Quantitative and qualitative damage caused by Halyomorpha halys (Hemiptera: Pentatomidae) on soybean crop at different growth stages

The brown marmorated stink bug Halyomorpha halys, an invasive species native to East Asia, is now present and abundant on soybean throughout Europe where it has become a major pest damaging the crop. Because a better understanding of the impact of H. halys is crucial to implement effective and sustainable pest management, the present study aimed to assess the stages at which soybean is most susceptible to H. halys attacks, and the qualitative and quantitative alterations caused by its feeding on soybean seeds. Therefore, soybean plants were exposed to stink bug adults for 2 weeks at different development stages and were examined at harvest for damage. Stay-green syndrome occurred most severely as a result of H. halys attacks at soybean development stages R4-R5. In the same period, the bug feeding activity significantly reduced the number of seeds per pod, thus indicating a higher damage rate at the R4-R5 stage when soybean surveillance should be intensified in order to properly target pest management strategies. The lower number of seeds per pod corresponded to an increase in the seed weight due to plant compensation mechanisms, leading to grain yields that did not differ in relation to the time of attack or the rate of damaged seeds. However, while not causing overall a loss of weight production, H. halys attacks were shown to cause qualitative damage to soybean seeds, especially by altering protein content and mobilizing several primary metabolites from storage macromolecules, which will have to be considered depending on the intended use of the production.