By: Steven Cook PhD
To calculate the cost of pesticides, Dr. Cook looked at the effects of commonly used pesticides and miticides on the metabolic physiology of caged nurse bees. Bees were exposed to different groups of compounds found in agricultural settings. One round of experiments focused on 2 controversial neonicotinoids, imidacloprid and clothianidin. Three variables were measured: 1) body weight, 2) metabolic rates (CO2/O2) via a technique calledrespirometry and 3) concentrations of two key nutritional components, lipids and proteins. As a worker bee’s role in the hive changes so, too, does its nutritional requirements. Thus measurements were taken at these normal transition phases (days 4, 7, 14 and 21).
Dr. Cook found that physiological effects of the neonics were both compound and dose dependent. While many details can be gleaned from the graphs below, here are two interesting findings: by day 14 both compounds (at high doses) 1) drastically reduced protein content and 2) increased lipid content.
Black = control group (no exposure)
Green = imidacloprid
Orange = clothianidin
Dashed lines = high dose
Solid lines = low dose