Hormonal enhancement of insecticide efficacy in Tribolium castaneum: Oxidative stress and metabolic aspects

• Published in: Comparative biochemistry and physiology. Toxicology & pharmacology 2015-04, Vol.170, p.19-27
• Main Authors: Plavšin, Ivana, Stašková, Tereza, Šerý, Michal, Smýkal, Vlastimil, Hackenberger, Branimir K., Kodrík, Dalibor
• Format: Article
• Language: English
• Subjects: Adipokinetic hormone; Animals; Energy Metabolism - drug effects; Energy Metabolism - physiology; Insect Hormones - administration & dosage; Insect Hormones - toxicity; Insecticide; Insecticides - administration & dosage; Insecticides - toxicity; Metabolism; Mortality; Neuropeptides - administration & dosage; Neuropeptides - toxicity; Oxidative stress; Oxidative Stress - drug effects; Oxidative Stress - physiology; Pyrrolidonecarboxylic Acid - administration & dosage; Pyrrolidonecarboxylic Acid - analogs & derivatives; Pyrrolidonecarboxylic Acid - toxicity; RNA interference; Tribolium - drug effects; Tribolium - metabolism
• ISSN: 1532-0456; 1878-1659
• DOI: 10.1016/j.cbpc.2015.01.005

Insect anti-stress responses, including those induced by insecticides, are controlled by adipokinetic hormones (AKHs). We examined the physiological consequences of Pyrap-AKH application on Tribolium castaneum adults (AKH-normal and AKH-deficient prepared by the RNAi technique) treated by two insecticides, pirimiphos-methyl and deltamethrin. Co-application of pirimiphos-methyl and/or deltamethrin with AKH significantly increased beetle mortality compared with application of the insecticides alone. This co-treatment was accompanied by substantial stimulation of general metabolism, as monitored by carbon dioxide production. Further, the insecticide treatment alone affected some basic markers of oxidative stress: it lowered total antioxidative capacity as well as the activity of superoxide dismutase in the beetle body; in addition, it enhanced the activity of catalase and glutathione-S-transferase. However, these discrepancies in oxidative stress markers were eliminated/reduced by co-application with Pyrap-AKH. We suggest that the elevation of metabolism, which is probably accompanied with faster turnover of toxins, might be responsible for the higher mortality that results after AKH and insecticide co-application. Changes in oxidative stress markers are probably not included in the mechanisms responsible for increased mortality.