Establishing the role of detoxifying enzymes in field‐evolved resistance to various insecticides in the brown planthopper (Nilaparvata lugens) in South India

Abstract

The brown planthopper (BPH), Nilaparvata lugens (Stål), is one of the major pests of rice throughout Asia. Extensive use of insecticides for suppressing N. lugens has resulted in the development of insecticide resistance leading to frequent control failures in the field. The aim of the present study was to evaluate resistance in the field populations of N. lugens from major rice growing states of South India to various insecticides. We also determined the activity of detoxifying enzymes (esterases [ESTs], glutathione S-transferases [GSTs], and mixed-function oxidases [MFOs]). Moderate levels of resistance were detected in the field populations to acephate, thiamethoxam and buprofezin (resistance factors 1.05-20.92 fold, 4.52-14.99 fold, and 1.00-18.09 fold, respectively) as compared with susceptible strain while there were low levels of resistance to imidacloprid (resistance factor 1.23-6.70 fold) and complete sensitivity to etofenoprox (resistance factor 1.05-1.66 fold). EST activities in the field populations were 1.06 to 3.09 times higher than the susceptible strain while for GST and MFO the ratios varied from 1.29 to 3.41 and 1.03 to 1.76, respectively. The EST activity was found to be correlated to acephate resistance (r = 0.999, P ≥ 0.001). The high selection pressure of organophosphate, neonicotinoid, and insect growth regulator (IGR) in the field is likely to be contributing for resistance in BPH to multiple insecticides, leading to control failures. The results obtained will be beneficial to IPM recommendations for the use of effective insecticides against BPH.

Gut Bacterial Diversity of Insecticide-Susceptible and -Resistant Nymphs of the Brown Planthopper Nilaparvata lugens Stå l (Hemiptera: Delphacidae) and Elucidation of Their Putative Functional Roles

“…To assay the dose response of the BPH to the insecticides, the rice stem-dipping method was used [18]. Briefly, a total of 10-15 early fifth instar nymphs of the BPH were introduced into 500 ml plastic cups, each containing basal 10-cm-long, 50-60-day-old rice stems with their root portions placed on a mixture of vermicompost, sand, and water.…”

Galls of Guiera senegalensis J.F. GMEL (Combretaceae) as potential source of insecticides against the main cowpea pest Callosobruchus maculatus (Fab.) (Coleoptera: Bruchidae) detoxification enzymes

“…Ouagadougou laboratory strain could be tolerant to the toxic effect of G. senegalensis by increasing the activity of acetylcholinesterase and esterase enzymes. Malathi et al (2017) showed that the increased levels of esterases are responsible for the resistance to organophosphates, carbamates and pyrethroids in many insects.…”

“…In all the different locations, the oxidase enzymes from the different strains of C. maculatus showed strong susceptibility to the toxic effect of the compounds in the methanol extract of galls from G. senegalensis. Elevated level of mixed function oxidases has been involved in imparting resistance to organochlorines, pyrethroids, and neonicotinoids in many insect species (Malathi et al, 2017). The mixedfunction oxidase activities are involved in the respiratory electron transport chain (Wu et al, 2014).…”

“…The resistance of insects to synthetic pesticides results from three main mechanisms: (i) reduction of insecticide penetration, (ii) enhanced detoxification of insecticides before they reach their target-site by esterases (ESTs), glutathione S-transferases (GSTs) and cytochrome P450 monooxygenases (P450s) or mixed function oxidases (MFO), and (iii) modification of sensitivity of target enzymes to insecticides (Kim and Boo, 2004;Malathi et al, 2017).…”

Identification of SNPs involved in regulating a novel alternative transcript of P450 CYP6ER1 in the brown planthopper

“…Essentially, the increase in P450 enzymatic activity caused by the overexpression of P450 genes are associated with enhanced ability to detoxify insecticides in resistant insects (Daborn et al, 2001;Karunker et al, 2009;Bass et al, 2011). Moreover, for field populations of some pest insects, changes in P450 activity appear to be the predominant mechanism for resistance to neonicotinoid insecticides (Puinean et al, 2010;Yang et al, 2013;Malathi et al, 2017). Identification of the mechanisms regulating the expression of P450 genes will help in understanding the development of P450-mediated metabolic resistance in insects.…”