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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]

Fluxametamide, a novel isoxazoline insecticide, is newly registered for the control of various lepidopteran, coleopteran and thysanopteran insect pests on lethal and sublethal levels. In the present study, the toxicity and sublethal effects of fluxametamide on diamondback moth Plutella xylostella (L.), an invasive lepidopteran foliage feeder of cruciferous vegetables, were assessed to explore its bio-ecological impact on pest populations. The toxicity of fluxametamide to the third instar larvae of P. xylostella was 0.18 mg L−1 (LC50) at 72 h bioassay. After treatment with LC10 and LC30 concentrations of fluxametamide, the fourth instar larval duration, the rate of deformed pupa and adults, and the adult pre-oviposition period were significantly increased, whereas the pupation rate and pupal weight were significantly decreased in the F0 generation. In the F1 generation, sublethal effects of fluxametamide were indicated by a reduced fecundity, rate of pupation and adult emergence, pupal weight, and adult longevity, however a significant increase in eggs and total larval duration, deformed adults rate, and total longevity and pre-oviposition period was observed in the offspring. The intrinsic rate of increase (r), finite rate of increase (λ) and net reproductive rate (R0) of sublethal treatments were significantly lower than the control. The relative fitness of F1 was 0.68 and 0.64 in LC10 and LC30 treatments, respectively. The LC30 fluxametamide treatment exhibited increased glutathione S-transferase activities (elevated 1.433-fold) in P. xylostella. Our results suggest that in addition to its high lethal toxicity, the sublethal concentrations of fluxametamide might suppress the reproduction, development and survival of the P. xylostella population and its progeny, which can help to optimize integrated pest management program. [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]

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]

To investigate the effect of irrigation and mulch on the yield of strawberry (line FA-007), this study was conducted at the experimental fields of Pomology Division, BARI, Gazipur and RARS, BARI, Rangpur during Rabi season of 2012-13 and 2013-14. The experiment was conducted followed by the split-plot design with two mulches (black plastic and rice straw), three levels of irrigation (5, 10, and 15 days interval), and three replications. A significant difference was observed for most of the parameters among different treatments for both locations. Irrigation at 5 days interval with rice straw mulch in Gazipur and irrigation at 5 days interval with black polythene mulch in Rangpur were performed better for most of the yield-contributing characters and yield among all other treatments for both the years. But in respect to water productivity, 10 days irrigation interval with rice straw mulch in Gazipur and 10 days interval with black polythene mulch in Rangpur showed highest results among all other treatments. However, it can be concluded that any irrigation practices from the abovementioned options could be adopted by the farmers based on their feasibility and water availability for strawberry cultivation in Bangladesh. [ABSTRACT FROM AUTHOR]