No impact of transgenic cry1C rice on the rove beetle Paederus fuscipes, a generalist predator of brown planthopper Nilaparvata lugens

Differences in microbiome composition and transcriptome profiles between male and female Paederus fuscipes harbouring pederin-producing bacteria

Pederin, a group of antitumor compounds, is produced by an endosymbiotic bacterium of Paederus fuscipes. Pederin content differed between male and female P. fuscipes, but the reason why these differences are maintained remains unexplored. Here, the pederin-producing bacteria (PPB) infection rate in P. fuscipes was investigated. Furthermore, we assessed the microbiota structure differences in male and female P. fuscipes harbouring PPB and sequenced the transcriptome of both sexes to shed light on genes of interest. Of the 625 analysed beetles (275 females, 350 males), 96.36% of females and 31.14% of males were positive for PPB infection. PPB accounted for 54.36%-82.70% of the bacterial population in females but showed a much lower abundance in males (0.92%-3.87%). Reproductive organs possessed the highest PPB abundance compared with other parts of females, but no such relationships existed in males. Moreover, we provide the first transcriptome analysis of male and female P. fuscipes harbouring PPB and identified 8893 differentially expressed unigenes. Our results indicated that the pederin content difference between males and females might be caused by the PPB density difference in hosts. The biosequence data would be helpful for illustrating the mechanism that regulates PPB density in P. fuscipes.

Sublethal effects of chlorantraniliprole on Paederus fuscipes (Staphylinidae: Coleoptera), a general predator in paddle field

Paederus fuscipes is a general predator in rice fields and a non-target organism of chlorantraniliprole, an effective insecticide for insect-pest control in paddy fields. Pesticide hazards to non-target organisms have been a growing global problem for decades. This study was designed to evaluate the toxicity of chlorantraniliprole at lethal and sublethal levels against P. fuscipes larvae and adults. The LC₅₀ of chlorantraniliprole against P. fuscipes adults and larvae were respectively 535.49 and 111.24 mg a.i. L^-1, which is higher than the dosage recommended for use in the field (59.38 mg a.i. L^-1), but the LC₃₀ and LC₁₀ for larvae are lower than the recommended field dose which showed that the sublethal effects on immature stages are inevitable. Treatment at larval stage with LC₃₀ of chlorantraniliprole significantly elongated the pre-imaginal developmental and pre-oviposition periods. Also, adults exposed directly to chlorantraniliprole oviposited significantly less number of eggs in both LC₁₀ and LC₃₀ treatments. Furthermore, the larval predation efficiency and female bodyweight were also reduced due to exposure to sublethal doses. Meanwhile, the activities of antioxidant (SOD, POD and CAT) and detoxification (P450, AChE and GST) enzymes were also significantly affected by the exposure to these sublethal concentrations. These findings showed that sublethal doses of chlorantraniliprole adversely influenced P. fuscipes development and physiology, and therefore its use as part of integrative pest management should be given further considerations.

Emamectin benzoate induced enzymatic and transcriptional alternation in detoxification mechanism of predatory beetle Paederus fuscipes (Coleoptera: Staphylinidae) at the sublethal concentration

In this study, the detoxification enzyme activity and the transcriptional profile changes in the second instar through RNA-sequencing technology due to emamectin benzoate (EB) were assessed. The cytochrome P450 monooxygenases (P450) enzyme activity was not altered by EB due to the change in concentration and exposure time in all treatments. The glutathione S-transferase (GST) enzyme was not considerably varying in all treatments, while exposure time significantly changed the enzyme activity. Results showed that the esterase (Ests) activity was elevated with the increasing concentrations and exposure time. Two libraries were generated, containing 107,767,542 and 108,142,289 clean reads for the samples treated with LC₃₀ of EB and control. These reads were grouped into 218,070 transcripts and 38,097 unigenes. A total of 2257 differentially expressed genes (DEGs) were identified from these unigenes, of which 599 up-regulated and 1658 were down-regulated. The majority of these DEGs related to pesticides resistance were identified in numerous Kyoto Encyclopedia of Genes and Genomes (KEGG) pathways, e.g., steroid hormone biosynthesis, glutathione metabolism, drug metabolism-other enzymes, chemical carcinogenesis, pathways of cancer, metabolism of xenobiotics by cytochrome P450, drug metabolism of cytochrome P450, linoleic acid metabolism, retinol metabolism, and insect hormone biosynthesis. These pathways also shared the same genes as cytochrome P450 monooxygenases (P450s), glutathione S-transferases (GSTs), Esterase (Ests), UDP-glucosyltransferases (UGTs), and ATP-binding cassettes (ABCs). A heatmap analysis also showed that regulation of genes in a pathway causes a series of gene expression regulation in subsequent pathways. Our quantitative reverse transcription-PCR (qRT-PCR) results were consistent with the DEG's data of transcriptome analysis. The comprehensive transcriptome sequence resource attained through this study evidence that the EB induces significant modification in enzyme activity and transcriptome profile of Paederus fuscipes, which may enable more significant molecular underpinnings behind the insecticide-resistance mechanism for further investigations.

Effect of imidacloprid exposure on life history traits in the agricultural generalist predator Paederus beetle: Lack of fitness cost but strong hormetic effect and skewed sex ratio

A trade-off between life history traits in the evolution of insecticide resistance is common in insects because energy acquisition is mainly channeled for detoxification enzyme production. In addition, sublethal exposure to insecticides may have an effect on the physiology and behaviors of surviving insects. Similar to other agricultural pests, pesticide use may have led to insecticide resistance in populations of Paederus fuscipes Curtis. In this study, we determined the median lethal time of 10 field-collected strains in Taiwan for three insecticides that are commonly employed to manage agricultural pests. We determined that the susceptibility of these strains to cyhalothrin and fenitrothion were similar, with resistance ratios (RRs) ranging from 1 to 4; however, significantly different to imidacloprid (RRs: 1-16). The effect of imidacloprid resistance on the life history traits studied of Paederus beetles was limited; only a prolonged egg incubation period, and adult longevity decreased as imidacloprid resistance increased. Regarding sublethal exposure to imidacloprid, adult sex ratios were female biased in most combinations, though nonsignificant. The quality of offspring, particularly the length of eggs significantly decreased. In addition, a hormetic effect was apparent when the individual was exposed to LT₂₅ and LT₅₀; mean fecundity per female increased from 12.80 ± 8.95 (± standard error [SE]) to 42.70 ± 13.77 eggs compared with that of the control (7.10 ± 1.32). However, the hormetic effect was inconsistent among the tested strains, possibly because of the difference in insecticide resistance levels given that reproductive compensation was absent among the resistant population.

No Effect of Bt-transgenic Rice on the Tritrophic Interaction of the Stored Rice, the Maize Weevil Sitophilus Zeamais and the Parasitoid Wasp Theocolax elegans

During Bt transgenic rice storage, Bt Cry1Ab/Cry1Ac fused protein is exposed to the maize weevil Sitophilus zeamais and the parasitoid wasp Theocolax elegans. We have carried out a long-term risk assessment for Bt rice to these non-target organisms in the storehouse. Effects of Bt rice on S. zeamais and T. elegans have been carefully detected in a laboratory experiment of over 5 years. The survival, development, fecundity, and longevity of the maize weevil were compared between Bt rice and non-Bt rice treatments for every 5 generations from generation 1 to 25. Moreover, the development, adult body size and sex ratio of T. elegans were compared between them parasitizing S. zeamais feeding on Bt rice or non-Bt rice. We found that although Bt Cry1Ab/Cry1Ac fused protein exists in the Bt rice grains and S. zeamais digestive tracts, Bt rice is not harmful to the maize weevil S. zeamais and its parasitoid T. elegans.

Lethal and sublethal effects of emamectin benzoate on the rove beetle, Paederus fuscipes, a non-target predator of rice brown planthopper, Nilaparvata lugens

The use of pesticides in rice can not only manage the pest but also influence non-target organisms. The rove beetle (Paederus fuscipes), which is an important predator of the brown plant hopper (Nilaparvata lugens) in rice ecosystems, was tested to investigate acute and chronic effects of emamectin benzoate. The results from this study show that the LC50 of emamectin benzoate to adults of P. fuscipes at 72 h was 3.07 (1.84-4.54) mg a.i. L^-1, whereas the LC50 of emamectin benzoate to the second instar larvae of P. fuscipes at 72 h was 2.58 (1.95-3.19) mg a.i. L^-1. Tested sublethal doses (LC10 and LC30) had significant effects on the second instar developmental time of P. fuscipes compared with that of the control. The LC30 dose had a negative influence on the pre-imaginal developmental duration and the feeding potential of treated P. fuscipes larvae. Additionally, the LC30 reduced the pre-oviposition period, the fecundity and the body weight of adults emerged from treated larvae of P. fuscipes. In the sublethal experiment with adults, the fecundity and the feeding potential were significantly reduced at the LC30 dose. These results revealed that sublethal doses of emamectin benzoate negatively affected the development and biological activities of P. fuscipes, and we conclude that more attention should be paid to the use of this chemical as part of integrated pest management strategies.

Gumpy: a Python toolbox suitable for hybrid brain-computer interfaces

OBJECTIVE

The objective of this work is to present gumpy, a new free and open source Python toolbox designed for hybrid brain-computer interface (BCI).

APPROACH

Gumpy provides state-of-the-art algorithms and includes a rich selection of signal processing methods that have been employed by the BCI community over the last 20 years. In addition, a wide range of classification methods that span from classical machine learning algorithms to deep neural network models are provided. Gumpy can be used for both EEG and EMG biosignal analysis, visualization, real-time streaming and decoding.

RESULTS

The usage of the toolbox was demonstrated through two different offline example studies, namely movement prediction from EEG motor imagery, and the decoding of natural grasp movements with the applied finger forces from surface EMG (sEMG) signals. Additionally, gumpy was used for real-time control of a robot arm using steady-state visually evoked potentials (SSVEP) as well as for real-time prosthetic hand control using sEMG. Overall, obtained results with the gumpy toolbox are comparable or better than previously reported results on the same datasets.

SIGNIFICANCE

Gumpy is a free and open source software, which allows end-users to perform online hybrid BCIs and provides different techniques for processing and decoding of EEG and EMG signals. More importantly, the achieved results reveal that gumpy's deep learning toolbox can match or outperform the state-of-the-art in terms of accuracy. This can therefore enable BCI researchers to develop more robust decoding algorithms using novel techniques and hence chart a route ahead for new BCI improvements.

Toxicological and Biochemical Analyses Demonstrate the Absence of Lethal or Sublethal Effects of cry1C- or cry2A-Expressing Bt Rice on the Collembolan Folsomia candida

Assessing the potential effects of insect-resistant genetically engineered (GE) plants on collembolans is important because these common soil arthropods may be exposed to insecticidal proteins produced in GE plants by ingestion of plant residues, crop pollen, or root exudates. Laboratory studies were conducted to evaluate the potential effects of two Bacillus thuringiensis (Bt)-rice lines expressing Cry1C and Cry2A in pollen and leaves and of their non-Bt conventional isolines on the fitness of the collembolan Folsomia candida and on the activities of its antioxidant-related enzymes, superoxide dismutase and peroxidase, and of its detoxification-related enzymes, glutathione reductase and glutathione S-transferase. Survival, development, reproduction, and the intrinsic rate of increase (r_m) were not significantly reduced when F. candida fed on the Bt rice pollen or leaf powder than on the non-Bt rice materials; these parameters, however, were significantly reduced when F. candida fed on non-Bt rice pollen or non-Bt leaf-based diets containing the protease inhibitor E-64 at 75 μg/g. The activities of the antioxidant-related and detoxification-related enzymes in F. candida were not significantly affected when F. candida fed on the Bt rice materials, but were significantly increased when F. candida fed on the non-Bt rice materials containing E-64. The results demonstrate that Cry1C and Cry2A are not toxic to F. candida, and also indicate the absence of unintended effects on the collembolan caused by any change in plant tissue nutritional composition due to foreign gene transformation.

Transgenic Bt rice lines producing Cry1Ac, Cry2Aa or Cry1Ca have no detrimental effects on Brown Planthopper and Pond Wolf Spider

Transgenic rice expressing cry genes from the bacterium Bacillus thuringiensis (Bt rice) is highly resistant to lepidopteran pests. The brown planthopper (BPH, Nilaparvata lugens) is the main non-target sap-sucking insect pest of Bt transgenic rice. The pond wolf spider (PWS, Pardosa pseudoannulata) is one of the most dominant predators of BPH in rice fields. Consequently, the safety evaluation of Bt rice on BPH and PWS should be conducted before commercialization. In the current study, two experiments were performed to assess the potential ecological effects of Bt rice on BPH and PWS: (1) a tritrophic experiment to evaluate the transmission of Cry1Ac, Cry2Aa and Cry1Ca protein in the food chain; and (2) binding assays of Cry1Ac, Cry2Aa and Cry1Ca to midgut brush border membrane proteins from BPH and PWS. Trace amounts of the three Cry proteins were detected in BPH feeding on Bt rice cultivars, but only Cry1Ac and Cry2Aa proteins could be transferred to PWS through feeding on BPH. In vitro binding of biotinylated Cry proteins and competition assays in midgut protein vesicles showed weak binding, and ligand blot analysis confirmed the binding specificity. Thus, we inferred that the tested Bt rice varieties have negligible effects on BPH and PWS.