Contaminated dust preparation

1) The AI-containing dust, obtained from dressed seed with Heubach cylinder (see, is analysed. The percentage of AI content in the dust is used to calculate the quantity of dust to distribute on the surface of the bottom of the hoarding cage (Table 4).

2) To allow homogeneous dispersal of dust on the cage substrate in proportion to the quantity of AI deposited at 5 m, it is necessary to mix the dust with an inert material (talc) through geometric dilutions, starting from a dose that is 1000 times more concentrated. An appropriate quantity of talc is used as a dispersing agent in order to reach the desired concentration (Table 4).

Talc has been suggested as a dispersing agent because it is a common mineral material, not toxic to bees, usually added to seed boxes to reduce friction and stickiness, and to ensure smooth flow of seed during planting. Krupke et al. (2012) found that waste talc expelled during and after sowing represents a route of pesticide exposure for bees.

Table 4. Example of the calculation of dust and AI quantity to distribute in the bottom surface of the hoarding cage.

Table 4