Regulation of three subtypes of SOD gene in Aleuroglyphus ovatus (Acari:Acaridae) under lead stress.

Superoxide dismutase (SOD) is an important enzyme that acts as the first line of protection in the mite antioxidant defense system, involved in eliminating reactive oxygen species (ROS) under harsh environmental conditions. Nevertheless, the SOD gene family was yet to be reported in stored grain pest mite (Aleuroglyphus ovatus). In this study, A. ovatus was used to evaluate the response of SOD gene during lead stress. A. ovatus were separately exposed to different concentration lead (12.5, 25, 50, and 100 mg/kg), which induce the dynamic trend of SOD enzyme activity initially increased and then reduced with an increase in lead concentration, whereas they were still substantially higher than the control group. Moreover, after lead stress, it was found that all of the three SOD genes showed enhanced relative messenger RNA expression at high concentrations and decreased relative expression at low concentrations, which indicated that lead stress induces the expression of AoSODs. The present work implies that AoSODs play an important role in resisting oxidative damage caused by lead stress.

The loss of Halloween gene function seriously affects the development and reproduction of Diaphorina citri (Hemiptera: Liviidae) and increases its susceptibility to pesticides.

The citrus industry has suffered severe losses as a result of Huanglongbing spread by Diaphorina citri. Controlling the population of D. citri is the key to preventing and controlling the spread of Huanglongbing. Ecdysteroids are key hormones that regulate insect development and reproduction. Therefore, the Halloween gene family involved in the ecdysone synthesis of D. citri is an ideal target for controlling the population growth of this insect. In this study, we successfully cloned four Halloween genes expressed during D. citri development. Silencing of one of the four genes resulted in a significant decrease in 20E titers in nymphs and significant decreases in the developmental, survival and emergence rates. Inhibiting Halloween gene expression in adults impeded the growth of the female ovary, diminished yolk formation, lowered vitellogenin transcription levels, and hence impaired female fecundity. This showed that Halloween genes were required for D. citri development and reproduction. DcCYP315A1 and DcCYP314A1 were highly expressed when D. citri was exposed to thiamethoxam and cypermethrin, and silencing these two genes made D. citri more sensitive to these two pesticides. Inhibition of DcCYP315A1 and DcCYP314A1 expression not only significantly delayed the development and reproduction of D. citri but also increased its susceptibility to pesticides. Therefore, these two genes are more suitable as potential target genes for controlling D. citri.

Complete mitochondrial genome of Idea leuconoe (Lepidoptera: Danaidae) and related phylogenetic analyses.

In the present study, we first sequenced and determined the complete mitochondrial genome (mitogenome) of the giant Danaidae butterfly, Idea leuconoe (Lepidoptera: Danaidae). The mitogenome was a typical closed, circular, double-stranded DNA molecule of 15,278 bp length (GenBank accession number: KR815449), similar to the metazoan mitogenomes containing 37 genes and one A + T-rich region. All the protein-coding genes (PCGs) were initiated with a typical ATN codon. Seven genes (COII, ATP6, COIII, nad4, nad4L, cytb, and nad1) adopted the standard ATG start codon, but the remaining six genes were initiated with ATA. All the 13 PCGs harbored complete termination codons (TAA). The overlap nucleotides ATGATAA were conserved for the ATP8/ATP6 gene. The largest intergenic spacer was located between trnGln and nad2, a common finding in Lepidoptera butterflies. All the transfer RNA genes in the I. leuconoe mitogenome could be folded into typical clover-leaf secondary structures, except for trnSer (AGN) that lacked a dihydrouridine arm. The control region with 94.8% A + T content was 444 bp in length and located between rrnS and trnMet. Finally, the phylogenetic relationships obtained using the maximum likelihood and Bayesian methods confirmed two well-supported phylogenetic trees of Danaidae, Papilionidae, and Nymphalidae from the order Lepidoptera, which were consistent with the traditional morphological classification. Results provided additional information for butterfly phylogenetic analysis and insights into the evolution of genomes.

Effect of temperature on development and reproduction of the carmine spider mite, Tetranychus cinnabarinus (Acari: Tetranychiae), fed on cassava leaves.

The effect of five constant temperatures (16, 20, 24, 28 and 32 °C) on the development, survival and reproduction of Tetranychus cinnabarinus (Boisduval) [= Tetranychus urticae Koch (red form)] fed on cassava leaves was examined in the laboratory at 85% relative humidity. Development time of various immature stages decreased with increasing temperature, with total egg-to-adult development time varying from 27.7 to 6.7 days. The lower thermal threshold for development was 10.8 °C and the thermal constant from egg to adult was 142.4 degree-days. Pre- and post-oviposition period and female longevity all decreased as temperature increased. The longest oviposition period was observed at 20 °C with 20.4 days. Under different temperatures, mated females laid, on average, 1.0, 2.9, 4.7, 4.7 and 4.9 eggs per day, respectively. The maximum fecundity (81.5 eggs per female) was at 28 °C and the intrinsic rate of increase (r m ) was highest (0.25) at 32 °C. The results of this study indicate that T. cinnabarinus population could increase rapidly when cassava leaves serve as a food source. At the appropriate temperature T. cinnabarinus could seriously threaten growth of cassava.

The complete mitochondrial genome of Trabala vishnou guttata (Lepidoptera: Lasiocampidae) and the related phylogenetic analyses.

The bluish yellow lappet moth, Trabala vishnou guttata is an extraordinarily important pest in China. The complete mitochondrial genome is sequenced and determined firstly, which is based on traditional PCR amplification and primer walking methods with a length of 15,281 bp, including 13 protein-coding (PCG) genes, 22 transfer RNA (rRNA) genes, two ribosomal RNA (tRNA) genes, and an A + T-rich region. The gene order and orientation of the T. vishnou guttata mitogenome were identical to the other sequenced Lasiocampidae species. The overall nucleotide composition of T. vishnou guttata is A (40.27 %), T (40.59 %), C (11.58 %) and G (7.56 %), respectively. All the PCGs initiate with the three orthodox start codons ATN except for coxI with CGA start codon. Three PCGs (coxI, coxII and nad4) used incomplete stop codon T, while the other 10 PCGs terminate with complete stop codon TAA. All tRNA genes have a typical clover-leaf structure except for the absence of a dihydrouridine arm in trnS (AGN). The length of A + T-rich region is 383 bp. Phylogeny is established to reveal the genetic relationship between T. vishnou guttata and other lepidopteran species based on 13 PCGs nucleotide sequences of the sequenced species (32 taxa) by Maximum likelihood and Bayesian methods. Phylogenetic analyses presents that T. vishnou guttata and its closely related species (Dendrolimus taxa) are clustered on Lasiocampidae group. It is a sister clade relationship between Lasiocampidae and other families in Bombycoidea with a bootstrap value of 83 % and a posterior probability of 0.75. This study supports that Lasiocampidae may be independent from Bombycoidea.

Population genetic structure of Cheyletus malaccensis (Acari: Cheyletidae) in China based on mitochondrial COI and 12S rRNA genes.

Cheyletus malaccensis is a predatory mite widely distributed in grain storages. It has been regarded as an important biological control agent for pest mites. In this study, we investigated the population genetic structure of C. malaccensis distributed in China based on the partial regions of mitochondrial COI and 12S rRNA genes. We collected 256 individuals of C. malaccensis from stored grain in 34 sites of China. We detected 50 COI gene haplotypes and nine 12S rRNA gene haplotypes. There were three clades in the haplotype network and Bayesian and maximum parsimony phylogenetic trees based on COI sequences, and two based on 12S rRNA sequences. The clustering of haplotypes was not correlated with their geographical distributions. The analysis of molecular variance, AMOVA, indicated that the genetic differentiation between populations was relatively weak. The major genetic differentiation was found within populations. We suggest that the genetic structure of C. malaccensis observed in this study may be the result of long-term climate fluctuations and recent human disturbances.

Effect of photoperiod on development and demographic parameters of Neoseiulus barkeri (Acari: Phytoseiidae) fed on Tyrophagus putrescentiae (Acari: Acaridae).

Effects of five photoperiods (Light:Dark = 4:20, 8:16; 12:12, 16:8, 20:4) on the development, survival and reproduction of Neoseiulus barkeri Hughes fed on storage mite Tyrophagus putrescentiae (Schrank) were examined under laboratory conditions at 85 % relative humidity and 24 °C. Development time of almost all immature stages in N. barkeri was the shortest (5.43 ± 0.12 days) under 12 h of daylight. Total duration of immature stages was as high as 8.55 ± 0.16 days during the longest photoperiod. Photoperiod had no effect on hatching rate, but did affect survival of larvae, protonymphs and deutonymphs. Total survivorship ranged from 20 (4:20) to 60 % (12:12). Under 12 h daylight, female adults had the shortest pre- and post-oviposition period, longest oviposition period and longevity, largest total number of eggs (15.95) and and highest daily egg production (1.43) per female. Under 12 h light, N. barkeri experienced its highest net reproductive rate (R 0  = 11.791), intrinsic rate of increase (r m  = 0.180), and finite rate of increase (λ = 1.197), and lowest mean generation time (t = 13.71 days) and population doubling time (DT = 3.86 days). All demographic parameters displayed a parabolic relationship with photoperiod. The results of the present study indicated that the photoperiod of 12:12 is optimal for the development and reproduction of N. barkeri fed on T. putrescentiae, and that N. barkeri may serve most efficiently as a biological control agent under this regime.

SEASONAL CHANGES OF FATTY ACID COMPOSITION IN Thitarodes pui Larvae, A HOST OF Ophiocordyceps sinensis.

BACKGROUND: Thitarodes larvae are the host of Ophiocordyceps sinensis and exist in the permafrost region of the Tibetan Plateau. OBJECTIVE: To understand the adaptation mechanism of Thitarodes larvae to seasonal fluctuations of ambient temperatures in the Tibetan Plateau by studying seasonal changes of the fatty acids composition in the larvae of T. pui. MATERIALS AND METHODS: The profile of fatty acids in the 6th instar T. pui larvae collected at the mid-month in a whole year were examined by GC-MS. RESULTS: There was a negative correlation between the total lipid and ambient (soil) temperature. Further study indicated that oleic, palmitic, linoliec, palmitoleic, stearic were the major fatty acids. The ratio of unsaturated fatty acids to saturated fatty acids (U/S) and the unsaturated index (UI) in triacylglycerols remain stable during the whole year, while the U/S and UI in phospholipids vary dramatically in response to soil temperature. CONCLUSION: The fluctuations in phospholipids were attributed to seasonal changes of oleic and linoleic. The changes of the fatty acid composition may result from their adaptation to the variation of temperature in different seasons.

Demographic analysis of the fitness of Problepsis superans (Lepidoptera: Geometridae) feeding on three ligustrum (Lamiales: Oleaceae) species.

Using the age-stage, two-sex life table, the effects of three ligustrum species, Ligustrum x vicaryi Hort., Ligustrum quihoui Carrière, and Ligustrum lucidum Aiton, on the fitness of Problepsis superans (Butler, 1885) (Lepidoptera: Geometridae) were assayed by considering life table parameters of P. superans at 27 +/- 1 degrees C, 70 +/- 5% relative humidity, and a photoperiod of 16:8 (L: D) h. The means and SEs of population parameters were calculated using the jackknife and bootstrap methods. The total developmental time of larval stage of P. superans on L. x vicaryi was significantly shorter than that on L. x vicaryi and L. quihoui, whereas higher fecundity was observed on L. x vicaryi. The highest value of the finite rate of increase was observed on L. x vicaryi. The intrinsic rate of increase of P. superans on L. x vicaryi, L. quihoui, and L. lucidum, was 0.147 +/- 0.004, 0.130 +/- 0.004, and 0.112 +/- 0.005, respectively, which differed significantly among the three ligustrum species. The net reproductive rate varied from 122.8 +/- 24.7 female offspring on L. lucidum to 242.2 +/- 36.2 female offspring on L. x vicaryi. The lowest mean generation time was observed on L. x vicaryi. The gross reproductive rate of P. superans on the three ligustrum species did not significantly differ. Based on growth and population parameters, the suitability of the three ligustrum species to P. superans is ranked from high to low in the order as L. x vicaryi, L. quihoui, and L. lucidum.

Diagenetic Genesis and Evolution of Coal-Bearing Tight Sandstone Reservoir in the Yangxia Formation, Northern Kuqa Depression, Tarim Basin.

Coal seams of the Yangxia Formation are widespread in the northern part of the Kuqa Depression in the Tarim Basin. During the thermal evolution of the coal seams, the generated fluids of different periods and natures have a significant impact on tight sandstone reservoirs. To further investigate the diagenetic characteristics and reservoir genesis of the tight sandstones due to the influence of coal seams, an in-depth exploration of the causes of dissolution and cementation in the reservoirs was conducted through thin-section casting, cathode luminescence, scanning electron microscopy, carbon-oxygen isotopic analyses, and X-ray diffraction of whole rock and authigenic clay minerals, along with burial evolution history and fluid evolution history. It is suggested that two phases of acidic fluids are mainly produced during the thermal evolution process of coal seams, including an early humic acid and a late organic carboxylic acid. The early phase humic acid plays a purifying role in reservoirs with coarse particles, rigidity-rich particles, and good permeability conditions. It selectively dissolves sedimentary calcareous mud and calcite, and the dissolution products are completely migrated. At the same time, it inhibits early carbonate cementation. The late organic carboxylic acid will dissolve potassium feldspar and some volcanic rock debris, and the dissolution products are difficult to migrate under the sealing conditions caused by lithological differences, which often take the cementation form of siliceous overgrowth and kaolinite or illite. In addition to the cementation resulting from the dissolution products of acidic fluids produced by the coal seams, the CO2-rich fluids generated by the coal seam thermal evolution will combine with ions such as Ca2+ from different sources, resulting in two phases of carbonate cementation. Based on the above research, this study summarizes a set of diagenetic evolution models for coal-bearing reservoirs.

The deficiency of acetylcholinesterase gene in Aleuroglyphus ovatus increases its susceptibility to phoxim and natural pyrethrins and inhibits its reproduction.

Acetylcholinesterase (AChE), an essential neurotransmitter hydrolase, is targeted by organophosphorus and carbamate pesticides, and its number varies among species. In Aleuroglyphus ovatus, a pest mite that endangers health and economy, Aoace1 and Aoace2 have been identified encoding 590 and 460 amino acids, respectively, with characteristic structures, including catalytic triads, oxyanion holes, acyl pockets, peripheral anion, and catalytic anion sites. Phylogenetic analysis reveals distinct clusters for each gene. Expression patterns indicate that Aoace1 predominates in eggs, while Aoace2 is substantially expressed in adults. Experiments on the response of the Aoace genes to phoxim and natural pyrethrins showed that except for the Aoace2 gene responded to natural pyrethrins, all the experimental groups showed a significant increase at LC30 agent concentration. RNA interference with Aoace1 and Aoace2 significantly reduced AChE activity, and increased mortality with LC30 concentrations of phoxim by 15.8 % and 31.5 %, while increased mortality with LC30 concentrations of natural pyrethrins by 43.4 % and 40.4 %, respectively. Knockdown of ace gene significantly decreased fecundity and vitellogenin gene expression. These findings suggest that Aoace1 and Aoace2 are involved in cholinergic and non-cholinergic functions, with Aoace2 being more influential, offering new insights for A. ovatus control strategies.

Sublethal Effects of Emamectin Benzoate on Development and Reproduction and RNAi of the Vitellogenin Gene in Spodoptera frugiperda.

Spodoptera frugiperda, one of the most destructive corn pests in the world, invaded China in December 2018. In this study, sublethal concentrations (LC10 and LC30) of emamectin benzoate (EB) were used to treat pesticide-free treatment (PFT) and EB treatment (ET) of S. frugiperda. In PFT, compared with the control (CK), the pupal weight, hatching rate, and pupation rate of LC10 and LC30 groups were significantly reduced. The fecundity and the expression of vitellogenin gene (SfVg) were decreased after LC30 treatment, while the LC10 treatment groups showed no significant difference from the control group. In ET, compared to CK, the fecundity was increased by 11.14 and 18.8%. The expression of SfVg was upregulated by 2.6 times after LC30 treatment. Moreover, RNAi-mediated SfVg knockdown resulted in a nearly 70% reduction in oviposition. The result provided a theoretical basis for optimizing the application of EB and Vg-dsRNA in the control of S. frugiperda.

Endoplasmic reticulum-targeted delivery of celastrol and PD-L1 siRNA for reinforcing immunogenic cell death and potentiating cancer immunotherapy.

The prospect of employing chemoimmunotherapy targeted towards the endoplasmic reticulum (ER) presents an opportunity to amplify the synergistic effects of chemotherapy and immunotherapy. In this study, we initially validated celastrol (CEL) as an inducer of immunogenic cell death (ICD) by promoting ER stress and autophagy in colorectal cancer (CRC) cells. Subsequently, an ER-targeted strategy was posited, involving the codelivery of CEL with PD-L1 small interfering RNAs (siRNA) using KDEL peptide-modified exosomes derived from milk (KME), to enhance chemoimmunotherapy outcomes. Our findings demonstrate the efficient transportation of KME to the ER via the Golgi-to-ER pathway. Compared to their non-targeting counterparts, KME exhibited a significant augmentation of the CEL-induced ICD effect. Additionally, it facilitated the release of danger signaling molecules (DAMPs), thereby stimulating the antigen-presenting function of dendritic cells and promoting the infiltration of T cells into the tumor. Concurrently, the ER-targeted delivery of PD-L1 siRNA resulted in the downregulation of both intracellular and membrane PD-L1 protein expression, consequently fostering the proliferation and activity of CD8+ T cells. Ultimately, the ER-targeted formulation exhibited enhanced anti-tumor efficacy and provoked anti-tumor immune responses against orthotopic colorectal tumors in vivo. Collectively, a robust ER-targeted delivery strategy provides an encouraging approach for achieving potent cancer chemoimmunotherapy.

Stress response and tolerance mechanisms of spirobudiclofen exposure based on multiomics in Panonychus citri (Acari: Tetranychidae).

The toxicity of insecticides used in the field decreases gradually to sublethal concentrations over time. Therefore, it is necessary to study sublethal effects of pesticides for controlling population explosion. Panonychus citri is a global pest which control is based on insecticides. This study explores the stress responses of spirobudiclofen on the P. citri. Spirobudiclofen significantly inhibited survival and reproduction of P. citri, and the effects aggravated as concentration increased. The transcriptomes and metabolomes of spirobudiclofen-treated and control were compared to characterize spirobudiclofen molecular mechanism. Transcriptomics indicated stress induced by spirobudiclofen stimulated immune defense, antioxidative system, cuticle formation, and lipid metabolism, as deduced from RNA-seq analysis. Meanwhile, our study found that tolerance metabolism in P. citri was regulated by promoting the metabolism of glycerophospholipids, glycine, serine, and threonine. The results of this study can provide a basis for exploring the adaptation strategies of P. citri to spirobudiclofen stress.

Chronic lead exposure prolongs the immature stages of brown-legged grain mite, Aleuroglyphus ovatus, in a long-term population study.

An important aspect of environmental pollution, lead contamination is a widespread problem in several ecosystems. The present study aimed to evaluate the potential effects of low concentration lead stress on the development and reproduction of Aleuroglyphus ovatus. They were fed with artificial diet containing four different concentrations of lead (12.5, 25, 50, and 100 mg/kg). The results showed that there were both accelerating effect of lead (at low concentrations), as well as retarding effects (at high concentrations) on the development of the mite, and lead stress significantly prolonged the immature stages of A. ovatus and this inhibitory effect was greater with greater lead concentrations. The immature stages in the L group were shorter than those in the S group. In the S and L groups, the oviposition periods were significantly longer in the treatments with lower lead concentrations than in the control, while they were significantly shorter in those treatments of higher lead concentrations. Age-specific survival rate (lx) started to decline earlier in the S group, whereas there were no differences between the L group and CK. Age-specific fecundity rate (mx) peaked earlier in the S group than in CK, while mx peaked later in L1 and L2 than in CK. The rm value and net reproduction rate (R0) of treated A. ovatus decreased with increasing lead concentrations. Lower lead concentrations could promote population expansion while higher concentrations could inhibit population size. These results confirmed the developmental effect of lead stress on A. ovatus, highlighting that heavy metal contamination has negative effects on organisms in their natural environment.

The metabolism and detoxification effects of lead exposure on Aleurolyphus ovatus (Acari: Acaridae) via transcriptome analysis.

Aleurolyphus ovatus Troupeau is one of the most predominant species of the Acaridae family worldwide. Recent reports have demonstrated that the accumulation of lead in stored grains and dietary items exceeds the required standards. However, the molecular mechanism of heavy metal stress on mites has not been reported. To understand the mechanism underlying the heavy metal response of A. ovatus, comparative transcriptome analysis was performed in this study using an Illumina high throughput mRNA sequencing (RNA-seq) platform. A. ovatus was fed on artificial diets containing two different concentrations of lead, namely, a low concentration of 12.5 mg/kg (LAO) and a high concentration of 100 mg/kg (HAO), while the mites in the control (NAO) group were not exposed to lead. A total of 44,362 unigenes, with an average length of 1547 bp, were identified. Of these, 996 unigenes were successfully annotated in seven functional databases. The number of differentially expressed genes (DEGs) in A. ovatus under different lead concentrations was compared. In NAO versus LAO group, including 310 up-regulated and 1580 down-regulated DEGs. In NAO versus HAO group, including 3928 up-regulated and 1761 down-regulated DEGs. Gene Ontology (GO) and Kyoto Encyclopedia of Genes and Genomes (KEGG) enrichment indicated that detoxification enzyme genes were significantly expressed in pathways, such as cytochrome P450 foreign body metabolism, glutathione metabolism and drug metabolism-cytochrome pathway. The results of gene annotation and quantitative real-time PCR showed that high concentration of lead significantly stimulated the expression of metabolic detoxification enzyme genes such as glutathione S transferase (GST) and superoxide dismutase (SOD), while low concentration inhibited their expression. This study will provide a basis for the molecular mechanism of A. ovatus in response to heavy metal lead stimulation in stored grain.

Effect of temperature on development and reproduction of Neoseiulus barkeri (Acari: Phytoseiidae) fed on Aleuroglyphus ovatus.

The effect of five constant temperatures (16, 20, 24, 28 and 32°C) on the development, survival and reproduction of Neoseiulus barkeri Hughes fed on Aleuroglyphus ovatus Toupeau (Acari: Acaridae) was examined in the laboratory at 85% relative humidity. Development time of different immature stages decreased with increasing temperature, total egg-to-adult development time varied from 5.0 ± 0.13 to 17.5 ± 0.29 days. The lower thermal threshold for development was 9.7 ± 2.48°C and the thermal constant from egg to adult was 111.1 ± 12.34 degree-days. Pre- and post-oviposition period and female longevity all shortened as temperature increased. The longest oviposition period was observed at 24°C with 20.4 ± 1.13 days. At 20, 24, 28 and 32°C, mated females laid on average 0.7 ± 0.08, 1.5 ± 0.04, 1.6 ± 0.11 and 1.5 ± 0.11 eggs per day, respectively, but no eggs were laid at 16°C. Both the maximum fecundity (30.9 eggs per female) and the highest intrinsic rate of increase (r (m) = 0.166) were obtained at 28°C. The results of this study indicated that a mass rearing of N. barkeri with A. ovatus as prey is feasible at the appropriate temperature.

Characterization of Chitin Synthase A cDNA from Diaphorina citri (Hemiptera: Liviidae) and Its Response to Diflubenzuron.

Diaphorina citri Kuwayama is the vector of HLB and one of the most common pests in citrus orchards in southern China. One of the most significant genes in D. citri's growth and development is the chitin synthase gene. In this study, the CHS gene (DcCHSA) of D. citri was cloned and analyzed by bioinformatics. According to RT-qPCR findings, DcCHSA was expressed at many growth processes of D. citri, with the greatest influence in the fifth-instar nymph. The molting failure rate and mortality of D. citri rose as DFB concentration increased in this research, as did the expression level of DcCHSA. Feeding on DcCHSA caused a large drop in target gene expression, affected nymph molting, caused failure or even death in freshly eclosion adults, increased mortality, and reduced the molting success rate over time. These findings showed that DcCHSA was involved in nymph to adult development and may aid in the identification of molecular targets for D. citri regulation. It provided new ideas for further control of D. citri.

Effects of Long-Term Exposure to Cadmium on Development, Reproduction and Antioxidant Enzymes of Aleuroglyphus ovatus (Acari: Acaridae).

Grain contaminated by cadmium (Cd) has become a serious food security problem, and it is necessary to determine and evaluate the toxic effect and defense mechanism of long-term heavy metal pollution in grain. In order to evaluate the effects of long-term heavy metal Cd stress on the stored grain pests, Aleuroglyphus ovatus were fed with an artificial diet supplemented with different concentrations of Cd (0, 5, 10, 20 mg/kg). The development, fecundity and detoxification enzymes of A. ovatus were analyzed and observed. In this study, the immature duration of A. ovatus was significantly prolonged under long-term Cd stress. Moreover, the survival duration of female adults was significantly shortened. The total number of eggs laid and the daily number laid per female adult decreased significantly. There were significant differences in protein content at protonymph and tritonymph stages when the concentration of Cd exceeded 10 mg/kg. The protein content of female adults was higher than that of male adults. The activity of detoxification enzymes showed differences in different conditions, such as development stage, Cd concentration and gender. These findings confirmed that A. ovatus were sensitive to Cd, and their offspring were severely affected under long-term Cd stress. Therefore, A. ovatus is a good model for evaluating the toxicity of long-term heavy metal Cd stress. The study provides the basis and enriches the research content of heavy metal pollution on mites, contributing to the harmonious and healthy development between the environment and human beings.

Knockdown of hexokinase in Diaphorina citri Kuwayama (Hemiptera: Liviidae) by RNAi inhibits chitin synthesis and leads to abnormal phenotypes.

BACKGROUND: Silencing specific genes in pests using RNA interference (RNAi) technology is a promising new pest-control strategy. The Asian citrus psyllid, Diaphorina citri Kuwayama, is the most important citrus pest because it transmits Candidatus Liberibacter asiaticus, which causes huanglongbing. Chitin is essential for insect development, and enzymes in this pathway are attractive targets for pest control. RESULTS: The hexokinase gene DcHK was characterized from D. citri to impair proper growth and chitin synthesis through RNAi. The transcription of DcHK was more highly developed in third-instar nymphs, adults and the Malpighian tube. The RNAi needed for D. citri is dose-dependent, with 600 ng µl-1 dsDcHK sufficient to knockdown endogenous DcHK expression. The messenger RNA (mRNA) level was lowest at 36 h after dosing, and there were significant effects on the relative levels of mRNA in the chitin synthesis pathway (DcTre, DcG6PI, DcGNAT, DcGFAT, DcPGM, DcUAP and DcCHS), leading to mortality, reduced body weight and abnormal or lethal phenotypes. CONCLUSION: RNAi can be triggered by orally delivered double-stranded RNA in D. citri. These results can provide support for HK genes as a new potential target for citrus psyllid control. © 2022 Society of Chemical Industry.