On 26 October the colonies of one of the groups were treated with 50 ml of 0.25 M oxalic acid (2.2%) syrup (50% sugar water with 2% Promotor L, Calier Lab) that was dispensed by trickling onto the combs with a syringe. The same day, the colonies of the other group received syrup without oxalic acid. On 16 November the administration was repeated according to the method described above.

Note: 1 liter of 50% sugar-water solution with 22.5 gr oxalic acid.

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