Toxicity and biochemical effects of itol A on the brown planthopper, Nilaparvata lugens (Stål) (Hemiptera: Delphacidae)

• Published in: Pesticide biochemistry and physiology Vol. 152; pp. 90 - 97
• Main Authors: Ling, Si-Quan, Xu, Ya-Nan, Gu, Yan-Ping, Liu, Shu-Yu, Tang, Wen-Wei
• Format: Journal Article
• Language: English
• Published: United States Elsevier Inc 01.11.2018
• Subjects: Acid Phosphatase - metabolism; Adenosine Triphosphatases - metabolism; Animals; Antioxidant system; Enzyme activity; Female; Glutathione - metabolism; Glutathione Transferase - metabolism; Hemiptera - drug effects; Hemiptera - metabolism; Insecticides - toxicity; Itol A; Lethal Dose 50; Malondialdehyde - metabolism; Nilaparvata lugens; Oxidative stress; Oxidoreductases - metabolism; Salicaceae; Toxicity; Antioxidant system; Nilaparvata lugens; Itol A; Oxidative stress; Enzyme activity; Toxicity
• ISSN: 0048-3575; 1095-9939
• DOI: 10.1016/j.pestbp.2018.09.005

Itol A, a novel isoryanodane diterpene derived from Itoa orientalis Hemsl., has potent activities against insect pests. This study was conducted to determine the contact toxicity and biochemical effects of itol A on the Nilaparvata lugens. After macropterous females of N. lugens were exposed to itol A from 0.5 to 24 h, the mortality and poisoning symptoms were measured. Effects of itol A on the major enzymes activity and oxidative stress level were assessed in dose-response (with LD10-LD70 at 24 h) and time-course (with LD50 at 0.5–24 h) experiments for the potential toxicity mechanisms. Based on the results, the mortality of N. lugens showed significant dose- and time-dependent effects, with the 24-h LD50 value was 0.58 μg/insect. The symptoms of excitation, convulsion and paralysis were also observed. However, acetylcholinesterases (AChE) activity was not altered after itol A treatment compared to control. Na+/K+-ATPases, Ca2+-ATPases, Ca2+/Mg2+-ATPases, glutathione S-transferases (GSTs), cytochrome P450 monooxygenases (P450s), superoxide dismutases (SOD) and catalases (CAT) activities were significantly reduced in dose-response and time-course experiments. While acid phosphatases (ACP) and glutathione peroxidases (GPX) activities were significantly increased. We further revealed that itol A exposure resulted in the decrease of GSH/GSSG (reduced to oxidized glutathione) ratio and the increase of hydrogen peroxide (H2O2) and malondialdehyde (MDA) levels in both experiments. The results indicated that the inhibition of Na+/K+-ATPases, Ca2+-ATPases, Ca2+/Mg2+-ATPases, GSTs, P450s, SOD and CAT activities and the induction of oxidative stress was one of the potential biochemical mechanisms of itol A against N. lugens. [Display omitted] •Itol A exhibited potent contact toxicity against Nilaparvata lugens.•Na+/K+-ATPases, Ca2+-ATPases and Ca2+/Mg2+-ATPases activities were inhibited.•GSTs, P450s, SOD and CAT activities were inhibited and GSH/GSSG ratio was increased.•The oxidative stress was increased in terms of the dose- and time-response.