The role of pheromones in the insect world
He decided to use Mayer’s VNO cauterization technique on her rats. She closed the female rats’ VNOs and brought in the males. Even close contact with the males and their urine failed to in...
He decided to use Mayer’s VNO cauterization technique on her rats. She closed the female rats’ VNOs and brought in the males. Even close contact with the males and their urine failed to induce ovulation in the females whose VNOs had been closed. This discovery showed a link between the animal VNO and the mammalian 7 reproductive system. It was, Johns told us, “a thrilling discovery.” Her finding is now referred to as the Johns Effect.
The role of pheromones in the insect world had been investigated nearly two decades before Margaret Johns discovered the importance of the rat VNO in the late 1970s. In 1959, German organic chemist Adolph Butenandt identified the female silkworm moth’s sex pheromone, the airborne substance that attracts male moths to her at mating time. He called the pheromone bombykol, a label derived from the moth’s Latin name, Bombyx mori. Learn more at http://astrobiosociety.org/category/pheromones/
Butenandt accomplished his task by first gathering more than half a million female moths. From there he began the delicate My process of extracting the pheromone from the moths’ abdomens, where it is produced in specialized glands. All told, _ the moths produced less than 7 milligrams of bombykol, but that was enough for the study of the pheromone’s molecular structure.
The female silkworm moth can release ten—billionths of a ' gram of bombykol every second. When a male moth is exposed to the pheromone, he beats his wings, a sign that he is excited. 4 So potent is bombykol that male moths, which can detect as few 4.5 as one or two molecules of it from significant distances, can follow the female’s pheromone trail for miles. Such long-distance communication also occurs among other insects whose pheromones are considered to be some of the most biologically active compounds ever documented. Extreme volatility of pheromone molecules (meaning they are easily evaporated) translates into detection at incredibly low levels). However, the moth is unbeatable at sensing minute wafts of pheromones.
Looking for Love
Pheromones can improve the reproductive success rates of a number of animals. One study performed by scientists at Damascus University examined how a pheromone extracted from the wool of rams could improve the reproductive rates of adult merino mutton ewes. The researchers found that females treated with ram pheromones experienced enhanced ovulation. They also conceived more readily and showed significantly improved birth rates, and their lambs were healthier.
The examples that follow are designed to show you the scope of “love” pheromones in the animal world. While there are many more examples to relate, each of these serves to illustrate how pheromones work in courting and mating rituals.
On the Fly
Researchers have found that the male fruit y’s semen contains pheromones that can do a number of things to affect and even control the female's reproductive cycles, from inducing her to ovulate so that his sperm, and not another y’s, will fertilize her egg, to quelling her urge to copulate so that she will have less desire to mate with another male. These “anti-female” pheromones improve the odds that the male’s sperm will make It to the female's egg, thus ensuring that his progeny will live to carry on the family line.
Certain genetic strains of female fruit flies exude an intoxicating pheromone that makes the spindly-legged males weak at the knees. The chemical makeup of the female’s essence, which resembles oil of citronella (another powerful magnet for the male), attracts him instantly.
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ABOUT THE AUTHOR
Alexander P is a blogger who studies pheromones.