PHYSIOLOGY ,BIOCHEMISTRY , AND TOXICOLOGY Alterations in Antioxidant Enzyme Activity, Lipid Peroxidation, and Ion Balance Induced by Dichlorvos in Galleria mellonella (Lepidoptera: Pyralidae) T. KAYIS, 1,2 M. COSKUN, 1 O. DURSUN, 3 AND I. EMRE 3 Ann. Entomol. Soc. Am. 108(4): 570–574 (2015); DOI: 10.1093/aesa/sav038 ABSTRACT Dichlorvos (DDVP; 2,2-dichlorovinyl dimethyl phosphate) is an organophosphate insecti- cide widely used in the control of pests. This study aims to determine the changes caused by DDVP in the antioxidant enzyme activity, lipid peroxidation level, and ion content of a model organism, Galleria mellonella L. (Lepidoptera: Pyralidae). Larvae of G. mellonella were fed sublethal concentrations of DDVP (2, 4, 6, and 8 mg/100 g feed). Exposure to DDVP resulted in induction of superoxide dismutase and catalase activities, and lipid peroxidation in larvae. Potassium and sodium ion levels were signifi- cantly altered by DDVP exposure. These results suggest that DDVP causes oxidative stress and lipid peroxidation and alters the antioxidant enzyme activities and ion balance in G. mellonella larvae. Addi- tionally, these results indicate that G. mellonella is a useful model for testing the effects of insecticides. KEY WORDS dichlorvos, antioxidant enzyme, lipid peroxidation, ion balance, Galleria mellonella Organophosphate insecticides act by disrupting the ner- vous system in both insects and mammals by inhibiting acetylcholinesterase. These chemicals are widely used for the control of agricultural, industrial, and domestic pests (Howard and Pope 2002, Clark 2006). Dichlorvos (DDVP; 2,2-dichlorovinyl dimethyl phosphate) is an or- ganophosphate pesticide commonly used to protect stored products and grains, control ecto and endopara- sites of farm animals, and combat indoor and outdoor pests (Ojo et al. 2014). Nontarget organisms, including humans, are exposed to sublethal concentrations of or- ganophosphates primarily through food, drinks, and in- halation (WHO 2001) that can result in neurologic and behavioral disorders, genotoxic and oxidative damage (Bolognesi 2003, Costa 2006, Kayis et al. 2012, Deb and Das 2013). Moreover, organophosphates alter the flow of ions across membranes (Gallicchio et al. 1987) and loss of ionic balance (Swann et al. 1991). Lipid peroxidation is one of the important reactions that determine oxidative damage in organisms by mea- suring the malondialdehyde levels (Cervera et al. 2003, Migula et al. 2004). Like other organisms, insects have antioxidant enzymes to scavenge reactive oxygen spe- cies. These enzymes include superoxide dismutase (SOD; EC 1.15.1.1), catalase (CAT; EC 1.11.1.6), and glutathione peroxidases (GPx; EC 1.11.1.9). While su- peroxide dismutase catalyzes the dismutation of super- oxide radical to hydrogen peroxide and oxygen, catalase and glutathione peroxidases protect cells by transforming peroxides to water and molecular oxygen (Fridovich 1975, Halliwell 1999, Wang et al. 2001). Antioxidant enzyme activities and malondialdehyde lev- els in insects have been shown to change under oxida- tive stress. These changes may serve as biomarkers in insects (Lozinskaya et al. 2004, Li et al. 2005, Emre et al. 2013). Ion homeostasis in insects is regulated by the Malpi- ghian tubules and the gut (O’Donnell 2008). The or- gans play a key role in the detoxification of toxic substances, such as insecticides (Chahine and O’Don- nell 2011, Harrop et al. 2014). Using insects as model organisms for determining or- ganophosphate toxicity could lower costs, accelerate screening, and provide ethical benefits (Berger 2008). Galleria mellonella L. (Lepidoptera: Pyralidae) is a lepi- dopteran species that has a short lifecycle, ideal larval size, and easily rears on artificial nutrients (Coskun et al. 2006, Dubovskiy et al. 2008, Emre et al. 2013). The lar- vae of G. mellonella have been used as whole-organism virulence models for various species of pathogenic fungi, viruses, and bacteria because they can live at mamma- lian body temperature and also have immune responses similar to those of mammals (Bu ¨ yu ¨ kgu ¨ zel et al. 2007, Kavanagh and Fallon 2010, Ramarao et al. 2012). This study aims to determine the effects of DDVP on antioxidant enzyme activities, lipid peroxidation, and the ion content of G. mellonella and to investigate the feasibility of using G. mellonella as a model organism in physiological, biochemical, and toxicological studies. Materials and Methods Determination of LC 50 of DDVP in G. mellonella Larvae. To determine the median lethal concentration (LC 50 ) of DDVP, 20 larvae were raised 1 Department of Biology, Faculty of Science and Letters, Adıyaman University, Adıyaman 02040, Turkey. 2 Corresponding author, E-mail: tkayis@adiyaman.edu.tr. 3 Department of Biology, Faculty of Science and Letters, C ˛ ukurova University, Adana 01330, Turkey. V C The Authors 2015. Published by Oxford University Press on behalf of Entomological Society of America. All rights reserved. For Permissions, please email: journals.permissions@oup.com Downloaded from https://academic.oup.com/aesa/article/108/4/570/72622 by guest on 12 August 2022