Neonicotinoid Insecticides: Oxidative Stress in Planta and Metallo-oxidase Inhibition

Abstract

Neonicotinoids not only control insect pests but also sometimes independently alter plant growth and response to stress. We find that imidacloprid, thiacloprid, acetamiprid, thiamethoxam, and clothianidin but not nitenpyram and dinotefuran induce foliar lesions and peroxidative damage in soybean ( Glycine max ) seedlings assayed with the 3,3'-diaminobenzidine stain. The chloropyridinyl-carboxylic acid (COOH) but not the -carboxaldehyde (CHO) metabolites induce peroxidative damage but in a different pattern. Surprisingly, the chlorothiazolyl -CHO and -COOH metabolites induce chlorosis but no clear superimposable peroxidative damage or cell death. Four metallo-oxidases known to modulate reactive oxygen species were not sensitive in vitro to the parent neonicotinoid itself but were to several CHO and COOH metabolites and related compounds, with a sensitivity order of CHO > COOH and tyrosinase > xanthine oxidase and aldehyde oxidase > catalase. Although metallo-oxidase inhibition does not correlate overall with lesion formation, it may play an as yet unknown role in plant response to neonicotinoids.

Nad

“…76 In addition to their toxicity for insects, neonicotinoids have also been associated with an improved resistance to microbial pathogens. 77,78 In fact, Arabidopsis rosettes sprayed with neonicotinoids show an enhanced resistance to powdery mildew and induction of SA-mediated plant defense responses. 76 The authors suggested that some neonicotinoids stimulate defense responses by mimicking SA tridimentional structure.…”

“…Accumulated NAD derivatives (nicotinamide and nicotinate) are indeed suspected to have a modest effect or no effect at all on incompatible interactions: for example, neonicotinoids spraying rather promoted NAD recycling and increased NAD(P) pools which in turn improved tolerance against drought or pathogens via molecular mechanisms. 77,78 Nicotinamide is a key metabolite derived from NADcleavage pathways. 36,45 As stated before, studies of isonicotinamide (a nicotinamide chemical analog) support a role for nicotinamide-related metabolites in plant defense responses.…”

Electrochemical detection of extracellular hydrogen peroxide in Arabidopsis thaliana: a real‐time marker of oxidative stress

“…The addition of an insecticide containing thiacloprid as an active component decreased H 2 O 2 production by cells (Table 2). This class of insecticides has been reported to enhance plant vigour and stress tolerance in some cases, independently of their insecticidal function (Ford et al . 2011).…”

Analytical approach, dissipation pattern and risk assessment of pesticide residue in green leafy vegetables: A comprehensive review

“…However, conflict between countries regarding acceptable levels may hinder international trade; therefore, the standardization of MRLs is necessary. In this regard, two organizations, the European Union at the European level and the Codex Alimentarius Commission of the Food and Agriculture Organization (Codex Alimentarius, 2012) have Ford et al, 2011;Im et al, 2015;Ko et al, 2014;Namgung et al, 2014;Park et al, 2016;Uneme, 2010;Wołejko et al, 2016 Azoxystrobin are applied for individual pesticides in specific crops to determine halflives, dissipation patterns, PHI and PHRL Park et al, 2013;Rahman et al, 2012Siddamallaiah & Mohapatra, 2016). Therefore, for the purposes of safety and dietary risk assessment, an effective analytical method must be developed to quantitatively determine the parent compound and its metabolites, if any, in specific crops, even though the metabolites are not included in the definition of residue.…”