Agarose gel (2%) stained with SYBR® Safe of the monoplex and multiplex PCR products referring to the detection thresholds of the pathogens in honey bee products. M: 100 bp marker. 1 2.5 spores/g of pollen for Nosema ceranae 2 15 spores/g of pollen for Ascosphaera apis 3 0.8 spore/g of pollen for Paenibacillus larvae 4 multiplex PCR for N. ceranae (2.5 spores/g of pollen), A. apis (15 spores/g of pollen) and P. larvae (0.8 spore/g of pollen) 5 multiplex positive controls for N. ceranae (218 bp), N. apis (321 bp), A. apis (485 bp) and P. larvae (700 bp) 6 negative control. M: 100 bp marker 7 1.25 spores/mL of honey for N. ceranae 8 7.5 spores/mL of honey for A. apis 9 0.4 spore/mL of honey for P. larvae 10 multiplex PCR for N. ceranae (1.25 spores/mL of honey), A. apis (7.5 spores/mL of honey) and P. larvae (0.4 spore/mL of honey) 11 multiplex positive controls for N. ceranae (218 bp), N. apis (321 bp), A. apis (485 bp) and P. larvae (700 bp) 12 negative control. M: 100 bp marker 13 5 spores/g of royal jelly for N. ceranae 14 30 spores/g of royal jelly for A. apis 15 1.6 spores/g of royal jelly for P. larvae 16 multiplex PCR for N. ceranae (5 spores/g of royal jelly), A. apis (30 spores/g of royal jelly) and P. larvae (1.6 spores/g of royal jelly) 17 multiplex positive controls for N. ceranae (218 bp), N. apis (321 bp), A. apis (485 bp) and P. larvae (700 bp) 18 negative control.