Posts Tagged ‘Lepidoptera’

Insect Minute – The Arctic Woolly Bear Moth

Friday, July 13th, 2012

As a kid in North Carolina, many of us grew up with the notion that banded woolly bear caterpillars could be used to predict the severity and length of the coming winter. If the band around the center of the caterpillar’s body was wide, we knew we were in for a winter full of snow days and sledding! I am sorry to report that this is, indeed, a wives’ tale. There can be a lot of color variation within one clutch of banded woolly bear caterpillar eggs and the band width typically grows with age. Disappointed? Me too.

Banded woolly bear - Photo by graftendno1

Never the less, there is a woolly bear caterpillar that does have a very interesting relationship with winter. It is called the Arctic woolly bear caterpillar. Although their names are similar and they superficially look alike, these two are very different. The banded woolly bear caterpillar is in the family Arctiidae and is common in all of North America. The arctic woolly bear is member of the family, Lymantriidae, and is found in the Arctic Circle.  This is where is gets really interesting, folks.

The banded woolly bear has two broods in the summer, the first of which pupates and emerges in the same year, the second will pupate over winter and emerge the following spring. The life cycle is very different in the Arctic. Due to the brief growing season, the caterpillar has to feed for several summers to achieve the critical body mass it needs to pupate. As the arctic woolly bear awaits the coming summers it overwinters as a caterpillar, hiding in a hibernacula, allowing the body to freeze, relying on cryoprotectants, such as antifreeze compounds, to minimize permanent tissue damage caused by temperatures nearing -60°C. When the summer returns the caterpillar thaws, reanimates and returns to feeding. This cycle can repeat up to 14 times, meaning 14 years (!) of freezing and thawing and eating, before it pupates and becomes an adult. However a 1998 study by Morewood and Dean showed that it is more common for the cycle to continue for 7 years before pupation. Still, quite impressive!

Arctic Woolly Bear from Discovery documentary, Frozen Planet

Transcript of Insect Minute 2 – Arctic Woolly Bear:

Hi this is Heather with your Insect Minute brought to you by WKNC and the NC State Insect Museum.
The Arctic circle is an unlikely place to find an insect, right? WROOONG! Insects are everywhere and have adapted cool strategies for contending with harsh conditions. The Arctic Woolly Bear Moth is native to this extreme environment. Upon emerging from its egg, the caterpillar begins to eat voraciously. As summer comes to an end it finds a rock to hunker down on and as the arctic freezes over, so does the caterpillar. When the thaw returns the following June, the caterpillar reanimates and returns to its frantic feeding schedule. The cycle is repeated 7 times, which means this moth lives as a caterpillar for 7 years, freezing and defrosting every year. It survives by producing a kind of antifreeze in its blood which protects vital areas from freezing. In the final year the caterpillar develops into an adult, mates, lays eggs and the cycle for the next generation begins.
If you’d like to learn more about the arctic woolly bear visit the museum’s website at insectmuseum.org where you also find out information about the museum and read our blog where we talk about interesting stuff going on in the world of entomology.

Want to read more?

  1. Morewood, W. Dean & Richard A. Ring (1998). “Revision of the life history of the High Arctic moth Gynaephora groenlandica (Wocke) (Lepidoptera: Lymantriidae)“. Can. J. Zool. 76 (7): 1371–1381. DOI:10.1139/cjz-76-7-1371
  2. ARCTIC WOOLLY BEAR WEBSITE (!!!) – http://www.arcticcaterpillars.org/Site/Arctic_Woolly_Bear/Arctic_Woolly_Bear.html
  3. Bennett, V.A., Lee, R. E., Jr., Nauman, J.S. and Kukal, O. (2003) Selection of overwintering microhabitats used by the arctic woollybear caterpillar, Gynaephora groenlandica. CryoLetters 24(3): 191-200.

Insect Morphology Seminar – foregut & infrabuccal pouch

Tuesday, February 21st, 2012

We began our exploration into the insect digestive system with Ann Carr’s lovely presentation on the foregut and the infrabuccal pouch. The infrabuccal pouch is a very neat structure that evolved independently in three orders: Hymenoptera, Isoptera and Coleoptera. It is basically a pocket in the mouth of an insect, like a termite, where it sequesters and “domesitcates” microbes that are used to aid in the digestion of its food.

What I found most interesting about her presentation is that there is an analogous structure found in Lepidopterans that is used for pollen digestion. The infrabuccal pouch of a Lepidopteran is similar in structure and found in the same area but has one big difference…SPINES!!!

check out this spine in the infrabuccal pouch of a Lepidopteran

These spines help to break down the pollen grains before they move into the foregut. I have been unable to find any publications or anyone that confirm whether there are microbiota in the Lepidopteran infrabuccal pouch. Which raises the question, is this a homonym? Meaning, is this a different structure deserving of a different name or is it a homologous structure? This also leads to our next…READER’S CHALLENGE!!

Can you find a paper that outlines the biotic makeup of the infrabuccal pouch in Lepidoptera OR can you find a paper that supports that this structure should be renamed as it does not serve the same function as the infrabuccal pouch in Hymenoptera, Isoptera and Coleoptera?

The winning paper of the week in our discussion group was, hands down, Keith Bayless with his paper about the evolution of flea-born transmission of bubonic plague in Yersinia pestis. I found this paper so interesting because, even as an entomologist, when I think of the PLAGUE I think of fleas passing it along with very little effort. It turns out that out of 2,000 species only 80 are even capable of harboring plague bacteria and the ones that can transmit the bacteria aren’t even that good at it! The flea only appeared to be excellent transmitters of the plague because they had such a close relationship with their host and could bite them (meaning us!) multiple times thereby increasing the chance of infection. There is a lot more interesting information in this paper and I encourage you to read it!

Other Papers This Week
1. The functional morphology of the honey stomach (aka crop) of the honey bee
2. Cephalotes ants and the special structures they have to harbor symbiotic organisms
3. Pretty cool paper on the proventriculus and the role it plays in the immunity of the tsetse fly
4. Ever wonder how starvation and parasitism effects foregut constriction in the midgut of Manduca sexta larvae? Here is your answer.
5. The contribution of the midgut bacteria of Aedes aegypti in blood digestion and egg production and how antibiotics affect it

Insect of the week – number 99

Friday, December 9th, 2011

Beautiful specimen of Inga sparsiciliella (Clemens, 1864), photographed by kestrel360 in northeastern Tennessee.

Insect of the week – number 92

Friday, October 21st, 2011

Stunning photo of Diaphania hyalinata (Linnaeus, 1767), captured by cwulmer.

Insect of the week – number 79

Friday, July 8th, 2011

Insect of the week – number 72

Friday, May 20th, 2011
moth