but I’ll admit that I wasn’t excited about that at all at first.  I only learned it when I was writing up my report anyway.  I was initially more interested in the smashing good looks of these mites!  Look at how cute these little guys are:

mite

Mite on blue orchard bee

All those little wrinkles!  And the stubby little legs!  Adorable!*  Plus, it was exciting to look at one species and find another hidden on it.  Discoveries like these are part of why I enjoy working with the SEM so much.  Science is just so cool!

* I am willing to concede that I am horribly weird for thinking a bee parasite is cute, but I can’t help it.  :)

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Unless otherwise stated, all text, images, and video are copyright © 2011 DragonflyWoman.wordpress.com

Swarm Sunday – 6/19/2011 – 6/25/2011

dragonfly swarm banner

The swarming picked up a bit this week, but it’s still a slow start to the season.  No migratory swarms were reported, but there were six static swarms.  Most of them were in the south:

  • Pittsburgh, PA
  • Mineola, TX
  • Tyler, TX
  • rural TX near Yantis
  • Russellville, AR
  • Ponchatoula, LA
Exciting!  I also learned this week that a dragonfly researcher in New England is going to start a project similar to mine soon looking specifically at migration of dragonflies.  He will be looking for input from the public too.  I’ll keep you posted when I hear more!

Keep the reports coming everyone!

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Have you seen a dragonfly swarm?

I am tracking swarms so I can learn more about this interesting behavior.  If you see one, I’d love to hear from you!  Please visit my Report a Dragonfly Swarm page to fill out the official report form.  It only takes a few minutes!

Thanks!

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Want more information?

Visit my dragonfly swarm information page for my entire collection of posts about dragonfly swarms!

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Unless otherwise stated, all text, images, and video are copyright © 2011 DragonflyWoman.wordpress.com

Friday 5: Songs for Insect Lovers

I love music and I am always thrilled when my love for music collides with my love for insects.  I even have a whole playlist on my iPod devoted to insect-themed songs or songs with insects in the title!  Today I’m going to share 5 of my favorites from my Entomophilia playlist.  They’re even all on YouTube, so feel free to take a listen to any you haven’t heard.

Spider by They Might Be Giants

If you’re not familiar with TMBG, they write some really bizarre songs.  They’re super fun though!  Spider is actually my very favorite TMBG song, but it is very odd.  It’s also among their shortest:

Love it!  This “video” is of course not an official music video, but it did have the version of the song closest to the album version of those available on YouTube.  What’s with the yak/musk ox/whatever?

Ticks by Brad Paisley

I am not ashamed to admit that I am a country music lover.  And I really love country music.  I sing along to the country station at the top of my lungs nearly every time I drive.  When Ticks came out, I was ecstatic!  I bought it immediately and have listened to it at least a hundred times.  It’s got everything to make it a stereotypical country song, but it’s also got the great humorous element that pervades Brad Paisley’s songs:

Ah, Brad Paisley.  Is there anything you can’t do?  The man even sings with Clint Eastwood on his most recent album.  Swoon!

Boll Weevil by Presidents of the United States of America

The album this song is a part of was enormously popular when I was in 11th grade.  I can remember everyone singing Peaches over and over and over again in my math class…  Don’t like that song anymore, but I have always been in love with Boll Weevil.  It’s got a catchy tune and a strange subject matter.  In other words, classic Presidents of the United States of America!

Fireflies by Owl City

This is a current pop song, which makes it unique among the songs on my insect playlist.  I really loved this song when it first came out, but it’s played on the radio WAY too much!  I’m starting to like it less…  But, it’s still a good song.  If you haven’t heard it, I think it’s worth a listen:

I like the rest of the album pretty well too!  It’s fun and easy to sing along to, so it’s great to have along on long car trips.  At least it is if you’re me and sing for 8 hours straight as you drive…  :)

Perform This Way by Weird Al Yankovic

Okay, okay.  We all know I’m a huge geek and, as far as I’m concerned, part of being a geek is loving Weird Al.  I have all of his CDs and I can sing most of the songs all the way through from memory.  My husband even got me an early graduation gift and bought me tickets for Weird Al’s recent concert in Tucson.  I was 6 feet away from the guy and couldn’t have been happier!  This song is not specifically about insects, but there is one part that involves wearing a suit of bees.  Thus, it earns a spot on my list!  Plus, it’s the best Lady Gaga parody EVER!  The video was just released this week:

It is quite possibly the scariest music video I’ve ever seen!  Oh wait.  The Lady Gaga video for Born This Way is way more disturbing…

I’ve stuck to songs that I have on my iPod and actually listen to on a regular basis here, but there are tons of other bug themed and bug titled songs out there!  Anyone care to offer other suggestions?  And be sure to check out Biodiversity in Focus‘ weekly Tunes Tuesday for a weekly dose of insect song goodness!  It’s always got something fabulous to listen to.

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Unless otherwise stated, all text, images, and video are copyright © 2011 DragonflyWoman.wordpress.com

Well-Nigh Wordless Wednesday: Spider and Young

I was involved with a conservation-centered biological survey of a Mexican ranch a few years back and I came across this spider as we toured around setting up sampling sites:

spider with young

A spider - with spiderlings!

I didn’t notice until I looked at the photos later, but the eggs were hatching while I was there and there were baby spiders everywhere.  Super cool – and such a spectacular animal!

(If anyone knows which spider this is, I’d love to know!)

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Unless otherwise stated, all text, images, and video are copyright © 2011 DragonflyWoman.wordpress.com

From the Literature: On Diving Spiders and Physical Gills

I love Twitter!  Since I’ve started using it, I’ve learned more about a wider variety of scientific studies than I ever did before.  It’s a great source of science news!  This story absolutely exploded on Twitter a couple of weeks ago.  I can see why it was so popular though: it’s a super cool story!  Aquatic spiders + special webs for holding air underwater = SCUBA spiders!  This story has it all.  It also happens to be closely aligned to my own area of expertise, so it’s time for another From the Literature!

This adorable little guy is the diving bell spider, Argyroneta aquatica:

diving bell spider

Diving bell spider. Image from http://www.nytimes.com/2011/06/14/science /14obspider.html?_r=1&smid=tw-nytimesscience&seid=auto

This spider is one of the only spiders in the world that spends its entire life underwater, from egg to adult.  Like its aquatic insect relatives, the diving bell spider has a number of adaptations that help it survive in water.  Its respiratory adaptations are especially interesting.  See that sheen along the abdomen of the spider in the photo?  That is an air bubble held in place by specialized hairs that trap air against the body when the spider surfaces.  Underwater, the spider can use that air store to breathe.  In addition to carrying the air film, this species does something truly spectacular: they build special silk webs underwater, fill them with air that they carry from the surface, and then use the air stored in the silk balloon (the diving bell) to breathe!  However, neither the air film carried by the spiders on their bodies nor the air contained within the diving bell are enough to completely satisfy the oxygen requirements of the spiders, so they depend on occasional surface trips to survive.

Scientists have known that these spiders use the diving bell as a sort of SCUBA tank for a while, but many questions remained.  No one knew what the oxygen conditions inside the bubble are, how much gas exchange occurs between the air inside the diving bell and the water outside, or how effectively the diving bell acts as a physical gill for the spiders.  (Please see my post Better Breathing Underwater in Aquatic Insects for a complete description of how physical gills work, why oxygen flows from water into an underwater air bubble, and why these air bubbles do not last forever.)  These unanswered questions drove researchers Roger Seymour and Stefan Hetz to look into the oxygen dynamics of the diving bell more thoroughly.  In the process, they discovered some exciting things about both the spiders and the unique air containers they build!

The researchers did several different things for their study.  First, they measured the volume of empty diving bells and used specialized oxygen detecting equipment to measure the oxygen levels both inside the bells and in the water surrounding them.  This information allowed the researchers to use mathematical equations to determine the potential rate of flow of oxygen from the water into the air bubble.  They also measured the oxygen inside the bubble while the spider was inside to calculate the rate of flow of oxygen from the diving bell to the spider, the spider’s oxygen consumption.  Using these two pieces of information, they could then show how effectively the diving bell acted as a physical gill, that is how long a spider could stay submerged when using a diving bell.  The researchers also measured the oxygen levels within the diving bells when spiders voluntarily returned to the surface  to reveal the oxygen level at which the respiratory requirements of the spiders were no longer met by the diving bell and they were compelled to replenish it with fresh air from the surface.  Finally, the pair measured the metabolic rates of the spiders directly using a respirometer, a machine that measures the amount of carbon dioxide released and/or oxygen absorbed by a biological organism.

Based on the result of all these measurements, Seymour and Hetz revealed several interesting things about the spiders and their diving bells.  First, they showed that the larger a diving bell, the more effectively it acted as a physical gill and the longer the spider could remain underwater.  Not only do larger bells contain more oxygen to begin with, but the flow from the water into the bell as the spider consumes oxygen is greater in larger bells than smaller.  Also, the larger spiders, those with greater oxygen requirements as measured with the respirometer, produced larger bells.  The authors further showed that diving bells easily provided the entire oxygen requirement of inactive spiders in warm, stagnant water (i.e., water with low dissolved oxygen) for over a day.  If the spiders moved around, built or cared for cocoons containing eggs  (cocoons are stored inside the diving bells!), ate prey that they captured, etc, then they had to return to the surface more often.  If they remained mostly still, the diving bell more than adequately provided their respiratory oxygen requirements for long periods of time.  Clearly the bells are acting as highly effective physical gills for the spiders!

Seymour and Hetz also demonstrated that the spiders stay within the diving bells until the oxygen drops d to 5-20% of the original level.  At this point, the bell apparently provides insufficient oxygen for the spiders and they return to the surface to collect air to replenish the diving bell.  The spiders also appeared to enlarge their bells if their oxygen demands increased or if the dissolved oxygen levels in the water dropped.

A few important implications are suggested by the results of this study.  The observations and measurements reported in the study were made in rather unfavorable conditions: warm, still water with low dissolved oxygen.  If diving bells are enough to meet the respiratory needs of the spiders for over a day under poor conditions like these, then spiders may be able to stay underwater nearly indefinitely in cooler and/or flowing waters.  This is important for several reasons.  If you happen to be an aquatic spider, you represent a nutritious meal to other aquatic animals such as fish, amphibians, and large insects.  Minimizing your trips to the surface, and thereby minimizing the attention you draw to yourself, is desirable.  It likely requires a lot of energy to make trips to the surface and back as well, so staying underwater as long as possible may help the spiders conserve energy.

diving bell spider in diving bell with cocoon

Diving bell spider in diving bell with cocoon. Image source: http://www.arkive.org/water-spider/argyroneta-aquatica/image-A12753.html

The spiders are also apparently able to respond to their environmental conditions and adjust the properties of their diving bells to match!  Seymour and Hetz observed their spiders enlarging bells under several conditions.  Spiders that captured prey enlarged their bells and added air to them before they started eating.  Spiders with cocoons also enlarged the bells as the broods inside developed, so the parents may be able to compensate for the increasing oxygen demands of their offspring as they develop by modifying the bell.  Apart from demonstrating how effectively the diving bell acts as a physical gill, I think the most exciting result from this study is that it reveals how these spiders intentionally modify their environment in response to their changing needs.

In summary, the diving bell does act as a physical gill for diving bell spiders as scientists have long proposed.  These bells allow the spiders to stay underwater for a very long time, and the spiders can adjust the bells to match their oxygen requirements and the dissolved oxygen levels of the water.  However, even under the most favorable conditions, the air contained within the diving bell will eventually need to be replenished, so the spiders will always depend on air from the surface and must have access to the surface to survive.

Super cool, right?  Aquatic spiders are amazing enough on their own, but spiders that build little air balloons to breathe underwater are infinitely more interesting!  Because I think it’s helpful to see it, I’ll end this post with a YouTube video (not my own) of a diving bell spider building a diving bell.  (I recommend turning the sound off – it’s got obnoxious music).  Enjoy!

Literature Cited:

Seymour RS, & Hetz SK (2011). The diving bell and the spider: the physical gill of Argyroneta aquatica. The Journal of experimental biology, 214 (Pt 13), 2175-81 PMID: 21653811

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Unless otherwise stated, all text, images, and video are copyright © 2011 DragonflyWoman.wordpress.com

Swarm Sunday – 1/1/11-6/18/11

dragonfly swarm banner

It’s Swarm Sunday!  Things seem to be getting off to a bit of a slow start this year, but I’m hoping the swarming activity will pick up soon.  With all the water that’s been dumped on the US and Canada this year and the flooding happening around the US, I think conditions will be right for a very good year!

I haven’t gotten many swarm reports so far this year, but some of them have come from places far outside the US.  Exciting!  This is what I’ve gotten since New Year’s 2011:

US:

  • Static:
    • Temple Terrace, FL
    • Clearwater, FL
    • East Tawas, MN
    • Center Sandiwich, NH
    • Yuma, AZ (this is exciting for me!)
    • Stacy, MN
    • Howell Township, NJ
    • Hartland, WI
    • Texas, near Galveston and Houston
  • Migratory:
    • Ponce Inlet Jetty, FL
Cambodia:
  • Phnom Penh – static

Australia:

  • Coffs Harbour, New South Wales – static
  • north of Perth, Western Australia- static

Looks like this year is starting out a lot like last year with most sightings in Florida and the Great Lakes region and a few scattered around New England.  I’m super excited that I’ve started getting reports from other countries too!  Australia had a ton of dragonfly activity after a series of summer floods, though most were reported in 2010 and not listed here.  I’ve also got reports from Cambodia, Indonesia, India, Belize, Mexico, and Spain!

Swarming should be picking up here soon, so keep an eye out – and please consider reporting any swarms you see!

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Unless otherwise stated, all text, images, and video are copyright © 2011 DragonflyWoman.wordpress.com