Antennal transcriptome analysis of Psyttalia incisi (silvestri) (Hymenoptera: Braconidae): identification and tissue expression profiling of candidate odorant-binding protein genes.

BACKGROUND: Olfaction plays an important role in host-seeking by parasitoids, as they can sense chemical signals using sensitive chemosensory systems. Psyttalia incisi (Silvestri) (Hymenoptera: Braconidae) is the dominant parasitoid of Bactrocera dorsalis (Hendel) in fruit-producing regions of southern China. The olfactory behavior of P. incisi has been extensively studied; however, the chemosensory mechanisms of this species are not fully understood. RESULTS: Bioinformatics analysis of 64,515 unigenes from the antennal transcriptome of both male and female adults P. incisi identified 87 candidate chemosensory genes. These included 13 odorant-binding proteins (OBPs), seven gustatory receptors (GRs), 55 odorant receptors (ORs), 10 ionotropic receptors (IRs), and two sensory neuron membrane proteins (SNMPs). Phylogenetic trees were constructed to predict evolutionary relationships between these chemosensory genes in hymenopterans. Moreover, the tissue expression profiles of 13 OBPs were analyzed by quantitative real-time PCR, revealing high expression of seven OBPs (1, 3, 6, 7, 8, 12, and 13) in the antennae. CONCLUSION: This study represents the first identification of chemosensory genes and the determination of their expression patterns in different tissues of P. incisi. These results contribute to a better understanding of the function of the chemosensory system of this parasitoid species.

Effects of low-concentration spinetoram wax-based bait stations on Bactrocera dorsalis (Diptera: Tephritidae).

Spinetoram wax-based bait station (SWBB) is a maintenance-free, long-lasting, and eco-friendly management measure for Bactrocera dorsalis. However, the impacts of low-concentration spinetoram on B. dorsalis have not yet been determined. Therefore, our study aimed to determine the impacts of low-concentration SWBBs on the biology, demographics, detoxifying enzymes, and gut microorganisms of B. dorsalis. Our results showed that low-concentration SWBBs posed dose-dependent effects on the lifespan and fecundity of B. dorsalis adults. Both the LC10 and LC30 treatments significantly reduced the fecundity, while only the latter led to significant deleterious effects on the longevity of adults. Transgenerational bioassays revealed that exposure to LC30 significantly affected the development period of larvae and pupae as well as the livability of pre-adult stage of the progeny. However, except for the ovipositional period, no significant effects on the biological traits of F1 adults were observed. In terms of the F1 demographic parameters, dose-dependent effects were observed. Moreover, both the LC10 and LC30 treatments significantly extended the mean generation time, while the latter remarkably decreased the finite and intrinsic rates. Additionally, the significant induction of CarE activity by the LC10 and LC30 treatment was maintained until 24 and 48 h respectively. The CYP450 O-deethylation activity in the LC30 treatment was significantly enhanced at 24 and 48 h intervals when compared to the control. Regarding the intestinal bacterial community, after B. dorsalis adults were exposed to low-concentration SWBBs, the relative abundances of Providencia and Vagococcus were significantly increased, whereas those of Lactococcus and Brachyspira experienced a significant decrease. The obtained results are expected to serve as a foundation for the application of spinetoram in "lure-and-kill" strategies against B. dorsalis.

The complete mitochondrial genome of Psyttalia incisi (Silvestri, 1916) (Hymenoptera: Braconidae).

Psyttalia incisi (Silvestri, 1916), an important solitary opiinae endoparasitoid, plays a crucial role in biological control programs against tephritid pests. In this study, the entire mitochondrial (mt) genome of P. incisi was sequenced and characterized. The whole mitogenome of P. incisi is 15,188 bp long with a G + C content of 14.80%, and encodes all 37 genes that are typically found in animal mt genomes, which contains 13 protein-coding genes (PCGs), 22 transfer RNA genes (tRNAs), and two ribosomal RNA genes (rRNAs). A maximum-likelihood (ML) tree demonstrates that P. incisi is closely related to Psyttalia lounsburyi, Psyttalia humilis, and Psyttalia concolor.

Efficacy of wax-based bait stations for controlling Bactrocera dorsalis (Diptera: Tephritidae).

BACKGROUND: Bactrocera dorsalis is a notorious pest and spraying of insecticides has been the major approach to controlling its damage. However, insecticide abuse has led to negative impacts on public health and insecticide resistance; hence, sustainable strategies, such as bait stations, need to be developed and taken into account for B. dorsalis management. In this study, we integrated insecticide, sugar, olfactory and visual elements into a wax matrix to formulate a long-lasting bait station. We determined its efficacy against B. dorsalis under field conditions. RESULTS: The optimal bait station was a wax matrix incorporated with 1% spinetoram, 1% yellow pigment, and 3% ammonium acetate, and was spherical in shape with a 6 cm diameter. The longevity of this bait station was at least 10 weeks under field conditions. In a release and recapture experiment performed in Orchard 1, the bait stations were as effective as bait spray in controlling sterile fly populations, and more effective than the control. In a 2-year field trial conducted in Orchard 2, the number of female B. dorsalis and fruit infestation in the area where bait stations had been deployed was similar to the areas treated with cover spray. In Orchard 3, deployment of bait stations combined with chemical cover spray treatment decreased the population of female B. dorsalis and fruit damage more effectively than cover spray alone. CONCLUSIONS: Overall, wax-based bait stations can be regarded as a viable alternative to insecticides or a synergistic method for managing B. dorsalis. © 2022 Society of Chemical Industry.

The complete mitochondrial genome of Fopius arisanus (Sonan 1932) (Hymenoptera: Braconidae).

Fopius arisanus (Sonan, 1932), an important egg parasitoid of several notorious tephritid pests, plays a key role in biological control programs. In the present study, the whole mitochondrial genome of F. arisanus was sequenced and characterized. The mitogenome of F. arisanus is 16,425 bp in length with 14.94% GC content, and contains 13 protein-coding genes (PCGs), 22 transfer RNA genes (tRNAs), and two ribosomal RNA genes (rRNAs). The phylogenetic trees demonstrated that F. arisanus is sister group to Psyttalia concolor, P. humilis, P. lounsburyi and Diachasmimorpha longicaudata.

Boosting CH3OH Production in Electrocatalytic CO2 Reduction over Partially Oxidized 5 nm Cobalt Nanoparticles Dispersed on Single-Layer Nitrogen-Doped Graphene.

Herein, we successfully synthesized partially oxidized 5 nm cobalt nanoparticles dispersed on a single-layer nitrogen-doped graphene (SL-NG) (denoted as PO-5 nm Co/SL-NG) catalyst by a unique and simple one-pot synthesis strategy, which was efficiently applied for highly selective electrocatalytic reduction of carbon dioxide to methanol in 0.1 mol dm-3 aqueous NaHCO3 medium under mild conditions, reaching the maximum faradaic efficiency (FE) of 71.4% for methanol at -0.90 V versus saturated calomel electrode (SCE), possessing a strong electrocatalytic current density of 4 mA cm-2 and a high yield of 1.10 mmol dm-3 h-1, and the corresponding overpotential is as low as 280 mV. Moreover, at -1.0 V versus SCE, a high current density of 10 mA cm-2 can be obtained, and the FE for methanol still remains 23.2%. Notably, the proposed catalyst exhibits prominent stability after 10 h electroreduction of CO2, and the morphology, particle size, structure, and element contents of the catalyst almost remain stable. This work first provides an advanced PO-5 nm Co/SL-NG for selective electroreduction of carbon dioxide into methanol, which simultaneously possesses the merits of high current density, low overpotential, high selectivity, superior FE, and good stability, outperforming most reported electrocatalysts.

Label-Free Simultaneous Analysis of Fe(III) and Ascorbic Acid Using Fluorescence Switching of Ultrathin Graphitic Carbon Nitride Nanosheets.

A simple chemical oxidation and ultrasound exfoliation method has been developed to synthesize the two-dimensional and ultrathin-layer materials-graphitic carbon nitride nanosheets (g-C3N4 NNs). The prepared ultrathin g-C3N4 NNs display strong fluorescence and stability, including good photostability and excellent antisalt ability. Herein, a new "on-off-on" fluorescent switching sensor is designed. The iron ion (Fe3+) has an ultrasensitive response to quench the fluorescence of g-C3N4 NNs based on the synergistic effect between inner filter effect and photoinduced electron transfer. The linear limit for Fe3+ was from 0.05 to 30 µmol L-1 with a detection limit of 0.018 µmol L-1. Meanwhile, the fluorescence of g-C3N4 NNs can recover through the redox reaction between Fe3+ and ascorbic acid (AA). In addition, the linear range for AA was from 0.2 to 112.5 µmol L-1 with a 0.086 µmol L-1 detection limit. The proposed method exhibited rapid response, excellent selectivity, wide detection range, and low detection limit for simultaneous analysis of Fe3+ and AA, and it was applied for the determination of Fe3+ and AA in water sample and human serum with satisfactory results.