Egg masses treatment with micronutrient fertilizers has a suppressive effect on newly-emerged nymphs of the brown marmorated stink bug Halyomorpha halys

Abstract

The brown marmorated stink bug Halyomorpha halys is an invasive Asiatic pentatomid recently introduced in Europe. It is regarded as a major pest of many crops due to its marked polyphagy, high reproduction potential and high mobility. Among European countries where H. halys established in the last years, most of economic losses have been reported in Italy. A promising control approach against H. halys is based on the suppression of its gut primary symbiont ‘ Candidatus Pantoea carbekii’ ( P. carbekii), vertically transmitted through maternal secretions containing symbiotic bacteria smeared during oviposition, which are ingested by neonates. Symbiont elimination is regarded as a promising pest control strategy based on the application of antimicrobial substances. Here, an anti-symbiont activity is shown in response to the application of micronutrient fertilizers showing antimicrobial activity, resulting in H. halys nymphal mortality under laboratory conditions. Exposure to four commercial products, available for organic farming, was tested in combination with a pesticide additive on isolated stink bug egg masses, by measuring survival to II nymphal instar of neonates emerging from treated eggs. Zinc, copper and citric acid biocomplexes showed the most effective impact on H. halys survival, causing more than 90% nymph mortality. Molecular diagnosis for P. carbekii confirmed that observed effects were attributable to missed symbiont acquisition. Taken together, our results provide indication for the potential field use of micronutrient fertilizers as controls tool against H. halys. Future work will provide indications to maximize the effect of this approach in the field, enabling to design a new, eco-friendly approach for the control of this pest threatening Italian and European agriculture.