3.4.1. Colony Endpoints

Many authors quantified demographic parameters (number of adult bees, quantity of capped or uncapped brood and/or eggs) or the hive production (number of honey, pollen or nectar combs). In most cases (49%), the number of individuals or combs were estimated by using several similar ye<sup>t</sup> different techniques of frame observation (Figure S5a). Frame or hive weight was also used (13%) to assess brood development and colony size or productivity.

The techniques used to quantify Nosema or Varroa infestation (e.g., samples washed with water or alcohol, powdered sugar, microscopy, sticky boards, etc.) represented 8% of the techniques used at the colony scale. Virus infection was analyzed by PCR (8% of the techniques). The mortality of the entire colony (over the winter or not) was only studied in 7% of the cases. Some authors did not specify which techniques had been implemented (8%). Other methods included moisture and temperature sensors, queen marking to evaluate their renewal, honey extraction techniques, in vitro rearing to study the larvae emergence rate, mathematical models, or field studies that attempt to correlate observed mortality rates with potentially harmful events for bees (i.e., climate events, pesticide use).
