Start Date: Aug 26, 2013
End Date: Aug 25, 2015
This project will be part of a larger ARS project related to guarding honeybee health around agricultural areas. ARS scientists are investigating the repellency of certain agrochemicals to prevent honeybee movement into field prior to spraying with agrochemicals that are known to have negative effects on bee health. Apiaries will be established adjacent to a cotton field. Daily field observations will be made by Texas A&M personnel to determine the honeybee population structure/density in the cotton field to help determine movement patterns and field penetration for the majority of the workers during fruit set. A likely repellent, permethrin, will then be sprayed in the evening from a ground rig once flowers have closed. Daily field observations will then resume to determine if the bees are present in the typical pre-treatment area, post-treatment. Colony health assessment will be recorded throughout the experiment. In addition, pollen traps will be used to determine if the honeybees did in fact move to another crop/host as opposed to moving to another part of the cotton field. USDA ARS personnel will identify the pollen. Temperature inversions are caused when there is cooler air trapped under a layer of warmer air, which severely limits the amount of mixing in the atmosphere, and are typically associated with evening through early morning hours. Applicators are trained to identify inversions and avoid spraying during inversion conditions as small spray particles can become trapped in the inversion and drift offsite as a concentrated cloud. This project will investigate if aerial applications treatments can be optimized for use during these inversions such that spray drift is minimized. Using USDA-ARS wind tunnel facilities, initial efforts will focus on setting up spray equipment to produce larger spray droplets with sufficient mass to penetrate the inversion layer and deposit onto the crop. Field studies will follow using USDA aircraft in areas where nighttime applications can safely be made (i.e. large, open fields). Evaluations will focus on comparing spray deposition and drift from daytime and nighttime applications. Texas A&M personnel will conduct use field deposition and drift data to assess spray movement into nearby waterways and ways to mitigate this movement. This will lead to recommendations for nighttime applications that would help mitigate bee exposure to agrochemicals in cotton crops.