Mortality of honey bees

1) Mortality of honey bees should be assessed on sheets suitable for the collection of dead bees (e.g. linen sheets) which are spread out in front of the hives and at the front, middle and back of the tunnels. From experiences with semi-field studies in general, it is known that most bees which are dying in the crop area can be found in the front and back corner of the tunnels. The middle linen is necessary as a path for walking during the application.

2) Before the start of the test, such paths should be created in each tunnel by removing of the plants and by smoothing the ground. Subsequently, the paths are covered with the aforementioned sheets in order to facilitate the collection of the dead bees in the crop area.

3) Additionally the dead bees are noted and counted in the dead bee traps which are fixed at the entrance of the hives. The assessments could be done according to the Table 5.

4) The assessments of the number of dead bees should be conducted at approximately the same time in the morning in order to cover the same time span from one day to another. During each assessment, the number of dead bees should be differentiated into adult worker bees, drones, freshly emerged bees, pupae and larvae.

Table 5. Time schedule for hive mortality assessment in semi-field brood tests
DBA = days before application, DAA = days after application.


Evaluation of number of dead honey bees

At least 3DBA to 1DBA

Once a day, if possible at about the same time


Once shortly before application


2 hours after application

6 hours after application

1 to 7DAA

Once a day, if possible at about the same time

Outside the tunnels:

8 to 27(± 2)DAA

Once a day, if possible at about the same time at monitoring site (dead bee trap only)