Harmful bedbugs in fruit growing

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Bedbugs can cause great damage to agricultural crops. Harmful agents of this genus include the rice bug (Nezara viridula), the red-legged tree bug (Pentatoma rufipes) and the marbled tree bug (Halymorpha halys). Nezara and Halyomorpha are invasive species that have developed new habitats through climatic changes, global trade and plant imports. The marbled tree bug was first discovered in Europe in 2004 near Zurich. In Germany (Constanz) the tree bug was found in 2011, in Italy (Emilia Romagna) in 2012 and in Austria (Vorarlberg) in 2015. An initially insignificant, rapid spread in recent years and already significant damage (Northern Italy — EUR 350 million) has since taken place in the countries. The marbled tree bug prefers to suck on fruits of over 100 plant species and can therefore cause great damage in agriculture. North of the Alps usually develops a generation, but in warm years there can also be a partial or fully developed second generation. The host plant circle of this type of bedbug also includes representatives of the special crops, in addition to peach and pear and hazelnut, the apple is strongly affected by this type of bedbug. Meanwhile, this type of bedbug in Switzerland and southern Germany causes damage to fruit and vegetable crops. In 2017, major damage was recorded in Switzerland in the area around Zurich and in 2019 in the cantons of Zurich and Thurgau more than 20 % losses were recorded in pear plants. In the canton of Thurgau alone, the damage to pears is estimated at CHF 3 million in 2019. These manifest themselves in fruit deformations, caused by suction damage. Marketing of infested fruits is no longer possible. There are currently no successful regulatory strategies. Chemical control is not possible due to the way of life (migration of bedbugs from April to August) and the associated frequent application of insecticides even during the flowering period. Furthermore, no effective plant protection products are currently authorised in Germany, Switzerland and Austria. This puts the domestic production of high-quality fruits and vegetables in the Lake Constance region at risk. In the project, together with Agroscope, the Swiss Cantons, the University of Applied Sciences Weihenstephan-Triesdorf (Battle Office), the KOB and the Vorarlberg Chamber of Agriculture, as well as the Agricultural Technology Center Augustenberg and the CABI, the first regulatory strategy against the marbled tree bug is to be developed and applied. The focus is on country-specific monitoring of the samurai wasp (Trissolcus japonicus) and the protection of plants through networking. This useful person has enormous potential for regulation. Thus, 75 % of the 60-80 % parasitised eggs in the area of origin of the marbled tree bug are occupied by Trissolcus japonicus alone. It is also non-resident, but is probably to be found or expected as a result of the introduction of the harmful pathogen. The first findings have already been reported in Switzerland. After examination of the authorities, a release may be considered. In combination with other processes (cultural protection nets, accompanying use of chemical products, mass catching, fishing strips, promotion of other opponents), a strategy can then be developed. Expert knowledge, as well as observations and experiences from practice and public are incorporated into the project. In addition, house and small gardeners as well as settlement areas benefit from releases, as bedbugs already appear as lents (e.g. balconies, sheds, apartments).

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