Efficacy of Selected Commercial Bio‐Products in Disrupting Symbiont Acquisition and Survival of <i>Halyomorpha halys</i> (Hemiptera: Pentatomidae)

ABSTRACT The brown marmorated stink bug (BMSB), Halyomorpha halys (Hemiptera: Pentatomidae), is an invasive pest from East Asia that threatens crops by damaging fruit yield and quality. Conventional insecticides against BMSB disrupt integrated pest management, harming beneficial insects and triggering secondary pest outbreaks. This study examines alternative control methods by applying some bio‐products (Dentamet, Hagax, Nimbecidine) to BMSB 1‐day‐ and 5‐day‐old egg masses in the laboratory and hazelnut orchard conditions to inhibit acquisition of ‘ Candidatus Pantoea carbekii ’ and assess nymphal mortality. The tested bio‐products included Dentamet (zinc, copper, citric acid), Hagax (copper hydroxide and oxychloride), and Nimbecidine (neem oil + Azadirachtin), with Nu‐Film‐P as an additive. In laboratory trials, bio‐products did not significantly affect the hatching rate of 1‐day‐old eggs; however, Nimbecidine significantly reduced the hatching of 5‐day‐old eggs (65.0%, p &lt; 0.05). Regarding survival, Dentamet applied to 1‐day‐old eggs resulted in the highest nymphal mortality (66.2% in the first instar and 75.5% total mortality by the end of the second instar, p &lt; 0.05), while Hagax and Nimbecidine showed lower, non‐significant effects on mortality compared to controls. In orchard trials, Dentamet produced the highest mortality (&gt; 30% in both egg age groups) but showed statistical significance only in 5‐day‐old eggs (31%, p &lt; 0.05). Real‐Time PCR confirmed substantial reduction in symbiont acquisition in nymphs hatching from egg masses treated 1‐day post‐oviposition with Dentamet, evidenced by decreased log2 −ΔΔCt values (−17.24), indicating approximately 150 000‐fold reduction in symbiont abundance and providing molecular verification of the inhibition mechanism. These findings indicate that only Dentamet demonstrated substantial mortality effects under laboratory conditions, particularly on nymphs hatching from egg masses treated 1‐day post‐oviposition. However, the limited statistically significant effects in orchard conditions indicate that application timing, frequency, and dosages need to be optimized to enhance efficacy. Further laboratory and field studies are necessary to fully assess the feasibility of this symbiont‐targeted approach.