The Bed Bug’s Piercing Penis (A Guest Post)

By Rachael Pahl

Sex is a dangerous, but necessary, part of life. Across the animal kingdom, there are a multitude of things that can go wrong. You could be injured in a fight by someone who wants to steal your mate, or maybe your partner eats you because you’re taking too long. Either way, nature must have a pretty good reason for the traumatizing effects of sex.


A male bed bug traumatically inseminates a female. Image by
Rickard Ignell at the Swedish University of Agricultural Sciences
posted at Wikimedia Commons.

Bed bugs have a particularly risky way of having sex. When a male bed bug wants to mate, he will pierce the female’s abdomen with his penis (called a lanceolate) and release sperm directly into her body cavity. Talk about forceful! This mode of reproduction in bed bugs is known as traumatic insemination; aptly named.

With what seems like a horrific way of reproducing, it’s hard to imagine that there are any benefits for the female. I’m sure you can come up with a plethora of things that could go wrong: infection, damage of major organs, bleeding, even death. Researchers Ted Morrow and Göran Arnqvist with Uppsala University in Sweden, argue that the female has a counter-adaptation to this antagonistic strategy. The area of the abdomen that the male pierces has been modified into a pocket lined with specialized tissues to prevent serious damage to the female. This area is termed the spermalege. Edward and Göran hypothesized that sex is not harmful to the female if the spermalege is punctured, but can be dangerous if any other area is pierced. They also hypothesized that more mating occurrences and improper punctures would reduce the lifespan of the female.

To test their hypotheses, Edward and Göran observed the number of times a female was inseminated and where she was pierced (on the spermalege or somewhere else). They had two set-ups to observe mating rate: (1) a female was placed with four males where lots of mating would take place and (2) a female was placed with four males, three of which had their penis glued to their abdomen so that they could not mate. These two set-ups allowed the researchers to observe the differences in female life span between those who had a high mating rate and those who had a low mating rate. Then, the researchers wanted to see where the female was being pierced and how that affected her life span. In addition to traumatic insemination by male bed bugs, the researchers used a pin to pierce the spermalege or an area outside the spermalege and then compared the damage.

The study produced two big results. First, females who mated more had a shorter lifespan than those who mated less. This was because the sperm and other fluids deposited caused an immune response as they were seen as foreign objects; too much of these foreign substances can have negative effects on the organism. Second, females that were pierced through the spermalege lived longer than those who were pierced outside the spermalege, suggesting that the spermalege functions to reduce damage and/or infection during insemination.

So what are the benefits of traumatic insemination and how does the spermalege reduce the costs to the female? Well, there is a lot of paternal ambiguity in the animal kingdom. The direct deposition of sperm into the abdomen may ensure paternity by getting the sperm as close to the ovaries as possible before another male bed bug can mate with her. This method also reduces courtship time and avoids female resistance, meaning that other males may not have the chance to steal the female away. The spermalege protects females from traumatic insemination by localizing damage to one area that can easily repair itself. Since the spermalege is lined with cuticle, it prevents the leakage of blood and sperm from the wound. The spermalege may also function to prevent entry of pathogens into the bloodstream. In the end, this traumatic insemination is no more dangerous than any other kind of sex, however painful and horrible it sounds. It may even be less risky if done correctly.


For more information, check out:

Morrow, E., & Arnqvist, G. (2003). Costly traumatic insemination and a female counter-adaptation in bed bugs Proceedings of the Royal Society B: Biological Sciences, 270 (1531), 2377-2381 DOI: 10.1098/rspb.2003.2514

Why You Can’t Hibernate the Winter Away

You open your eyes, slap the alarm, and pull the covers a little tighter around your shoulders. It’s still dark outside and you dread the moment that you step out from under the warm comforter and the cold sucks your breath out. Can’t you just hibernate and sleep the winter away?

A dormouse in his snuggly hibernation state.
Image by Krysztof Dreszer at Wikimedia.

Actually, no. Hibernation and sleep are two completely different physiological processes (shown by studies of brain function). And chances are, you don’t have the physiological bits needed to hibernate safely.

Hibernation has more to do with energy and body temperature than it does with sleep. Hibernation is defined as a process in which an animal allows its body temperature to approximate the environmental temperature for several days or longer. It is a strategy that some animals use during periods of food shortage to conserve the energy that would normally be used to generate body heat. When food is scarce in the winter, the animal will lower its metabolism (the burning of food molecules to create energy and heat), which will result in the animal having less energy (and entering a sleep-like state) and less heat (until the body approaches the environmental temperature). So really, hibernation is the reduction of metabolism when food is scarce. Lack of activity and cold body temperatures are just the by-products.

Almost all species that hibernate are small mammals, including some hamsters, dormice, jumping mice, ground squirrels, marmots, woodchucks, bats, marsupials and monotremes. Bears, common examples of hibernating species, are actually debated by scientists as to whether they should even be considered hibernators due to the fact that their metabolisms and body temperatures do not decline as much as those of other hibernating species. The only bird species known to hibernate is the poorwill.

Each hibernating species has a specific range of body temperatures that their body can endure. Their first line of defense is to find a hibernaculum (a chamber or cavity in which to hibernate that is more insulated than the exposed environment). If the hibernaculum becomes so cold that the animal’s body temperature drops below its minimum endured range, it will either increase its metabolism slightly to raise its body temperature or it will arouse (wake up). Arousal is the process of increasing metabolic heat production to near-normal levels. All hibernating species seem to undergo multiple periods of temporary arousals during hibernation and scientists are still unsure why. Increasing the metabolism and body temperature from lower levels is an energetically costly process (similar to how your car uses more gas to accelerate than to maintain a higher speed). In most hibernating species, the process of increasing the metabolism uses a specialized tissue called brown fat.

Fat cells come in two main types: white fat and brown fat. White fat, the squishy stuff that we constantly try to diet and exercise away, is filled with lipids (fats) that we store to generate energy in the future. Brown fat cells also contains lipids, but they are specialized to break them down faster. Brown fat is found in newborn mammals and adult hibernators and is commonly located on the upper back, neck, chest and belly (like a vest) and around major arteries. Brown fat cells have lots of mitochondria (the metabolic parts of the cell that break down food molecules like lipids to generate energy). Brown fat mitochondria is specialized in that they have a protein called uncoupling protein 1 that causes them to generate heat rather than energy when they break down lipids. When the body becomes stressed, it releases norepinephrine, a stress hormone, which causes brown fat cells to increase the rate at which they break down lipids to generate heat. This heat warms the major arteries and increases blood flow, which then distributes the heat throughout the body.

A PET scan shows brown fat in a human.
Image by Hellerhoff at Wikimedia.

Although humans are born with a fair amount of brown fat, we lose it as we age. More specifically, it converts to white fat. We used to think that we lost it completely, but in recent years we have learned that some lean adults maintain a few pockets of brown fat in their necks and chests that obese people are more likely to lose. Researchers are currently exploring if and how we can convert some of our adult white fat to brown fat in order to increase our metabolisms and potentially combat obesity and diabetes.

So for now, we can’t hibernate the winter away. But continuing research into hibernating animals may hold an important secret to our own health.

Collective Personality and Our Environment

We are all familiar with the concept of the personality of an individual. We are less familiar with group- or collective personalities (although most teachers can tell you at length about the personalities of each of their classes). The concept is the same: whereas an individual personality relates to an individual’s consistent behaviors across time and contexts, a collective personality relates to a group’s consistent behaviors across time and contexts. Collective personalities can be strongly influenced by the composition and size of the animal group, but also by the environment.


A social spider web by Harvey Barrison at Wikimedia Commons.

This week at Accumulating Glitches I talk about how the environment influences group personalities in social spiders. Check it out here.

And to learn more, check this out:

Modlmeier, A., Forrester, N., & Pruitt, J. (2014). Habitat structure helps guide the emergence of colony-level personality in social spiders Behavioral Ecology and Sociobiology, 68 (12), 1965-1972 DOI: 10.1007/s00265-014-1802-z

Caught in My Web: Ants as a Liquid, Beautiful Bees, Ant Zombies, Tumbling Spiders and More Insect Oddities

Image by Luc Viatour at Wikimedia.

For this edition of Caught in My Web, we explore all kinds of creepy crawly weirdness.

1. Ant colonies have the amazing property of being able to act both as a solid and as a liquid. IFL Science! and the New York Times highlight how the physics of ants can inspire the production of self-healing structures.

2. From Wired: This fly species invades ant brains… then pop their heads off!

3. This Moroccan spider tumbles away from danger, likely crippling the predator with laughter:

4. National Geographic shares some of the most beautiful images of bees that you will ever see.

5. This TED insect playlist includes 11 talks on everything from firefly love to robotic insects.

How To Get Into An Animal Behavior Graduate Program: Deciding Where to Apply

Is the idea of grad school stressing you out?
Image by freedigitalphotos.net.

If you are contemplating applying to graduate school in scientific research, the choice of where to apply can feel overwhelming. Each scientific field can be broken down into countless sub-fields. Each sub-field has countless researchers studying countless topics. How do you know which to choose? What if your choices pigeon-hole your career before you even get it off the ground? What schools have the best programs? What if the schools I choose are too competitive for me to get into? Although these are legitimate concerns, choosing graduate programs to apply to doesn’t have to be so stressful… and it can even be fun.

As with most everything, the earlier you start your planning, the less stressed you will be when the time comes to act. As soon as you realize that you are considering graduate school for research, start a list of possible labs you may want to work in. This list should include: possible mentors, the universities and departments they are affiliated with, the topics they study, and the techniques they use. Later, as you start to narrow your list, you may also want to include information such as: where the school is located, financial support offered, the minimum GPAs required, test scores required, courses required and application due dates.

For many of us scientific researchers, the realization that we wanted to pursue research as a career came from the inspiration we got from discovering a particular study or scientific story. The source of your inspiration is a great place to start. Look up the study that inspired you and other similar studies by some of the same authors. Often, the head of the research lab (called the Principal Investigator or P.I.) is the last author listed in the research paper. The paper should also mention what university and department each author is affiliated with. Now, armed with names of researchers and schools, start web-surfing and filling in the details on your list. If you find other interesting papers, researchers, or schools, allow yourself to follow the leads and add to your list. Keep an open mind during this stage: Most researchers study a range of research topics that they often list on university-affiliated or personal websites; If you are interested in animal behavior, you could pursue a degree in Animal Behavior, Biology, Zoology, Ecology Evolution and Behavior, Psychology or even Neuroscience; And try not to eliminate any programs based on geography unless you know in your heart that if it were the only program to accept you that you still would not go. By the end of this process, if you have a list of 15-20 possible labs to apply to, you should be in good shape.

Once you have a list of possible labs, it is time to narrow down your list to the 6-12 labs you will actually apply to. Here are some factors to consider:

1. The most important factor in graduate student success is whether you can work well with your advisor. Some labs will list current or past lab members on their webpages. If you can find email addresses, email some lab members to get their opinion of the P.I.’s abilities as a mentor. You can also ask faculty members at your university or use social media sites such as Facebook or LinkedIn to find out if any of the potential advisors you are interested in has a reputation.

2. Look up each researcher’s publications and webpages to get a sense of that person’s past and present research topics. Obviously, it is important to find a research topic that can keep you interested for the 4-8 years that it will take you to complete your degree. If you are considering a career in academia, it is also important to consider the techniques that you may learn from a lab. Unfortunately, animal behavior research techniques alone are not very marketable to research labs looking for a Postdoc or Research Scientist, in part because it is hard to obtain grants for studying animal behavior alone. A combination of animal behavior techniques with techniques in physiology, ecology, or evolution will make you much more employable when you complete your degree.

3. The rank or reputation of the school may contribute to your marketability when you complete your degree. There are some reputable graduate program rankings, such as U.S. News and World Report’s annual ranking of schools. Their ranking of graduate programs in biology can be found here. You can also get a sense of a school’s reputation by the number of publications from faculty in the program in a given year. Again, faculty at your current school and social media sites can be helpful with this insight as well.

4. Most graduate programs in animal behavior offer financial support in the form of teaching assistantships (T.A.s) and research assistantships (R.A.s) that cover tuition, healthcare, and provide a stipend. However, the availability, pay, and time commitment of these positions are not always equal. Contact the departments you are interested in to find out what kind of financial support they provide to their graduate students and how reliably available the positions are.

5. The location of the school may be important to you, as you will live in this place for the 4-8 years that it takes you to complete your degree. However, you won’t get out much once you start your program, so it really doesn’t matter where you are anyway.

6. If you are concerned about your GPA, GRE scores, or lack of coursework, you can sometimes find minimum requirements for a program on their website. You can also call departments and ask.

Good luck and have fun with your list!

And for more advice on applying to graduate programs, go here.