Diagnosis and Variation in Appearance of Brown Stink Bug (Hemiptera: Pentatomidae) Injury on Apple

Adult brown stink bugs, Euschistus servus (Say), were caged individually on limbs with apple fruit of 6 cultivars in research orchards in West Virginia. Studies were performed to describe specific characteristics of damage that could be used for field and/or laboratory diagnosis of stink bug injury to apple fruit at harvest. These characteristics were separated into surface and subsurface features. On the apple surface, 3 prevailing types of stink bug injury were observed in the field: (1) a discolored dot, i.e., stink bug feeding puncture; (2) a discolored dot with a depression in the fruit; and (3) a discolored dot with a discolored depression in the fruit. Subsurface characters were related to the extent of damage observed on the fruit skin. Common subsurface damage ranged from a stylet sheath to corky tissue of variable color, shape, and size that sometimes was not contiguous with the skin. Laboratory evaluations under a dissecting microscope revealed that the size of the stink bug feeding puncture was ~0.17 mm diam. This character was the only consistent, definitive symptom of stink bug injury present among all observed damage. Due to variability in other surface and subsurface characters, and potential problems with visual apparency of injury in the field, evaluations of suspected stink bug damage should be performed with 40X magnification in the laboratory to confirm the presence of stink bug feeding punctures.