The brown marmorated stink bug is becoming becomes a national problem in Switzerland. Losses compared to the previous year have doubled. In 2018 they were at 10 percent; in 2019 it is already 20 percent or above. "If this continues, we can forget about the pear production here," says producer Sepp Burri (see video 1). The Task Force Plant Protection of the Swiss Fruit Association and the Association of Central Switzerland Fruit Producers met yesterday with the Federal Office for the Environment and the Federal Office for Agriculture to find solutions.
A deformed pear on the tree and the same one, cut in half / picture: Swiss Fruit Association
The extent of the damage requires quick solutions to support local fruit production. Particularly affected are the pear crops adjacent to houses, barns or settlement areas. During the field inspection in Hünenberg, the extent of the economic damage could be appraised. The meeting discussed the increasing damage caused by newly introduced pests and the interaction of pesticides. The participants recognized the urgent need to protect cultures and water bodies. Another meeting in October 2019 will set out the common strategy to request resources for problem solving.
Chemical control is not possible
There are no approved insecticides to combat the aforementioned bugs. Chemical control is very difficult, as the adult animals already migrate from their winter quarters (buildings) to the cultures in April. A general approach to preventing immigration into the cultures is also being examined. However, since migration already takes place at the beginning of April, this approach involves a great deal of risk (snow, etc.) and additional high investments.
A possible opponent of the bugs could be the samurai wasp, originally from Asia. In China, this animal is the natural enemy of the bug. The wasp's larvae will eat the bugs eggs. Thus, the spread of the bugs could be stopped. There is still a lot of research needed. Like the bug, the wasp is an alien species here.
Switzerland-wide occurrences of the pest
Since last year, monitoring of the occurrence of Asian tree bugs has been carried out throughout Switzerland. In the canton of Lucerne, this tree bug is being monitored in Oberkirch and Buchrain, in the canton of Zug in Hünenberg and Cham. The canton of Zurich and other cantons also report larger occurrences of the pest. Even with house and apartment owners, the bugs are unpopular. They will try to find shelter in residential buildings during winter time. When they are crushed, the insects excrete a foul-smelling substance.
For more information: www.swissfruit.ch