Recuperation of brood production in Bombus terrestris colonies during a pulsed exposure to imidacloprid.

Recuperation of brood production in standardised Bombus terrestris colonies (N = 60) during the 14-day ‘off dose’ period of pulsed exposure, wherein bees fed exclusively on undosed control syrup. The ‘off dose’ period followed a 14-day ‘on dose’ period during which bees' fed on syrup dosed with imidacloprid at the given concentrations (in µg kg⁻¹  =  parts per billion). Recuperation (ΔBrood) is determined by analyzing the difference in brood production between the ‘on dose’ (days 1–14) and ‘off dose’ (15–28) periods, specifically: ΔBrood  =  Brood_off − Brood_on, with a positive value indicating increased production of brood when ‘off dose’. Data represent the means and error bars indicate ± SE. The solid line indicates the following logarithmic trend: ΔBrood = 1.428 × ln(dosage) + 6.533, R² = 0.38. Dashed line indicates ΔBrood = 0.