Broflanilide effectively controls Helicoverpa armigera and Spodoptera exigua exhibiting diverse susceptibilities to chlorantraniliprole and emamectin benzoate

The larval gut of Spodoptera frugiperda harbours culturable bacteria with metabolic versatility after insecticide exposure

Spodoptera frugiperda (fall armyworm) poses a substantial risk to crops worldwide, resulting in considerable economic damage. The gut microbiota of insects plays crucial roles in digestion, nutrition, immunity, growth and, sometimes, the degradation of insecticides. The current study examines the effect of synthetic insecticides on the gut microbiome of third instar S. frugiperda larvae using both culture-dependent techniques and 16S rRNA gene sequencing for bacterial community profiling and diversity analysis. In untreated larvae, the sequencing approach revealed a diverse microbiome dominated by the phyla Firmicutes, Proteobacteria and Bacteroidota, with key genera including Bacteroides, Faecalibacterium and Pelomonas. In parallel, 323 bacterial strains were isolated and assigned to the orders Bacillales, Burkholderiales, Enterobacterales, Flavobacteriales, Lactobacillales, Micrococcales, Neisseriaies, Pseudomonadales, Sphingobacteriales and Xanthomonadales. The prevailing culturable species included Serratia marcescens, Klebsiella variicola and Enterobacter quasiroggenkampii. Treatment with sublethal concentrations of three insecticides (broflanilide, spinosad and indoxacarb) caused significant changes in gut microbiome diversity and composition. Treated larvae showed a shift towards increased Proteobacteria abundance and decreased Firmicutes. Specifically, Acinetobacter and Rhodococcus were dominant in treated samples. Functional predictions highlighted significant metabolic versatility involving nutrient processing, immune response, detoxification, xenobiotic metabolism, and stress response, suggesting microbial adaptation to insecticide exposure. Network correlation analysis highlighted disrupted microbial interactions and altered community structures under insecticide treatment. These findings enhance our understanding of how insecticides impact the gut microbiota in S. frugiperda and may inform future strategies for managing pest resistance through microbiome-based approaches.

Nanoporous 3D Polyurethane for Toosendanin Adsorption, Encapsulation, and High-Efficient Utilization

Nanoporous 3D-polyurethane (3D-PU) was prepared based on nano-CaCO3 templated controllably confined polymerization assembly and weak acid etching strategies. Nanopores with diameters ranging from 48 to 72 nm were distributed on 3D-PU, facilitating its high BET surface area of 468.0 m2/g. The 3D-PU exhibited enhanced adsorption selectivity to multi-H-bond donors and acceptors, multirings contained compounds based on pore filling, hydrogen-bonding, and π-π interactions; therefore, the novel 3D-PU had promising adsorption ability to toosendanin (TSN) with a maximum theoretical adsorption capacity of 361.6 mg/g. Adsorption isotherm, kinetic, and thermodynamic investigations revealed that the adsorption was heterogeneous and was supported by multiple adsorption sites, controlled by a chemical adsorption mechanism, endothermic, spontaneous, and with increased entropy. Based on the optimized adsorption, the loading capacity (LC) of 3D-PU toward TSN attained 23.4%. After encapsulation, the effective period of TSN was extended to 11 days, the photolysis half-life of TSN was increased 3.2 times, and the LC50 for Aphis citricola was reduced approximately 6.0 times, indicating that 3D-PU effectively improved the performance of TSN. The porous 3D-PU can serve as a promising carrier for more pesticide adsorption, encapsulation, safe, highly efficient, and environmentally friendly utilization.

Genomic predictions of invasiveness and adaptability of the cotton bollworm in response to climate change

Agricultural pests cause enormous losses in annual agricultural production. Understanding the evolutionary responses and adaptive capacity of agricultural pests under climate change is crucial for establishing sustainable and environmentally friendly agricultural pest management. In this study, we integrate climate modeling and landscape genomics to investigate the distributional dynamics of the cotton bollworm (Helicoverpa armigera) in the adaptation to local environments and resilience to future climate change. Notably, the predicted inhabitable areas with higher suitability for the cotton bollworm could be eight times larger in the coming decades. Climate change is one of the factors driving the dynamics of distribution and population differentiation of the cotton bollworm. Approximately 19,000 years ago, the cotton bollworm expanded from its ancestral African population, followed by gradual occupations of the European, Asian, Oceanian, and American continents. Furthermore, we identify seven subpopulations with high dispersal and adaptability which may have an increased risk of invasion potential. Additionally, a large number of candidate genes and SNPs linked to climatic adaptation were mapped. These findings could inform sustainable pest management strategies in the face of climate change, aiding future pest forecasting and management planning.

Life table study of sublethal concentrations of emamectin benzoate against Spodoptera frugiperda (Lepidoptera, Noctuidae)

The fall armyworm, Spodoptera frugiperda J.E. Smith (Lepidoptera: Noctuidae), is a well-known agricultural pest in North and South America and has invaded Africa, the Far East, and Australia in the past decade. To investigate the integrated management of S. frugiperda, the sublethal impacts of emamectin benzoate were studied. Leaf-dipping bioassays were used to investigate the effects of sublethal (LC10 and LC30) concentrations of emamectin benzoate on S. frugiperda demographic parameters, and data were interpreted based on the age-stage, two-sex life table theory. The results showed that the developmental time of larvae was prolonged while the fecundity decreased after sublethal concentration treatment. Furthermore, the intrinsic and finite rates of increase, as well as the net reproductive rate, significantly declined following LC30 concentration exposure, whereas the average generation time was extended in comparison to the control group. The intrinsic rate of increase (rm) dropped to 0.14 (LC10) and 0.13 (LC30)/day, compared to the control group (0.18/day). The net reproductive rate (R0) dropped from 775.40 to 303.10 and 193.30 after the LC10 and LC30 concentration treatment, respectively. In this study, sublethal concentrations of emamectin benzoate adversely affected the developmental time, fecundity, and life table parameters of S. frugiperda.

Control efficacy and joint toxicity of broflanilide mixed with commercial insecticides to an underground pest, the black cutworm in highland barley

BACKGROUND

The highland barley, Hordeum vulgare L., is a staple food crop with superior nutritional functions in Xizang, China. It is often damaged by the black cutworm, Agrotis ipsilon (Hufnagel), which is an underground pest and difficult to effectively manage. To introduce a novel insecticide with unique mode of action, broflanilide (BFL) and its binary mixtures with chlorantraniliprole (CAP), fluxametamide, β-cypermethrin or imidacloprid were screened out as seed treatment to control black cutworm in highland barley in the present study.

RESULTS

In the laboratory bioassays, BFL had outstanding insecticidal activity to black cutworm with a median lethal dose (LD50) of 0.07 mg kg-1. The mixture of BFL × CAP at the concentration ratio of 7:40 exhibited the highest synergistic effect with a co-toxicity coefficient of 280.48. In the greenhouse pot experiments, BFL and BFL × CAP seed treatments at 8 g a.i. kg-1 seed could effectively control black cutworm, with a low percentage of injured seedlings <20% and high control efficacies of 93.33-100% during a period of 3-12 days after seed emergence. Moreover, BFL and BFL × CAP seed treatments could promote the seed germination and seedling growth of highland barley at the tested temperatures of 15, 20 and 25 °C.

CONCLUSION

Our results indicated that BFL and BFL × CAP were effective and promising insecticides as seed treatment to control black cutworm in highland barley. © 2024 Society of Chemical Industry.

Sublethal and transgenerational effects of broflanilide on the citrus red mite, Panonychus citri

BACKGROUND

The citrus red mite, Panonychus citri is a serious pest of the citrus industry and has developed resistance to many acaricides. Broflanilide is a novel meta-diamide insecticide that binds to a new site on the γ -aminobutyric acid receptor with high potency against pests. However, little information has been reported about its effect on the citrus red mite.

RESULTS

Broflanilide exhibited higher toxicity to female adults and eggs of a laboratory strain of P. citri The median lethal concentration (LC50), 9.769 mg/L and 4.576 mg/L, respectively) than other commonly used acaricides and was also toxic to two P. citri field strains. Broflanilide treatment with LC10, LC20, and LC30 significantly decreased the fecundity and longevity of female adults of F0 P. citri compared with the control. The duration of larva, protonymph, deutonymph and adult, and total life span in the F1 generation were significantly reduced after treatment of F0 with broflanilide. Population parameters, including the intrinsic rate of increase (r) and finite rate of increase (λ), were significantly increased, and the mean generation time (T) of F1 progeny was significantly reduced in the LC20 treatment. The predicted population size of F1 increased when parental female adults were treated with sublethal concentrations.

CONCLUSION

Broflanilide had high acaricidal activity toward P. citri, and exposure to a sublethal concentration significantly inhibited the population growth of F0. The transgenerational hormesis effect is likely to cause population expansion of F1. More attention should be paid when broflanilide is applied to control P. citri in citrus orchards. © 2024 Society of Chemical Industry.

The novel insecticide broflanilide dysregulates transcriptional networks associated with ion channels and induces hyperactivity in zebrafish (Danio rerio) larvae

Broflanilide is a novel insecticide that is classified as a non-competitive γ-aminobutyric acid (GABA) receptor antagonist. However, indiscriminate use can have negative effects on non-target species. The objective of this study was to determine the sub-lethal toxicity potential of broflanilide in early staged zebrafish. Embryos/larvae were assessed for multiple molecular and morphological endpoints following exposure to a range of concentrations of broflanilide. The insecticide did not affect hatch rate, the frequency of deformities, nor did it impact survival of zebrafish at exposure concentrations up to 500 μg/L over a 7-day period from hatch. There was also no effect on oxidative consumption rates in embryos, nor induction of reactive oxygen species in fish exposed up to 100 μg/L broflanilide. As oxidative stress was not prominent as a mechanism, we turned to RNA-seq to identify potential toxicity pathways. Gene networks related to neurotransmitter release and ion channels were altered in zebrafish, consistent with its mechanism of action of modulating GABA receptors, which regulate chloride channels. Noteworthy was that genes related to the circadian clock were induced by 1 μg/L broflanilide exposure. The locomotor activity of larval fish at 7 days was increased (i.e., hyperactivity) by broflanilide exposure based on a visual motor response test, corroborating expression data indicating neurotoxicity and motor dysfunction. This study improves the current understanding of the biological responses in fish to broflanilide exposure and contributes to risk assessment strategies for this novel pesticide.

Mechanisms underlying the effects of low concentrations of chlorantraniliprole on development and reproduction of the fall armyworm, Spodoptera frugiperda

It is well known that sublethal dose of insecticides induces life history trait changes of both target and non-target insect species, however, the underlying mechanisms remain not well understood. In this study, the effects of low concentrations of the anthranilic diamide insecticide chlorantraniliprole on the development and reproduction of the fall armyworm (FAW), Spodoptera frugiperda, were evaluated, and the underlying mechanisms were explored. The results showed that exposure of FAW to LC₁₀ and LC₃₀ chlorantraniliprole prolonged the larvae duration, decreased the mean weight of the larvae and pupae, and lowered the pupation rate as well as emergence rate. The fecundity of female adults was also negatively affected by treatment with low concentrations of chlorantraniliprole. Consistently, we found that exposure of FAW to LC₃₀ chlorantraniliprole downregulated the mRNA expression of juvenile hormone (JH) esterase (SfJHE), leading to the increase of JH titer in larvae. We also found that treatment with low concentrations of chlorantraniliprole suppressed the expression of ribosomal protein S6 kinase1 (SfS6K1) in female adults, resulting in the downregulation of the gene encoding vitellogenin (SfVg). These results provided insights into the mechanisms underlying the effects of low concentrations of insecticides on insect pests, and had applied implications for the control of FAW.

Lethal and sublethal effects of broflanilide on four tephritid pests (Diptera: Tephritidae)

BACKGROUND

Fruit flies are internationally important quarantine or invasive pests of many fruits and vegetables and can cause serious economic losses. Long-term reliance on insecticides for controlling these pests has led to increasing resistance to multiple insecticides; hence, a new agent is needed. In this study, the acute toxicity and sublethal effects of the novel insecticide broflanilide on four adult fruit fly species, Bactrocera dorsalis, Bactrocera cucurbitae, Bactrocera tau, and Bactrocera correcta, were evaluated.

RESULTS

Broflanilide was effective against B. dorsalis and B. correcta, with lethal concentration values (amount required to kill 50% of animals; LC₅₀ ) of 0.390 and 1.716 mg/L. However, for B. cucurbitae (19.673 mg/L) and B. tau (24.373 mg/L), the LC₅₀ was 50-60 times higher than that of B. dorsalis. The survival rates of B. correcta and B. cucurbitae were significantly lower under LC₅₀ treatment than those of the control (corrected for mortality rate). Sublethal concentrations of broflanilide stimulated fecundity in all species except B. tau. The hatching rate at LC₅₀ was significantly lower for B. correcta and B. tau compared with the control and even more so for B. correcta, which was zero.

CONCLUSION

Broflanilide is potentially an effective insecticide for controlling B. dorsalis and B. correcta. However, the variation in toxicity of broflanilide to the four fruit flies suggests that species variation needs to be carefully considered. Our results highlight the importance of clarifying the sublethal effects of insecticides on target insects to ensure the comprehensive evaluation and rational use of insecticides. © 2023 Society of Chemical Industry.

Toxicity and Sublethal Effects of Diamide Insecticides on Key Non-Target Natural Predators, the Larvae of Coccinella septempunctata L. (Coleoptera: Coccinellidae)

Coccinella septempunctata (ladybird) is an extremely important natural predator that feeds on aphids. An assessment of the toxicity of pesticides on environmental organisms is an essential component of Integrated Pest Management (IPM) strategies. This study evaluated diamide insecticides' toxicity at lethal and 30% lethal doses (LR₃₀) against C. septempunctata larvae. The pre-imaginal median lethal doses (LR₅₀) of chlorantraniliprole 10% SC, tetrachlorantraniliprole 10% SC, and broflanilide 10% SC were calculated to be 42.078, 289.516, and 0.0943 g active ingredient (a.i.)/ha, respectively. The mortality tests demonstrated that chlorantraniliprole and tetrachlorantraniliprole are comparatively less toxic to C. septempunctata than broflanilide, which were detected to be highly toxic to C. septempunctata. The mortality rates of the groups treated with the three diamide insecticides tended to stabilize after 96 h, extending to the pre-imaginal stage. Furthermore, when compared to broflanilide, which had a much higher potential risk, the hazard quotient (HQ) values indicated that chlorantraniliprole and tetrachlorantraniliprole have a lower risk potential for C. septempunctata in farmland and off farmland. The LR₃₀ dose induces abnormalities in the development phase 4th-instar larvae weight, pupal weight, and adult weight of treated C. septempunctata. The study emphasizes the importance of assessing the adverse effects of diamide insecticides on natural predator species that serve as biological control agents in agricultural IPM strategies.

Baseline Susceptibility, Cross-Resistance, and Sublethal Effects of Broflanilide, a Novel Meta-Diamide Pesticide, in Spodoptera litura

Spodoptera litura is a damaging and notorious insect pest of agricultural crops that has developed resistance to various insecticides. Broflanilide is a novel pesticide with a unique mode of action that displays high efficiency against lepidopterous larvae. We here determined the baseline susceptibility of a laboratory strain of S. litura to broflanilide and 10 other popular insecticides. Furthermore, we measured susceptibility and cross-resistance using three common insecticides in 11 field-collected S. litura populations. Broflanilide caused the highest toxicity among all tested insecticides, with the laboratory strain and all field-collected populations showing high susceptibility. Moreover, no cross-resistance was detected between broflanilide and the other tested insecticides. We subsequently evaluated the sublethal effects of broflanilide and found that treatment with the 25% lethal concentration (LC25) prolonged the development duration in the larvae, reduced the pupation rate and pupae weight, and decreased egg hatchability. Finally, the activities of three detoxifying enzymes were measured in S. litura after treatment with the LC25 dose. The results suggested that enhanced cytochrome P450 monooxygenase (P450) activity could be involved in broflanilide detoxification. Overall, these findings demonstrate the strong toxicity and significant sublethal effects of broflanilide in S. litura and suggest that increased P450 activity may be associated with broflanilide detoxification.

A novel V263I mutation in the glutamate-gated chloride channel of Plutella xylostella (L.) confers a high level of resistance to abamectin

The frequent and extensive use of insecticides leads to the evolution of insecticide resistance, which has become one of the constraints on global agricultural production. Avermectins are microbial-derived insecticides that target a wide number of insect pests, including the diamondback moth Plutella xylostella, an important global pest of brassicaceous vegetables. However, field populations of P. xylostella have evolved serious resistance to avermectins, including abamectin, thereby threatening the efficiency of these insecticides. In this study, a novel valine to isoleucine mutation (V263I) was identified in the glutamate-gated chloride channel (GluCl) of field P. xylostella populations, which showed different levels of resistance to abamectin. Electrophysiological analysis revealed that the V263I mutation significantly reduced the sensitivity of PxGluCl to abamectin by 6.9-fold. Genome-modified Drosophila melanogaster carrying the V263I mutation exhibited 27.1-fold resistance to abamectin. Then, a knockin strain (V263I-KI) of P. xylostella expressing the homozygous V263I mutation was successfully constructed using the CRISPR/Cas9. The V263I-KI had high resistance to abamectin (106.3-fold), but significantly reduced fecundity. In this study, the function of V263I mutation in PxGluCl was verified for the first time. These findings provide a more comprehensive understanding of abamectin resistance mechanisms and lay the foundation for providing a new molecular detection method for abamectin resistance monitoring.

Spodoptera exigua Multiple Nucleopolyhedrovirus Increases the Susceptibility to Insecticides: A Promising Efficient Way for Pest Resistance Management

Spodoptera exigua is a polyphagous pest of diverse crops and causes considerable economic losses. The overuse of chemical insecticides for controlling this pest results in insecticide resistance, environmental pollution and toxicity to other non-target organisms. Therefore, a sustainable and efficient way for pest management is urgently required. In this study, laboratory bioassays of eleven commonly used insecticides, the specific entomopathogen of S. exigua (Spodoptera exigua multiple nucleopolyhedrovirus, SeMNPV), and SeMNPV-insecticide combinations against the S. exigua laboratory population and two field populations were tested. Our results indicated that the two field populations had developed resistance to almost half of the tested insecticides, while SeMNPV had good virulence in all populations. Interestingly, the combined use of SeMNPV enhanced the toxicity of the tested insecticides against all populations to a different extent and considerably reduced the insecticide resistance of S. exigua field populations or even recovered the susceptibility to above insecticides. Furthermore, the field trial showed that the combined application of SeMNPV contributed to promoting the control efficacy of emamectin benzonate and chlorfenapyr. These results provide a promising efficient way for pest resistance management and an environmentally friendly approach for controlling S. exigua with the combined application of nucleopolyhedroviruses and insecticides.

Variation in the toxicity of a novel meta-diamide insecticide, broflanilide, among thrips pest species and developmental stages

BACKGROUND

Thrips pests cause increasing damage to crops around the world. Widespread usage of some insecticides against thrips has now led to the evolution of resistance to several active ingredients, and new insecticides are required. This study examined the toxicity of the novel insecticide broflanilide to multiple populations of several thrips pests.

RESULTS

Bioassays showed that thrips populations had LC₅₀ values ranging from 0.5 to almost 300 mg·L^-1 . A population of Frankliniella occidentalis had the highest LC₅₀ value at 290.63 mg·L^-1 , while a population of Echinothrips americanus had the lowest LC₅₀ value at 0.51 mg L^-1 . LC₅₀ values among seven populations of Thrips palmi ranged from 2.5689 to 23.6754 mg·L^-1 , indicating intraspecific variation in toxicity. In this species, the toxicity of broflanilide was relatively higher in adults than in larvae. More than 90% of eggs of T. palmi could not develop into larvae when treated with 5-50 mg L^-1 broflanilide. Compared to five commonly used insecticides, broflanilide showed relatively high toxicity to T. palmi. Field control tests with T. palmi showed that control efficacy (from 90.44% to 93.14%) was maintained from day three to day 14 after treatment with 22.5 and 45 ga.i hm^-1 broflanilide.

CONCLUSION

Broflanilide is potentially a useful insecticide for controlling Thrips hawaiiensis, Frankliniella intonsa, Megalurothrips usitatus. E. americanus, and some populations of T. palmi. However, the variation in toxicity of this insecticide to different species, populations, and developmental stages indicates that target species and life stages may need to be carefully considered. © 2022 Society of Chemical Industry.

Establishment of Toxicity and Susceptibility Baseline of Broflanilide for Aphis gossypii Glove

The Aphis gossypii is an important pest that can damage cotton plants and can cause a huge economic loss worldwide. Chemical control is a main method to manage this pest, but the cotton aphid resistance to insecticides has become a severe problem in the management of the cotton aphid. It is important to introduce a novel insecticide for rotational application with other insecticides. Broflanilide, as a meta-diamide insecticide with a special mode of action, showed high efficiency against lepidopterous larvae. However, we found that broflanilide possessed high insecticidal activity against the sap-sucking pest A. gossypii. The susceptibility of A. gossypii to broflanilide from 20 field populations in main cotton planting areas of China in 2021 was determined by the leaf-dipping method. LC₅₀ values of broflanilide to A. gossypii ranged from 0.20 μg mL^-1 to 1.48 μg mL^-1. The susceptible baseline of A. gossypii to broflanilide was established with the LC₅₀ value of 0.41 μg mL^-1 and might be used to calculate the resistance ratio (RR) of cotton aphid population in broflanilide resistance monitoring. The RR value of field populations in China was from 0.49 to 3.61 in 2021. It suggested that the broflanilide may be a potential agent in the resistance management of A. gossypii to insecticides. These results are significantly useful for the rational chemical control of cotton aphids.

MicroRNAs miR-14 and miR-2766 regulate tyrosine hydroxylase to control larval-pupal metamorphosis in Helicoverpa armigera

BACKGROUND

The cotton bollworm, Helicoverpa armigera, is a worldwide polyphagous pest, causing huge economic losses in vegetable, cotton and corn crops, among others. Owing to long-term exposure to Bacillus thuringiensis (Bt) toxins, evolution of resistance has been detected in this pest. As a conservative and effective neurotransmitter, dopamine (DA) has an important role in insect growth and development. In this study, we investigated the regulatory functions of DA and its associated non-coding RNA in metamorphosis in H. armigera.

RESULTS

Expression profiles indicated that DA and DA pathway genes were highly expressed during larval-pupal metamorphosis in H. armigera. RNA interference and pharmacological experiments confirmed that tyrosine hydroxylase (TH), dopa decarboxylase, vesicular amine transporter and DA receptor 2 are critical genes related to the development of H. armigera from larvae to pupae. We also found that miR-14 and miR-2766 targeted the 3' untranslated region to post-transcriptionally regulate HaTH function. Application of miR-2766 and miR-14 antagomirs significantly increased levels of HaTH transcripts and proteins, while injection of miR-2766 and miR-14 agomirs not only suppressed messenger RNA and protein levels of HaTH, but also resulted in defective pupation in H. armigera.

CONCLUSION

These results suggest that DA deficiency inhibits larval-pupal metamorphosis in H. armigera. Potentially, DA pathway genes and their microRNAs could be used as a novel target for H. armigera management. © 2022 Society of Chemical Industry.

Laboratory efficacy of selected synthetic insecticides against second instar invasive fall armyworm, Spodoptera frugiperda (Lepidoptera: Noctuidae) larvae

Maize is the most essential crop of China and its productivity has been recently endangered by the fall armyworm (FAW), Spodoptera frugiperda. Chemical pesticides are one of the most important strategies for managing FAW on a short-term basis. The seven synthetic insecticides including novel and conventional belong to four chemical group, spinetoram and spinosad (spinosyns), lambda-cyhalothrin, cypermethrin and bifenthrin (pyrethroids), abamectin (avermectins), broflinilide (diamides), were assessed for their efficiency in causing mortality to second instar S. frugiperda larvae at 24, 48 and 72 h post-treatment at five different serial concentrations (10 to 0.625 mg liter-1). The second instar S. frugiperda larvae were susceptible to the tested synthetic insecticides, however, the toxicity index of synthetic insecticides was estimated based on lethal concentration 50 (LC50), while, LC50 was calculated from the data of larval mortality. The broflanilide and abamectin proved to be the most toxic having the highest toxicity index of 100 and 78.29%, respectively, followed by cypermethrin and bifenthrin were showed toxicity index of 75.47 and 66.89%, respectively. The LC50 values were 0.606 and 0.774 mg liter-1 for broflanilide and abamectin, respectively, followed by cypermethrin and bifenthrin were showed LC50 values of 0.803 and 0.906 mg liter-1 at 72 h post-treatment. Rest of the other synthetic insecticides were showed moderate toxicity index of 42.11 to 62.09%, based on LC50 values were 1.439 to 0.976 mg liter-1 at 72 h post-treatment. The efficiency of synthetic insecticides was increased by increasing concentration level and exposure time. The screened synthetic insecticides among seven insecticides perhaps, provide basis for the development of novel insecticides for controlling S. frugiperda population after further research to evaluate and validate the laboratory results in the field.

Novel Galactosyl Moiety-Conjugated Furylchalcones Synthesized Facilely Display Significant Regulatory Effect on Plant Growth

The expansion of weed infestation has increased the demand on new herbicides. A series of novel galactosyl moiety-conjugated furylchalcones was facilely synthesized in which the furyl group (A ring) was combined with the substituted benzene group (B ring), and a galactosyl moiety was introduced. All these galactosyl furylchalcones were predicted to be phloem-mobile. Most of the galactosyl furylchalcones significantly promoted early seedling growth of sorghum and barnyardgrass under dark conditions, but all of them revealed considerable anti-growth ability on illuminated pot plants; especially, 1-(3'-(4″-O-β-d-galactopyranosyl)furyl)-3-(4″-nitrophenyl)-2-en-1-one (B₁₁) had a better herbicidal activity against rapeseed and Chinese amaranth than haloxyfop-R-methyl. The median efficient concentrations (EC₅₀) of compound B₁₁ against cucumber and wheat were 9.55 and 26.97 mg/L, respectively, also showing a stronger suppressing capacity than 2,4-D. Molecular docking with phosphoenolpyruvate carboxylase protein showed a stable binding conformation in which the galactosyl group interacted with LYS363 and GLU369, the furan ring and carbonyl bound with ARG184, and the crosslink of the nitro group with GLU240 formed a salt bridge. The results demonstrate that galactosyl furylchalcones possess the great potential as new herbicides for weed management, and further evaluations on more weeds are required for practical application.

Sublethal doses of broflanilide prevents molting in the fall armyworm, Spodoptera frugiperda via altering molting hormone biosynthesis

Broflanilide is a novel insecticide with a unique mode of action on the insect GABA receptor and is registered worldwide for the control of agricultural pests. It shows high efficacy in controlling the fall armyworm (FAW) Spodoptera frugiperda, which is a destructive pest to various crops. FAW was exposed to sublethal concentrations of broflanilide to determine its impact on insect development. Sublethal doses (LD₁₀ and LD₃₀) caused failure of ecdysis, reduced body length of larvae, malformation of pupae, and vestigial wing formation in adults. Also, broflanilide at LD₃₀ significantly reduced the amount of molting hormone (MH). After exposure to LD₁₀ or LD₃₀ broflanilide, expression of five Halloween genes, which participate in MH biosynthesis, were found to be altered. Specifically, the transcript levels of SfrCYP307A1 (Spook), SfrCYP314A1 (Shade) and SfrCYP315A1 (Shadow) in 3rd day larvae were significantly decreased as well as SfrCYP302A1 (Disembodied) and SfrCYP306A1 (Phantom) in 5th day pupae. In contrast, the transcript levels of SfrCYP302A1 in 3rd day larvae, SfrCYP307A1 and SfrCYP314A1 in 5th day pupae, and SfrCYP306A1, SfrCYP307A1 and SfrCYP315A1 in 0.5th day adults were significantly increased. Our results demonstrate that broflanilide caused the failure of ecdysis in FAW possibly by influencing the intake of cholesterol through inhibition of feeding and also via altering expression of genes important for MH biosynthesis.

Low concentration acetamiprid-induced oxidative stress hinders the growth and development of silkworm posterior silk glands

Acetamiprid is a new type of nicotinic insecticide that is widely used in pest control. Its environmental residues may cause silkworm cocooning disorder. In this study, silkworms that received continuous feeding of low concentration acetamiprid (0.15 mg/L) showed significantly decreased silk gland index and cocooning rate. Gene expression profiling of posterior silk glands (PSGs) revealed that the differentially expressed genes were significantly enriched in oxidative stress-related signal pathways with significant up-regulation. The contents of both H₂O₂ and MDA were increased, along with significantly elevated SOD and CAT activities, all of which reached maximal values at 48 h when H₂O₂ and MDA's contents were 10.46 and 7.98 nmol/mgprot, respectively, and SOD and CAT activities were 5.51 U/mgprot and 33.48 U/gprot, respectively. The transcription levels of antioxidant enzyme-related genes SOD, Mn-SOD, CuZn-SOD, CAT, TPX and GPX were all up-regulated, indicating that exposure to low concentration acetamiprid led to antioxidant response in silkworm PSG. The key genes in the FoxO/CncC/Keap1 signaling pathway that regulates antioxidant enzyme activity, FoxO, CncC, Keap1, NQO1, HO-1 and sMaf were all up-regulated during the whole process of treatment, with maximal values being reached at 72 h with 2.91, 1.46, 1.82, 2.52, 2.32 and 4.01 times of increases, respectively. These results demonstrate that exposure to low concentration acetamiprid causes oxidative stress in silkworm PSG, which may be the cause of cocooning disorder in silkworm. Our study provides a reference for the safety evaluation of environmental residues of acetamiprid on non-target insects.