N-Heterocyclic Carbene-Derived 1,3,5-Trimethylenebenzene: On-Surface Synthesis and Electronic Structure.

1,3,5-Trimethylenebenzene (1,3,5-TMB), a 3-fold-symmetric triradical with a high-spin ground state, is an attractive platform for investigating the unique spin properties of π-conjugated triangular triradicals. Here, we report the on-surface synthesis of N-heterocyclic carbene (NHC)-derived 1,3,5-TMB (N-TMB) via surface-assisted C-C and C-N coupling reactions on Au(111). The chemical and electronic structures of N-TMB on the Au(111) surface are revealed with atomic precision using scanning tunneling microscopy and noncontact atomic force microscopy, combined with density functional theory (DFT) calculations. It is demonstrated that there is substantial charge transfer between N-TMB and the substrate, resulting in a positively charged N-TMB on Au(111). DFT calculations at the UB3LYP/def2-TZVP level of theory and multireference method, e.g., CASSCF/NEVPT2, indicate that N-TMB possesses a doublet ground state with reduced Cs symmetry in the gas phase, contrasting the quartet ground state of 1,3,5-TMB with D3h symmetry, and exhibits a doublet-quartet energy gap of -0.80 eV. The incorporation of NHC structures and the extended π-conjugation promote the spin-orbital overlaps in N-TMB, leading to Jahn-Teller distortion and the formation of a robust doublet state. Our results not only demonstrate the fabrication of polyradicals based on NHC but also shed light on the effect of NHC and π-conjugation on the electronic structure and spin coupling, which opens up new possibilities for precisely regulating the spin-spin exchange coupling of organic polyradicals.

Silver Surface-Assisted Dehydrobrominative Cross-Coupling between Identical Aryl Bromides.

Cross-coupling reactions represent an indispensable tool in chemical synthesis. An intriguing challenge in this field is to achieve selective cross-coupling between two precursors with similar reactivity or, to the limit, the identical molecules. Here we report an unexpected dehydrobrominative cross-coupling between 1,3,5-tris(2-bromophenyl)benzene molecules on silver surfaces. Using scanning tunneling microscopy, we examine the reaction process at the single-molecular level, quantify the selectivity of the dehydrobrominative cross-coupling, and reveal the modulation of selectivity by substrate lattice-related catalytic activity or molecular assembly effect. Theoretical calculations indicate that the dehydrobrominative cross-coupling proceeds via regioselective C-H bond activation of debrominated TBPB and subsequent highly selective C-C coupling of the radical-based intermediates. The reaction kinetics plays an important role in the selectivity for the cross-coupling. This work not only expands the toolbox for chemical synthesis but also provides important mechanistic insights into the selectivity of coupling reactions on the surface.

Sterility of Cydia pomonella by X ray irradiation as an alternative to gamma radiation for the sterile insect technique.

The codling moth Cydia pomonella is a major pest of global significance impacting pome fruits and walnuts. It threatens the apple industry in the Loess Plateau and Bohai Bay in China. Sterile insect technique (SIT) could overcome the limitations set by environmentally compatible area-wide integrated pest management (AW-IPM) approaches such as mating disruption and attract-kill that are difficult to suppress in a high-density pest population, as well as the development of insecticide resistance. In this study, we investigated the effects of X-ray irradiation (183, 366, 549 Gy) on the fecundity and fertility of a laboratory strain of C. pomonella, using a newly developed irradiator, to evaluate the possibility of X-rays as a replacement for Cobalt60 (60Co-γ) and the expanded future role of this approach in codling moth control. Results show that the 8th-day is the optimal age for irradiation of male pupae. The fecundity decreased significantly as the dosage of radiation increased. The mating ratio and mating number were not influenced. However, treated females were sub-sterile at a radiation dose of 183 Gy (20.93%), and were almost 100% sterile at a radiation dose of 366 Gy or higher. Although exposure to a radiation dose of 366 Gy resulted in a significant reduction in the mating competitiveness of male moths, our radiation biology results suggest that this new generation of X-ray irradiator has potential applications in SIT programs for future codling moth control.

Exposure to lambda-cyhalothrin and abamectin drives sublethal and transgenerational effects on the development and reproduction of Cydia pomonella.

The codling moth Cydia pomonella (Lepidoptera: Tortricidae) is a major invasive pest of pome fruits and walnuts worldwide. Lambda-cyhalothrin (LCT) and abamectin (AM) have been frequently used in C. pomonella control, but control of this pest is very difficult because shortly after hatching, larvae of this insect bore tunnels and hide inside host plant fruit. In this study, a simulated field spray bioassay method was developed against neonate larvae of C. pomonella and concentration-response bioassays were conducted to evaluate the susceptibility of the neonate larvae to LCT and AM. Exposure of neonate larvae to sublethal concentration (LC30) of LCT or AM significantly reduced the survival rate of larvae (4th and 5th instars), lowered the mean weight of larvae and pupae, and decreased the daily maximal number of eggs laid and the total number of eggs laid (fecundity) per female. The sublethal effects, including reduced body mass, mean fecundity and net reproductive rate, extended mean generation time, and shortened oviposition period, were also found in transgenerational offspring. Furthermore, the transgenerational maternal effects were more obvious for AM than LCT, in comparison to the control. Additionally, the estimated population size was decreased by exposure to LC30 of LCT and AM, and the observed reduction of fecundity and population size within and across generations was likely the result of the downregulation of the reproduction-related vitellogenin gene (CpVg) after exposure to LC30 of LCT and AM. These results provide a better understanding of the overall effects of LCT and AM on C. pomonella and the transgenerational effects which should be taken into consideration when using insecticides in order to control C. pomonella.

Insecticide resistance in the Cydia pomonella (L): Global status, mechanisms, and research directions.

The codling moth, Cydia pomonella (Lepidoptera: Tortricidae) is a major pest of pome fruit and walnuts worldwide. Although environmentally compatible integrated control strategies, such as mating disruption, attract-kill strategy, and sterile insect technique have been conducted for management of this notorious pest, effects to control of codling moth have mainly relied on insecticides. In consequence, different levels of insecticide resistance towards organophosphates, neonicotinoids, hydrazines, benzoylureas, pyrethroids, diamides, spinosyns, avermectins, JH mimics, carbamates, oxadiazines and C. pomonella granulovirus (CpGVs) have developed in codling moth in different countries and areas. Both metabolic and target-site mechanisms conferring resistance have been revealed in the codling moth. In this review, we summarize the current global status of insecticide resistance, the biochemical and molecular mechanisms involved, and the implications for resistance management.

Consistency of postoperative pain assessments between nurses and patients undergoing enhanced recovery after gynaecological surgery.

AIMS AND OBJECTIVES: To explore the consistency of pain intensity and pain location assessed by nurses and patients in gynaecology undergoing enhanced recovery after surgery pathway. BACKGROUND: Several studies have shown that clinical nurses' assessment of patients' pain is not always accurate. Little is known about the accuracy of nurses' pain assessments for gynaecological patients. Postoperative pain assessment and management is an essential part of enhanced recovery after surgery. DESIGN: Comparative cross-sectional study. METHODS: A total of 160 patients were recruited and only 85 patients and 17 nurses participated. Patients and nurses recorded pain scores (using an 11-point Numeric Rating Scale) and pain location (incision pain, surgical area pain in the abdominal cavity, other pain or no pain) on Pain Assessment Forms at 4 hr after surgery and on the first and second postoperative days. We used the STROBE guidelines to report our study. RESULTS: The patients' pain score was higher than that of nurses from 4 hr to second day after laparoscopic surgery at rest. The pain scores of both nurses and patients decreased over this period of time. All the intraclass correlation coefficients were between 0.214-0.296. At the three time points, surgical area pain in the abdominal cavity and abdominal incision pain were the main pain areas. All the kappa coefficients were between 0.164-0.255. CONCLUSIONS: The consistency of postoperative pain assessment about pain score and pain location between nurses and patients was not high. We should attach importance to systematic pain assessment, and more detailed enhanced recovery after surgery pathways should be developed about pain assessment. RELEVANCE TO CLINICAL PRACTICE: Continuing education for nurses regarding pain assessment is necessary. Nurses should accept the patient's self-reported pain. There should be a step that gives more time for pain assessment in enhanced recovery after surgery pathways.

2D Co-crystallization of molecular homologues promoted by size complementarity of the alkyl chains at the liquid/solid interface.

Co-crystallization of organic molecules is an important strategy for the fabrication of molecular materials. In this contribution, we investigated the mixing behavior of 5-(benzyloxy)-isophthalic acid homologues (BIC-Cn, n = 6, 8, 10, 12, and 14) at the liquid/solid interface using a scanning tunneling microscope. Deposition of the single component of BIC-Cn always results in typical honeycomb networks, whereas co-deposition of two BIC-Cn homologues leads to hybrid double-walled honeycomb networks or phase separation depending on the difference in the length of their alkyl chains. 2D co-crystallization can only be realized for BIC-C6/BIC-C10 or BIC-C8/BIC-C12 which have a four-methyl unit difference in their alkyl chains. The size complementarity of the alkyl chains in the two components suggests that it is responsible for the 2D co-crystallization, though hydrogen bonding contributes a lot both to the pristine honeycomb network and to the hybrid co-crystal. This result is of importance for understanding the role of van der Waals interaction and its interplay with hydrogen bonding in 2D co-crystallization.

LC50 of lambda-cyhalothrin stimulates reproduction on the moth Mythimna separata (Walker).

Lambda-cyhalothrin has long been recommended as an effective insecticide to control the oriental armyworm, Mythimna separata (Walker), a notorious migratory pest of agricultural plants. Previous researches have suggested that survival, development, and reproduction of insects are influenced by sublethal concentrations of insecticides. However, the effects of sublethal concentrations of lambda-cyhalothrin on M. separata are less known. In this study, we determined the toxicity and effects of LC20 and LC50 concentration of lambda-cyhalothrin on development and reproduction of M. separata. Results indicate that LC20 of lambda-cyhalothrin tends to decrease the life traits of M. separate, with a shortening larvae period of offspring and oviposition period, whereas LC50 of lambda-cyhalothrin stimulates daily maximal fecundity and forwards the oviposition peak, suggesting a stimulation of reproduction by LC50 of lambda-cyhalothrin. The M. separata population was increased by an LC50 concentration of lambda-cyhalothrin, resulting in a net reproductive rate (R0) and intrinsic rate of increase (rm) significantly higher than that of the control. Transcripts of vitellogenin (MsVg) and vitellogenin receptor (MsVgR) genes were suppressed at day 1 after emergence of moth which developed from the larvae exposed to LC20 and LC50 of lambda-cyhalothrin, but were significant induced when the moth begin to lay eggs (day 4), with a more remarkable induction by LC50 of lambda-cyhalothrin than those of LC20 of lambda-cyhalothrin. Our results indicate that the observed stimulation of reproduction is therefore the results of up-regulation of MsVg and MsVgR by LC50 of lambda-cyhalothrin.

Gene expression analysis and enzyme assay reveal a potential role of the carboxylesterase gene CpCE-1 from Cydia pomonella in detoxification of insecticides.

Carboxylesterases (CarEs) are responsible for metabolism of xenobiotics including insecticides in insects. Understanding the expression patterns of a such detoxifying gene and effect of insecticides on its enzyme activity are important to clarify the function of this gene relevant to insecticides-detoxifying process, but little information is available in the codling moth Cydia pomonella (L.). In this study, we investigated the expression profiles of CarE gene CpCE-1 at different developmental stages and in different tissues of C. pomonella, as well as the larvae exposed to chlorpyrifos-ethyl and lambda-cyhalothrin by using absolute real-time quantitative PCR (absolute RT-qPCR). Results indicated that CpCE-1 expression was significantly altered during C. pomonella development stages, and this expression differed between sexes, with a higher transcript in females than males. Meanwhile, CpCE-1 is overexpressed in cuticle, midgut and head than silk gland, fat body and Malpighian tubules. Exposure of third instar larvae to a non-lethal dosage of chlorpyrifos-ethyl and lambda-cyhalothrin resulted in induction of CpCE-1 transcript. The total carboxylesterase enzyme activity was inhibited by chlorpyrifos-ethyl in vivo; in contrast, the activity of Escherichia coli produced recombinant CpCE-1 was significantly inhibited by both lambda-cyhalothrin and chlorpyrifos-ethyl in vitro. These results suggested that CpCE-1 in C. pomonella is potentially involved in the development and in detoxification of chlorpyrifos-ethyl and lambda-cyhalothrin.

Toxicity of Six Insecticides on Codling Moth (Lepidoptera: Tortricidae) and Effect on Expression of Detoxification Genes.

The codling moth, Cydia pomonella (L.), is a key worldwide fruit pest that has evolved high levels of resistance to almost all classes of conventional insecticides. Neonicotinoids, a new reduced-risk biorational insecticide class, have remained an effective control approach. In this study, the toxicity and sublethal effect of conventional and reduced-risk biorational insecticides on transcripts abundance of three detoxification genes in codling moth were determined. Bioassays on a codling moth laboratory strain suggested that acetamiprid had the highest oral toxicity against the third-instar larvae compared with the other five pesticides. Results also indicated that acetamiprid exhibits long-term efficacy against codling moth even at 120 h post feeding. Real-time quantitative polymerase chain reaction showed that the detoxification genes CYP9A61, CpGST1, and CpCE-1 were differentially induced or suppressed by deltamethrin, cypermethrin, methomyl, carbaryl, and imidacloprid, depending on the type of insecticides; in contrast, no significant difference in CYP9A61, CpGST1, and CpCE-1 expressions were observed after acetamiprid exposure, when compared with the control. These results suggest that the reduced-risk biorational insecticide acetamiprid is an effective insecticide with no induction of detoxification genes and can be integrated into the management of codling moth.

Raoultella sp. strain L03 fixes N2 in association with micropropagated sugarcane plants.

N2 -fixing bacteria belonging to the genus Raoultella of the family Enterobacteriaceae are widely associated with plants. Raoultella sp. strain L03 was isolated from surface-sterilized sugarcane roots. In this study, we inoculated the strain L03 to microbe-free micropropagated plantlets of the main sugarcane cultivar ROC22 grown in Guangxi, China and determined N2 -fixation and association between strain L03 and sugarcane plants. Inoculation of strain L03 increased plant biomass, total N, N concentration and chlorophyll, and relieved N-deficiency symptoms of plants under an N-limiting condition. An (15) N isotope dilution assay revealed (15) N isotope dilution in the inoculated sugarcane plants and incorporation of the fixed (14) N from air into chlorophyll. Moreover, a gfp-tagged and antibiotic-resistant L03 strain was reisolated from surface-sterilized sugarcane plants and was detected in plant tissues by fluorescent microscopy. This study for the first time demonstrates that a Raoultella bacterium is able to fix N2 in association with the plant host.

[Effect of Modified Guipi Decoction on Blood Pressure and Quality of Life in Hypertension Patients Complicated Depression].

OBJECTIVE: To study the effect of Modified Guipi Decoction (MGD) on blood pressure and quality of life (QOL) in hypertension patients complicated depression. METHODS: Totally 245 hypertension patients complicated depression were randomly assigned to the treatment group (125 cases, treated with MGD) and the control group (120 cases, treated with Sertraline). Final recruited qualified patients were 117 cases in the treatment group and 111 cases in the control group. The therapeutic course for all was 4 weeks. Changes of blood pressure, scores rated by Hamilton Depression Scale-17 (HAMD-17), Hamilton Anxiety Rating Scale (HAMA), short-form 36 health survey questionnaire (SF-36), and Treatment Emergent Symptom Scale (TESS) were observed before and after treatment, thereby judging their efficacies. RESULTS: (1) Compared with before treatment in the same group, systolic and diastolic blood pressures significantly decreased in the treatment group after 2 weeks of treatment; systolic blood pressure significantly-decreased after 2 weeks of treatment and diastolic blood pressure significantly decreased after 3 weeks of treatment in the control group (all P < 0.05, P < 0.01). Decreased valley values of systolic and diastolic blood pressures at week 2, 3, and 4 after treatment were obviously higher than those at week 1 after treatment in the two groups (P < 0.05, P < 0.01). Compared with the control group at week 4 after treatment, valley value of systolic blood pressure obviously decreased in the treatment group (P <0. 01). Decreased valley values of systolic and diastolic blood pressures in the treatment group were higher than those of the control group (P <0. 01). The success rate of target blood pressure was 60. 7% (71/117 cases) in the treatment group and 42. 3% (47/111 cases) in the control group, with statistical difference (χ² = 7.6781, P < 0.01). (2) Compared with before treatment in the same group, the score of HAMD-17 at week 2, 3, and 4 after treatment all decreased in the two groups (P < 0.01). Compared with the control group, the score of HAMD-17 at week 4 after treatment decreased more obviously in the treatment group, with higher difference in decreased value (P < 0.05). The effective rate was 79.5% (93/117) in the treatment group, higher than that in the control group [66.7% (74/111); χ² = 4.7741, P < 0.05]. (3) Compared with before treatment in the same group, the score of HAMA at week 1, 2, 3, and 4 after treatment all obviously decreased in the two groups (P <0. 05, P <0. 01). Compared with the control group, the score of HAMA at week 3 and 4 after treatment decreased more obviously in the treatment group, with higher difference in decreased value (P < 0.05, P < 0.01). (4) After 4 weeks of treatment, except physical function in the control group, SF-36 total score and the score for each factor were obviously higher in the two groups (P < 0.05, P < 0.01). MGD showed superior effect in improving physical function, physical activity, overall health, emotion activity, and health changes to that of Sertraline (P < 0.05, P < 0.01). (5) The incidence of insomnia, tremor, liability to agitation, dizziness was obviously less in the treatment group than in the control group (P < 0.05). CONCLUSIONS: MGD had favorable clinical effect on hypertension patients complicated depression. Meanwhile, it also could improve their blood pressure and QOL.

The Toxicology and Biochemical Characterization of Cantharidin on Cydia pomonella.

Cantharidin, a natural toxin produced by beetles in the families Meloidae and Oedemeridae, reported to be toxic to some pests, is being developed as a biopesticide in China. This study evaluates the toxicity and biochemical characterization of cantharidin on the codling moth, Cydia pomonella (L.) (Lepidoptera: Tortricidae), an economically important fruit pest, under both laboratory and field conditions. Laboratory dose response bioassays showed that the LC50 value of cantharidin against neonate larvae was 0.057 mg ml(-1). Exposure of the larvae to 0.024 and 0.057 mg ml(-1) of cantharidin resulted in significant reduction in larval body weight. Neonate larvae exposed to LC10 of cantharidin showed increased glutathione S-transferase activity and significantly reduced the carboxylesterase and cytochrome P450-dependent mixed-function oxidase activities. Results also showed 16 and 25% ovicidal activity at concentrations of 0.057 and 0.14 mg ml(-1) of cantharidin, respectively. Field trials demonstrated cantharidin has a significant effect on both the first and second generations of C. pomonella larvae, but it exhibits a lower control efficiency than the chemical reference emamectin benzoate. Cantharidin may be considered a valuable tool for the control of codling moth.

Key amino acid associated with acephate detoxification by Cydia pomonella carboxylesterase based on molecular dynamics with alanine scanning and site-directed mutagenesis.

Insecticide-detoxifying carboxylesterase (CE) gene CpCE-1 was cloned from Cydia pomonella. Molecular dynamics (MD) simulation and computational alanine scanning (CAS) indicate that Asn 232 in CpCE-1 constitutes an approximate binding hot-spot with a binding free energy difference (ΔΔGbind) value of 3.66 kcal/mol. The catalytic efficiency (kcat/km) of N232A declined dramatically, and the half inhibitory concentrations (IC50) value increased by more than 230-fold. Metabolism assay in vitro reveals that the acephate could be metabolized by wild CpCE-1, whereas N232A mutation is unable to metabolize the acephate, which suggests that the hot-spot Asn 232 is a crucial residue for acephate metabolism. Mutation detection suggests that low frequency of Asn 232 replacement occurred in Europe field strains. Our MD, CAS, site-directed mutagenesis, and metabolism studies introduce a new amino acid residue Asn 232 involved in the metabolism of the acephate with CpCE-1, and this method is reliable in insecticide resistance mechanism research and prediction of key amino acids in a protein which is associated with specific physiological and biochemical functions.

Identification of G Protein-Coupled Receptors (GPCRs) Associated with Lambda-Cyhalothrin Detoxification in Cydia pomonella.

While previous studies have reported G protein-coupled receptor (GPCR)-mediated insecticide resistance in various arthropods, the understanding of GPCR-associated resistance mechanisms in Cydia pomonella remains limited. In this study, a total of 95 CpGPCR genes categorized into four families were identified in C. pomonella. Results revealed high expression levels of the majority of the CpGPCRs during the first larval stage and in the head of C. pomonella. Exposure to lambda-cyhalothrin significantly increased the expression of 15 CpGPCRs, including CpGPCR70, which is highly expressed in all larval stages and shows the highest expression in the midgut. RNA interference (RNAi) demonstrated that downregulation of CpGPCR70 leads to reduced expression of key resistance-related genes and a decreased tolerance of larvae to lambda-cyhalothrin. These findings indicate that CpGPCR70 plays a crucial role in regulating the expression of detoxifying genes involved in lambda-cyhalothrin resistance, offering valuable insights for the development of more effective pest control strategies.

Quercetin stimulates an accelerated burst of oviposition-based reproductive strategy in codling moth controlled by juvenile hormone signaling pathway.

The advantageous characteristics of invasive pests, particularly their ability to reproduce and adapt to the environment, have been observed. However, it remains unclear what specific inherent superiority enables fruit pests to successfully invade and dominate in interactions with other species. In this study, we report that Cydia pomonella (Linnaeus), a notorious invasive pest of pome fruits and walnuts globally, employs unique reproductive strategies in response to quercetin, a plant compound in host fruits. By monitoring adult dynamics and fruit infestation rates, we observed a competitive relationship between C. pomonella and the native species Grapholita molesta (Busck). C. pomonella was able to occupy vacant niches to ensure its population growth. We also found that quercetin had different effects on the reproductive capacity and population growth of C. pomonella and G. molesta. While quercetin stimulated the fecundity and population growth of G. molesta, it inhibited C. pomonella. However, C. pomonella was able to rapidly increase its population after exposure to quercetin by adopting an 'accelerated burst' of oviposition strategy, with each individual making a greater reproductive contribution compared to the control. We further demonstrated that the effect of quercetin on oviposition is regulated by the juvenile hormone (JH) signaling pathway in C. pomonella, allowing it to prioritize survival. The enhanced reproductive fitness of G. molesta in response to quercetin is attributed to the regulation of JH titers and key genes such as Met and Kr-h1, which in turn up-regulate reproduction-related genes Vg and VgR. In contrast, C. pomonella is inhibited. These findings shed light on the mechanisms interspecific competition and help to improve our understanding of the global spread of C. pomonella, which can be attributed to its inherent superiority in terms of reproductive strategy.

Side effects of X-ray irradiation on flight ability of Cydia pomonella moth.

BACKGROUND: The sterile insect technique (SIT) has proven to be an effective approach in managing the population of major invasive pests. Our previous studies showed that irradiation of Cydia pomonella males at a dosage of 366 Gy X-rays resulted in complete sterility. However, the mating competitiveness of sterilized males is significantly compromised, which can be attributed to a decline in their ability to fly. RESULTS: In this study, we examined the flight patterns of both male and female adults of C. pomonella. The results revealed significant variations in the average flight speed of both genders at different stages of maturity, with females displaying longer flight duration and covering greater distances. Effect of irradiation on the flight performance of 3-day-old male moths was further evaluated, as they demonstrated the longest flight distance. The findings indicated a significant decrease in flight distance, duration, and average speed, due to wing deformities caused by irradiation, which also limited the dispersal distance of moths in orchards, as indicated by the mark-and-recapture assay. Reverse-transcription quantitative polymerase chain reaction analysis revealed a down-regulation of flight-related genes such as Flightin, myosin heavy chain, and Distal-less following radiation exposure. CONCLUSION: These findings demonstrate that X-ray irradiation at a radiation dose of 366 Gy has a detrimental effect on the flight ability of male C. pomonella adults. These insights not only contribute to a better understanding of how radiation sterilization diminishes the mating competitiveness of male moths, but also aid in the development and improvement of SIT practices for the effective control of C. pomonella. © 2023 Society of Chemical Industry.

Secondary metabolites in host pears defense against two fruit borers and cytochrome-P450-mediated counter-defense.

Herbivorous insects have evolved metabolic strategies to survive the challenges posed by plant secondary metabolites (SMs). This study reports an exploration of SMs present in pears, which serve as a defense against invasive Cydia pomonella and native Grapholita molesta and their counter-defense response. The feeding preferences of fruit borers are influenced by the softening of two pear varieties as they ripen. The content of SMs, such as quercetin and rutin, increases due to feeding by fruit borers. Notably, quercetin levels only increase after C. pomonella feeding. The consumption of SMs affects the growth of fruit borer population differently, potentially due to the activation of P450 genes by SMs. These two fruit borers are equipped with specific P450 enzymes that specialize in metabolizing quercetin and rutin, enabling them to adapt to these SMs in their host fruits. These findings provide valuable insights into the coevolution of plants and herbivorous insects.

Metabolic functional redundancy of the CYP9A subfamily members leads to P450-mediated lambda-cyhalothrin resistance in Cydia pomonella.

BACKGROUND: The evolution of insect resistance to pesticides poses a continuing threat to sustainable pest management. While much is known about the molecular mechanisms that confer resistance in model insects and few agricultural pests, far less is known about fruit pests. Field-evolved resistance to synthetic insecticides such as lambda-cyhalothrin has been widely documented in Cydia pomonella, a major invasive pest of pome fruit worldwide, and the increased production of cytochrome P450 monooxygenases (P450s) has been linked to resistance in field-evolved resistant populations. However, the underlying molecular mechanisms of P450-mediated insecticide resistance remain largely unknown. RESULTS: Here we found that functional redundancy and preference of metabolism by P450s genes in the CYP9A subfamily confer resistance to lambda-cyhalothrin in Cydia pomonella. A total of four CYP9A genes, including CYP9A61, CYP9A120, CYP9A121, and CYP9A122, were identified from Cydia pomonella. Among these, CYP9A120, CYP9A121, and CYP9A122 were predominantly expressed in the midgut of larvae. The expression levels of these P450 genes were significantly induced by a lethal dose that would kill 10% (LD10 ) of lambda-cyhalothrin and were overexpressed in a field-evolved lambda-cyhalothrin resistant population. Knockdown of CYP9A120 and CYP9A121 by RNA-mediated interference (RNAi) increased the susceptibility of larvae to lambda-cyhalothrin. In vitro assays demonstrated that recombinant P450s expressed in Sf9 cells can metabolize lambda-cyhalothrin, but with functional redundancy and divergence through regioselectivity of metabolism. CYP9A121 preferred to convert lambda-cyhalothrin to 2'-hydroxy-lambda-cyhalothrin, whereas CYP9A122 only generated 4'-hydroxy metabolite of lambda-cyhalothrin. Although possesses a relatively low metabolic capability, CYP9A120 balanced catalytic competence to generate both 2'- and 4'-metabolites. CONCLUSION: Collectively, these results reveal that metabolic functional redundancy of three members of the CYP9A subfamily leads to P450-mediated lambda-cyhalothrin resistance in Cydia pomonella, thus representing a potential adaptive evolutionary strategy during its worldwide expansion. © 2022 Society of Chemical Industry.

Transcription Factor AhR Regulates Glutathione S-Transferases Conferring Resistance to lambda-Cyhalothrin in Cydia pomonella.

Aryl hydrocarbon receptor (AhR) enhances insect resistance to insecticides by regulating the detoxification network. Our previous studies have confirmed that overexpressions of cytochrome P450 monooxygenases (P450s) and glutathione S-transferases (GSTs) are involved in lambda-cyhalothrin resistance in Cydia pomonella. Here, we report that CpAhR regulates the expression of GST and P450 genes, thus conferring resistance. Expression patterns indicated that the expression of CpAhR was highly induced by lambda-cyhalothrin exposure and upregulated in a lambda-cyhalothrin-resistant population. RNA interference (RNAi) of CpAhR decreases the expression of key resistance-related genes (CpGSTe3, CpCYP9A121, and CpCYP9A122) and the activity of the GST enzyme, reducing the tolerance to lambda-cyhalothrin. Furthermore, ß-naphthoflavone, a novel agonist of AhR, was first proven to be effective in increasing CpAhR expression and larval tolerance to lambda-cyhalothrin. These results demonstrate that CpAhR regulates the expression of key detoxifying genes and GST activity, resulting in the development of resistance to lambda-cyhalothrin in C. pomonella.