How to fight against the Japanese beetle? The example of Ticino

The Japanese scarab is the size of a five -cent piece.Image: DPA

Small. Meanwhile, extremely voracious, the Japanese beetle was detected for the first time in the Lake Geneva region at the end of July. However, In Ticino, the authorities have been fighting against its expansion for several years. Moreover, Here’s what they learned.

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It is barely the size of a five -cent piece, but the damage it causes can be considerable. Furthermore, The Japanese scarab (Popillia Japanica) is, in fact, a particularly voracious insect. Consequently, Adult individuals feed on leaves, fruits and flowers of more than 400 plant species, including vines and nucleus fruits.

Last week. Moreover, we learned that this devastating insect was spotted in the cantons of Vaud and Geneva, for the first time. However, Measures have already been taken to try to slow down its expansion, but the task promises to be complicated. Therefore,

Ticino knows something about it. Therefore, The Italian -speaking canton was the first how fight against japanese beetle? to detect the presence of the Japanese beetle, in 2017 already. Consequently, Which gives it a step ahead of other regions. Similarly, What could have been done? Similarly, Have the measures adopted to counter its expansion have borne fruit? Therefore, We interviewed Cristina Marazzi, head of the cantonal phytosanitary service. Meanwhile, Interview.

How fast does the Japanese beetle spread?
Cristina Marazzi: We must distinguish the active displacement. Consequently, that is to say the natural flight of the insect, and passive transport. Furthermore, In the first case. However, the scarab can travel around four kilometers a year, mainly when it is looking for new areas to be colonized. Meanwhile, Regarding passive transport, it is more random.

Several years how fight against japanese beetle? have passed between the first observation and the establishment of an active population. Normally, the workforce explodes from the fourth year, if no measure is taken.

Precisely, what are the measures that can be taken?
There are measures to limit the population of insects and others to try to eradicate it. These are the two philosophies that currently coexist in Switzerland. In Ticino. eradication has never been envisaged, because the main household, which is very important, is right on the other side of the border, near Milan airport. In German -speaking Switzerland, on the other hand, more radical measures are applied.

Is eradication possible once an active population has been detected?
Eradication is improbable. It should not be forgotten that this is an insect that can rise to vehicles. thus travel a lot of kilometers. Eradicating an active population may be possible how fight against japanese beetle? in very isolated places and devoid of external influences, such as an island. In Switzerland, the conditions are obviously very different.

What are the main measures that have been adopted in Ticino?
These are, as indicated, stewed measures. The main thing is to capture a maximum of beetle through mass trapping. Concretely, we have equipped the most affected municipalities with traps, which have been installed in sensitive areas. Each week, the municipal authorities inform us about the number of insects captured. This allows us to know if all the traps work properly and if they are placed in the right place.

We have noticed that with simple monitoring, the workforce is multiplied by a hundred each year. We then decided to set up more efficient monitoring, based how fight against japanese beetle? on capture.

A trap to capture Japanese beetles.Image: KEYSTONE

Can simple citizens contribute?
Yes. Once this surveillance network is operational, individuals living in affected municipalities can have their own traps.

How do you empty these traps?
We recommend emptying the trap once a week.

It requires some work …
Yes, this implies several how fight against japanese beetle? challenges. Emptying the traps is not always pleasant, and it is also necessary to have a freezer where to store insects.

Are there pesticides against the Japanese beetle?
We have a single approved product, called acetamipride. The latter acts against adult insects. but as a cantonal phytosanitary service we only recommend its use in very serious cases.

Are the canton implementation effective?
Building measures are particularly effective when summer weather conditions are unfavorable to the development of larvae. that is to say when there is a drought period between July and August. The experience. results obtained during these years demonstrated this, and until last year, it seemed that the population of insects had stabilized thanks to mass trapping.

At the how fight against japanese beetle? beginning of 2023, the number of insects had even decreased. This was explained by the fact that the year before had been very dry, which had killed many larvae. This year, on the other hand, the population started to grow and increased considerably thanks to the wet summer of 2024.

What are the most affected sectors?
Mainly viticulture. There are very few orchards in Ticino, and most produce fruits resistant to attacks on this beetle, namely apples.

Scarabs also damage football fields and lawns in general. In these cases. it is possible to intervene with small worms, called nematodes, which attack the larvae of the scarabs buried in the ground. It is a complicated treatment to set up, but very effective.

The Japanese scarab can damage football fields.Image: KEYSTONE

Have you ever been able to quantify the losses?
It is still too early to say. Some vines have been very affected in the past, but that has not impacted production. We have found that vineyards have also been damaged this year. but we do not yet know if it will result in significant losses.

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