Fruit and berry producers are under great pressure from the large number of pests. Both old and new pests are causing problems for farmers, as can be seen from several articles in the Swiss magazine for fruit and viticulture. Their fruit or berries are a favourite target for the small parasites, which can cause quite a lot of damage.

The use of plant protection products could prevent the damage caused by the pests. The problem? Plant protection products are in short supply everywhere.

Fruit association calls for emergency authorisations

The example of the marmorated stink bug shows that the spread of the pests has fatal consequences for the harvest of fruit and berry producers and that only plant protection products can put an end to them.

The pest, which was introduced to Switzerland in 2004, had spread over the years to such an extent that the federal government had to issue temporary emergency authorisations for various plant protection products in 2020 at the request of the fruit association in order to combat the pest. The «BauernZeitung», among others, reported on this. In the meantime, the marmorated stink bug can be kept well under control thanks to its natural antagonist, the Asian ichneumon wasp, which the Federal Office for the Environment (FOEN) has authorised as a neozoan. It is to be hoped that the benefits of the wasp in the control of stink bugs that have now been established will remain a long-term success without any undesirable side effects.

Agroscope, the federal centre of excellence for research in the agriculture and food sector, was granted approval for the field trial to control the bug. However, the trial could have backfired. Beneficial insects that are not native to this country can cause just as much damage as pests that are at home here. The Asian ladybird, which was originally introduced to control aphids, is a prime example of this. The invader makes wine inedible and threatens the native ladybird. This makes the Asian ladybird one of the invasive species that, according to the UN World Biodiversity Council, is a major contributor to species extinction.

Spotted leaf miner and Mediterranean fruit fly on the rise

While fruit and berry producers were recently still worried about the marmorated stink bug, the Japanese beetle is now on the rise. It was first discovered in Switzerland in July 2023 and has been spreading ever since. The pest should not be taken lightly: It can infest over 400 host plants. An emergency authorisation was required, partly due to the rapid spread of pests such as the Japanese beetle, against which no authorised plant protection products are available. These have become more frequent recently.

The spotted wing drosophila and the Mediterranean fruit fly are also problematic. If heavily infested, the spotted wing drosophila can lead to the defoliation of entire fruit trees – even before the harvest: «The moth can form two to three generations per year, with the eggs being laid on the underside of the leaf and the larvae developing in the leaf,» said David Szalatnay from the fruit specialist centre at Strickhof in Zurich at this year's plant protection conference organised by the Zurich Fruit Association. The spotted wing drosophila can also be controlled in a targeted and beneficial way with plant protection.

The Mediterranean fruit fly is another pest that is increasingly keeping farmers on their toes. It lays its eggs under the skin of ripening fruit. It is particularly problematic that egg laying is often overlooked during the harvest. A special feature of the fruit fly larvae is that they can jump up to 16 centimetres. As the Mediterranean fruit fly is an important pest in countries where citrus fruits are grown, the beneficial insect is persistent in Switzerland and appears here again and again. In this case, too, there is no plant protection product authorised in Switzerland to control the Mediterranean fruit fly.