4.2.3. Mortality assessment
1) By agreement, daily mortalities are collected all over the dedicated surfaces of plastic covered lanes. Bees dying among the crops are not collected.
2) Dead bees are collected every day in the morning in order to be accurate, and data express the mortality of the previous day. Additionally, bees can be collected twice on the treatment day (D0 in the morning, and D0+ in the evening in order to look at an eventual acute effect). The total mortality rate recorded in a tunnel for a given day results from adding up mortality rates observed in each of the six plastic lanes in the tunnel (lane 1 to lane 6).
3) During the first days, as well as in the control tunnel, mortality could be considered "normal" without, therefore, being natural. Bees hurt themselves against the net when introduced in the tunnel or when trying to escape. They try to locate themselves above the hive and at both ends of the tunnel. So in all tunnels, part of the recorded mortality during the first days is linked to biological and technical reasons. The impact of substances should be considered over this level and is usually recorded in the control.