Submitted to: Journal of Entomological Science
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 3/2/2009
Publication Date: 5/1/2009
Citation: Leskey, T.C., Short, B.D., Wright, S.E., Brown, M.W. 2009. Diagnosis and variation in appearance of brown stink bug (Hemiptera: Pentatomidae) injury on apple. Journal of Entomological Science. 44:1-10. Interpretive Summary: Adult brown stink bugs, Euschistus servus (Say), cause injury to apples, although this phenomenon was recognized only recently because of the similarity in appearance to symptoms associated with calcium deficiency and referred to as cork spot and bitter pit. We performed laboratory and field studies aimed at describing specific characteristics that could be used to conclusively identify brown stink bug damage. The only character that was a consistent and definitive symptom of stink bug injury was the presence of a stink bug feeding puncture, (approximately) 0.17 mm in size. 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 a microscope at 40x magnification to confirm the presence of stink bug feeding punctures. This new knowledge will insure that proper diagnosis of stink bug damage is determined to reduce pesticide application.
Technical Abstract: Adult brown stink bugs, Euschistus servus (Say), were caged individually on limbs with apple fruit of six 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, three 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 (approximately) 0.17 mm. 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.