The preliminary results are in!: A post from our undergraduate research intern, Micki Palmersheim!;

First off, thank you to everyone that contributed towards funding this experiment. Your combined generosity gave me an invaluable research experience and the opportunity to learn from three inspiring scientists. Because of this funding, I was able to continue to grow my passion for bees and research.

This summer I investigated sub-lethal effects of neonicotinoids on the Alfalfa Leafcutter bee. This bee is a solitary species, which means that individuals live alone rather than in a hive as seen in honey bees. Each female bee of this species puts a unique amount of investment into each of her offspring. She will spend up to a whole day making a cell for a single egg, and complete about eight cells in a nest. This investment requires very delicate nest building behaviors that if interrupted, could be detrimental to the fate of the offspring.

Below are photos of an Alfalfa Leafcutter bee and an example of what the nests look like. You can see in the photo of the nests that the top nest is made up of 5 cells, and the bottom nest has 4 cells.

 

 

Our goal was to determine whether field relevant concentrations of neonicotinoids would impact the alfalfa leafcutter bees' physiology enough to interrupt their nest building behavior.

We approached this question in four steps...

1. First, we determined a concentration of neonicotinoid that would be high enough to predictably cause sub-lethal effects, but low enough that no lethal effects were observed.

2. Second, we exposed bees to the concentration determined in the first step and released these bees in cages erected in an alfalfa field. We observed and compared behaviors of exposed and unexposed, or control, bees.

3. Third, we allowed the caged bees to construct nests. We compared the architecture of the nests constructed by bees that were exposed and unexposed to neonicotinoids.

Below is a photo of me recording behavioral observations as I keep an eye on the yellow nest block, which is duct-taped to the center pole.

 

4. Finally, we attempted to use an Ellman's assay to interpret upregulated acetylcholinesterase enzymes as a biomarker for exposed bees.

Below is a photo of Alfalfa Leafcutter bees in a well plate waiting for me to weigh them.

 

By the end of the experiment, we had collected some surprising initial results: In the first step, we determined lethal dosages in our trial to be much lower than previously published, but higher than what is typically found in the field. We started to see lethal effects at about 59ng/ml, where field relevant dosages are typically between 1.0-10ng/ml.

We also noted a dramatic difference in the number of nests constructed between exposed and unexposed bees. While our control bees that were not exposed to neonicotinoids constructed up to 18 completed nests, the same number of bees that were exposed to 1.0ng/ml neonicotinoid did not complete any nests. The x-ray pictures below show the difference in nesting between the two treatments (top: control, bottom: exposed), with the two straws in the bottom picture indicating that the exposed bees began to build nests, but did not fully complete any.

 

 

With Raph's assistance in statistical wizardry, I still have to run analysis on our results from this summer to determine the significance. I will be spending my fall semester running a few more replicates of the lab-based experiments to strengthen our statistics. My goal for my last year as an undergrad is to continue to gather supporting data, and with the guidance of my mentors and my advisor, Dr. Julia Bowsher, will begin to write a manuscript on my summer project. After I graduate, I have plans on pursing a Ph.D. in entomology to continue researching bee health.

-Micki Palmersheim