Table 2. Percentage of B. terrestris workers showing positive proboscis extension response (PER) and total sample sizes at the 10th CS-US trial, 11th CS trial (final level of learning acquisition) and after 2 h in the memory retention test for different treatment groups.

Pesticide: bees chronically exposed to pesticide clothianidin. Parasite: bees ingested parasite N. ceranae spores. Both: bees chronically exposed to pesticide clohianidin and ingested parasite N. ceranae spores.

Treatment group	10th Trial % PER (n)	Final level of learning acquisition % PER (n)	Memory retention test % PER (n)
Control	54.5 (22)	68.2 (22)	23.8 (21)
Pesticide	69.6 (23)	69.6 (23)	36.8 (19)
Parasite	57.7 (26)	69.2 (26)	43.5 (23)
Both	57.7 (26)	65.4 (26)	31.8 (22)