dimanche 18 juin 2017

107- Natural vs synthetic -5- Pheromones

NATURAL VS SYNTHETIC - PHEROMONES

In the late 1980s, I was a young fruit production advisor in the South-East of France for a specialized technical group, the GRCETA of Basse Durance.
After the group was contacted by an Australian company, I had the opportunity to participate in the first trials to test on a large scale the protection against oriental fruit moth (one of the most dangerous pests in this area) by pheromones, with the technique called sexual confusion. This Australian company was trying to test its diffuser and its pheromone under conditions of high pressure of the pest. Logically, it wanted to do it in the region internationally known as the most problematic one.


You have to know that at that time, the oriental fruit moth turned into a real nightmare for peach growers in the region. The pest populations were extremely high. There were some problems with the loss of efficiency of the usual insecticides, forcing farmers to do frequent pesticide interventions with insufficient levels of efficiency, hence both technical and economic problems. At the time, there was virtually no mention of the environmental consequences, but from the current perspective, it is scary...

The fact is that this Australian company came up with this innovative technique, plunging us into an abyss of reflection, and doubt.
Imagine thirty years ago, the proposal to solve a critical problem of insects without insecticides. For us, advisers, in whom the farmers of the group sometimes blindly confided to help them to solve their problems, it seemed insane. We were very motivated by the innovation, but sincerely, given the seriousness of the situation in some areas, we were also very suspicious.
The experimental zone was chosen in a concrete area of ​​Provence which was in such a critical situation with regard to the oriental fruit moth that some farmers began to consider a conversion of crops when faced with the impossibility of controlling the damage.


After a whole season of experiments, the farmers' surprise at the results was pleasing to see. Without being wonderful, they were superior, without insecticide, to the enhanced program that they needed to implement, and that included more than 15 chemical sprayings.
After two years of testing, the conclusion was that to resolve a much degraded situation, it was necessary to go through a first phase that combines chemical protection with sexual confusion, enough time to reduce the level of infestation (1 to 2 years). From this moment, confusion alone is enough to avoid the damage.
At that time, as a technician participating in the tests, I always had a number of diffusers in my car in order to be able to replace one, or to complete a dose in a difficult place. The consequence?
I was pursued every day, both in the car and outside, by a wild horde of oriental fruit moth males, persuaded that I was the princess of their dreams...


Pheromones are natural substances, emitted by living organisms to transmit information to their conspecifics.
Their role is well known in most animals, and in some plants.

These are generally volatile compounds, produced by exocrine glands. Unlike hormones designed to be used internally by the body, pheromones are produced to be released outside the body to transmit a message or signal to individuals of the same species. Their role in the sexual reproduction of insects is well known and has been the subject of numerous studies.
It is thanks to sexual pheromones that, for example, Lepidoptera (butterflies) male are able to locate females, allowing them to mate and continuity of the species.
Each insect has its own "aromatic bouquet" in order to attract individuals only from its own species.
In addition, pheromones have different types of roles such as sexual attraction, alarm, aggregation, territoriality, and exist in almost all animals, even in humans. Bees use them to indicate flowering areas, ants to mark their paths, dogs and cats to mark their territory, humans in situations of fear or sexual desire for example.
They can also be found in products designed to calm or repel dogs or cats, or even to make you irresistible in a night club.


The principle of the technique of sexual confusion is thus the following one.
The pheromone contained in the diffuser is the same as that emitted by the oriental fruit moth female so that the male is able to find it, and thus can mate. The diffuser is made of a porous plastic which allows a progressive diffusion of the pheromone for several weeks.
In nature, a female emits the pheromone that is carried by the air. The male receives this olfactory message through a specific receiver and follows the trail until it finds the female.


The technique of sexual confusion consists in distributing a large number of diffusers in the cultivated plots. In this way, the points of emission are so numerous that the male is practically unable of finding the female.
The mating is disturbed, the reproduction does not take place, so the insect is no longer a problem for the farmer.

Traditional protection involves killing existing insect pests to prevent them from breeding and causing crop damage.
Sexual confusion means preventing insect pests from being able to reproduce. They are therefore not present in the crop and don't cause damage.
This is a profound change in the concept of crop protection. It is a technique of prevention of the damage.

So we have a technique that works well, and that avoids the application of chemicals on the crop. It should be noted that pheromones are used in agriculture in at least 3 different techniques:
Sexual confusion, which consists in diffusing a very large quantity per hectare, so as to disturb the males in their system of approximation of the females, drastically reducing the possibilities of mating and therefore of reproduction. Pest populations decline "naturally", and consequently, damage to crops.
Monitoring trapping, which consists of placing a few pheromone traps on the farm, in order to capture individuals and to monitor populations (beginning of flights, peaks of flights, time of hatching and risks). This technique, the first historically speaking, to use pheromones, makes possible to locate with a great accuracy the exact moment of intervention with insecticides, synthetic or natural. That was one of the foundations of Integrated Production.


Mass trapping, which consists of placing traps with a large quantity of pheromones, in a reduced number per hectare, in order to capture a large number of individuals, thus reducing the pest population without applying pesticides. This technique is much used with food attractants, more than with pheromones.

The technique of sexual confusion has developed considerably and is now used to protect crops, especially in vineyards and orchards, against mainly lepidoptera, diptera, hymenoptera and beetles.
Obviously, the technique was very quickly authorized in organic farming. It is logical, a technique that allows effective protection without using pesticides, neither synthetic nor even natural, deserves attention.

But in fact, these pheromones, freed in large quantities and permanently, where do they come from?
No, there are no swarms of worker pressing on the abdomen of billions of female butterflies to draw a microdrop of pheromone each time.
It is chemistry, pure and hard.
These pheromones are synthetic, precise copies of natural ones, derived from chemistry, naughty chemistry.
They are then enclosed in plastic diffusers, also derived from the naughty chemistry.

But can these synthetic chemicals, released into the air from crops, reach the food?
Without any doubt. My personal experience of the 1980s has amply demonstrated that these pheromones are deposited on everything around them. Otherwise, I would not have been pursued by all these confused and excited males!
Their effect is fleeting, it is true, but the reality is there.

So, would organic agriculture allow large-scale use of synthetic chemicals that come into direct and permanent contact with food?
Well yes, absolutely.


However, the gravity of the case must be put into perspective. These are synthetic products, yes, but they are exact copies of natural molecules.

As in the case of azadirachtin, right?
For azadirachtin (and you will soon see that this is not a unique case), the copy of the natural product is refused because it is synthetic and therefore incompatible with the ideology of the organic, despite all the technical and environmental advantages in relation to the extraction and use of the original natural substance.

Except that this prohibition of principle, questionable in itself, but consistent with organic ideology, is not always applied. There are situations where a breach of the rules is possible.

Note that the consumer of organic products, ultimately the engine of the system, is not aware of these changes in the rules of the game.
The information it receives remains the same. No chemistry in organic production.
But what would he say, the organic consumer, convinced that there is no chemistry in the organic production, and that he really takes care of his health and the planet, if he learns that they lie to him every day, that he is jobbed by those same people in whom it has placed its confidence?

Is this a double standard?

It must be recognized that agriculture is not easy, and that crops must be well protected from diseases and pests, even in the case of organic products. And if there is no organic solution, we will find one, almost organic. We should not lose the market.
This is not sexual confusion, it is intellectual confusion.

Picture: http://www.vitisphere.com/upload/breves/1442481694_g1.jpg

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