Different development and fecundity between Spodoptera frugiperda USA and China populations, influenced by ecdysone-related genes.

The fall armyworm (FAW), Spodoptera frugiperda, is one of the most harmful plant pests in the world and is globally distributed from the American continent to the Asian region. The FAW USA population (Sf-USA) and China population (Sf-CHN), which belong to corn strain, showed different developmental periods and fecundity rates in lab conditions. Sf-USA had faster development and higher fecundity compared with Sf-CHN. To examine these differences, transcriptomic data from two FAW populations were analyzed and compared. Twelve gigabytes of transcripts were read from each sample and 21,258 differentially expressed genes (DEGs) were detected. DEGs with log2 fold change ≥ 2 were identified and compared in two populations. In comparison to the Sf-CHN, we discovered that 3471 and 3851 individual DEGs upregulated and downregulated, respectively. Comparing transcriptome profiles for differential gene expression revealed several DEGs, including 39 of ecdysone (E)-, 25 of juvenile hormone-, and 15 of insulin-related genes. We selected six of E-related genes, such as Neverland, Shade, Ecdysone receptor, Ecdysone-inducible protein 74 (E74), E75, and E78 from DEGs. Gene expressions were suppressed by RNA interference to confirm the physiological functions of the selected genes from Sf-USA. The Sf-USA showed developmental retardation and a decrease in fecundity rate by suppression of E-related genes. These findings show that biological characteristics between Sf-USA and Sf-CHN are influenced by E-related genes.

Insights on reproduction-related genes in the striped fruit fly, Zeugodacus scutellata (Hendel) (Diptera: Tephritidae).

The striped fruit fly, Zeugodacus scutellata is a significant pest in East and Southeast Asia by damaging Cucurbitaceae blossoms and fruits. To control this pest, a novel strategy to suppress the gene(s) associated with sexually dimorphic phenotypes has been devised and implemented in a laboratory scale. However, comprehensive transcriptomic analysis related to this sex differentiation of Z. scutellata was necessary to determine effective target genes for the genetic control. We performed de novo assembly of the transcript obtained by paired-end sequencing using an Illumina HiSeq platform and let to 217,967 unigenes (i.e., unique genes) with a minimum length of 200 bp. The female produced 31, 604, 442 reads with 97.93% of Q20, 94.76% of Q30, and the male produced 130, 592, 828 reads with 97.93% of Q20 and 94.76 of Q30%. The differentially expressed genes were used to predict genetic factors associated with sex differentiation, which included Rho1, extra-macrochaetae (emc), hopscotch (hop), doublesex (dsx), sex-lethal (sxl), transformer-2 (tra-2), testis-specific serine/threonine-protein kinase (tssk1), tektin1 (tkt1) and 2 (tkt2), odorant binding proteins (OBPs), fruitless (fru), vitellogenin receptor, and hormone receptors in Z. scutellata. In addition, this transcriptome analysis provides the additional gene associated with sex determination and mating behaviors, which would be applied to develop a novel sterile insect technique against Z. scutellata.

Variations in methyl bromide concentration with distance and time during quarantine fumigation.

Methyl bromide (MB) is a highly toxic and ozone-depleting substance and should be replaced. Worker exposure to high MB concentrations during fumigation has been previously reported. However, variations in MB concentration as a function of distance from fumigated objects or of time after degassing have not been reported so far. In this study, air samples were collected at various distances from fumigated objects (oranges, wood in containers, and wood in tarpaulin) during injection and degassing and analyzed via gas chromatography according to the Occupational Safety and Health Agency method. In addition, MB concentrations were directly measured over time using a gas detector during degassing. Non-linear regression analysis of the logarithmically transformed data indicated a clear decrease in MB concentration with distance as well as time. Non-linear regression models were constructed to describe the decrease in MB concentration with distance from the objects and with time during degassing (P < 0.05 for all models). The results of this study could aid in establishing appropriate safety guidelines, and hence, in preventing risks related to MB exposure.

Heart Rate Variability Analysis in Workers Exposed to Methyl Bromide as a Quarantine Treatment.

OBJECTIVE: To determine whether methyl bromide (MB) fumigation work for plants imported in Korea affects workers' health by assessing heart rate variability (HRV). METHODS: We measured HRV indices (TP, VLF, LF, HF, HR, SDNN, pNN50 and HRV-index) and urinary bromide ion (Br-) in 62 fumigators (study group) and 34 inspectors (the control group) before and after fumigation work. In addition, the relationship between Br- concentration and HRV indices was analysed. RESULTS: The fumigators' post-work HRV indices and Br- level were changed compared with their pre-work values (P < 0.001). Conversely, inspectors' values were not shown a difference before and after work. The HRV indices in all subjects were negatively correlated with the Br- levels (P < 0.05). CONCLUSIONS: Fumigators with high Br- concentrations and low post-work HRV indices following MB fumigation work experienced adverse effects on their autonomic nervous systems.

Negative effect of methyl bromide fumigation work on the central nervous system.

Methyl bromide (MB) is a fumigant that has been widely used for killing pests on plants in trade, soils, and structures worldwide due to its excellent permeability and insecticidal effect; however, MB should be replaced because it is an ozone-depleting substance. It is well-known that MB is highly toxic and hazardous to workers, but the effects of exposure in asymptomatic workers have not been explored. The purpose of this study is to investigate the impact of MB fumigation on the health of fumigators at a sensitive level. The electroencephalogram (EEG) and urinary bromide ion levels of 44 fumigators (the study group) and 20 inspectors (the control) were measured before and after fumigation work from February to August 2019 in Busan, Korea. The mean post-work concentration of bromide ion (18.311 µg/mg CRE) in the fumigators was significantly increased from the pre-work level (7.390 µg/mg CRE) (P<0.001). The fumigator post-work median frequencies (MDF) and alpha-to-theta ratios (ATR) of EEG index were significantly decreased compared to the pre-work values (P<0.05 for all indices). In contrast, there were no significant differences in inspector EEG indices and urinary bromide ion. The urinary bromide ion levels in all the subjects were negatively correlated with MDF (P = 0.032). In conclusion, fumigators' EEG indices and urinary bromide ion suggested that occupational exposure to MB negatively affected the health of workers, although the workers were asymptomatic.

Burrowing mayfly Ephemera orientalis (Ephemeroptera: Ephemeridae) as a new test species for pesticide toxicity.

The potential of mayfly Ephemera orientalis McLachlan eggs and first-instar larvae in ecotoxicological testing was investigated. Both stages of E. orientalis showed high tolerance to various environmental variables, such as water temperature, pH, water hardness, and dissolved organic carbon. Toxicological assays were conducted with three insecticides (emamectin benzoate, endosulfan, and cypermethrin), one fungicide (mancozeb), and one herbicide (paraquat dichloride). The two toxicity endpoints for the assay were the 14-day egg median hatching rate (EHC50) in static and renewal exposure systems and 24-h median larval mortality (LC50). Cypermethrin was the most toxic to both eggs (EHC50 in static system = 36.9 µg/L; EHC50 in renewal system < 0.15 µg/L) and larvae (LC50 = 4.5 µg/L), and paraquat dichloride was the least toxic to eggs (EHC50 in static system = 54,359.8 µg/L; EHC50 in renewal system = 49541.3 µg/L) and larvae (LC50 = 9259.5 µg/L). The results were compared to literature data of Daphnia magna Straus and Cloeon dipterum Linnaeus to determine its relative sensitivity to pesticides. These three species had different toxicities to the tested pesticides, especially according to the exposure system. E. orientalis eggs in the static system were found to be less sensitive were D. magna and C. dipterum, but eggs in the renewal system and larvae had similar or higher sensitivities to the tested pesticides. The results revealed that this species has potential for use in ecotoxicological testing of pesticides. Because of its geographic distribution, E. orientalis may be used as an alternative or complementary test species for ecotoxicological studies in Northeast Asian countries, where natural populations of the international standard species, D. magna, are rarely found.

Chlorpyrifos-induced biomarkers in Japanese medaka (Oryzias latipes).

Chlorpyrifos (CHL) is an organophosphate compound that is widely used as an insecticide. Due to its repeated use and high environmental residual property, CHL is frequently passed into aquatic environments by runoff. Consequently, there may be an adverse effect on aquatic vertebrate animals, including fish. Therefore, in this study, we assessed how CHL affected Japanese medaka (Oryzias latipes). The acute toxicity of CHL in adult fish after 96 h of exposure was determined to be 212.50, 266.79, and 412.28 µg L(-1) (LC25, LC50, and LC95, respectively). Acetylcholinesterase (AChE), glutathione S-transferase (GST), and carboxylesterase (CE) activities were obtained from the livers of dead or surviving fish, and the results showed 4.8-fold lower, 4.5-fold higher, and 18.6-fold lower activities for the AChE, GST, and CE, respectively, for 64-h exposure at a concentration of 400 µg L(-1) of CHL. In the embryo toxicity test, curved spines were observed in embryos that were exposed to CHL for 48 h in a concentration-dependent manner. With identification of biomarkers for CHL in the fish, two protein peaks, 5550.86 and 5639.79 m/z, were found to be upregulated. These two proteins can be used as protein biomarkers for CHL contamination in aquatic systems. A phosphatidyl choline with an m/z ratio of 556.32 dramatically decreased after CHL exposure in the fish; thus, it may be considered as a lipid biomarker for CHL. It is assumed as the first report to identify a phospholipid biomarker using a lipidomics approach in fish toxicology. Taken together, these results demonstrated the adverse effects of CHL on Japanese medaka and reveal several candidate biomarkers that can be used as diagnostic tools for determining CHL.

Exposure of mayfly Ephemera orientalis (Ephemeroptera) eggs to heavy metals and discovery of biomarkers.

The objective of this study was to assess acute toxicity of heavy metals in eggs of mayfly Ephemera orientalis McLachlan, and to elucidate relationships between heavy metal toxicity and protein expression patterns determined using surface-enhanced laser desorption/ionization time-of-flight mass spectrometry (SELDI-TOF-MS). Acute toxicity analysis was conducted using five heavy metals (cadmium, chromium, copper, lead, and mercury), and the toxicity endpoint was established from the egg hatching rate during a 14-day exposure period. Median hatching toxicity (HC50) values were determined for each heavy metal, and the most toxic heavy metal was found to be mercury (0.11 mg/L), followed by copper (0.32 mg/L) and lead (4.39 mg/L). E. orientalis eggs were highly tolerant to cadmium and chromium (>120 mg/L). Proteinchip array analysis using a strong anion exchange proteinchip (Q10) in conjunction with SELDI-TOF-MS was used to assess the protein expression patterns after exposure to heavy metals at the EHC10 (prohibiting hatching concentration to 10% eggs), except for cadmium and chromium, which were used at concentrations of 1, 10, and 100mg/L. Three novel biomarker candidate proteins, i.e., 4269, 4283, and 4623 m/z, were identified for the detection of heavy metal toxicity in aquatic ecosystems at the level of HC10 in E. orientalis eggs. SELDI-TOF MS analysis for detecting differential expression of proteins was found to be more effective than Q10 proteinchip separation in the mayfly eggs.

Endosulfan-induced biomarkers in Japanese rice fish (Oryzias latipes) analyzed by SELDI-TOF-MS.

The objective of this study was to find and validate estrogen-related biomarkers from plasma proteins in Oryzias latipes after exposure to an estrogen disrupting compound, α-endosulfan. The acute toxicity of α-endosulfan on O. latipes after 96 h of exposure was 13.72, 16.18, and 22.18 µg L(-1) for the LC10, LC20, and LC50 values, respectively. To confirm estrogenic disturbance by α-endosulfan, the expression level of vitellogenin in the liver of male fishes was measured at the LC10 value, and it was found to be significantly different from the reference group, confirming the estrogenic effect of endosulfan in this concentration range. Proteinchip® array techniques using a weak cation exchange (CM10) and a strong anion exchange proteinchip (Q10) in conjunction with surface-enhanced laser desorption/ionization time of flight mass spectrometry (SELDI-TOF-MS) were used to determine plasma proteins of O. latipes differently expressed in response to endosulfan exposure at LC10 and LC20 concentrations. Analysis of protein profiling of the male fish exposed to α-endosulfan detected 48 significantly different protein peaks and the proteins at m/z 2819, 8462, 8860, and 9462 were significantly different (p<0.05). The protein peaks at m/z 2819, 8860, and 9462 were up-regulated and the peak at m/z 8462 was down-regulated. Therefore, these four differentially expressed proteins could be used as biomarkers to rapidly determine a possible risk of endosulfan on aquatic ecosystems, although these are not necessarily produced as a result of endocrine disruption.