Do nanoparticles cause hormesis? Early physiological compensatory response in house crickets to a dietary admixture of GO, Ag, and GOAg composite

Highlights

• Low amounts of GO, AgNPs, or GO-AgNPs triggers an early stress response in crickets.

• Nanoparticles (GO, AgNPs, or GO-AgNPs) can disturb the energy budget of crickets.

• Initial suppression of energy consumption/assimilation is compensated afterwards.

• Increased activity of digestive enzymes accompanies the compensation response.

• Insects treated with GO-AgNPs composite retained more body water.

Abstract

This study aimed to identify the physiological responses of house cricket females following short-term exposure to relatively low dietary doses of graphene oxide (GO, 20 μg · g⁻¹ food), silver (Ag, 400 μg · g⁻¹ food) nanoparticles (NPs), or graphene oxide‑silver nanoparticle composite (GO-AgNPs, 20: 400 μg · g⁻¹ food). Energy intake and distribution were measured on the third, sixth, and tenth day. A semi-quantitative API®ZYM assay of digestive enzyme fingerprints was performed on the third and tenth day of continuous treatment. Physicochemical properties of the NPs were obtained by combining SEM, EDX spectrometry, AFM, and DLS techniques.

The obtained results showed decreased energy consumption, particularly assimilation as an early response to dietary NPs followed by compensatory changes in feeding activity leading to the same consumption and assimilation throughout the experimental period (10 days). The increased activities of digestive enzymes in NP-treated females compared to the control on the third day of the experiment suggest the onset of compensatory reactions of the day. Moreover, the insects treated with GO-AgNP composite retained more body water, suggesting increased uptake. The observed changes in the measured physiological parameters after exposure to NPs are discussed in light of hormesis.