Biochemical responses of the Protaetia brevitarsis Lewis larvae to subchronic copper exposure

Copper (Cu) is one of the most commonly detected heavy metals in livestock manure pollution. Protaetia brevitarsis Lewis larvae are widely used in the decomposition of livestock manure. During decomposition, heavy metals in livestock manure can accumulate in P. brevitarsis larvae and affect normal growth and reproduction. Therefore, this research focused on characterizing the toxic effects of Cu to P. brevitarsis Lewis larvae. Larvae were exposed to Cu concentrations of 0, 100, 200, 400, and 800 mg kg^-1 in edible fungi residue for 7, 14, 21, and 28 days. Results showed that the soluble protein content was markedly increased in 200 and 400 mg kg^-1 treatment groups on day 28. Compared to the control group, superoxide dismutase (SOD) and glutathione S-transferase (GST) activities were significantly stimulated on day 7 and then decreased as exposure length was increased (e.g., after 14, 21, and 28 days). Catalase (CAT) activity was also significantly increased after 7 days of exposure. Malondialdehyde (MDA) levels were markedly increased in the 100, 200, and 400 mg kg^-1 treatment groups on day 7. However, as time and Cu concentration were increased, MDA levels gradually decreased. These results indicate that Cu has biochemical effects on P. brevitarsis Lewis larvae, and both time and dose affect this biochemical response.