To get Nosema spores for experimental infection of bees, workers were collected from infected colonies and their midgut were dissected and macerated. Macerate containing spores was washed three times by centrifugation in Insect Ringer's solution. Concentration of spores was determined by counting spores in a Neubauer chamber under light microscopy. The lowest infective dose of 60,000 spores per bee was applied. Spore inoculums and/or thiamethoxam solution were prepared fresh for inoculation and sterile filter pipette tips for individual bees were used. Each day, dead bees were removed from cages and counted.