by Thomas Vatrano and Marco Penitenti
La asian bug (Halyomorpha halys) is an insect native to eastern Asia which in recent years has spread widely in Italy, causing serious damage to numerous agricultural cropsIt is an extremely polyphagous species, capable of feeding on over three hundred plant species, including olive groves (along with orchards and vegetables). Insect bites cause necrosis, deformations, fruit drop and loss of quality commercial. The insect overwinters in sheltered environments and, favored by mild winters, is able to complete multiple generations per year, increasing its presence during the growing seasons of crops. Since its first discovery in Italy in 2012, the The Asian bug has progressively colonized the North, the Centre and, more recently, the South and the islandsUpdated monitoring indicates that, in 2024, the species is now permanently present in all Italian regions, with a strong capacity to adapt to agricultural and urban environments.
Le traditional defense strategies, based on insecticides, they showed significant limitations and environmental risksThe prolonged use of synthetic molecules has favored the development of resistance, as well as damaging beneficial organisms and biodiversity. For this reason integrated approaches are gaining ground which include the use of insect nets, agronomic management of refuge sites and, above all, biological control.
In recent years, the introduction of the parasitoid Trissolcus japonicus, known as samurai wasp, has given encouraging results: this hymenopteran lays eggs inside the bedbug's eggs, reducing their reproductive capacityData from various Italian regions show an increasing rate of natural parasitization, a sign that the parasitoid is establishing itself permanently and contributes to population containment of the Asian bug.
However, recent research has shown that thethe effectiveness of biological control may be compromised by some biopesticidesi. Natural products permitted in organic farming, such as calcium polysulphide, sulphur and their mixtures with mineral powders, have shown ahigh mortality of Asian stink bug nymphs, but also negative side effects on the parasitoid, with mortality exceeding 80%Other products, such as azadirachtin, kaolin, and orange oil, have proven to be more selective, maintaining low toxicity on the samurai wasp and therefore proving more compatible with integrated pest management programs.
Field trials conducted on pear trees between 2021 and 2022 have highlighted that strategies based on diatomaceous earth alternating with sulfur or calcium polysulfide They reduced fruit damage with an efficacy comparable to, and in some cases superior to, strategies based on chemical insecticides such as acetamiprid.
Also entomopathogenic fungi beauveria bassiana e Akanthomyces muscarius they have shown a good ability to reduce lesions on the fruits, albeit with variability linked to environmental conditions and company management.
These findings suggest that theTargeted use of natural products, integrated with the release of the samurai wasp, can represent a valid alternative to chemical treatments, as long as they are carefully evaluate the timing and methods of application so as not to interfere with the activity of beneficial insects.
This month of July a specimen was photographed in the province of Catanzaro, evidence of the now consolidated presence also in Southern ItalyFavourable climatic conditions and the ability of this species to exploit numerous plant hosts make further expansion and increasing pressure on local crops likely.
The situation confirms the need for constant monitoring and constantly updated defence strategies, which combine techniques of agronomic management, selective biopesticides and biological controlAn integrated approach, supported by research and field observation, currently represents the only viable way to sustainably address the threat of the brown marmorated stink bug, reducing environmental impact while preserving crop productivity.
