Monday, July 23, 2012

Bees and gender in Insects

Male honeybee (drone)

What: I've been thinking more about my last post and the importance of words in relation to our understanding of the world around us. I was telling a friend about the woodchuck that's growing fat off our kale, and how he had gotten the broccoli too. My friend asked how I knew it was a "he" and then pointed out how it was weird that animals automatically and unconsciously becomes "he" when the gender is unknown (I'm always conscious of when someone uses the pronoun "she" in a gender neutral situation). The pronoun "it" lacks so much emotion and humanity, like describing an automaton, so, because we like to anthropomorphize animals (e.g. Bambi), we assign gender to them. I even hear people refer to my bees and egg laying chickens as male.

As a naturalist my first questions are often around identification, particularly with insects. I posted an ID request to the community. John Carr sent a response "It's a female dolichopodidae." Well female is awfully specific, but animal scientific classifications ending in -idae (-aceae for plants) are family groupings, which are pretty general (Curculionidae, the weevil family, contains over 40,000 species). This is from a guy who specializes in IDing midges and their relatives, and he could get gender but only ID down to family. So what was he cuing into that said female and not male? Turns out the answer is more about what makes a male a male.

Female honeybees guarding the hive

Ecological notes: So even with the vast evolutionary divergence of insects into every ecosystem around the world, some morphological adaptations are still conserved or at least have converged. One of those things is a male's ability to detect a female, and they do this in a variety of ways, like hearing, smelling, or seeing females from a great distance. Male mosquitoes, for example, have enlarged antennae to pick up that horrendous and penetrating bzzzzzz sound the females make as they look for that perfect patch of skin. What I'll call foot moths (and cover in a future post) have huge antennae for "smelling" the sex pheromones from females.

Male honeybees, aka drones, have enlarged eyes to spot a queen before other males do. The first picture in the post is a drone; note how the eyes are so big that they actually touch in the middle of the head. The next picture shows a bunch of females at the entrance to the hive, their eyes considerably smaller and not touching on the tops of their heads. Drones are pretty much useless to the colony other than for reproduction. They hanging around feeding on honey, begging for food, and grooming themselves. When the timing is right they'll start going for exploratory flights to breeding sites. These change frequently, so a male needs to be able to spot one from a distance. The story is far more complicated than this, but it's a neat start and I"m tired, maybe more later...

Where: My backyard

Other notes: Ryan Morra and I noticed a whole bunch of female worker bees crawling around on the ground near the hive. I went back with my camera after he left and spotted one a worker dragging another, much lighter colored worker out of the hive. At one point the lighter one started to fly and the other one held on and pulled it back down. Once it got to the edge of the platform the darker one left the lighter one to die on her own. In the middle of summer, this generation of worker bees have the shortest lifespan of just a few weeks (c.f. winter life span can be several months). Kicking out unproductive bees is essential, I guess, to maintaining efficiency.

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