The Effects of Thiamethoxam on Bombus impatiens Foraging Efficiency

T'ai Roulston, Department of Environmental Science, University of Virginia, 291 McCormick Road, Charlottesville VA 22903

The recent decline in the global bumble bee population has been a major source of anxiety for environmentalists, and pesticides are potentially one of the main factors driving this development.  This experiment examines whether a neonicotinoid pesticide, thiamethoxam, impacts the foraging efficiency of an adult worker bumble bee (Bombus impatiens).  Sublethal levels of thiamethoxam were established through experimentation, and we determined that exposure to dosages of 25 μgL-1 of thiamethoxam and below were nonlethal and showed no evidence of effect on Bombus impatiens individuals in the lab.  We intentionally chose to test the bees with a level of pesticide that was not only sublethal but showed no apparent effects in the lab.  Therefore, we could see how this substance interferes with the challenging task of foraging naturally in the environment.  Individual bees were then randomly assigned to either a pesticide or a control treatment, exposed to their treatment, and returned to a naturally foraging colony system.  Over five weeks, the movements of all the bees were tracked with RFID technology.  Their weights were documented before and after every foraging trip.  We found that bees exposed to thiamethoxam were significantly less efficient at foraging than those in the control treatment.  Bumble bees in the control treatment were able to return from foraging trips carrying a larger proportion of their body weight than those in the pesticide treatment.  In addition, control bees were able to bring back a greater amount of resources with respect to the time they spent outside the colony.  Therefore, the pesticide produces negative, sublethal effects within the bees, decreasing their ability to assist in nutrient collection.  This experiment seeks to provide information that can better identify the significance of pesticides in the decline of bumble bees while elucidating influential and contemporary areas of methodology.   



Additional Abstract Information

Presenter: Emma Grover

Institution: University of Virginia

Type: Poster

Subject: Ecology

Status: Approved

Time and Location

Session: Poster 5
Date/Time: Tue 12:30pm-1:30pm
Session Number: 4113