The Stink Bug Complex in Alabama Field Crops with a Focus on the Brown Marmorated Stink Bug
Type of DegreeMaster's Thesis
Entomology and Plant Pathology
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The brown marmorated stink bug, Halyomorpha halys (Stål), was first confirmed in the state of Alabama in 2010. Population spread was observed by researchers, prompting further studies in 2014-2017. There are now 29 counties confirmed to have H. halys. Preliminary data from field corn ear samples in 2013 indicated an increase in stink bug damage in commercial field corn of north Alabama. Field corn samples during the summers of 2014-2016 showed ear injury from stink bugs and sap beetles in most corn fields of north Alabama. Though not every field in the study showed high stink bug feeding injury, the fields with high stink bug injury justify the increasing importance of scouting methods in corn fields in north Alabama. Halyomorpha halys is a new addition to the stink bug complex that feed on corn. The starburst symptom caused by infection of Fusarium verticilloides was also common. In 2014, corn collected on 11 August showed significantly less stink bug and sap beetle injury than corn collected ten days later. In 2015 and 2016 corn from the edge of the field showed significantly more stink bug injured kernels than samples taken from the middle of the field. Halyomorpha halys is spreading throughout the state of Alabama. Stink bug injury to field corn in North Alabama has increased significantly. A study of the stink bug complex including H. halys was designed to evaluate treatment thresholds in cotton in 2016-2017. The untreated cotton plots had significantly more boll injury than plots that were treated with bifenthrin on threshold or those treated with a weekly application to provide maximum protection. There was no significant difference between maximum and threshold spray regimes in terms of internal boll injury. Cotton yield was significantly reduced in untreated compared to treated plots in 2017, but not in 2016. The data suggest that thresholds can be used to reduce the number of insecticide application, even in the presence of H. halys. Impact of H. halys was evaluated in field corn by caging two adult stink bugs for five days at different growth stages of corn from VT to R6. Feeding by adult H. halys caused significantly more kernel injury than the uninfested controls at pretassel, silk, dough, and dent stages. Stink bug injury from two feeding adult H. halys in five days averaged 16 kernels per ear in Prattville, AL and 12 kernels per ear in Shorter, AL. Ear deformation was significantly higher in the infested compared with uninfested corn at pretassel stage (V10-VT).