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The fall armyworm (FAW), Spodoptera frugiperda, is one of the most devastating invasive polyphagous pests, which has attracted recent global attention by developing resistance to various insecticidal active ingredients with independent mode of action. Fluxametamide, a newly commercialized isoxazoline insecticide, is exceptionally selective towards several lepidopteran pests. The present study aimed to evaluate resistance risk in FAW to fluxametamide and the fitness costs associated with fluxametamide resistance. A field-collected and genetically mixed population of FAW was artificially selected through continuous exposure to fluxametamide. After successive selection of 10 generations, there was no obvious increase in the LC50 (RF: 2.63-fold). The realized heritability (h2) of fluxametamide resistance was estimated as h2 = 0.084 using a quantitative genetic approach. Compared with the susceptible F0 strain, the Flux-SEL (F10) strain of FAW displayed no significant cross-resistance to broflanilide, chlorantraniliprole, fipronil, indoxacarb, lambda cyhalothrin, spinetoram, and tetraniliprole, except emamectin benzoate (RF: 2.08-fold). Increased activity of glutathione S-transferase (ratio 1.94) was observed in the Flux-SEL (F10) strain of FAW, while the cytochrome P450 and carboxylesterase activities were not altered. The fluxametamide-selection significantly affected the development and reproductive traits of FAW with a lower R0, T and relative fitness (Rf = 0.353). The results alluded that the risk of fluxametamide resistance evolution in FAW is relatively lower; however, proactive implementation of resistance management approaches should be done to maintain the field efficacy of fluxametamide against FAW. [ABSTRACT FROM AUTHOR]

The appearance and rapid spread of the fall armyworm (Spodoptera frugiperda) (FAW) represents a serious threat to maize cultivation in India and elsewhere in South Asia. Chemical control illustrates one of the major means of reducing the infestation of FAW in maize-growing zones. However, existing information regarding the field-efficacy and non-target toxicity of different insecticides against this pest is not adequate and is also unable to capture the momentum change in the scenario of residual toxicity and insecticide resistance for redacting sustainable management. The present study was framed to establish the most suitable insecticidal schedule against FAW for maize producers. In the period from winter 2019–2020 to spring–summer 2020, seven treatment schedules against FAW were evaluated, and the efficacy was calculated according to the per cent maize plant damage (PD) by larvae, while safety was enumerated based on larval parasitization by Campoletis chlorideae and the abundance of coccinellid predators. In both seasons, the highest cumulative efficacy (9.88 and 10.19% PD) was confirmed for T3 (constituted with Barazide®, Delegate®, and Ampligo®) with a significantly higher yield (52.39 and 52.66 q ha−1), whereas T7 (Proclaim Fit®, Ampligo®, and Delegate®) and T6 (Fimecta®, Ampligo®, and Spintor®) exhibited a high cumulative efficacy (11.06 to 12.23% PD). T3 was found to be safe to coccinellid predators and the per cent larval parasitism by C. chlorideae was significantly higher in this module (2.57 and 2.75%) compared to T4 and T5 (1.00 to 1.67%). The residues of Barazide®, Delegate®, and Ampligo® were below detectable levels in maize plant, grain and soil samples. Therefore, the module could be recommended against FAW in the near future. [ABSTRACT FROM AUTHOR]

Management of the black looper Hyposidra talaca (Walker), the most demolishing foliage feeder of tea in Himalayan foothills, is based on the use of chemical insecticides, though poor field efficacy of various commercially formulated products has recently been reported. In the present study, insecticide resistance of H. talaca to some traditional and newer insecticides was evaluated from north-eastern tea growing belt of India. Six populations of H. talaca were collected in three consecutive years, 2017 to 2019, from five locations (Dooars, Kalimpong, Sikkim, Assam, and Darjeeling). These areas represent the major and commercially exportable best-quality Indian tea production belts. The Darjeeling and Assam populations showed low to very high lethal concentration ratios (LCRs) (16.67 to 140.32, respectively) to bifenthrin, deltamethrin and diflubenzuron while, highest LCR to quinalphos was observed in the Dooars population (119.81). Similarly, very low to extremely high LCRs to emamectin benzoate and flubendiamide (4.00 to 65.25 and 16.43 to 148.94, respectively) were observed in all six populations. However, pyridalyl (LCR ≤ 77.09) and spinetoram (LCR ≤ 82.03) showed higher toxicity than that of cyantraniliprole (LCR ≤ 120.98) to field populations of H. talaca, irrespective of locations. The pairwise correlation coefficients of log LC50 values revealed that emamectin benzoate was significant but negatively correlated with bifenthrin. LCRs to the tested insecticides were heterogeneous and highly variable among locations and years. Specific resistance management strategies should be established, especially in locations where H. talaca has developed very high levels of resistance to newer chemistry insecticides. [ABSTRACT FROM AUTHOR]

The diamondback moth Plutella xylostella (L.) (Lepidoptera: Plutellidae) is a devastating pest that infests several cruciferous vegetable crops worldwide and has developed insecticide resistance in most chemical classes. Fluxametamide is a novel neuroactive isoxazoline compound that binds to a unique site on the γ -aminobutyric acid (GABA) receptor and has an exceptional insecticidal activity on a range of lepidopteran caterpillars. The present study aimed to assess the risk of resistance in P. xylostella to fluxametamide under laboratory conditions. After the repeated exposure to fluxametamide for successive 18 generations of P. xylostella , there was 3.095-fold increase in the LC 50. When the realized heritability (h 2 ) of P. xylostella to fluxametamide in the open field was assumed to be the laboratory-estimated value (h 2 = 0.180) and the mortality was 70–90%, only 22.9–33.1 generations were expected to be required to obtain a 10-fold increase in fluxametamide resistance. Compared with the laboratory susceptible strain (F 0), the Flux-SEL (F 18) strain exhibited a very low level of cross-resistance to emamectin benzoate (5.17-fold) and no significant cross-resistance to fipronil or flubendiamide. With the F 0 and the Flux-SEL test strains (F 12 , F 15 and F 18), the specific activities of cytochrome P450 and glutathione S -transferase showed a remarkable increase during selection, while the esterase activity did not differ significantly. The results indicated that a potential risk of resistance development to fluxametamide exists in P. xylostella after continuous exposure. These pieces of information will be crucial in formulating rational fluxametamide application and resistance management guidelines for controlling P. xylostella under field condition. [Display omitted] • First report of laboratory-selected fluxametamide resistance in Plutella xylostella. • P. xylostella carries a potential risk of field-evolved resistance to fluxametamide. • The estimated h 2 of fluxametamide resistance in Flux-SEL (F 18) strain was 0.180. • Flux-SEL (F 18) strain was weakly resistant to emamectin benzoate. • The activities of P450 and GST increased significantly in Flux-SEL strains during selection. [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]