A recent lecture on pheromones and their use in mating disruption in vineyards inspired the following personified explanation :
(A photo of a pheromone emission device that I took at Pinord Priorat last summer)
It’s the reason dating websites, with their elaborate algorithms, have been created and received with such great success. It’s every single sexually mature adult’s nightmare, and such fear is further instilled in us every day by the myriad of messages received from the popular media. It sounds like an episode of How I Met Your Mother.
“What if I don’t find the one?”
Imagine. You walk into a bar in, say, New York City, or the booming metropolis of your choosing. The number of eligible young singles astounds you.
You are attracted to one gorgeous specimen in particular so you decide to approach, despite your state of overstimulation that borders on overwhelming. (S)he turns you down quickly. No worries, there are plenty more fish in the sea, especially tonight, where the sea seems to be more of an overcrowded fishbowl. You continue your quest…
Scene change. 2 years later. You’re at another party, like the last, still single, still on the hunt. It seems like your number missed opportunities has increased exponentially. It’s beginning to paralyze you. There are just too many out there, the chances of finding the right one are too slim. Are all the random encounters even worth it, if nothing seems to last? And the clock is ticking, you hate to admit it, but you know it is. Which each passing day the wrinkles are appearing, you are certain that your appeal is diminishing little by little. Not to mention the biological clock… all your friends are on their second child by now… is it too late?
I’ll stop there so as not to depress anyone. This is precisely the state that we induce in the technique known as mating disruption or sexual disruption, one of the primary, most environmentally friendly, and most effective forms of combat against the dreaded Grape Berry Moth. These pests have both a direct impact on the berries, which they feed on producing little holes (primarily an aesthetic problem, not so much of a concern in wine production). These holes provide an open channel into the sugary innards of the grape, a perfect pathway for fungi, especially Botrytis cinerea, which causes grey mold, a major grapevine disease.
So what to do? Instead of attacking the moths once they are born, why not prevent them from successfully mating?
Enter the technique of mating disruption. Small plastic devices loaded with female moth pheromones are distributed throughout the vineyard, with 2 primary modes of action.
First, a high concentration can be used to create a sort of “pheromone fog”, where the males are so overstimulated by the pheromones in the air that they can’t orient themselves to find females at all… a bit the initial case of panic felt at the first evening described above.
The second approach uses a higher number of emission sources (>1000/hectare vs ~500/hectare in the first case) with a lower dose of pheramones in each. Here’s the really scary situation – the males waste so much time and energy trying to mate with the plastic pheromone emitting devices that by the time they find a real female, their fertility has vastly diminished and the success rate of matings is destroyed.
Sad? Yes. Frighteningly reminiscent of the typical dating scene? Possibly.
But the technique is highly effective, especially when all of the producers of a given area combine their efforts to use it, and growing in popularity. There are no residues, less energy used than with spraying (no tractor or sprayer necessary), and the only negative side effect for the grape growers is that he might attract a bunch of male moths after installing the devices.
Sorry Mr. Moth…