Activity Of Detoxifying Enzymes Research Articles

Inheritance of resistance to S-metolachlor in a waterhemp (Amaranthus tuberculatus) population from central Illinois

AbstractWaterhemp [Amaranthus tuberculatus (Moq.) Sauer] is a dioecious weed that has evolved resistance to very-long-chain fatty-acid elongase (VLCFAE)–inhibiting herbicides via rapid metabolism. Although detoxification enzyme activities are associated with S-metolachlor resistance in two multiple herbicide–resistant (MHR) A. tuberculatus populations from Illinois, the genetic basis of resistance is unknown. Therefore, our goal was to investigate inheritance of S-metolachlor resistance in the Stanford, Illinois–resistant (SIR) population. Specifically, our research objectives were to: (1) generate a uniformly resistant, full-sib near-inbred line (DK3-2) via three generations of recurrent selection for resistance using preemergence S-metolachlor; (2) develop A. tuberculatus populations segregating for S-metolachlor resistance via reciprocal single-plant (one male × one female) full-sib mating of DK3-2 and a VLCFAE-inhibiting herbicide-sensitive population, SEN; (3) quantify S-metolachlor resistance levels in parental lines and their F1 progenies via greenhouse dose–response analysis; and (4) evaluate inheritance of S-metolachlor resistance in F2 progenies. Dose–response analysis using six to eight S-metolachlor concentrations (0.015 to 15.0 μM, varying per population) generated lethal dose (LD) estimates of 50% (LD50) and 90% (LD90) for SIR, SEN, DK3-2, and F1 progenies. LD estimates indicated DK3-2 has a higher magnitude of S-metolachlor resistance than the SIR population, demonstrating single crosses significantly increased S-metolachlor resistance in DK3-2. Levels of S-metolachlor resistance in F1 populations were intermediate compared with DK3-2 and SEN. Segregation of S-metolachlor resistance in F2 families from the paternal-derived lines fit a single-gene model (R:S = 3:1), indicating a single, dominant gene confers S-metolachlor resistance in SIR. However, F2 segregation results from the maternal-derived lines fit a duplicate recessive epistasis model (R:S = 9:7), indicating a second recessive gene may also modify S-metolachlor resistance in SIR. Results and germplasm derived from this research can assist in identifying the gene(s) conferring resistance to S-metolachlor in A. tuberculatus.

Comparative metaproteomics reveal co-contribution of onion maggot and its gut microbiota to phoxim resistance

Pesticide resistance inflicts significant economic losses on a global scale each year. To address this pressing issue, substantial efforts have been dedicated to unraveling the resistance mechanisms, particularly the newly discovered microbiota-derived pesticide resistance in recent decades. Previous research has predominantly focused on investigating microbiota-derived pesticide resistance from the perspective of the pest host, associated microbes, and their interactions. However, a gap remains in the quantification of the contribution by the pest host and associated microbes to this resistance. In this study, we investigated the toxicity of phoxim by examining one resistant and one sensitive Delia antiqua strain. We also explored the critical role of associated microbiota and host in conferring phoxim resistance. In addition, we used metaproteomics to compare the proteomic profile of the two D. antiqua strains. Lastly, we investigated the activity of detoxification enzymes in D. antiqua larvae and phoxim-degrading gut microbes, and assessed their respective contributions to phoxim resistance in D. antiqua. The results revealed contributions by D. antiqua and its gut bacteria to phoxim resistance. Metaproteomics showed that the two D. antiqua strains expressed different protein profiles. Detoxifying enzymes including Glutathione S-transferases, carboxylesterases, Superoxide Dismutase, Glutathione Peroxidase, and esterase B1 were overexpressed in the resistant strain and dominated in differentially expressed insect proteins. In addition, organophosphorus hydrolases combined with a group of ABC type transporters were overexpressed in the gut microbiota of resistant D. antiqua compared to the sensitive strain. 85.2% variation of the larval mortality resulting from phoxim treatment could be attributed to the combined effects of proteins from both from gut bacteria and D. antiqua, while the individual contribution of proteins from gut bacteria or D. antiqua alone accounted for less than 10% of the variation in larval mortality caused by phoxim. The activity of the overexpressed insect enzymes and the phoxim-degrading activity of gut bacteria in resistant D. antiqua larvae were further confirmed. This work enhances our understanding of microbiota-derived pesticide resistance and illuminates new strategies for controlling pesticide resistance in the context of insect-microbe mutualism.

Unveiling the Impact of Thiophanate-Methyl on Arthrospira platensis: Growth, Photosynthetic Pigments, Biomolecules, and Detoxification Enzyme Activities

Background: The intensive and injudicious use of pesticides in agriculture has emerged as a major concern due to its detrimental impact on aquatic ecosystems. However, the specific impact of broad-spectrum fungicides, such as Thiophanate-methyl (TM), on cyanobacteria remains a subject of ongoing research and debate. Methods: In order to fill this knowledge gap, The present study aimed to comprehensively investigate the toxicological effects of TM (10–30 µg/L) on the growth, photosynthetic pigments, oxidative stress, and biochemical composition of the non-nitrogen-fixing cyanobacterium Arthrospira platensis. Results: Our findings unequivocally demonstrated that TM exposure significantly inhibited the growth of A. platensis. Moreover, the decrease in chlorophyll content indicated a pronounced negative impact on the photosynthetic system of A. platensis caused by TM exposure. Notably, TM induced oxidative stress in A. platensis, as substantiated by a significant increase in lipid peroxidation (MDA) within the culture. Furthermore, the intracellular generation of hydrogen peroxide (H2O2) exhibited a positive correlation with higher TM dosages, while the levels of vital antioxidant enzymes, such as catalase (CAT) and ascorbate peroxidase (APX), exhibited a discernible decrease. This suggests that TM compromises the antioxidant defense mechanisms of A. platensis. Additionally, TM was found to enhance the activity of a plethora of enzymes involved in the detoxification of pesticides, including peroxidase (POD) and glutathione-S-transferase (GST), thereby indicating a robust detoxification response by A. platensis. Interestingly, exposure to TM resulted in a general suppression of biocomponent production, such as total proteins and total carbohydrates, which exhibited a diminishing trend with increasing TM concentration. Conversely, the lipid content witnessed a significant increase, possibly as an adaptive response to TM-induced stress. Conclusions: These findings contribute to a deeper understanding of the ecological implications of pesticide usage and emphasize the urgent need for the adoption of sustainable and environmentally-friendly agricultural practices to safeguard aquatic ecosystems.

Environmental impacts of industrial activities on floral coverage with special emphasis on detoxification enzyme activities in Cataglyphis savignyi as pollution biomarker

The present study investigates the environmental impact of industrial activities on floral coverage within the major industrial district of Borg El-Arab City, Egypt. Additionally, it aims to evaluate the detoxification enzymatic activity of Cataglyphis savignyi as a pollution biomarker. To achieve this objective, seasonal soil samples were collected from the studied sites to determine soil properties and heavy metal concentrations. Furthermore, a seasonal specimen of C. savignyi was collected to study the enzymatic activity of acetylcholinesterase (AChE) and glutathione-S-transferase (GST). Heavy metal contamination pollution indices were calculated, and fourteen plant species were identified at the investigated sites for four successive seasons from 2020 to 2021. The soil physicochemical parameters significantly varied in the industrial sites compared to the control site. The accumulation of heavy metal contamination in soil for investigated sites followed the order Ni > As > Pb > Hg. Calculated Cdeg and PLI for industrial 3 revealed a very high degree of contamination, attributed to increased industrial activity from the chemical and silicate factories that characterize this region. The current results highlight the inhibition of GST levels in C. savignyi at the industrial site compared to the control site. In contrast, AChE increases, which might be due to heavy metals enhancing acetylcholine activity at synapses. Consequently, the antioxidant enzymatic activities are useful as biomarkers for assessing and monitoring environmental contamination. In conclusion, this study underscores insects as potent biomarkers for heavy metal contamination, marking a significant advancement in environmental monitoring. These bioindicators offer crucial insights into the impacts of climate change and industrial pollution. The research reveals distinct plant diversity variations and higher heavy metal content in industrial sites, indicating pronounced contamination. Additionally, the study highlights altered enzyme activities in insects, emphasizing their utility as biomarkers for assessing environmental contamination. This work represents a substantial leap forward in comprehending the complex dynamics between contamination and ecological balance.

Sublethal effects of chlorantraniliprole on biological characteristics, detoxifying enzyme activity and gene expression profile in the Allium mongolicum Regel leaf beetle Galeruca daurica (Coleoptera: Chrysomelidae)

AbstractAllium mongolicum Regel leaf beetle, Galeruca daurica (Coleoptera: Chrysomelidae) is rampantly harmful in Inner Mongolia grassland. However, the current management strategies for this pest still heavily rely on chemical control using traditional insecticides or those with novel action. In the study, we conducted an indoor bioassay to evaluate the sublethal effects of chlorantraniliprole on the biological characteristics. Additionally, we assessed the activity of detoxification enzymes, specifically the primary enzymes carboxylesterase (CarE) and cytochrome P450, and insect's secondary metabolic enzymes, namely glutathione S‐transferase (GST) and uridine diphosphate glycosyltransferase (UGT), as well as its gene expression profile. The developmental period of the 3rd instar larvae of G. daurica was significantly prolonged after treatment with chlorantraniliprole, which negatively affected the hatching, pupation and diapause rates as well as their body weight. The larvae showed different dynamics of the enzyme activities within 24 h of chlorantraniliprole treatment. Different sublethal concentrations of chlorantraniliprole showed an inducing effect on the activities, while no significant difference in activity was observed for P450. Expression profiling of detoxifying enzyme genes screened by transcriptome data has revealed that 6 CarE, 2 GST, 7 UGT and 31 P450 genes were up‐regulated. In conclusion, chlorantraniliprole's sublethal effect on 3rd instar G. daurica larvae resulted in a deceleration of their growth and developmental processes and significantly increased the activity levels of CarE, GST and UGT. The detoxifying proteins encoded by up‐regulation genes may involve in the detoxification metabolism of chlorantraniliprole. Our results provide a basis for understanding the molecular mechanisms of chlorantraniliprole action and detoxification in this key grassland insect pest.

Global transcriptome analysis reveals fungal disease responsive core gene regulatory landscape in tea

Fungal infections are the inevitable limiting factor for productivity of tea. Transcriptome reprogramming recruits multiple regulatory pathways during pathogen infection. A comprehensive meta-analysis was performed utilizing previously reported, well-replicated transcriptomic datasets from seven fungal diseases of tea. The study identified a cumulative set of 18,517 differentially expressed genes (DEGs) in tea, implicated in several functional clusters, including the MAPK signaling pathway, transcriptional regulation, and the biosynthesis of phenylpropanoids. Gene set enrichment analyses under each pathogen stress elucidated that DEGs were involved in ethylene metabolism, secondary metabolism, receptor kinase activity, and various reactive oxygen species detoxification enzyme activities. Expressional fold change of combined datasets highlighting 2258 meta-DEGs shared a common transcriptomic response upon fungal stress in tea. Pervasive duplication events caused biotic stress-responsive core DEGs to appear in multiple copies throughout the tea genome. The co-expression network of meta-DEGs in multiple modules demonstrated the coordination of appropriate pathways, most of which involved cell wall organization. The functional coordination was controlled by a number of hub genes and miRNAs, leading to pathogenic resistance or susceptibility. This first-of-its-kind meta-analysis of host–pathogen interaction generated consensus candidate loci as molecular signatures, which can be associated with future resistance breeding programs in tea.

Mechanism of the Change in the Intestinal Microbiota of C-Strain Spodoptera frugiperda (Lepidoptera: Noctuidae) after an Interspecific Transference between Rice and Corn.

Spodoptera frugiperda (J.E.Smith) (Lepidoptera: Noctuidae) was first found in 2019 in Yunnan, China, and it was characterized as a corn strain; it was also found on rice strains there, and it damages rice in China, but little is known about the effect of host plant transfer on the intestinal microbiota and the activities of detoxification enzymes in the C-strain (corn strain) S. frugiperda. The intestinal microbiota and the protective enzyme activity of S. frugiperda that were transferred from rice plants were assessed, and the fourth generation of insects transferred from corn were studied; the gene types of S. frugiperda that were transferred from rice plants were tested using mitochondrial Tpi gene sequences. The results showed that the intestinal microbiota in the C-strain S. frugiperda were changed after the host transference, and the diversity and richness of the intestinal bacterial communities of the S. frugiperda feeding on rice were significantly reduced after the transfer of the host from corn. The predominant species of intestinal bacteria of the S. frugiperda on rice transferred from corn were Enterococcus and Enterobacter, with relative abundances of 28.7% and 66.68%; the predominant species of intestinal bacteria of the S. frugiperda that were transferred from rice and feeding on corn were Enterococcus (22.35%) and Erysipelatoclostridium (73.92%); and the predominant species of intestinal bacteria of S. frugiperda feeding on corn was Enterococcus, with a relative abundance of 61.26%. The CAT (catalase) activity of the S. frugiperda transferred from corn onto rice from corn was reduced, the POD (peroxidase) activity was significantly increased after the transfer from corn, and no significant variations were found for the SOD (superoxide dismutase), CarE (carboxylesterase), and GST (glutathione S-transferase) activities of S. frugiperda after the host plant transfer. The results showed that after feeding on rice, the activities of CAT and POD in the in S. frugiperda body changed in order to resist plant secondary metabolites from corn or rice, but there was no significant change in the detoxification enzymes in the body. In summary, switching the host plant between corn and rice induced variations in the intestinal microbiota in C-strain S. frugiperda owing to the strain difference between the C-strain and the R-strain (rice strain), and this was consistent with the results of the activities of detoxification enzymes. The results indicat that changes in intestinal microbiota and physiological enzymes may be important reasons for the adaptive capacity of C-strain S. frugiperda to rice.

Assessment of cytisine as an insecticide candidate for Hyphantria cunea management: Toxicological, biochemical, and control potential insights

In the present study, the toxicological effects of cytisine on the H. cunea larvae were investigated, and the potential of cytisine as a botanical insecticide through field simulation experiments was evaluated. The results showed that cytisine treatment (0.25–2.5%) exerted significant biotoxic effects on the H. cunea larvae, including diminished weight, disruption of both positive (HcCKS1, HcPLK, HcCCNA) and negative (HcGADD and HcCDKN) regulatory genes associated with larval growth, increased mortality, and heightened oxidative damage (H2O2 and MDA). Cytisine treatment significantly reduced glucose content and inhibited the expression of key rate-limiting enzyme genes (HcPFK, HcPK, HcHK1, HcCS, and HcIDH2) within glycolysis and the tricarboxylic acid cycle pathways. Under cytisine treatment, detoxification enzyme activities (CarE and GST) and expression of detoxification genes (HcCarE1, HcCarE2, HcCarE3, HcGST1, and HcGST3) were inhibited in H. cunea larvae. An increased contents of SOD, CAT, ASA and T-AOC, as well as expression of antioxidant enzyme genes HcSOD1 and HcCAT2, was found in cytisine-treated H. cunea larvae. Simultaneously, this is accompanied by a significant reduction in the expression of four antioxidant enzyme genes (e.g., HcPOD1 and HcPOD2). In the field experiment, a cytisine aqueous solution (25 g/L) with pre-sprayed and directly sprayed ways demonstrated potent insecticidal activity against H. cunea larvae, achieving a mortality rate of 53.75% and 100% at 24 h, respectively. Taken together, cytisine has significantly weight inhibition and lethal toxicity on the H. cunea larvae, and can be developed as a botanical insecticide for H. cunea control.

Indoxacarb resistance in Iranian populations of Tuta absoluta (Lepidoptera: Gelechiidae): Cross-resistance, biochemical and molecular mechanisms

Tuta absoluta (Meyrick) is an invasive tomato pest that occurs worldwide, including Iran. This study investigates the occurrence of resistance to indoxacarb, an oxadiazine insecticide, and the underlying mechanisms in Iranian populations of T. absoluta. Bioassays were performed on second-instar larvae using indoxacarb alone and in combination with three synergists: Piperonyl butoxide (PBO), diethyl maleate (DEM), and triphenyl phosphate (TPP). The activities of the main detoxification enzymes, including glutathione S-transferases (GST), general carboxylesterases (CarEs), and P450 monooxygenases (P450s), were evaluated. In addition, the presence of known amino acid substitutions in the IV segment 6 domain of the T. absoluta sodium channel was investigated. The results showed that resistance rates to indoxacarb in Iranian populations ranged from 2.37- to 14.45-fold. However, pretreatment with synergists did not significantly increase the toxicity of indoxacarb. Enzyme assays showed that Ardabil (Ar) and Kerman (Kr) populations had the highest CarEs activity, while Ar population showed the highest P450 activity. However, the observed increases in enzyme activities were <2-fold. Two indoxacarb resistance mutations, F1845Y and V1848I, were detected. Apart from a significant and positive correlation between LC50 values of indoxacarb and thiocyclam hydrogen oxalate, no cross-resistance between indoxacarb and other insecticides was detected. Overall, these results suggest that populations of T. absoluta in Iran have developed resistance to indoxacarb, primarily through changes at the target site.

First report on evaluation of commercial eugenol and piperine against Aedes aegypti L (Diptera: Culicidae) larvae: Mortality, detoxifying enzyme, and histopathological changes in the midgut

Dengue fever is a worldwide public health problem, and efforts to eradicate it have focused on controlling the dengue vector, Aedes aegypti. This study aims to assess the toxicity and effect of commercial eugenol and piperine on Ae. aegypti larvae through enzyme detoxification and histopathological changes in the midgut. Laboratory-reared Ae. aegypti larvae were treated with various concentrations of commercial eugenol and piperine and observed after 24, 48, and 72 h. Biochemical methods were used to assess detoxification enzyme activity for acetylcholinesterase, glutathione S-transferase, and oxidase, and changes in the midgut were examined using routine histological examination. In terms of larvicidal activity, piperine exceeded eugenol. Piperine and eugenol had LC50 and LC90 values of 3.057 and 5.543 μM, respectively, and 6.421 and 44.722 μM at 24 h. Piperine and eugenol reduced oxidase activity significantly (p < 0.05), but increased acetylcholinesterase and glutathione S-transferase activity significantly (p < 0.05). After being exposed to piperine and eugenol, the food bolus and peritrophic membrane ruptured, the epithelial layer was interrupted and irregular, the epithelial cells shrank and formed irregularly, and the microvilli became irregular in shape. Commercial piperine and eugenol behave as potential larvicides, with processes involving altered detoxifying enzymes, specifically decreased oxidase function and increased GST activity, as well as midgut histological abnormalities.

Effects of elevated CO2 and spinetoram on the population fitness and detoxification enzymes activities in Frankliniella occidentalis and F. intonsa

Effects of elevated CO2 and spinetoram on the population fitness and detoxification enzymes activities in Frankliniella occidentalis and F. intonsa

Metabolic Resistance of Sogatella furcifera (Hemiptera: Delphacidae) toward Pymetrozine Involves the Overexpression of CYP6FJ3.

Sogatella furcifera (Horváth), which mainly threatens rice, shows various levels of pesticide resistance due to long-term overuse of pesticides. Our resistance monitoring of 20 field populations in Sichuan, China, revealed that they were susceptible to highly resistant toward pymetrozine (0.4-142.2 RR), and JL21 reached the highest level of resistance. The JL21 population exhibited cross-resistance to triflumezopyrim and dinotefuran but sensitivity to sulfoxaflor, acetamiprid, clothianidin, and nitenpyram. The increased P450 activity were support to involve in pymetrozine resistance by detoxification enzyme activities and synergist determination. Among 16 candidate P450 genes, CYP6FJ3 (5.25-fold) was the most up-regulated in JL21, while no significant change was found after LC25 pymetrozine treatment. Furthermore, the knockdown by RNAi and heterologous overexpression by the GAL4/UAS system confirmed that the CYP6FJ3 overexpression was involved in the pymetrozine resistance, and recombination in vitro confirmed that CYP6FJ3 could hydroxylate pymetrozine. Therefore, the overexpression of CYP6FJ3 promotes pymetrozine metabolic resistance in S. furcifera.

Unveiling the role of bZIP transcription factors CREB and CEBP in detoxification metabolism of Nilaparvata lugens (Stål)

The basic leucine zipper (bZIP) superfamily is a crucial group of xenobiotics in insects. However, little is known about the function of CAAT enhancer binding proteins (CEBP) and cAMP response element binding protein (CREB) in Nilaparvata lugens. In the present study, NlCEBP and NlCREB were cloned and identified. Quantitative polymerase real-time chain reaction (qRT-PCR) analysis showed the expression of NlCEBP and NlCREB was significantly induced after chemical insecticides exposure. Silencing of NlCEBP and NlCREB increased the susceptibility of N. lugens to insecticides, and the detoxification enzyme activities were also significantly decreased. In addition, comparative transcriptome analysis revealed that 174 genes were significantly co-down-regulated after interfering with the two transcription factors. GO analysis showed that co-down-regulated genes are mostly related to energy transport and metabolic functions indicating the potential regulatory role of NlCEBP and NlCREB in detoxification metabolism. Our research shed lights on the functional roles of transcription factors NlCEBP and NlCREB in the detoxification metabolism of N. lugens, providing a theoretical basis for pest management and comprehensive control of this pest and increasing our understanding of insect toxicology.

Adverse effects of thiamethoxam on the behavior, biochemical responses, hepatopancreas health, transcriptome and intestinal flora of juvenile Chinese mitten crab (Eriocheir sinensis)

Frequent detection of thiamethoxam in global surface waters has provoked great concern in environmental safety, as thiamethoxam exhibits high toxicity to aquatic arthropods. However, little systematic investigation has been conducted on the chronic toxicity of thiamethoxam to crustaceans. This study exposed Eriocheir sinensis to thiamethoxam (0, 0.5, 5 and 50 μg/L) in water for 28 days. No significant difference in mortality was observed among all groups. A high concentration of thiamethoxam (50 μg/L) impaired the righting ability of E. sinensis. Thiamethoxam significantly increased antioxidant enzyme activities (superoxide dismutase, total antioxidant capacity and glutathione peroxidase) and malondialdehyde levels. Simultaneously, detoxification enzyme activities (aminopyrine N-demethylase, erythromycin N-demethylase and glutathione-S-transferase) increased under chronic thiamethoxam stress. In addition, thiamethoxam caused immune and hepatopancreas damage. Moreover, thiamethoxam induced intestinal flora dysbiosis by altering the microbiome structure. The reduced complexity of the gut microbiota further illustrated that thiamethoxam could disrupt the stability of the microbiota ecological network. The transcriptomic results revealed that the number of downregulated DEGs increased in a dose-dependent manner, and most downregulated DEGs were enriched in energy metabolism-related pathways. These results indicate that thiamethoxam can adversely affect the crab behavior, biochemistry, intestinal microflora and transcriptomic responses.

Bottom-Up Effects of Drought-Stressed Cotton Plants on Performance and Feeding Behavior of Aphis gossypii.

Drought, a major stress for crop plants, is expected to increase in frequency due to climate change. Drought can alter crop growth and levels of secondary plant metabolites, which in turn can affect herbivores, but this latter point is still controversial. This study used three different polyethylene glycol (PEG-6000) levels (0%, 1%, and 3%) to simulate drought stress and evaluated their effects on cotton plants and the impacts on the performance of the cotton aphid Aphis gossypii. Cotton plants under drought stress showed decreased water content, above-ground biomass, and nitrogen content and increased soluble protein, soluble sugar, and tannin contents. Based on analysis of the developmental time and fecundity data from individuals and at the population level, a significantly lower fecundity and population abundance of A. gossypii were detected on cotton plants with drought stress, which supports the "plant vigor hypothesis". The poor development of A. gossypii is possibly related to lower xylem sap and phloem ingestion under drought stress. In addition, the increased tannin content of cotton plants induced by drought and lower detoxification enzyme activities of A. gossypii may have affected the responses of aphids to drought-stressed plants. Overall, the results showed that drought stress altered the physiological characteristics of the cotton plants, resulting in adverse bottom-up effects on cotton aphid performances. This implies that the adoption of drip irrigation under plastic film that can help alleviate drought stress may favor the population growth of cotton aphids.

Investigating the role of the ROS/CncC signaling pathway in the response to xenobiotics in Spodoptera frugiperda using Sf9 cells

Spodoptera frugiperda (fall armyworm, FAW) is an invasive polyphagous lepidopteran pest that has developed sophisticated resistance mechanisms involving detoxification enzymes to eliminate toxic compounds it encounters in its diet including insecticides. Although its inventory of detoxification enzymes is known, the mechanisms that enable an adapted response depending on the toxic compound remain largely unexplored. Sf9 cells were used to investigate the role of the transcription factors, Cap n′ collar isoform C (CncC) and musculoaponeurotic fibrosarcoma (Maf) in the regulation of the detoxification response. We overexpressed CncC, Maf or both genes, and knocked out (KO) CncC or its repressor Kelch-like ECH associated protein 1 (Keap1). Joint overexpression of CncC and Maf is required to confer increased tolerance to indole 3-carbinol (I3C), a plant secondary metabolite, and to methoprene, an insecticide. Both molecules induce reactive oxygen species (ROS) pulses in the different cell lines. The use of an antioxidant reversed ROS pulses and restored the tolerance to I3C and methoprene. The activity of detoxification enzymes varied according to the cell line. Suppression of Keap1 significantly increased the activity of cytochrome P450s, carboxylesterases and glutathione S-transferases. RNAseq experiments showed that CncC mainly regulates the expression of detoxification genes but is also at the crossroads of several signaling pathways (reproduction and immunity) maintaining homeostasis. We present new data in Sf9 cell lines suggesting that the CncC:Maf pathway plays a central role in FAW response to natural and synthetic xenobiotics. This knowledge helps to better understand detoxification gene expression and may help to design next-generation pest insect control measures.

The contribution of gut bacteria to pesticide resistance of Tribolium castaneum (Herbst)

The stored product pest, Tribolium castaneum (Herbst) (Coleoptera: Tenebrionidae), has developed resistance against many classes of pesticides applied in grain storage. Knowledge about mechanisms behind pesticide resistance is essential to developing novel pest management strategies. Although more and more studies reveal that pesticide resistance of insects is associated with their symbionts, the link between gut symbionts and host resistance to contact pesticides has not been reported in T. castaneum. This study aims to reveal the relationship between gut bacteria and resistance of T. castaneum against contact pesticides and to determine its underlying mechanism. Ten culturable bacteria were isolated from the guts of pesticide-resistant T. castaneum adults, among which two isolates, Bacillus cereus and Achromobacter xylosoxidans, exhibited the ability to decompose and utilize malathion, pirimiphos-methyl, and deltamethrin for their growth. Reintroduction of a detoxifying bacterial isolate to sterile beetles significantly increased survival rates and activities of metabolic detoxification enzymes of adult T. castaneum when exposed to pesticides. Furthermore, in the absence of pesticides, two detoxifying bacteria had positive effects on the development of the F1 generation of T. castaneum. Positive effects of these two gut bacteria on host pesticide detoxification metabolism and fitness facilitate the formation of symbiont-mediated pesticide resistance in T. castaneum. These results provide further insight into the function and evolution of microbe-insect symbioses and enable novel pest management strategies by depleting these bacteria with antibiotics to increase host sensitivity to pesticides.

The effects of carvacrol on development and gene expression profiles in Spodoptera frugiperda

The fall armyworm, Spodoptera frugiperda, is a highly polyphagous agricultural pest that is widely distributed around the world and causes severe crop yield loss. Carvacrol showed adverse effects on many pests, such as larval death and growth inhibition. While the effects of carvacrol on S. frugiperda larvae are not yet known. In this study, the effects of carvacrol on S. frugiperda, including larval growth inhibition and mortality induction, were observed. The detoxification and digestive enzyme activities of larvae with 1.0 and 2.0 g/kg carvacrol treatments were analyzed. Carvacrol boosted the enzyme activities of carboxylesterase (CarE) and glutathione S-transferase (GST) while decreasing the activities of α-amylase (AMS), lipase (LIP), and trypsin. A total of 3422 differentially expressed genes were identified in the larvae treated with 2.0 g/kg carvacrol, of which the DEGs involved in xenobiotic detoxification, food digestion, and insecticidal targets were further examined. These results suggest that carvacrol could regulate growth and development by affecting the process of food digestion, and exert its toxicity on the larvae through interaction with a variety of insecticidal targets. While the altered expressions of detoxification enzymes might be related to the detoxification and metabolism of carvacrol. Our findings offer a theoretical foundation for the use of carvacrol for S. frugiperda control in the field.

Insecticide Susceptibility and Detoxification Enzyme Activity of Frankliniella occidentalis under Three Habitat Conditions.

Frankliniella occidentalis is a highly destructive and invasive agricultural pest that has developed resistance to a variety of insecticide classes. Different planting structures and insecticide use frequency can directly affect the resistance development of F. occidentalis. In this study, the susceptibility of three field strains of F. occidentalis, collected over one year (April to November) from three habitat conditions (facility agriculture area, FA; open field crop area, OF; agroforestry intersection area, AI), to spinetoram, spinosad, emamectin benzoate, chlorfenapyr, acetamiprid, and imidacloprid were monitored and compared. At the same time, the detoxification enzyme activity of F. occidentalis in different habitats was determined. The results showed that the susceptibility of the F. occidentalis population in FA was significantly lower than that of populations from OF and AI. Among them, the F. occidentalis population in FA had developed low levels of resistance to spinetoram (RR = 9.18-fold), emamectin benzoate (RR = 5.47-fold), chlorfenapyr (RR = 6.67-fold), and acetamiprid (RR = 7.49-fold), and had developed moderate level resistance to imidacloprid (RR = 11.67-fold), while still being relatively sensitive to spinosad. The population of F. occidentalis from OF had developed low level resistance to spinetoram (RR = 5.24-fold) but was still relatively sensitive to the other five insecticides. The resistance of F. occidentalis from AI to six insecticides was at relatively sensitive levels. The results of the enzyme activities of detoxification enzymes, including carboxylesterase (CarE), glutathione S-transferase (GST), acetylcholinesterase (AChE), and the cytochrome P450 enzyme system (CYP450), revealed that the activities of the FA population of F. occidentalis were significantly higher than those of the other two populations. The change of CarE activity in F. occidentalis was consistent with that of spinetoram resistance, indicating that CarE may be involved in the metabolic resistance of F. occidentalis to spinetoram. Among the three populations, the resistance and detoxification enzyme activities of F. occidentalis of the FA population to six insecticides were higher than those of the other two populations. Our findings, along with other strategies, are expected to help with the resistance management of F. occidentalis in different habitats.

Auricularia auricular Adsorbs Aflatoxin B1 and Ameliorates Aflatoxin B1-Induced Liver Damage in Sprague Dawley Rats.

Aflatoxin B1 (AFB1), as a class I carcinogen, poses a substantial health risk to individuals. Contamination of food sources, particularly grains and nuts, with Aspergillus flavus (A. flavus) contributes to the prevalence of AFB1. The impact of global warming has spurred research into the development of AFB1 prevention technologies. While edible fungi have shown potential in detoxifying AFB1, there is a scarcity of literature on the application of Auricularia auricular (A. auricular) in this context. This study aimed to investigate the ability and underlying mechanism of A. auricular mycelia to adsorb aflatoxin B1, as well as evaluate its protective effects on the AFB1-induced liver damage in SD rats. Additionally, the effects of temperature, time, pH, and reaction ratio on the adsorption rate were examined. Combining thermodynamic and kinetic data, the adsorption process was characterized as a complex mechanism primarily driven by chemical adsorption. In SD rats, the A. auricular mycelia exhibited alleviation of AFB1-induced liver damage. The protective effects on the liver attributed to A. auricular mycelia may involve a reduction in AFB1 adsorption in the intestine, mitigation of oxidative stress, and augmentation of second-phase detoxification enzyme activity. The adsorption method for AFB1 not only ensures safety and non-toxicity, but also represents a dietary regulation strategy for achieving effective defense against AFB1.