Feeding damage by brown marmorated stinkbug, Halyomorpha halys, on commercial hazelnuts

Halyomorpha halys (Stäl) (brown marmorated stink bug, Hemiptera: Pentatomidae), an invasive insect pest, has established populations in Oregon. H. halys is a potential pest of many specialty crops in the Willamette Valley, including hazelnuts (Corylus avellana L.), of which Oregon is the largest domestic commercial producer. The objectives of this study were to characterize the damage caused to hazelnut kernels by feeding of H. halys adults, and to determine how the timing of feeding during kernel development could influence the types of damage observed. In a 2012 field trial, adult male H. halys were allowed to feed on developing nuts for one-week periods, from initial hazelnut development until harvest using mesh exclusion cages. Developing nuts unexposed to insect feeding served as control. Damage appeared to correspond with the hazelnut kernel’s physiological development periods. Trends observed suggested that when stink bugs fed on young hazelnuts, development of the kernels could cease. When the insects fed on kernels during mid-development, kernels appeared malformed. When stink bugs fed on fully expanded or mature nuts, significantly more kernels with white, necrotic kernel tissue (corking) resulted, compared to kernels unexposed to feeding H. halys. Trials were repeated during the 2013 growing season.