Science

Pesticides Putting The Breaks On Love Lives Of Cockroaches

Environmental pollution affects not only humans and plants but also animals, birds, insects, microorganisms, etc. The effects of environmental pollution ranges from outright increase in mortality rates to even interference in sexual developments.

Let’s examine the case of the humble cockroaches. Yes, we know, cockroaches are a menace and we would rather see them dead than alive. They carry diseases, and their droppings contaminate foods. But pause to think, all creations are there for a reason, from the most complex and dangerous creations (human beings in particular), to the most simple and harmless creations.

Cockroaches are very important part of the food chain as they provide food for birds, arthropods, mammals, etc. Powdered cockroaches are turned into creams to treat burns in China, while cockroach syrup is used in treating gastroenteritis symptoms. Cockroaches also play a role in the nitrogen cycle by feeding on decaying organic matter and by so doing release trapped nitrogen. And because cockroaches are high in protein, we can snack on them! So, you see, the humble cockroach is really useful, and not the vermin we made it out to be.

Cockroaches have sweet tooth (that is just an expression to say that cockroaches love sweet-tasting foods, not that they actually have real teeth like humans!). They just cannot get enough of sugary foods. This trait (habit) for sugary foods was seized upon by scientists to produce sweet-tasting powders and liquids laced with poisons in a bid to control the cockroach populations.

After years of successes in controlling the cockroach populations with poisoned sugary products, evolution kicked in. In a classic case of once bitten, twice shy; the survivors started avoiding sugary things. They passed on the trait to their offspring so that the latter will not touch sugary things with a ten foot pole, even if their lives depended on it! Evolutionary pressure turned the sweet taste of sugar to a bitter taste in the mouths of the cockroaches. This was exemplified by the German cockroach, which is found in every parts of the world except the Antarctica. The German cockroaches no longer go for sugary foods. So, you are not the only health-conscious living thing, cockroaches have also joined the health club!

And just as the human population is affected by health-conscious birth control devices, so also is the population of cockroaches being affected by their newfound healthy lifestyle. The female German cockroaches (Blattella germanica) with an aversion to sugar in the form of glucose, no longer accept mating sugary gift from the males, which is a cockroach nuptial ritual.

In the good old days before pesticides disrupted the cockroach coitus, when a male cockroach wanted to mate with his female counterpart, he has to entice her by offering her a gift – just like humans do! The “loverboy” cockroach will turn his backside towards his “girlfriend”, open his wings and squirt out a liquid from his tergal (posterior) gland, which consists of sugars (maltose and maltotriose), fats (phospholipids and cholesterol), and various amino acids.

For the female to be able to sample this choice meal, it must mount the male. While the lady friend is busy sampling this delicious homemade meal, the cunning loverboy in a flash uses one of his two penises to lock onto her genitalia while the other penis offloads the sperm (i.e. spermatophore). This manoeuvre is known as the double barrel lock-and-pop. Cockroach copulation is not a “wham bang, thank you mam” affair. It can last as much as 90 minutes, depending on the quality of the courtship secretion.

Thus, if the meal is good and the sex great, the two lovebirds can spend time afterwards cannibalising each other’s body parts – the nearest equivalence in humans of such exotic sexual ritual is the “lovebites”. But if the meal is not so good, the female will disengage and scuttle away – reminds you of anyone? In other words, even in the insect world, the rich get more sex while the poor get little or no sex.

What is happening with this new health-conscious German cockroaches, according to Wada-Katsumata and coworkers writing in the May 2022 edition of the journal, Communications Biology, is that the female saliva breaks down the sugary courtship gift to glucose. If you could still remember your secondary school biology (C’mon, your brain is not that old. Even the oldest man in my village at 90, can still rattle off “The process of food digestion” to his great grandchildren!). Anyway, saliva contains amylase and glucosidase enzymes, which breakdown carbohydrates (complex sugars) into simple sugars. The longer your food stays in your mouth, the more time the enzymes have to act on the carbohydrates. A complete breakdown of the carbohydrates in your food into simple sugars, which your body can then absorb, occurs in the stomach (the small intestine, actually). The glucose, converted from the male’s sugary gift by the salivary glucosidase, now tastes bitter in the evolutionarily-conditioned mouth of the female cockroach as aforementioned, and she runs away halfway into the mating manoeuvre.

What a crying shame. But, don’t write off the German male cockroaches, yet. Where there is a will, there is a way. And if you are familiar with the works of the great philosopher, Plato, he famously wrote in his Socratic dialogue, Republic: “our need will be the real creator”; meaning: necessity is the mother of invention. The randy old stoats have devised a way to solve the problem of short nuptial feeding, which results in interrupted and often failed courtship. So, instead of spending ages doing a protracted coitus ritual, they now complete the process in seconds. While the female is suspiciously sampling the goody homemade meal, the male quickly execute the double barrel lock-and-pop manoeuvre in as little as three seconds flat. Now, that’s a lovemaking record if ever there was one.

“I enjoyed that, darling. It was good,” says the loverboy cockroach to his indifferent girlfriend, who by the way is still sampling the nuptial meal, oblivious of what just happened. “Did the earth move for you as it did for me?!” the loverboy asks rapturously, basking in the aftertaste of lovemaking.

Please, when next you see cockroaches, do have pity on the poor rascally things. Their sex lives are already kaput (messed up) without you trying to kill them as well.