Physiology of a hatch? (or, Bug Sex, Death & the Flyfisher)

[nightfish]

Hey guys,

As I was at work tonight, the Decker hatch had Callibaetis resting all over my desk, the walls, the lights, pretty much everywhere. One of the things I've noticed about these bugs...as they rest, they almost always point the same direction...on the walls they're all head up, but on flat surfaces, they seem to prefer the view to the north. Weird, but true. Interesting.

But what I spent a good deal of the night wondering, is what exactly is the physiological process that causes a nymph to rise & emerge, then molt to the spinner stage? Is it more than the correct light, position of the sun, temperature or season? Is it a hormone that an immature bug hasn't yet started to produce that keeps the hatches to their clock?

And, what exactly happens, physically, as a dun molts to a spinner? Are the clear wings & longer tails the inner part of the dun structure, guy bugs polishing their wings (gotta have a clean ride for the Prom!), gals fussing with the curl on their tails, or are new sets grown for the Big Dance?

[Teewinot]

Nick -- I'm sure we could find you some good sleeping pills if that's what you need.

[jdubya]

NF, there probably isn't that much work done on mayfiles per se, but there have probably been a few hundred thousand articles published on those questions using the fruit fly, drosophila, as the model system. these guys are clearly affected by light cycles, temperature, humidity: the internal clocks set off cascades of hormones and other chemical mediators that do the kinds of things you are describing. The cool thing about fruit flies is that you can easily engineer mutations in them and then look for the response in the fruit fly. some of these can be lethal such that the fly does not progress past a set point (like a birth defect) while others provide for an adult fly albiet with a few difficulties.

one of my fav's of the latter type is called "ken doll": no obvious external genitalia!!

if you really want to get into these kinds of questions, i can help direct you to some info source but it does get deep (i.e., how many angels can dance on the head of a pin) in a hurry. But you have paid for most of the research thru your tax dollars so there you have it!

[Ouzel]

For some lighter reading you might try 'Western Hateches' by Haffel and 'H'; can't remember their names. In addition to being a helpful guide about hatches it does give some background about how this comes about.