Lithium sulphate

Copper sulphate (CuSO₄, > 98%), lithium sulphate (Li₂SO₄, > 98%), 1,2-dichloroethane (DCE, ≥ 99.0%), 1-bromooctane (99%), trioctylphosphine (97%), and 2,2′:5′,2′′-terthiophene (TT, 99%) were acquired from Sigma-Aldrich. All reagents were used without additional purification. Ultrapure water from a MilliQ filtration system (> 18.2 MΩ cm) was used throughout to generate aqueous solutions. The tetraoctylphosphonium tetrakis(pentafluorophenyl)borate (P₈₈₈₈TB) ionic liquid used as an oil phase supporting electrolyte was prepared as detailed previously^{41 (link)}.

We further tested lithium citrate (Roth ≥ 98% Ph. Eur), lithium sulphate (Roth ≥ 99%), lithium carbonate (Roth ≥ 99%), lithium acetate (Roth ≥ 99%) and lithium lactate (Sigma Aldrich 95%) at concentrations of 4 and 25 mM (n = 3 cages each). In the control tests, the caged bees were fed with Apiinvert® only (n = 33 cages). As an additional control, magnesium chloride (Roth ≥ 98,5%) and the alkali salts potassium chloride (Roth ≥ 99%) and sodium chloride (Roth ≥ 99%) were fed in the same manner at a concentration of 25 mM (n = 3 cages each). For detailed comparison with LiCl, lithium citrate was tested at additional concentrations. All cage tests were performed in the same way as described under “Effective concentration of lithium chloride”.