Tuesday, January 16, 2018

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

A reposting of an article by Rachael Pahl on January 26, 2015.

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

1 comment:

  1. Bedbugs are ever unwanted in households and commercial premises. Bedbugs will infest readily and if not controlled in enough time, will continue to wreck havoc reaching high level infestation which may be complex to eliminate completely….
    Bedbugs! These insects invade homes and wreak havoc wherever they will intentionally attack. Effective bed bug control may seem impossible when it comes to a high level stubborn infestation, but there must be light at the end of the tunnel to eliminate these small, pesky pests.
    Bed bugs are tricky bugs. When they get into a home or business, they can get into hard to reach locations, not just your beds. These insects can dwell in outlets, wall voids, electronics, behind baseboards and anywhere close to resting and sleeping human sites. They can also be deep inside upholstered furniture or under rugs unsparingly. The trick to beating these hitch hiking, tricky bugs is understanding their habits and habitats. Bedbugs are for sure are real nuisance. Bedbug infestations seem to be increasing around the world at an alarming rate not even being threatened by available control measures, possibly due to insecticide resistance. Resistance to pyrethroid insecticides is already widespread in the whole world. The bedbug infestation occurs in aggregations when conditions are favorable, but the arthropods disperse when conditions are unfavorable. Active female dispersal can potentially lead to treatment failures and should be taken into account when using control methods.
    New tactics against these bugs are needed for this escalating public health concern in locations with high occupant turnover, such as hotels, hospitals, and nursing homes. Indeed, in the past decade bedbugs have become a worldwide urban pest, with the number of households affected markedly increased.

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