An Examination of the External and Internal Signs of Cotton Boll Damage by Stink Bugs (Heteroptera: Pentatomidae)

Abstract

Small- and medium-sized bolls were exposed to stink bugs, primarily Nezara viridula (L.), Acrosternum hilare (Say), and Euschistus servus (Say), for a 48-h feeding period. Bolls were then examined for external and internal evidence of feeding 2, 4, 6, 8, and 10 d later. No relationship was documented between numbers of external feeding marks and internal warts that form when the interior of the boll is pierced. In fact, approximately 20% of damaged bolls with internal warts lacked external marks. Therefore, external marks cannot be used to accurately estimate the occurrence or amount of internal boll damage by stink bugs. Neither size nor number of external marks or warts increased significantly among the five post-feeding sampling dates. All visual signs of damage were present by the second day. There were significantly more damaged bolls with the combination of external marks, stylet sheaths, and warts (approximately 70%) than any other combination of feeding signs. There was a significant increase in lint and seed damage through time. Finally, a strong relationship existed between the presence of a feeding stylet sheath and wart number. A regression equation was generated to predict the presence of internal wart damage (warts) based on the number of stylet sheaths observed. A sampling program based on the incidence of stylet sheaths could potentially be used in a cotton pest management program to effectively assess stink bug injury to cotton bolls without destroying the developing bolls.