miR-584-5p / Ykt6 - mediated autophagy - lysosome - exosome pathway as a critical route affecting the toxic effects of lead on HK-2 cells.

Lead is a widespread environmental pollutant with serious adverse effects on human health, but the mechanism underlying its toxicity remains elusive. This study aimed to investigate the role of miR-584-5p / Ykt6 axis in the toxic effect of lead on HK-2 cells and the related mechanism. Our data suggested that lead exposure caused significant cytotoxicity, DNA and chromosome damage to HK-2 cells. Mechanistically, lead exposure down-regulated miR-584-5p and up-regulated Ykt6 expression, consequently, autophagosomal number and autophagic flux increased, lysosomal number and activity decreased, exosomal secretion increased. Interestingly, when miR-584-5p level was enhanced with mimic, autophagosomal number and autophagic flux decreased, lysosomal number and activity increased, ultimately, exosomal secretion was down-regulated, which resulted in significant aggravated toxic effects of lead. Further, directly blocking exosomal secretion with inhibitor GW4869 also resulted in exacerbated toxic effects of lead. Herein, we conclude that miR-584-5p / Ykt6 - mediated autophagy - lysosome - exosome pathway may be a critical route affecting the toxic effects of lead on HK-2 cells. We provide a novel insight into the mechanism underlying the toxicity of lead on human cells.

Lysosome-related exosome secretion mediated by miR-26b / Rab31 pathway was associated with the proliferation and migration of MCF-7 cells treated with BPA.

Bisphenol A (BPA), one of the typical environmental endocrine disruptors (EEDs), can promote the proliferation and migration of cancer cells, but the mechanism of which remains largely unclear. Exosome secretion plays an important role in the stress response of cells to environmental stimuli. This study was designed to explore whether exosome secretion was involved in the toxic effect of BPA on the proliferation and migration of MCF-7 cells, and the related mechanism. Our data shows that the IC50 value of MCF-7 exposure to BPA was about 65.82 µM. The exposure of MCF-7 to 10 µM BPA resulted in a decreased miR-26b expression and the activation of miR-26b/Rab-31 pathway, consequently, the number and activity of lysosomes decreased, the secretion of exosomes increased, cell proliferation and migration were enhanced obviously. Interestingly, miR-26b mimic up-regulated the number and activity of lysosomes via miR-26b/miR-31 pathway, exosome secretion was down-regulated, cell proliferation and migration decreased. Further, when GW4869 was used to directly inhibit the exosome secretion of MCF-7 treated with BPA, their proliferation and migration were down-regulated. Herein, we concluded that the stimulating effect of BPA on the proliferation and migration of MCF-7 cells was associated with the lysosome - related exosome secretion via miR-26b / Rab31 pathway.

Exosomal secretion may be a self-protective mechanism of its source cells under environmental stress: A study on human bronchial epithelial cells treated with hydroquinone.

Accumulating evidence reveals that exosome plays an important role in cell-to-cell communication in both physiological and pathological processes by transferring bioactive molecules. However, the role of exosomal secretion in the adaption of its source cells to the stimuli of environmental chemicals remains elusive. In this study, we revealed that the exposure of hydroquinone (HQ; the main bioactive metabolite of benzene) to human bronchial epithelial cells (16HBE) resulted in decreased ability of cell proliferation and migration, and simultaneously DNA damage and micronuclei formation. Interestingly, when exosomal secretion of HQ treated 16HBE cells was inhibited with the inhibitor GW4869, cellular proliferation and migration were further significantly reduced; concurrently, their DNA damage and micronuclei formation were both further significantly aggravated. Herein, we conclude that exosomal secretion of 16HBE cells may be an important self-protective function against the toxic effects induced by HQ.

Multi-generational Effects of Different Resistant Wheat Varieties on Fitness of Sitobion avenae (Hemiptera: Aphididae).

Crop resistance plays a role in preventing aphid damage, benefiting food production industries, but its effects are limited due to aphid adaptation and phenotypic plasticity. Therefore, furthering understanding of aphid-crop interactions will improve our ability to protect crops from aphids. To determine how aphids adapt to resistant varieties of wheat, Triticum aestivum L. over time, we performed a laboratory experiment to assess the multi-generational effects of three wheat varieties, Batis, Ww2730, and Xiaoyan22, with different resistance levels on the fitness of Sitobion avenae (Fab.) (Hemiptera: Aphididae). The results showed that Ww2730 and Xiaoyan22 were more resistant than Batis to S. avenae, regardless of whether the aphids were newly introduced or had been acclimated before being introduced to the three wheat varieties. However, the effect of resistance on aphid life-history traits was time dependent. Aphid weigh gain increased and they development faster of the acclimated generation compared to the newly introduced generation on all three varieties. And the fecundity on the three varieties and net reproduction rates on Batis and Xiaoyan22 significantly decreased. Aphid fitness in terms of individual life-history parameters improved, whereas aphid fitness in terms of reproductive decreased, and a convergence effect, the difference gaps and standard errors of all life-history traits among the three acclimated populations had narrowed and were less than those in the three first-generation populations, was observed during the 3-mo experimental period. We suggested that S. avenae could rapidly respond to wheat resistance through life-history plasticity.

Transcriptome response comparison between vector and non-vector aphids after feeding on virus-infected wheat plants.

BACKGROUND: Plant viruses maintain intricate interactions with their vector and non-vector insects and can impact the fitness of insects. However, the details of their molecular and cellular mechanisms have not been studied well. We compared the transcriptome-level responses in vector and non-vector aphids (Schizaphis graminum and Rhopalosiphum padi, respectively) after feeding on wheat plants with viral infections (Barley Yellow Dwarf Virus (BYDV) and Wheat dwarf virus (WDV), respectively). We conducted differentially expressed gene (DEG) annotation analyses and observed DEGs related to immune pathway, growth, development, and reproduction. And we conducted cloning and bioinformatic analyses of the key DEG involved in immune. RESULTS: For all differentially expressed gene analyses, the numbers of DEGs related to immune, growth, development, reproduction and cuticle were higher in vector aphids than in non-vector aphids. STAT5B (signal transducer and activator of transcription 5B), which is involved in the JAK-STAT pathway, was upregulated in R. padi exposed to WDV. The cloning and bioinformatic results indicated that the RpSTAT5B sequence contains a 2082 bp ORF encoding 693 amino acids. The protein molecular weight is 79.1 kD and pI is 8.13. Analysis indicated that RpSTAT5B is a non-transmembrane protein and a non-secreted protein. Homology and evolutionary analysis indicated that RpSTAT5B was closely related to R. maidis. CONCLUSIONS: Unigene expression analysis showed that the total number of differentially expressed genes (DEGs) in the vector aphids was higher than that in the non-vector aphids. Functional enrichment analysis showed that the DEGs related to immunity, growth and reproduction in vector aphids were higher than those in non-vector aphids, and the differentially expressed genes related to immune were up-regulated. This study provides a basis for the evaluation of the response mechanisms of vector/non-vector insects to plant viruses.

Exosomal miR-221 derived from hydroquinone-transformed malignant human bronchial epithelial cells is involved in cell viability of recipient cells.

miR-221, an oncogenic microRNA, can promote cell proliferation and is highly expressed in various types of tumors. However, the role of exosomal miR-221 in benzene-caused carcinogenesis remains elusive. Our study was designed to investigate whether exosomes secreted by the hydroquinone (HQ; an active metabolite of benzene)-transformed malignant cells can transmit miR-221 to normal recipient cells and its possible effects on cell viability. Our investigation revealed that expression levels of miR-221 were significantly increased in HQ-transformed malignant cells relative to normal controls. Furthermore, exposure of control cells to exosomes that were derived from HQ-transformed malignant cells increased miR-221 levels and promoted their proliferation. Analyses of the biological potency of exosomes derived from HQ-transformed malignant cells in which miR-221 levels were decreased using an inhibitor, showed that both miR-221 levels and proliferation of recipient cells were decreased, but still were higher than those of normal 16HBE cells. Our study indicates that exosomal miR-221 derived from HQ-transformed malignant human bronchial epithelial cells is involved in the proliferation of recipient cells.

High-voltage electrostatic field-induced oxidative stress: Characterization of the physiological effects in Sitobion avenae (Hemiptera: Aphididae) across multiple generations.

In recent decades, man-made electric fields have greatly increased the intensity of electrostatic fields that are pervasively present in the environment. To better understand the physiological alterations exhibited by herbivorous insects in response to changing electric environments, we determined the activities of anti-oxidative enzymes and the metabolic rate of Sitobion avenae Fabricius (Hemiptera: Aphididae) over multiple generations in response to direct and host-seed exposure to a high-voltage electrostatic field (HVEF) of varying strength for different durations. Under controlled greenhouse conditions, 20-min direct exposure of S. avenae and wheat seeds to a 2- or 4-kV/cm HVEF resulted in significantly increased superoxide dismutase (SOD) activity in the sixth, 11th, 16th, and 21st generations relative to the control activities, whereas significantly decreased SOD activity was detected in the second generation. In addition, the activities of catalase (CAT) and peroxidase (POD) in S. avenae showed significant decreases over multiple generations. We also examined the suppressive effects of the duration of 4-kV/cm treatment on aphid physiology. The results showed that exposure to the 4-kV/cm HVEF for 20 min exerted adverse effects on CAT and POD activities and significantly decreased the metabolic rates of S. avenae, as demonstrated through evaluations of CO2 production rate, and these parameters were not significantly affected by higher HVEF durations. Overall, these findings increase our understanding of plant-pest interactions under novel HVEF environments and provide information that can improve integrated management strategies for S. avenae. Bioelectromagnetics. 40:52-61, 2019. © 2018 Wiley Periodicals, Inc.

miR-222/GAS5 is involved in DNA damage and cytotoxic effects induced by temozolomide in T98G cell line.

Temozolomide (TMZ), a therapeutic DNA alkylator that can cause lethal DNA damage in cancer cells, is widely used for the standard chemotherapy against glioblastoma. However, long-term treatment with TMZ often causes drug resistance and poor prognosis, the mechanism of which remains largely unclear. This study aimed to investigate the possible role of miR-222/GAS5 axis on DNA damage and cytotoxic effects induced by TMZ in glioblastoma cells (T98G). Data suggest that the DNA comet tail length of T98G is positively correlated with the levels of miR-222 (R2  = 0.9808, P < 0.05), and negatively correlated with the levels of GAS5 (R2  = 0.8903, P < 0.05). The optical density value of T98G is negatively correlated with the levels of miR-222 (R2  = 0.7848, P < 0.05), and positively correlated with the levels of GAS5 (R2  = 0.6886, P < 0.05). Furthermore, comet tail length and optical density value are negatively and positively correlated with the levels of O-6-methylguanine-DNA methyltransferase, respectively (R2  = 0.8462, P < 0.05; R2  = 0.7018, P < 0.05). In conclusion, miR-222/GAS5 is involved in DNA damage and cytotoxic effects induced by TMZ, which means that miR-222/GAS5 may have great potential of being used as a biomarker for screening of chemotherapeutic alkylators.

Effects of zinc on CarE activities and its gene transcript level in the English grain aphid, Sitobion avenae.

As a selective stress, heavy metals play an important role in inducing the adaptive adjustments of insects to changing environments. Carboxylesterase (CarE) is one kind of biomarker that could help us to explore the adaptation mechanism of aphids to heavy metal stress. In this study, CarE activity and gene expression level were investigated in English grain aphids, Sitobion avenae (F.) (Hemiptera: Aphididae), exposed to Zn2+ at concentrations of 0, 400, and 1600 mg/kg for 5, 15, 25, and 30 generations. The results showed that the CarE activity was significantly different between different Zn2+ concentrations and different generations. The CarE activity significantly decreased with increasing generations. In the higher generations, the CarE activity was strongly inhibited by the 1600 mg/kg of Zn2+. Realtime quantitative PCR revealed that the CarE gene expression pattern in S. avenae was up-regulated under the condition of 400 mg/kg and 1600 mg/kg of Zn2+, but a significant difference was not found after long-term exposure to high concentrations of Zn2+. It was concluded that CarE could be the sensitive biomarker for S. avenae response to the presence of Zn2+. In order to adapt to heavy metal Zn2+ stress, S. avenae had particular patterns of gene expression under long-term stress.

Image detection model construction of Apolygus lucorum and Empoasca spp. based on improved YOLOv5.

BACKGROUND: The polyphagous mirid bug Apolygus lucorum (Meyer-Dür) and the green leafhopper Empoasca spp. Walsh are small pests that are widely distributed and important pests of many economically important crops, especially kiwis. Conventional monitoring methods are expensive, laborious and error-prone. Currently, deep learning methods are ineffective at recognizing them. This study proposes a new deep-learning-based YOLOv5s_HSSE model to automatically detect and count them on sticky card traps. RESULTS: Based on a database of 1502 images, all images were collected from kiwi orchards at multiple locations and times. We trained the YOLOv5s model to detect and count them and then changed the activation function to Hard swish in YOLOv5s, introduced the SIoU Loss function, and added the squeeze-and-excitation attention mechanism to form a new YOLOv5s_HSSE model. Mean average precision of this model in the test dataset was 95.9%, the recall rate was 93.9% and the frames per second was 155, which are higher than those of other single-stage deep-learning models, such as SSD, YOLOv3 and YOLOv4. CONCLUSION: The proposed YOLOv5s_HSSE model can be used to identify and count A. lucorum and Empoasca spp., and it is a new, efficient and accurate monitoring method. Pest detection will benefit from the broader applications of deep learning. © 2024 Society of Chemical Industry.

mTORC1 - TFEB pathway was involved in sodium arsenite induced lysosomal alteration, oxidative stress and genetic damage in BEAS-2B cells.

The mechanistic target of rapamycin (RAPA) complex 1 (mTORC1) - transcription factor EB (TFEB) pathway plays a crucial role in response to nutritional status, energy and environmental stress for maintaining cellular homeostasis. But there is few reports on its role in the toxic effects of arsenic exposure and the related mechanisms. Here, we show that the exposure of bronchial epithelial cells (BEAS-2B) to sodium arsenite promoted the activation of mTORC1 (p-mTORC1) and the inactivation of TFEB (p-TFEB), the number and activity of lysosomes decreased, the content of reduced glutathione (GSH) and superoxide dismutase (SOD) decreased, the content of malondialdehyde (MDA) increased, the DNA and chromosome damage elevated. Further, when mTORC1 was inhibited with RAPA, p-mTORC1 and p-TFEB down-regulated, GSH and SOD increased, MDA decreased, the DNA and chromosome damage reduced significantly, as compared with the control group. Our data revealed for the first time that mTORC1 - TFEB pathway was involved in sodium arsenite induced lysosomal alteration, oxidative stress and genetic damage in BEAS-2B cells, and it may be a potential intervention target for the toxic effects of arsenic.

Direct effects of barley yellow dwarf virus on the performance, parasitoid resistance, and feeding behavior of its vector Sitobion avenae (Hemiptera: Aphididae).

BACKGROUND: The complex interaction between plant viruses and their insect vectors is the basis for the epidemiology of plant viruses. The 'Vector Manipulation Hypothesis' (VMH) was proposed to demonstrate the evolution of strategies in plant viruses to enhance their transmission to new hosts through direct effects on insect vector behavior and/or physiology. However, the aphid vectors used in previous studies were mostly obtained by feeding on virus-infected plants and as a result, it was difficult to eliminate the confounding effects of infected host plants. Furthermore, the mechanisms of the direct effects of plant viruses on insect vectors have rarely been examined comprehensively. RESULTS: We fed Sitobion avenae on an artificial diet infused with a purified suspension of Barley yellow dwarf virus (BYDV) PAV strain to obtain viruliferous aphids. We then examined their growth and reproduction performance, resistance to the parasitoid Aphidius gifuensis Ashmead, and feeding behavior. The results indicate that (1) viruliferous aphids had a shorter life span and a lower relative growth rate at the nymphal stage; (2) A. gifuensis had a lower parasitism rate, mummification rate, and emergence rate in viruliferous aphids; (3) Viruliferous aphids spent more time on non-probing and salivation behavior and had a shorter total duration of penetration and ingestion compared with healthy conspecifics. CONCLUSION: These results suggest that plant virus infection may directly alter vector fitness and behavior that improves plant virus transmission, but not vector growth. These findings highlight the mechanisms of VMH and the ecological significance of vector manipulation by plant viruses, and have implications for plant virus disease and vector management. © 2024 Society of Chemical Industry.

MCF-7 cell - derived exosomes were involved in protecting source cells from the damage caused by tributyltin chloride via transport function.

Tributyltin chloride (TBTC) is a ubiquitous environmental pollutant with various adverse effects on human health. Exosomes are cell - derived signaling and substance transport vesicles. This investigation aimed to explore whether exosomes could impact the toxic effects caused by TBTC via their transport function. Cytotoxicity, DNA and chromosome damage caused by TBTC on MCF-7 cells were analyzed with CCK-8, flow cytometry, comet assay and micronucleus tests, respectively. Exosomal characterization and quantitative analysis were performed with ultracentrifugation, transmission electron microscope (TEM) and bicinchoninic acid (BCA) methods. TBTC content in exosomes was detected with Liquid Chromatography-Mass Spectrometry (LC-MS). The impacts of exosomal secretion on the toxic effects of TBTC were analyzed. Our data indicated that TBTC caused significant cytotoxicity, DNA and chromosome damage effects on MCF-7 cells, and a significantly increased exosomal secretion. Importantly, TBTC could be transported out of MCF-7 cells by exosomes. Further, when exosomal secretion was blocked with GW4869, the toxic effects of TBTC were significantly exacerbated. We concluded that TBTC promoted exosomal secretion, which in turn transported TBTC out of the source cells to alleviate its toxic effects. This investigation provided a novel insight into the role and mechanism of exosomal release under TBTC stress.

The resistance and correlation analysis to three species of cereal aphids (Hemiptera: Aphididae) on 10 wheat varieties or lines.

Winter wheat resistance is an efficient and environmentally friendly means to controlling aphids. By using principal component analysis and correlation analysis, we evaluated the resistance of 10 winter wheat varieties or lines from three countries to the following three aphid species: Sitobion avenae, Rhopalosiphum padi, and Schizaphis graminum. The data show that Batis was susceptible to Si. avenae and R. padi, but had adverse effect on the development of Sc. graminum; Astron was advantageous to WG and r(m) of Si. avenae and R. padi, but not to Sc. graminum; Amigo was resistant to Sc. graminum and R. padi, but susceptible to Si. avenae; 98-10-35 was resistant to Si. avenae and R. padi, but not to Sc. graminum; 98-10-30 was adverse to growth and fecundity of Si. avenae, but better for Sc. graminum and R. padi; Xiaoyan22 was susceptible to Sc. graminum, but not to R. padi; Ww2730 were resistant to Si. avenae, but susceptible to Sc. graminum; 186tm was susceptible to R. padi, but caused high mortality for Si. avenae and Sc. graminum. Correlation analysis suggests the wheat varieties or lines that were resistant to Si. avenae were always resistant to R. padi, but susceptible to Sc. graminum. However, the overall similarities in resistance classifications were not because of the same phenotypic characters of the wheat varieties or lines. We conclude that the wheat varieties or lines had specific different resistances to the three aphid species, and the resistant traits (antibiosis) can be defined at two or more hierarchical levels. There was even a stronger "trade-off" for the comparison of Si. avenae versus Sc. graminum and R. padi versus Sc. graminum.

Modification of non-vector aphid feeding behavior on virus-infected host plant.

Virus-infected host plants can have positive, neutral or negative effects on vector aphids. Even though the proportion of non-vector aphids associated with a plant far exceeds that of vector species, little is known about the effect of virus-infected plants on non-vector aphids. In the present study, the English grain aphid Sitobion avenae (Fabricius) (Hemiptera: Aphididae), a non-vector of Wheat dwarf virus (WDV) and Cereal yellow dwarf virus-RPV (CYDV-RPV), was monitored on, virus-infected, virus-free and leafhopper/aphid-infested, and virus- and insect-free (control) barley, Hordeum vulgare L. (Poales: Poaceae), plants. Electrical penetration graph recordings were performed. Compared with the control plants, S. avenae on infected plants exhibited reduced non-probing and pathway phase, and increased phloem sap ingestion phase, and more aphids reached sustained phloem ingestion. However, the electrical penetration graph parameters described above showed no significant differences in aphid feeding behavior on virus-free and vector pre-infested plants and the control barley plants during S. avenae feeding. The results suggest that WDV/CYDV-RPV-infected host plants positively affected the feeding behavior of the non-vector aphid S. avenae. Based on these results, the reasons and trends among the virus-infected host plants' effects on the feeding behavior of non-vector aphids are discussed.

Life table evaluation of survival and reproduction of the aphid, Sitobion avenae, exposed to cadmium.

The effects of cadmium (Cd) on the development, fecundity, and reproduction of the grain aphid, Sitobion avenae Fabricius (Hemiptera: Aphididae) were estimated by constructing a life table of S. avenae exposed to Cd. The concentrations of Cd in the soil were as follows: 0, 10, 20, 40, 80, and 160 mg/kg. The correlation analysis of the Cd concentration in soil and wheat revealed that the amount in the wheat increased with the increase of Cd concentrations in soil. The results indicated that, the latter part of the reproduction period was significantly affected by Cd, according to the curve of the total survival rate (l(x)). The net reproductive rate (R(0)), innate capacity of increase (r), and finite rate of increase (λ) of S. avenae all decreased under the stress of Cd, and were lowest at a Cd concentration of 20 mg/kg. Cd also negatively affected fecundity and m(x) (the number of offspring produced by an individual female). At 20 mg/kg, the decline of them was most obvious. In conclusion, survival and reproduction of S. avenae were inhibited under the treatment of the heavy metal Cd. Sitobion avenae was more sensitive to Cd at concentration of 20 mg/kg compared to the other concentrations. This concentration can be used to examine the mechanisms behind population genetics and biological mutation of S. avenae when exposed to heavy metal.

Assessment of Non-Consumptive Predation Risk of Coccinella septempunctata (Coleoptera: Coccinellidae) on the Population Growth of Sitobion miscanthi (Hemiptera: Aphididae).

How the non-consumptive effects (NCEs) of predators influence the development, survival, fecundity, and population growth of prey has not been well documented, which is the primary consideration for the compatibility of prey with its natural enemies in agricultural ecosystems. We herein employed the age-stage, two-sex life table to examine the NCEs of the predator Coccinella septempunctata on the life-history traits and population growth of prey Sitobion miscanthi via caged predator (prey co-existing with caged predator) and caged prey (predator co-existing with caged prey) treatments with daily different exposure times (i.e., 0 h (control), 12 h, and 24 h). The results indicated that the predation risk of a caged predator could reduce the first nymphal duration and net reproductive rate (R0) of S. miscanthi at 12 h, and the first nymphal duration, preadult duration, and mean generation time (T) at 24 h. However, the predation risk of the caged prey resulted in the prolongation of the pre-adult development time and total pre-reproductive period (TPRP) as well as lowered the intrinsic rate of increase (r), finite rate of increase (𝜆), R0, life expectancy, and reproductive value of S. miscanthi after both 12 h and 24 h. Furthermore, the predation risk of both the caged predator and caged prey could increase the percent of winged morph at 24 h. These findings indicate that S. miscanthi could respond to the predation risk of the caged predator by either accelerating the developmental rate or reducing the net reproductive rate, while S. miscanthi might reduce their fitness in response to the predation risk of caged prey. Furthermore, S. miscanthi might also alter to winged morphs for dispersal under both of the above treatments. The findings obtained have practical ramifications for managing this economically important pest in wheat production with reduced insecticide applications.

Fall Armyworm Gut Bacterial Diversity Associated with Different Developmental Stages, Environmental Habitats, and Diets.

The fall armyworm, Spodoptera frugiperda (Lepidoptera: Noctuidae), is a major invasive pest that seriously threatens world agricultural production and food security. Microorganisms play a crucial role in the growth and development of insects. However, the diversity and dynamics of gut microbes with different developmental stages, environmental habitats, and diets in S. frugiperda remain unclear. In this study, we found the changes of the microbiome of S. frugiperda across their life stages, and the bacteria were dominated by Firmicutes and Proteobacteria. The community composition of the egg stage was quite different from other developmental stages, which had the highest community diversity and community richness, and was dominated by Proteobacteria. The bacterial community compositions of male and female adults were similar to those of early larvae stage (L1-L2), and operational taxonomic units (OTUs) with abundant content were Enterococcus and Enterobacteriaceae bacteria, including Enterobacteria, Klebsiella, Pantoea, and Escherichia. The third instar larvae (L3) mainly consist of Enterococcus. The late stage larvae (L4-L6) harbored high proportions of Enterococcus, Rhodococcus, and Ralstonia. There was no significant difference in gut microbial composition between field populations and laboratory populations in a short period of rearing time. However, after long-term laboratory feeding, the gut microbial diversity of S. frugiperda was significantly reduced. Enterococcus and Rhodococccus of S. frugiperda feeding on maize showed higher relative proportion, while the microbial community of S. frugiperda feeding on artificial diet was composed mainly of Enterococcus, with a total of 98% of the gut microbiota. The gene functions such as metabolism, cell growth and death, transport and catabolism, and environmental adaptation were more active in S. frugiperda feeding on corn than those feeding on artificial diet. In short, these results indicate that developmental stage, habitat, and diet can alter the gut bacteria of S. frugiperda, and suggest a vertical transmission route of bacteria in S. frugiperda. A comprehensive understanding of gut microbiome of S. frugiperda will help develop novel pest control strategies to manage this pest.

Generalized population dynamics model of aphids in wheat based on catastrophe theory.

Wheat aphids are major wheat sap sucking pests found throughout the world. The analysis of wheat aphid population dynamics to develop aphid control strategies is therefore important. Even if all factors that control the size of aphid populations are known, several mathematical tools are needed to help us understand their combined effect. Based on the knowledge of population ecology and catastrophe theory, we proposed a generalized population dynamics model to describe variation of wheat aphid populations and obtained a dynamic threshold function for aphid control. Field survey data from 1997 to 2002 were used to validate this model. The results indicated the model could predict the results of practical measures against a pest if the factors of their immediate effects are known or could be estimated. By explaining and forecasting the size of an aphid outbreak and its probability of occurrence, this catastrophe model can provide a scientific basis for wheat aphid control.

Previous Aphid Infestation Induces Different Expression Profiles of Genes Associated with Hormone-Dependent Responses in Near-Isogenic Winter Wheat Lines.

Hormone-dependent responses in host plants induced by herbivore infestation have species-specific effects. This study focused on determining the relative expression profiles of the genes associated with hormone-dependent pathways in two near-isogenic wheat lines when attacked by cereal aphids. Infestation with Rhopalosiphum padi Linnaeus (Hemiptera: Aphididae) and/or Sitobion avenae Fabricius (Hemiptera: Aphididae) significantly upregulated the expression of marker genes related to the salicylic acid (SA)- and jasmonic acid (JA)-dependent pathways in the tested lines. In the resistant line 35-E4, previous infestation with R. padi significantly increased the relative expression of plant pathogenesis-related protein 1 at all sampling times but did not have a significant effect on the expression of the phenylalanine ammonia-lyase (PAL) gene. In addition, the expression levels of the lipoxygenase (LOX) and allene oxide synthase (AOS) genes immediately increased after the aphid attack. In susceptible line 35-A20, infestation with either R. padi or S. avenae led to significantly increased expression levels of the AOS and PAL genes. Moreover, sequential aphid infestation induced higher expression of AOS compared with a single-species aphid infestation, whereas the expression of the PAL gene was antagonistically affected by sequential aphid infestation. Overall, these results showed that aphid infestation induced SA- and JA-dependent responses in host plants. However, the expression profiles of these genes in resistant and susceptible host lines were significantly different.