The analysis of bee infection rates in Sect. 9.3 is only one of many similar analyses reported by Adler et al. (2020). A subsequent analysis examines how the mean infection intensity per colony is related to treatment. The authors use a Gaussian random-effects model with round/block as the additive random effect. Since mean infection is a positive number with an appreciable dynamic range, check first whether a transformation might be helpful to improve additivity. On the transformed scale, check whether there is a treatment effect. Which treatment level has the lowest mean infection, and which has the highest?