Written by Joe Ballenger
This is a really good question, for a number of reasons. There are sources which claim that male insects don’t contain sex hormones, but as far as I can tell, this goes back to a 1995 paper where a group of scientists weren’t able to replicate the results of a 1966 paper which explored this topic.
The literature is mostly agnostic on the topic of male sex hormones. Because female insects are the targets of most pest control efforts, more efforts have been put into controlling female reproduction than male reproduction. It’s still important, though, because the newer pest control tactics (like SIT) depend on manipulating male reproduction.
So even in graduate school, it kind of surprised me that this topic isn’t better studied.
We’ve talked about how insects produce male and female insects, and I’d refer you to these posts for an idea of how that works. Instead of talking about how bugs make boys and girls, this post will be about how the boy and girl parts get booted up so they can begin making babies.
Awhile back, Nancy wrote a post about what happens when an insect turns into a cocoon. She also made a video about insect physiology that talks about what happens when an insect molts, and what happens when it turns into an adult.
There’s a lot of hormones involved, which are explained in Nancy’s video. Briefly, a hormone called Juvenile Hormone (JH) keeps the insect from turning into adult. Another hormone, 20-hydroxyecdysone (20-E), tells the insect to shed it’s skin. These hormones are conserved throughout insects; all insects use these hormones in the same way. This is a very important system, and is essential for understanding how insects turn into adults.
In order to discuss insect sex hormones, however, we need to forget all about what happens in the larval stages. Adult insects have hormone systems which are completely different from the larval insects. In essence, adult and larval insects are completely different animals.