Ketone body treatments enhance in vitro brain mitochondrial respiration in an age-dependent manner. Ketone body treatments enhance in vitro brain mitochondrial respiration in an age-dependent manner. Forager mitochondria showed a significant increase in respiration following in vitro treatment with beta-hydroxybutyrate (BHB; GLM: P<0.0001). This effect was age dependent (GLM age × BHB interaction term: P<0.0001). Two-day-old bees showed lower respiration overall (GLM: P<0.0001). N=8, 8, 9 and 8, respectively. Please note that the bees represented in this figure are from a different colony from those in Fig. 2. Clare C. Rittschof et al. J Exp Biol 2018;221:jeb176917 © 2018. Published by The Company of Biologists Ltd