Sex on Six Legs_ Lessons on Life, Love, and Language From the Insect World - Marlene Zuk [61]
But time wasted is in the eye, or maybe the pheromone glands, of the beholder. Sure, if the beetles had a more foolproof way to determine who was who, they would have more time to feed, or hide from predators, or do crossword puzzles for that matter (what's a nine-letter word for "life-destroying chemical"?). Similarly, if human beings had pelvic girdles that could more easily accommodate a full-term fetus, childbirth would be a breeze and the militant advocates of natural versus medically assisted labor would have to find something else to clash about. But in both cases, evolution didn't produce the best solution, it produced what worked.
Seemingly maladaptive traits may persist because no genes for a more efficient matchmaking technique or a less painful birth process exist for natural selection to act upon. If a male beetle with a genetic mutation allowing him to sniff out females were to crop up, he might be wildly successful, and in time his progeny would outnumber the old models. Maybe someday that will happen, thanks to the vagaries of genetics. In the meantime, as long as we have chrysanthemums for them to plunder, the beetles muddle along. Alternatively, the trait might represent a compromise between competing selection pressures: you can have a good pheromone system, but then your predators can find you, or you can't perform some other essential task. A more capacious pelvis might come at the expense of walking. If the fetus were smaller when it was born, a solution many of our primate relatives opt for, we'd have babies with less brain power. Ironically enough, entomologists often exploit the pheromones of insects by constructing traps that emit an artificial version of that enticing odor that ordinarily means that romance beckons; when the hopeful suitors arrive, they are summarily dispatched. The lack of sex pheromones in the chrysanthemum beetles makes them that much more difficult to lure to their deaths.
A similar delay in figuring out who is male and who is female occurs in a species with one of the most grisly mating habits in the world, the African bat bug. These insects are related to bedbugs, although as the name implies, they ordinarily suck blood from bats in their caves rather than human beings in their beds. Both insects reproduce not via males depositing sperm in the female's reproductive tract but through a process called, accurately enough, traumatic insemination. The male literally pierces the body wall of the female and leaves his sperm to swim through her body cavity to fertilize her eggs. Males always stab the female's body in the same place, and when they do so their organ must pass through a specialized structure in the females that is unique to this insect group. This structure helps to protect them from the onslaught of bacteria and other nasty material that is introduced into the female's body with the sperm. The bugs seem to be unable to distinguish males from females until rather far along in this process, which means that a certain proportion of the time, males will attempt to mate with other males. Bat bug males, it turns out, also have structures at the wound site that are similar to those possessed by females, although these differ in some anatomical details. Scientists from the University of Sheffield in the United Kingdom who study the insects speculate that the males evolved these structures to signal other males that they are not females, and perhaps even to provide some protection from pathogens in the event that the male doesn't get the message. Here too, selection on males to be profligate with their mating attempts may simply have overruled selection to be more reserved,