Figure 8. Honey bee forager mortality from chronic doses of selenium.

Percentages of honey bee mortality after chronic dosage of selenate (N = 18–21), selenomethionine (N = 19–20) or methionine (N = 19–20) in 1 M sucrose at 6 concentrations. Control bees received 0 µg ml⁻¹, or 1 M sucrose only. Bees were fed 20 µl of each treatment for 6 days. Mortality was recorded for 5 subsequent days after the first dosage. Final percent mortality is shown. Letters above the means indicate statistically significant differences between groups (α = 0.05) using the Mann-Whitney U test. Values are means ± standard error (SE).