Search

Evaluation and identification of resistant donors for brown planthopper (BPH) Nilaparvata lugens (Stål.), an economically important insect pest of rice, is a continuous process to develop new resistant rice varieties. However, several rice landraces of north-eastern India are not yet characterized for BPH resistance. In the present study, a set of 218 rice landraces were screened in both greenhouse and open-field conditions for three consecutive years, and thereafter forty selected promising entries were explored to evaluate their phenotypic and genotypic reactions against BPH biotype 4. Based on phenotypic evaluations, five landraces were identified as resistant, while 31 were moderately resistant, and grouped under the major cluster I and II, respectively, in a circular dendrogram. Antixenosis and antibiosis studies of these landraces divulged that, compared to the susceptible check variety, resistant landraces exhibited the lowest feeding rate, survival, and nymphal and adult settling, but higher frequency of unhatched eggs of BPH. Un-infested resistant landraces registered higher levels of ascorbic acid, oxalic acid and crude silica, however, elevated levels of total free amino acid, potassium and crude silica were observed under BPH herbivory. The present study focuses on identifying new donors having BPH resistance resources which could be useful in genomic studies for the development of BPH biotype 4 resistant rice varieties. [ABSTRACT FROM AUTHOR]

Whitefly (Bemisia tabaci Gennadius) is a devastating pest of vegetables, cotton, and many other agricultural and horticultural crops worldwide. Since control of B. tabaci on vegetable crops solely depends on the use of chemical insecticides in India; monitoring the insecticide resistance of B. tabaci populations would be very much essential for achieving successful control and for managing the resistance development. Hence, the aim of the present study was to examine the resistance in different field strains of B. tabaci to traditional organophosphates and new chemical insecticides in India. The resistance ratios were recorded in the range of 30.67-131.48 fold for acephate, 29.17-83.67 fold for triazophos, 0.38-2.51 fold for indoxacarb, 4.55-34.52 fold for dinotefuran, 6.26-27.56 fold for tolfenpyrad, 7.87-31.89 fold for spiromesifen, 1.61-30.08 fold for pyriproxyfen, and 3.09-45.92 fold for flonicamid in comparison to that of the susceptible strain in the laboratory. Resistance levels of B. tabaci populations against the tested insecticides were significantly variable among localities. The present data will be helpful for the selection of proper insecticides on vegetable crops in the field for successful management of B. tabaci in near future. [ABSTRACT FROM AUTHOR]

The cotton whitefly, Bemisia tabaci (Gennadius) is a devastating polyphagous insect pest worldwide and has been shown to be resistant to insecticides in most chemical classes. The newly commercialized pyropene insecticide afidopyropen provided a new tool to control B. tabaci because of high selectivity and its novel mode of action. This study aimed to evaluate the susceptibility of B. tabaci Asia I from ten provinces of India to afidopyropen and other commonly used insecticides. Most field-collected populations were susceptible to afidopyropen, with LC 50 values varying from 4.37 to 16.62 mg L−1. However, four field populations (W-MH, K-UP, M-WB and L-PN) exhibited moderate levels of resistance (28.53, 19.09, 35.27 and 30.81-fold, respectively), but no cross-resistance to cyantraniliprole and pymetrozine. Diethyl maleate (DEM) significantly restored the susceptibility of W-MH, M-WB and L-PN strains of B. tabaci to afidopyropen, whereas piperonyl butoxide (PBO) significantly inhibited afidopyropen resistance in K-UP, M-WB and L-PN populations. The activities of glutathione S -transferase (GST) and P450 monooxygenase increased in the afidopyropen-resistant field strains, while esterase activity did not change significantly. The present study showed a regional variation in afidopyropen toxicities among B. tabaci Asia I populations from different agro-climatic zones of India, which suggests a potential risk of afidopyropen resistance development. Metabolic detoxification mediated by GST and P450 monooxygenase was associated with afidopyropen resistance in B. tabaci Asia I. [Display omitted] • First report of afidopyropen resistance in Bemisia tabaci Asia I. • Four field-strains exhibited moderate level of resistance. • No cross-resistance of afidopyropen with cyantraniliprole or pymetrozine. • Elevated GST and P450 activities in afidopyropen-resistant populations. [ABSTRACT FROM AUTHOR]

Evaluation and identification of resistant donors for brown planthopper (BPH) Nilaparvata lugens (St å l.), an economically important insect pest of rice, is a continuous process to develop new resistant rice varieties. However, several rice landraces of north-eastern India are not yet characterized for BPH resistance. In the present study, a set of 218 rice landraces were screened in both greenhouse and open-field conditions for three consecutive years, and thereafter forty selected promising entries were explored to evaluate their phenotypic and genotypic reactions against BPH biotype 4. Based on phenotypic evaluations, five landraces were identified as resistant, while 31 were moderately resistant, and grouped under the major cluster I and II, respectively, in a circular dendrogram. Antixenosis and antibiosis studies of these landraces divulged that, compared to the susceptible check variety, resistant landraces exhibited the lowest feeding rate, survival, and nymphal and adult settling, but higher frequency of unhatched eggs of BPH. Un-infested resistant landraces registered higher levels of ascorbic acid, oxalic acid and crude silica, however, elevated levels of total free amino acid, potassium and crude silica were observed under BPH herbivory. The present study focuses on identifying new donors having BPH resistance resources which could be useful in genomic studies for the development of BPH biotype 4 resistant rice varieties., Competing Interests: Sukamal Sarkar is an Academic Editor for PeerJ., (© 2022 Roy et al.)