Galleria mellonella (Linnaeus, 1758)

Sugeçti, Serkan & B, Kemal Büyükgüzel, 2022, Effects of Ni (II) p-hydroxybenzoate with caffeine on metabolic, antioxidant, and biochemical parameters of model insect Galleria mellonella L. (Lepidoptera: Pyralidae), Turkish Journal of Zoology 46, pp. 167-174 : 170-172

G. mellonella larvae due to the oxidative effect of Ni (II) p-hydroxybenzoate with caffeine.

Metabolic enzymes play an important role in the elimination of oxidative damage due to chemical and biological agents. Transferase enzymes such as AST, ALT, and GGT provide regulation of amino acid metabolism ( Hakkak et al., 2018; Sugeçti et al., 2021). CK and AMYL enzymes are involved in the regulation of energy metabolism. The other metabolic enzyme LDH activity is used as an indicator of cell damage ( Ciesielczuk et al., 2015). In the present study, ALT and GGT activity significantly decreased while AST activity increased at the highest concentration of Ni (II) p-hydroxybenzoate with caffeine. This change in transferase enzyme activities may be due to disruption of amino acid metabolism. CK, AMYL, and LDH levels were significantly increased in the hemolymph of G. mellonella larvae. In another study, it was reported that transferase enzymes such as AST, ALT, and GGT activities and metabolic enzymes such as CK, AMYL, and LDH levels increased due to the oxidative effect of oxfendazole, an anthelmintic drug ( Sugeçti and Büyükgüzel, 2018). Tunçsoy et al. (2021) reported that metabolic enzymes such as AST, ALT, GGT, LDH, CK, and AMYL levels significantly increased in hemolymph of G. mellonella larvae exposed to copper oxide nanoparticles. In another study, biochemical effects of Escherichia coli a

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Control 0.03 0.3 3 Concentrations (%)

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Control 0.03 0.3 3 Concentrations (%)

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infection on great wax moth were investigated. The authors found that the biochemical and immune responses of the insect was adversely affected in E. coli infection, and CK, GGT, AMYL, and ALP levels were increased, especially 8 h after with E. coli infection, as a result of oxidative damage in the hemolymph of G. mellonella larvae ( Sugeçti, 2021b). Data from these studies demonstrated that biological and chemical agents cause similar results on the same insect.

Enzymatic and nonenzymatic antioxidants play a key role in the elimination of oxidative damage caused by physiological and biochemical stresses (Büyükgüzel and Kalender 2007, 2009; Upadhyay et al., 2014; Mirończuk-Chodakowska et al., 2018; Kaur et al., 2021). In addition, amounts of some biomolecules such as protein and lipid in insects increase as an adaptation to oxidative damage ( Sak et al., 2011; Emre et al., 2013; Tunçsoy, 2020). In the current study, the levels of nonenzymatic antioxidants such as ALB, BIL, and UA were increased when compared to the control group. Nonenzymatic antioxidants may have been increased to prevent oxidative damage due to Ni (II) p-hydroxybenzoate with caffeine. In this study, the increase in amounts of TP and CHOL may be an adaptation developed against the oxidative damage. In another study, it was reported that antioxidant system was altered due to oxidative damage in the midgut of G. mellonella larvae exposed to a widely used biorational pesticide Bacillus thuringiensis ( Dubovskiy et al., 2008) . In a study by Tunçsoy and Meşe (2021), four different concentrations (5, 50, 250, and 1250 μg/mL) of titanium dioxide nanoparticles were added to diet of model organism G. mellonella larvae. The authors reported that antioxidant enzymes levels significantly increased in G. mellonella larvae. In another study, the oxidative effects of juglone on G. mellonella were investigated. The authors found that antioxidant enzymes were adversely affected and induced lipid peroxidation due to juglone in a concentration-dependent manner (Altuntaş et al., 2020). Our findings show that the oxidative stress caused by Ni (II) p-hydroxybenzoate with caffeine can be eliminated by nonenzymatic antioxidants.

Ions in insects are involved in the regulation of cellular functions, which is deteriorated due to stress caused by biological and chemical agents (Southall et al., 2006). In this study, hemolymph ion levels such as K, Phos, Mg, and Ca increased at the highest Ni (II) p-hydroxybenzoate with caffeine concentration. The change in the amount of ions may be for the regulation of the disturbed cellular