Fight strategy against pests in Lyon
Why did you choose to introduce biological fight methods against parasites?
The botanical garden chose this alternative method in order to respect and protect the environment
with a view to developping a progressive and durable management, refering to the agenda 21
introduced a several years ago by the town of Lyon, and also to the ISO 14001 certification
obtained in 2005.
This strategy is important for the health protection of the individual (public, personal, etc.) but also
for the protection of the auxiliary surrounding flora and fauna.
Over time, we have noticed that the parasites which could be found in our vegetable collections had
developed a strong immunization to pesticide, de facto leading to an overconsumption of
phytosanitary products, which volatile residues could harm the quality of the air and of the
superficial waters (rivers, quiet waters, etc.).
With the biological way, this resistance is made obsolete since the devastating insect is eradicated
directly with predation or parasitism, depending on the entomophagous which are used.
In the botanical garden of Lyon developed a strong immunization to pesticide, de facto leading to an
overconsumption of phytosanitary products, which volatile residues could harm the quality of the
air and of the superficial waters (rivers, quiet waters, etc.).
With the biological way, this resistance is made obsolete since the devastating insect is eradicated
directly with predation or parasitism, depending on the entomophagous which are used.
In the botanical garden of Lyon, the project of integrated fight, confirmed by the elected officials,
was launched by Mr Pautz, the director, at his arrival at the Garden, in 2000. We introduced our first
PBI program (integratted biological protection) in March 2001, considering the different parameters
peculiar to each of our greenhouses (temperature, hygrometry, luminosity, infestions, method of
cultivation, etc.) and by using the current knowledge on anti-parasitic fight to cut down pesticides
doses.
The botanical garden is classified as "ERP " ( établissement recevant du public ≈ establishment
opened to public), therefore, we often work with various schools and other teaching institutions.
Then, this choice was of major importance for a good consciousness raising to "clean" techniques
but also for a better welcome comfort for visitors as the greenhouses have to be open everyday, a
frequency we could not always respect when we still used the chemical method, because of the
treatments and according to the law.
Botanical garden of Lyon
The means
The means include a series of biological, prophylactic, farming, physical and chemical mesures and
also the implication of the staff, a considerable research work, a lot of observing, a collaboration
between different organisms (suppliers, research, etc.) and an appropriate budget to provide for the
achievement of this initiative. The development of all these parameters allowed to become more
efficient as the program progressed.
We can say that with the biological method, risk is a constant threat : will the release of a flock of
auxiliaries be enough to put an end to a pandemic of aphids, mealybugs or others? Nothing is less
certain as biological fight is not an exact science, as Mr Poyet stresses. He nevertheless admits this
risk taking is very interesting and very enriching to understand the mechanisms of Nature and
improve the integrated fight. Currently, biological fight accounts for 80% of the fight against pests
in the botanical garden, sometimes even more depending on the species. Chemical application is
still used on 20% of the garden plants.
The biological control of our various pests is established as follows :
100% for the (biological) whiteflies; no more chemical treatments
95% for the red spiders
80% for the mealybugs
90% for the aphids
80% for the "trips"
50% for the cactus scales
80% for the parasitoids "saissetia"
It would be mistaken to want to eliminate every single pest with biological protection, we must find
the right balance between parasites and auxiliaries in order to preserve the latests. That is why we
defined a threshold of parasitic tolerance providing at the same time good sanitary conditions, the
perpetuation of the collections and the maintenance of the auxiliary fauna.
This threshold of tolerance was defined according to the vegetable showing the botanical garden
wished to develop in the eyes of the public. The assessment of this threshold of tolerance
determines whether we will intervene or not.
We consider the threshold of assessment to be reached when the presence of pests becomes a
nuisance for the aestheticism of the plant without damaging its development. In such a case, the
intervention is entirely biological.
Mexical garden in Lyon
The threshold of tolerance is passed when the presence of pests causes a weakening and an
alteration of the vegetable (pigmentation, bleaching, distortion, defoliation, wilting, shriveling of
the overground parts, growing stop) which could lead to its wasting away.
In such a case, the intervention is biological in most cases, along with a little regulating chemical
application, if necessary, to kill eggs and larvae.
We try to maintain an auxiliary fauna so as to create the same conditions of life of a natural
Indeed, we have known for several years already that the more the biodiversity of a parcel is stable,
the better the ecosystem will know how to "fight" against the intrusion of pests. This notion is
naturally well accepted by the public and strengthened by continuous consciousness-raising
campaigns.
In the future,
The town council wishes to get to the point of using no phytosanitary products at all; it is the special
wish of Mr Boulens, in charge of the different parks.
It will be hard to take up the challenge, but it will be full of lessons for the future generations. The
wish of the town council of Lyon is to control the parasites at first, which is on the right track, and
then to fight against bacteriae and fungi in a biological way. We are looking into the use of phyto-
stimulants in order to strengthen the immune system of the vegetables, which would allow the
plants to fight more against parasites and diseases.
Message to the other towns of France
The shift from chemical treatment to biological treatment has to be done in stages, by setting
ourselves precise objectives. You must develop this strategy in a well-thought out way, where
tenacity rimes with efficiency. Both methods (chemical and biological) are complementary.
Mr Poyet concludes : "It is possible in a town district to run the anti-parasitic fight with biological
means, more and more French towns head for this option.
The biological method accounts for a significant overcharge in a "PBI" program (integrated
biological protection) which is nevertheless justified compared to the advantages it generates in
terms of ecotoxicity.
I think the overall view of the anti-parasitic fight which leads to the approach of the "PBI" cannot
be seen in a black-and-white way, but on the contrary as the expression of an alchemy. And I
believe the integrated fight to be a good example of this."
