Figure 1. Dietary administration of AgNPs cause cuticular demelanization in Drosophila.

(A) Flies are raised in AgNP doped food at various concentrations from the embryonic stage. When raised in 50 mg/L and above concentrations of nanoparticles, all adult flies (100%) appeared extremely lighter in body color with little or no melanin pigments left in their body. Since the eye color remains unchanged this suggests that AgNPs selectively interferes with the melanin pigmentation. (B) In Drosophila black (b) mutants accumulates excessive melanin pigments. Exposure of black flies to 50 mg/L AgNP effectively eliminates all melanin pigments from their body and the flies turned pale. (C) Sufficient accumulation of silver occurs in AgNP fed flies as determined by Atomic Absorption (AA) analysis. Flies fed with AgNO₃ were used for comparison. (C) Measurement of free silver (Ag+) with ion specific electrodes confirmed that 50 mg/L AgNP solution generates ionic Ag⁺ at a negligible quantity when compared to AgNO₃ solution in the same concentration. This led us to conclude that flies raised in AgNP doped food mostly consumed AgNPs and not free Ag⁺ to display the demelanization effect.