Figure 4.

Field-Relevant Concentration of Imidacloprid Reduces Foraging Rhythmicity and Activity in Bumblebee Foragers within the Colony in 12 h:12 h Light:Dark Conditions

(A) Representative actograms for a Bombus terrestris forager on control food and food containing 10 μg/L imidacloprid (IM).

(B) Proportion of foragers that were arrhythmic in LD for each treatment group.

(C) Mean rhythmicity for either control foragers or foragers fed 10 μg/L IM in LD (t₁₂₅ = 2.0, p = 0.048).

(D) Mean foraging activity for foragers in each treatment group in LD, during the day (t₁₇₀ = 3.8, p < 0.001) and the night (t₁₇₀ = 2.0, p = 0.042). Each data point in the histograms represents a single bee, n = 48–79 bees for each treatment for rhythmicity, n = 74–100 bees for each treatment for activity.

Data are represented as mean ± SEM, ∗p ≤ 0.05, ∗∗∗p ≤ 0.001, tested via one-way ANOVA with Tukey's multiple comparisons.