Cotton Bollworm Research Articles

Density Relationship of the Assassin Bugs Sycanus falleni Stål and Sycanus croceovittatus Dohrn (Hemiptera: Reduviidae) and Principal Corn Pests (Noctuidae: Lepidoptera) in Hoa Binh Province, Vietnam

The group of assassin bugs including the Sycanus falleni and Sycanus croceovittatus species were such potential candidates for biocontrol of key pests (fall armyworm Spodoptera frugiperda, black cutworm Agrotis ypsilon, cotton bollworm Heliothis armigera Hübner, maize caterpillar Mythimna loreyi (Lepidoptera: Noctuidae)) on Corn biomass in Hoa Binh Province. Seven species of assassin bugs belonging to the family Reduviidae as S. falleni Stål, S. croceovittatus Dohrn, Coranus spiniscutis Reuter, Coranus fuscipennis Reuter, Polytoxus fuscovittatus (Stål), Endochus nigricornis Stål, Sphedanoletes pubinotum Reuter were recorded on the Corn biomass, of which S. falleni and S. croceovittatus were common. The relationship between the density of the group of assassin bugs and the density species S. falleni, S. croceovittatus had a close relationship with each other (R=0.81, R=0.72 respectively). The relationship between the density of the group of assassin bugs and the density of their prey (4 key pests) on the Corn biomass in the Winter crops and Summer-fall crops were a close relationship with each other (R2= 0.5166, R2= 0.7274 respectively). The relationship between the density of the species S. falleni, S. croceovittatus and the density of their prey (4 key pests) in the Winter crops, and the Summer fall crops were a close relationship with each other (R2 =0.7815, R2 =0.5396 respectively). However, these relationships were not closely related in the Spring-Summer crops and Winter-Spring crops.

The oviposition of cotton bollworms stimulates the defense against its eggs and larvae in tomato plants.

Herbivorous insects sustain their populations by oviposition. To reduce the damage caused by herbivores, the host plant triggers a defensive response upon detection of egg deposition. However, the specific impact of the egg deposition time of the cotton bollworm Helicoverpa armigera (Lepidoptera: Noctuidae), on the tomato plant defense remains obscure. This study investigated the effects of tomato plant defenses on cotton bollworm eggs and larvae at different time intervals following egg deposition. The study revealed that tomato plant defense triggered by egg deposition did not directly affect the hatchability of the eggs. Nevertheless, it attracted Trichogramma chilonis 48 h after the egg deposition. Gas chromatography-mass spectrometry analysis of the oviposition-induced plant volatiles (OIPVs) revealed a considerable increase in the amount of α-pinene released by tomato plants 48 h after egg deposition. The olfactory results from Y-tube experiments showed that α-pinene exhibited a substantial attraction towards T. chilonis. In addition, it was found that the defense response induced by egg deposition for 24 and 48 h significantly inhibited the growth and development of the larvae. Metabolomics analysis revealed that the egg deposition of cotton bollworm altered the metabolite composition and caused significant modifications in the metabolic pathways of tomato plants. These findings provide novel insights into pest management by using egg-induced plant defenses to reduce egg hatching, and impede larval growth and development in herbivorous insects. © 2024 Society of Chemical Industry.

Metabolism of Furanocoumarins by Three Recombinant CYP9A Proteins From the Polyphagous Cotton Bollworm Helicoverpa armigera.

Furanocoumarins are a class of chemical compounds with phototoxic properties. For herbivores, efficient detoxification of such defense compounds is the prerequisite to feed successfully on furanocoumarin-containing plants. The cotton bollworm Helicoverpa armigera is a very important polyphagous pest in agriculture, but how it copes with toxic furanocoumarins in some of its host plants is not well understood. Given that cytochrome P450s are well known for their capacity in xenobiotic metabolism, this study attempted to explore the potential roles of cytochrome P450s in furanocoumarin transformation in this pest. Our data showed that two linear structures (psoralen and xanthotoxin) could be metabolized by three recombinant CYP9A enzymes, but no detectable depletion was observed for the linear one with the 8-dimethylallyloxy substituent on the coumarin moiety (imperatorin) and the angular furanocoumarin (angelicin). Initial epoxidation of the double bond connecting C2' and C3' of the furano ring following by cleavage of the epoxidated furan ring, leading to the formation of more soluble, less reactive and nonphotosensitizing metabolites, was identified as a common mechanism of linear furanocoumarin metabolism using a quadrupole/time-of-flight (Q-TOF) mass spectrometry interfaced with a high performance liquid chromatography (HPLC) system. Our data demonstrated that multiple P450s were involved in the detoxification of linear furanocoumarins in the cotton bollworm. These findings contribute to a better understanding of the biochemical basis of adaptation to plant defense chemicals in this economically important pest.

Method for disrupting the reproductive pheromone bond of the cotton bollworm on sunflower crops

Background: Synthetic analogs of sexual pheromones provide an effective method of biorational control of the number of phytophagous insects based on the directed disruption of reproductive functions in populations of the target pest on the protected crop without affecting the integrity of the agrocenosis. The work aims to determine the biological effectiveness of methods of mass trapping and disorientation of the cotton bollworm (Helicoverpa armigera) to protect sunflower (Helianthus annuus) crops.Methods: The experiments were carried out in 2022-2023 in the Central Zone of the Krasnodar Territory, Russia in the stationary scientific crop rotation at the Federal Research Center for Biological Plant Protection, Krasnodar (2.5 ha) and the Kononenko farm, Novovelichkovskaya village, Dinsky district (10 ha). The biological effectiveness of elimination and disorientation methods was judged by the degree of damage to plants and buds. The disorientation effect was calculated by the number of males captured at the disorientation sites compared to the control sites.Result: The decrease in males’ search activity (disorientation effect) reached 85.3%. The damage to buds by the pest in this variant was 2.0% compared to 10.8% in the control group. In the mass trapping variant, it equaled 1.5-3.0 and 7.5%, respectively, indicating the prospects of including these techniques in the H. armigera biorational control system.Conclusion: Our findings could aid future research on insect chemical communication to develop effective biological control methods.Keywords: Biological plant protection; Sunflower; Cotton bollworm; Synthetic sex pheromones; Elimination; Disorientation; Biological effectiveness

Effects of Bt-cotton cultivation on Helicoverpa armigera activity-density in agricultural landscapes in northwestern China.

Cotton bollworm, Helicoverpa armigera (Hübner), threatens many crops. Bacillus thuringiensis (Bt) cotton has been planted to control this severe pest in northern Xinjiang, China. In 2021 and 2022, we monitored the activity densities of H. armigera males using sex pheromone traps in Bt cotton and non-Bt maize fields. We assessed how much of the population variation of cotton bollworm in the fields within the Bt cotton planting area could be explained by (i) landscape composition [including the proportion of Bt cotton among total area of host crops (cotton, maize, wheat and vegetables)], (ii) landscape configuration (patch density - i.e. the number of patches within a given area) across 0.5-2.0 km scales, or (iii) the population density of the previous pest generation. Cotton bollworm activity-density exhibited two distinct peaks annually (mid- to late May and mid-July each year), with the number of males caught during the second peak significantly and positively correlated with the first peak's numbers. The suppressive effect of the proportion of Bt cotton in the landscape on bollworms was more pronounced at larger scales, and patch density had a significant positive effect on bollworm activity density. These findings support (i) the promotion of Bt cotton in northwestern China has reduced and suppressed the occurrence of cotton bollworms at the landscape scale and (ii) the importance of controlling spring populations for effective summer outbreak management, and (iii) that cotton bollworm control should be coordinated at a large scale across multiple crop fields. © 2024 Society of Chemical Industry.

SUITABLE INSECTICIDE FOR INTEGRATED PEST MANAGEMENT

The article presents the results of testing the oxadiazine insecticide Avaunt with the active substance indoxacarb against the cotton bollworm on cotton and the mulberry moth on mulberries. In all experiments, high efficiency against caterpillars of all ages was obtained, which greatly distinguishes it from other preparations - larvicides. Depending on the objects, the consumption rates of the preparation can be in the range from 0.3 to 0.45 l / ha. The preparation is practically non-toxic for entomophages - trichogramma, bracon and lacewing, which is especially valuable in integrated plant protection programs. KEYWORDS: Cotton, tomato, insecticide, avaunt, cotton bollworm, mulberry moth, entomophages, efficiency.

Cotton Bollworm (H. armigera) Effector PPI5 Targets FKBP17-2 to Inhibit ER Immunity and JA/SA Responses, Enhancing Insect Feeding.

The cotton bollworm causes severe mechanical damage to plants during feeding and leaves oral secretions (OSs) at the mechanical wounds. The role these OSs play in the invasion of plants is still largely unknown. Here, a novel H. armigera effector peptidyl prolyl trans-isomerase 5 (PPI5) was isolated and characterized. PPI5 induces the programmed cell death (PCD) due to the unfolded protein response (UPR) in tobacco leaf. We reveal that PPI5 is important for the growth and development of cotton bollworm on plants, as it renders plants more susceptible to feeding. The GhFKBP17-2, was identified as a host target for PPI5 with peptidyl-prolyl isomerase (PPIase) activity. CRISPR/Cas9 knock-out cotton mutant (CR-GhFKBP17-1/3), VIGS (TRV: GhFKBP17-2) and overexpression lines (OE-GhFKBP17-1/3) were created and the data indicate that GhFKBP17-2 positively regulates endoplasmic reticulum (ER) stress-mediated plant immunity in response to cotton bollworm infestation. We further confirm that PPI5 represses JA and SA levels by downregulating the expression of JA- and SA-associated genes, including JAZ3/9, MYC2/3, JAR4, PR4, LSD1, PAD4, ICS1 and PR1/5. Taken together, our results reveal that PPI5 reduces plant defense responses and makes plants more susceptible to cotton bollworm infection by targeting and suppressing GhFKBP17-2 -mediated plant immunity.

Management Strategy for Pink Bollworm (Pectinophora gossypiella) in Bt Cotton by Community Basis

Management Strategy for Pink Bollworm (Pectinophora gossypiella) in Bt Cotton by Community Basis

Camouflaged cotton bollworm instance segmentation based on PVT and Mask R-CNN

Many pests change their appearance color to seamlessly blend with the surrounding environment in agricultural ecosystems, thereby rendering themselves virtually invisible. When the pest’s color and texture resemble the background, accurately identifying and detecting it becomes challenging. In this study, we construct a new dataset focusing on the cotton bollworm and conduct in-depth optimization and improvement of the instance segmentation model based on the Pyramid Vision Transformer (PVT) and Mask R-CNN. To better capture the features of camouflaged organisms, the proposed model utilizes the PVT as a feature extraction network and Mask-RCNN for instance segmentation. We also introduce overlapping image embedding patch structure and further incorporate a feed-forward network with depthwise separable convolution. These improvements enhance the PVT’s capability to capture global and intricate features and significantly boost the accuracy of instance segmentation. Considering the computational efficiency demands in real-time agricultural applications, we introduce a linear spatial-reduction attention mechanism that effectively reduces computational complexity. The experimental results show that the model achieves the detection accuracy of 89.7% and the segmentation accuracy of 89.2% for camouflaged cotton bollworms.

Natural Enemies as Guardians of Crop Ecosystem with Special Emphasis on Rice and Cotton

Natural enemies, including predators, parasitoids, and pathogens, play a crucial role in the regulation of pest populations within agricultural ecosystems. This review examines the role of these biological control agents in maintaining the health and productivity of crop systems, with a specific focus on rice and cotton. In rice ecosystems, natural enemies such as spiders, dragonflies, and various insect parasitoids help manage pest populations like the rice stem borer and the planthopper. Similarly, in cotton crops, natural predators and parasitoids contribute to the control of key pests including the cotton bollworm and aphids. By integrating these natural enemies into pest management strategies, farmers can reduce reliance on chemical pesticides, enhance biodiversity, and promote sustainable agriculture. This review highlights the mechanisms through which these natural enemies operate, the benefits they provide to crop ecosystems, and case studies illustrating successful applications. The major emphasis is placed on understanding the interactions between these biological control agents and their environments, and how these relationships can be optimized to support resilient crop production systems and to manage these pests in cotton and rice crops.

Dynamic trends in maize diseases and pests across six regions in China over two decades

Maize production faces persistent threats from maize diseases and pests (MDPs) throughout its growth cycle, posing substantial risks to food security. However, understanding the spatio-temporal dynamics of MDPs occurrences on a regional scale has remained elusive due to a lack of continuous observation data. This study curated a comprehensive dataset spanning two decades, from 1999 to 2018, across six key maize planting regions in China [Spring sown area in Northern China (1-NC), Summer sown region in Huang-Huai-Hai Plain (2-HHP), Southwest Mountain Maize Region (3-SM), Southern Hilly Maize Region (4-SH), Northwest Irrigated Maize Region (5-NI), and Maize Region in Qinghai-Tibet Plateau (6-QTP)]. The average extent of MDP occurrence in 1-NC and 2-HHP exceeded that in other regions over the two-decade period. Furthermore, the occurrence of MDPs exhibited a substantial increase in 1-NC, 2-HHP, 3-SM, 4-SH, and 5-NI over the same period. Meanwhile, the average occurrence intensity of MDPs in 2-HHP surpassed that in other regions. Notably, maize leaf blight and the Asian maize borer emerged as predominant diseases and pests in 1-NC, 2-HHP, 3-SM, 4-SH, and 5-NI. A bivariate trend analyses highlighted a notable increase in the species count for both the extent and intensity of MDP occurrences, including double-spotted leaf beetle in 1-NC, and cotton bollworm in 2-HHP. This extensive, long-term analysis offers a foundation for devising comprehensive strategies for MDP control on a national scale, enabling the formulation of tailored forecasting and control measures across six planting regions.

The transcription factor RUNT-like regulates pupal cuticle development via promoting a pupal cuticle protein transcription.

Holometabolous insects undergo morphological remodeling from larvae to pupae and to adults with typical changes in the cuticle; however, the mechanism is unclear. Using the lepidopteran agricultural insect Helicoverpa armigera, cotton bollworm, as a model, we revealed that the transcription factor RUNT-like (encoded by Runt-like) regulates the development of the pupal cuticle via promoting a pupal cuticle protein gene (HaPcp) expression. The HaPcp was highly expressed in the epidermis and wing during metamorphosis and was found being involved in pupal cuticle development by RNA interference (RNAi) analysis in larvae. Runt-like was also strongly upregulated in the epidermis and wing during metamorphosis. Knockdown of Runt-like produced similar phenomena, a failure of abdomen yellow envelope and wing formation, to those following HaPcp knockdown. The insect molting hormone 20-hydroxyecdysonen (20E) upregulated HaPcp transcription via RUNT-like. 20E upregulated Runt-like transcription via nuclear receptor EcR and the transcription factor FOXO. Together, RUNT-like and HaPCP are involved in pupal cuticle development during metamorphosis under 20E regulation.

Monitoring Helicoverpa armigera Damage with PRISMA Hyperspectral Imagery: First Experience in Maize and Comparison with Sentinel-2 Imagery

The cotton bollworm (CBW) poses a significant risk to maize crops worldwide. This study investigated whether hyperspectral satellites offer an accurate evaluation method for monitoring maize ear damage caused by CBW larvae. The study analyzed the records of maize ear damage for four maize fields in Southeast Hungary, Csongrád-Csanád County, in 2021. The performance of Sentinel-2 bands, PRISMA bands, and synthesized Sentinel-2 bands was compared using linear regression, partial least squares regression (PLSR), and two-band vegetation index (TBVI) methods. The best newly developed indices derived from the TBVI method were compared with existing vegetation indices. In mid-early grain maize fields, narrow bands of PRISMA generally performed better than wide bands, unlike in sweet maize fields, where the Sentinel-2 bands performed better. In grain maize fields, the best index was the normalized difference of λA = 571 and λB = 2276 (R2 = 0.33–0.54, RMSE 0.06–0.05), while in sweet maize fields, the best-performing index was the normalized difference of green (B03) and blue (B02) Sentinel-2 bands (R2 = 0.54–0.72, RMSE 0.02). The findings demonstrate the advantages and constraints of remote sensing for plant protection and pest monitoring.

Optimizing Insecticide Application: Evaluating Frequency and Timing for Effective Management of Pink Bollworm Infestation

The pink bollworm (Pectinophora gossypiella), a significant pest affecting cotton crops, necessitates an optimized approach to insecticide application. This study investigates the critical factors of frequency and timing in insecticide application to enhance the efficacy of pest control measures. An experiment conducted at the Main Agricultural Research Station (MARS), University of Agricultural Sciences Raichur, focused on managing pink bollworm in Bt cotton using newer insecticides registered for cotton. Various spray frequencies and intervals were tested as part of an ETL (Economic Threshold Level) and prophylactic spray regimen. The results indicated that the treatment T1, which involved four sprays of profenofos 50 EC, chlorantraniliprole 18.50 SC, emamectin benzoate 5 SG, and bifenthrin 10 EC at 65, 80, 95, and 110 days after sowing (DAS), respectively, showed the lowest incidence of pink bollworm larvae, green boll damage, bad boll opening, locule damage, and the highest rate of good boll opening. This performance was comparable to treatment T5, which followed the same spraying schedule but with spinetoram 11.70 SC and fenpropathrin 10.00 EC instead of emamectin benzoate and bifenthrin, and treatment T9, which employed an ETL-based spray schedule using chlorantraniliprole 9.3 + lambda-cyhalothrin 4.6 ZC. Similarly, the highest yield of seed cotton was obtained from treatment T1 (18.10 q/ha), which was statistically equivalent to treatments T5 (18.12 q/ha) and T9 (18.10 q/ha). Additionally, the cost-benefit analysis revealed the highest benefit-cost ratio in treatment T1 (1.55), followed by treatments T9 (1.46) and T5 (1.44).

Overexpressing a cotton terpene synthase for (E)-β-ocimene biosynthesis in Nicotiana tabacum to recruit the parasitoid wasps

(E)-β-ocimene is a predominant component of volatile terpenes emitted from many plant species in response to herbivore attack, which plays an impotant role in direct and indirect defense of plants. In the current study, (E)-β-ocimene was induced and released in upland cotton Gossypium hirsutum plants infested by chewing caterpillars or sucking bugs. Using genome data mining, a key terpene synthase for (E)-β-ocimene biosynthesis in cotton, GhTPS16, was initially identified. In vitro, recombinant GhTPS16 catalyzed the formation of (E)-β-ocimene using geranyl diphosphate as a substrate. Besides, the GhTPS16 was transferred into Nicotiana tabacum to generate (E)-β-ocimene synthase overexpression lines. Consequently, compared with wild type plants both GhTPS16 expression and (E)-β-ocimene emission of transgenic plants were up-regulated. In behavioral trials, two parasitoid wasps, Peristenus spretus parasitizing green bug Apolygus lucorum and Microplitis mediator parasitizing cotton bollworm Helicoverpa armigera, showed tendency preference for synthetic (E)-β-ocimene and transgenic tobacco plants, respectively. These findings provide new insights into understanding the roles of (E)-β-ocimene in plant-insect interaction. Oversynthesis of (E)-β-ocimene in plants could enhance indirect defense by recruiting parasitoids to facilitate control of the two target pests, green bug and cotton bollworm.

Development of the insect adult fat body relies on glycolysis, lipid synthesis, cell proliferation, and cell adhesion.

The fat body of the holometabolous insect is remodeled by the degradation of the larval fat body and the development of the adult fat body during metamorphosis. However, the mechanism of adult fat body development is quite unclear. Using the agricultural pest Helicoverpa armigera, the cotton bollworm, as a model, we revealed that the development of adult fat body was regulated by glycolysis, triglyceride (triacylglycerol [TAG]) synthesis, cell proliferation, and cell adhesion. RNA sequencing detected a set of genes that were upregulated in the 8-d late pupal fat body at a late metamorphic stage compared with the 2-d pupal fat body at an earlier metamorphic stage. The pathways for glycolysis, TAG synthesis, cell proliferation, and cell adhesion were enriched by the differentially expressed genes, and the key genes linked with these pathways showed increased expression in the 8-d pupal fat body. Knockdown of phosphofructokinase (Pfk), acetyl-CoA carboxylase (Acc1), phosphatidylinositol 4,5-bisphosphate 3-kinase catalytic subunit (P110) and collagen alpha-1(IV) chain (Col4a1) by RNA interference resulted in abnormal eclosion and death at pupal stages, and repressed lipid droplets accumulation and adult fat body development. The expression of Acc1, P110, and Col4a1 was repressed by the insect steroid hormone 20-hydroxyecdysone (20E). The critical genes in the 20E pathway appeared to decrease at the late pupal stage. These data suggested that the development of the insect adult fat body is regulated by glycolysis, lipids synthesis, cell proliferation, and cell adhesion at the late pupal stage when the 20E signal decreases.

Development of resistance monitoring for Helicoverpa armigera (Lepidoptera: Noctuidae) resistance to pyramided Bt cotton in China.

The cotton bollworm, Helicoverpa armigera (Hübner) (Lepidoptera: Noctuidae), is a significant cotton pest worldwide. Bacillus thuringiensis (Bt) cotton producing Cry1Ac has been used since 1997 for the control of this pest in China and a significant increase in H. armigera resistance to Cry1Ac has occurred in northern China. To mitigate resistance evolution, it is necessary to develop and plant pyramided 2- and 3-toxin Bt cotton to replace Cry1Ac cotton. For sustainable use of pyramided Bt cotton, we used diet overlay bioassays to measure the baseline susceptibility of H. armigera to Cry2Ab in 33 populations collected in 2017, 2018, and 2021 in 12 locations from major cotton-producing areas of China. The lethal concentration killing 50% (LC50) or 99% (LC99) of individuals from the populations ranged from 0.030 to 0.138 µg/cm2 and 0.365 to 2.964 µg/cm2, respectively. The ratio of the LC50 for the most resistant and susceptible population was 4.6, indicating moderate among-population variability in resistance. The susceptibility of H. armigera to Cry2Ab did not vary significantly over years. A diagnostic concentration of 2 µg/cm2 was calculated as twice the LC99 from an analysis of pooled data for the field-collected populations. This concentration discriminated well between susceptible and resistant individuals, as it killed all larvae from a susceptible laboratory strain and 0%, 0%, and 23% of larvae from 3 laboratory strains with > 100-fold resistance to Cry2Ab. These baseline susceptibility data and diagnostic concentration for Cry2Ab will be useful for monitoring the evolution of H. armigera resistance to pyramided Bt cotton in China.

Lipases are differentially regulated by hormones to maintain free fatty acid homeostasis for insect brain development

BackgroundFree fatty acids (FFAs) play vital roles as energy sources and substrates in organisms; however, the molecular mechanism regulating the homeostasis of FFA levels in various circumstances, such as feeding and nonfeeding stages, is not fully clarified. Holometabolous insects digest dietary triglycerides (TAGs) during larval feeding stages and degrade stored TAGs in the fat body during metamorphosis after feeding cessation, which presents a suitable model for this study.ResultsThis study reported that two lipases are differentially regulated by hormones to maintain the homeostasis of FFA levels during the feeding and nonfeeding stages using the lepidopteran insect cotton bollworm Helicoverpa armigera as a model. Lipase member H-A-like (Lha-like), related to human pancreatic lipase (PTL), was abundantly expressed in the midgut during the feeding stage, while the monoacylglycerol lipase ABHD12-like (Abhd12-like), related to human monoacylglycerol lipase (MGL), was abundantly expressed in the fat body during the nonfeeding stage. Lha-like was upregulated by juvenile hormone (JH) via the JH intracellular receptor methoprene-tolerant 1 (MET1), and Abhd12-like was upregulated by 20-hydroxyecdysone (20E) via forkhead box O (FOXO) transcription factor. Knockdown of Lha-like decreased FFA levels in the hemolymph and reduced TAG levels in the fat body. Moreover, lipid droplets (LDs) were small, the brain morphology was abnormal, the size of the brain was small, and the larvae showed the phenotype of delayed pupation, small pupae, and delayed tissue remodeling. Knockdown of Abhd12-like decreased FFA levels in the hemolymph; however, TAG levels increased in the fat body, and LDs remained large. The development of the brain was arrested at the larval stage, and the larvae showed a delayed pupation phenotype and delayed tissue remodeling.ConclusionsThe differential regulation of lipases expression by different hormones determines FFAs homeostasis and different TAG levels in the fat body during the feeding larval growth and nonfeeding stages of metamorphosis in the insect. The homeostasis of FFAs supports insect growth, brain development, and metamorphosis.

The genome sequence of the Cotton Bollworm moth, Helicoverpa armigera (Hübner, 1808).

We present a genome assembly from an adult female Cotton Bollworm moth, Helicoverpa armigera (Arthropoda; Insecta; Lepidoptera; Noctuidae). The genome sequence has a total length of 362.20 megabases. Most of the assembly is scaffolded into 32 chromosomal pseudomolecules, including the W and Z sex chromosomes. The mitochondrial genome has also been assembled and is 15.36 kilobases in length.

Synthesis and antifeedant activity of 3H-indole derived oxime esters and oxime ethers against cotton bollworm

The O-acylation or O-alkylation of 3H-indole derived oximes is conveniently synthesized from indoles and the corresponding anhydrides or alcohols mediated by tert-butyl nitrite (TBN) under mild conditions. O-Acyloxime esters are obtained with yields up to 82% using anhydrides via a facile one-pot reaction. Fluorinated O-alkyloxime ethers are achieved with yields up to 38% using fluorinated alcohols through an optimized step-by-step strategy or a 2,2,6,6-tetramethylpiperidinyl-1-oxide (TEMPO)-assisted one-pot strategy. Meanwhile, the better reaction yields, up to 64%, are achieved for nonfluorinated O-alkyloxime ethers. These approaches allow access to a diversity of O-acyloxime esters and fluorinated/nonfluorinated O-alkyloxime ethers, underscoring broad substrate scopes, good functional tolerance and easily gram-scale. All the synthesized compounds were evaluated for their potential antifeedant activity and 5f shows good antifeedant activity against cotton bollworm with a negative logarithmic effective concentration for 50% feeding reduction (pEC50) at 4.217.