As reported by the "Neue Zürcher Zeitung", four Japanese beetles were spotted in an attractant trap in the municipality of Kloten in mid-July. The authorities immediately deployed 40 people to check traps and set new ones. Afterwards, it became clear that the specimens found were not isolated cases.

First population north of the Alps

The first population of Japanese beetles north of the Alps has established itself in Kloten. To stop them spreading to other regions, the authorities are using insecticides against the Japanese beetle in a concerted effort. This is because, as long as the beetles have not laid eggs, they can be easily and efficiently controlled with insecticides, according to entomologist Giselher Grabenweger of the Agroscope Research Station. The insecticides used by the authorities in Kloten have therefore been given temporary emergency approval. In addition, a ban on watering lawns and green areas applies until the end of September, as the Japanese beetle prefers to lay its eggs in wet soil. The control action in Kloten shows how important plant protection products are, also against the background of the increasing dangers posed by invasive pests.

Major threat to agriculture

More than 100 years ago, Japanese beetle grubs were introduced to America with flower bulbs. Since then, it has caused great damage there and must be controlled at great expense. The beetle attacks the leaves of various trees (e.g. apple, elm, lime, maple, peach), shrubs (e.g. grape berry, blackberry, rose) and other plants (e.g. corn, soybean). In the process, the Japanese beetle sometimes eats the plants bare except for the twigs and leaf skeletons. In the summer of 2014, the beetle was discovered for the first time on the European mainland near Milan. Three years later, it was detected for the first time in southern Ticino through traps set as a precaution. The beetle can travel several hundred meters under its own power. Or it is transported unnoticed over long distances by cars and trucks. The FOAG therefore urges vacation travelers to exercise caution. If possible, luggage and vehicle should be searched for the Japanese beetle on the return trip.

Invasive pests on the rise

Controlling the Japanese beetle is difficult. This is because the beetle has no natural enemies in Switzerland. A large-scale spread of the Japanese beetle would have major ecological and economic consequences. In 2020, Swiss Post, in collaboration with the Federal Plant Protection Service, presented a special stamp with an illustration of the Japanese beetle to mark the Year of Plant Safety. With this, it wanted to make the population aware of the danger of pests and plant diseases.

Not only insects like the Japanese beetle, but also invasive plants and plant diseases are on the rise all over the world. This has to do in particular with the ever-increasing movement of people and goods. Climate change is further exacerbating the problem, as pests suddenly feel at home in areas that were previously too cold for them. Research into new crop protection products will therefore remain central to protecting domestic agriculture and biodiversity in the future.