Posts Tagged ‘science’

Experiments: They don’t always work!

Thursday, August 26th, 2010

As many scientists know, experiments sometimes (often) don’t work out as expected. You just have to deal with it, because that’s how science works. You record what you observe and come to conclusions based on that. Oh, and if you find a method that doesn’t work, you look for a new one

I learned many things in that experiment back in July. (Yeah, I started this blog post a long time ago, during a frustrating lab experiment.) One very important thing: Tyrophagus putrescentiae eggs disintigrate in 70% ethanol. Important lesson! Next, we tried freezing, since it was extremely difficult to sort through the food in all ten vials  in one afternoon (every other day). Fortunately, freezing worked! Refrigeration probably would have also worked.

Anyway, science does not always go as planned, and you have to adjust to that.

Now I’m running a different experiment. It’s always interesting to find a different organism in your arena, but sometimes it’s hard to avoid. Those moths are sneaky! Fortunately, some of the little snafus aren’t likely to mess up your experimental results. Also, that’s why you use replication.

Okay, those are my musings for now. Any interesting experiment stories?

Jeffers Petroglyphs

Saturday, August 14th, 2010

Today I visited Jeffers Petroglyphs for the first time in years. I grew up in southern Minnesota, so I had the opportunity to visit this historic site a few times as a child and young adult. These petroglyphs are carved into red rock in southern Minnesota.

Some highlights of the trip:

The petroglyphs themselves (of course!)
Seeing the endangered species Prairie Bush Clover
The buffalo rub (shiny!)
Actually getting a guided tour
Throwing an arrow using an atlatl
Seeing prairie again (and pretty rocks! and lichens! Except the lichens cover some of the petroglyphs)
Having an opportunity to learn about a variety of topics
Seeing children enthralled by all there was to learn

There were monarch butterfly larvae in the visitor center, and we just missed watching one spin a chrysalis!We started with the multimedia presentation about the petroglyphs, which noted the importance of bison and showed a few key petroglyphs. After watching the presentation, we began to walk to the tour and got distracted by a large thistle plant with a hummingbird moth, bee and monarch butterfly on it. Plants and insects everywhere!

I don’t think I ever actually got a guided tour the other times I went to the petroglyphs. This included a special manipulation of the sun (using a source of shade and a mirror) to illuminate the petroglyphs. They popped out! A couple of the children were especially enthralled by the figures of the fighting men, one of whom was stabbed in the heart. One part of the site was recently cleared of soil and plants (a small area, but it had several petroglyphs.) There were some very interesting figures. It would be neat to see more of the site excavated to see what other figures lie below the soil! These figures were also easier to see, because they weren’t covered with lichen like many of the earlier revealed figures. (They are currently trying to remove some of the lichen from an area of the rock by placing a tarp over it. This will deprive the lichen of the sunlight it needs to survive.)

The tour guide provided some helpful information, as well as some stuff that really didn’t interest me. (I’m not very interested in the spiritual aspects. I prefer science.) Eventually, we got more onto the topic of science and discussed a lot about plants, animals, and anthropology. I am somewhat interested in cultures (especially ancient cultures and mythology), but what can I say? I am not spiritual and don’t believe in the supernatural.

Several children attended the events at Jeffers Petroglyphs, including the aforementioned guided tour. Then there was a special presentation to introduce children (and adults) to American Indian life (pre-technology). The children intently listened to the guide about the tools, clothes, and games/toys they used, including many things made from buffalo parts! The children were captivated by the presentation, especially since it was hands on and interactive. They got to participate and pretend they were Native American children.

Then the group moved outside to learn how to use an atlatl. A young 6-year-old boy went first and launched the arrow quite a long ways! Children as young as four tried and successfully used the atlatl. I even made a few throws, which skewed to the left, but went fairly far! An 8-year-old girl said she didn’t want to try it, but I could sense it was due to a lack of confidence. I goaded her into trying it and said I’d help her along the way. Well, she did it, we cheered her and she smiled with a sense of accomplishment. Sometimes trying is 95% of the battle.

Then we went to see the buffalo rub–one place where the bison would rub up against, most likely to fight itch and slough off dead skin, extra fur and ectoparasites. Eventually, parts of the rock were polished to a shiny smoothness!

I had mentioned to the tour guide earlier in the  day how much I would love to see the prairie bush clover, since it is threatened or endangered throughout its native range. She found some, including one that was still blooming and made sure to show us. It (Lespedeza leptostachya) looked quite different from its congener round headed prairie bush clover (Lespedeza capitata). Apparently the two have been hybridizing, something which could end up being bad for the threatened species.

All-in-all it was a fruitful day. I’d like to go back again some day, near dusk, where the petroglyphs are best lit. Plus there’s always more to learn!

For more on the trip, read here.

Mold Mites

Friday, June 18th, 2010

As some of you know, I am a graduate student at the University of Minnesota in the Department of Entomology. My focal species, however, is not an insect but an arachnid! More specifically, it is a mite. Here’s an adaptation of an exerpt from the introduction for my thesis proposal:

The mold mite Tyrophagus putrescentiae (Acari: Acaridae), is a stored product pest of economic significance that has been a problem in many types of food. This mite can cause significant damage to grains (Hughes 1976), cheese in cheese houses (Robertson 1952), cured ham (Arnau & Guerrero 1994) and pet food (Brazis et al. 2008). Recently, mites have been found in very large numbers infesting bagged dry (and semi-moist) dog food in grocery stores and other retail facilities. The mites burrow into and consume the kibble, destroying its quality. In addition to destroying food, there is evidence that the mite may be a source of allergens affecting dogs and humans (Brazis et al. 2008).

This mite is weakly sclerotized, which means its exoskeleton isn’t very hard, so it is prone to desiccation (drying out).  The mite collects moisture from the air via supracoxal gland and hygroscopic secretions in order to prevent desiccation (Wharton and Furumizo 1977). High relative humidity (>65%) is ideal for T. putrescentiae survival and reproduction/fecundity. Under ideal conditions mites have a generation time of 12.6 days and a population doubling time of 1.75 days, so they can quickly reach very large densities (Sánchez-Ramos and Castañera 2005).  The areas where this mite lives can be highly variable with regions of high and low humidity.  In areas of high humidity, rapid proliferation will occur when appropriate food sources are available. In areas of low humidity, the mites tend to clump together to avoid desiccation (Sánchez-Ramos and Castañera 2007).

Some other time I will talk more about dispersal behavior, since that will be what I will be studying. I will also be studying more about the effects of neryl formate, the alarm pheromone, which can cause escape behavior!

References & Other Resources

Arnau, J and L Guerrero. 1994. Physical methods of controlling mites in dry-cured ham. Fleischwirtsch 74:1311–1313.

Brazis, P, M Serra, A Sellés, F Dethioux, V Biourge and A Puigdemont. 2008. Evaluation of storage mite contamination of commercial dry dog food. Vet Dermatol. 4: 209-214. doi: 10.1111/j.1365-3164.2008.00676.x

Eaton, M and S A Kells. 2009. Use of vapor pressure deficit to predict humidity and temperature effects on the mortality of mold mites, Tyrophagus putrescentiae. Exp Appl Acarol. 47: 201–213. doi: 10.1007/s10493-008-9206-2

Hughes, A M. 1976. The mites of stored food and houses. Technical bulletin of the ministry of  agriculture, fisheries and food 9, Her Majesty’s Stationery Office, London. 400 pp.

Robertson, P L. 1952. Cheese mite infestation: an important storage problem. J Soc Dairy Technol 5: 86–95. doi:10.1111/j.1471-0307.1952.tb01555.x

Sánchez-Ramos, I and P Castañera. 2005. Effect of temperature on reproductive parameters and longevity of Tyrophagus putrescentiae (Acari: Acaridae) Exp Appl Acarol 36: 93–105. doi: 10.1007/s10493-005-0506-5

Sánchez-Ramos, I and P Castañera. 2007. Effects of relative humidity on development, fecundity and survival of 3 storage mites. Exp Appl Acarol 41: 87-100. doi: 10.1007/210493-007-9052-7

Wharton G W and R T Furumizo. 1977. Supracoxal gland secretions as a source of fresh water  for Acaridei. Acarologia 19: 112–116.

Darwin Day!

Tuesday, February 2nd, 2010

There is a petition to make February 12th Darwin Day. You should all go sign it here.

Scientists and non-scientists around the world (rightfully) appreciate the work of Charles Darwin. He is an important historical figure, and it is about time he is more formally publicly recognized. We need to show a greater appreciation for science and the discoveries the process has made possible.

Now all you apes go and sign the petition!
Also, remember that science isn’t a belief system. It’s a method of learning and discovery.

Spread the word to let Obama know that we want a scientist in the spotlight.

Good night to my fellow mammals.