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Simple Summary: Monolepta signata is a highly destructive agricultural pest that causes significant economic losses to important economic crops such as maize and cotton in its native area: Asia. This study uses the maximum entropy model, combined with bioclimatic variables and altitude, to predict the potentially suitable areas and spread patterns of M. signata worldwide. The research results show that, in addition to its native area, M. signata has potentially suitable areas all over the world. The potential geographical distribution of this pest is gradually expanding globally. By predicting the potential occurrence and spread areas of M. signata worldwide, this study provides an important theoretical basis for formulating effective prevention and control measures and early-warning strategies for this pest. Monolepta signata is a polyphagous and highly destructive agricultural pest, currently only distributed in Asia. In its place of origin, it poses a serious threat to important economic crops, for instance, maize (Zea mays L.) and cotton (Gossypium hirsutum L.). Based on morphological and molecular data research, it has been found that M. quadriguttata (Motschulsky), M. hieroglyphica (Motschulsky), and M. signata are actually the same species. This discovery means that the range of this pest will expand, and it also increases the risk of it spreading to non-native areas worldwide. It is crucial for global agricultural production to understand which countries and regions are susceptible to invasion by M. signata and to formulate corresponding prevention, control, and monitoring strategies. This study uses the maximum entropy model, combined with bioclimatic variables and elevation, to predict the potentially suitable areas and diffusion patterns of M. signata worldwide. The results indicate that in its suitable area, M. signata is mainly affected by three key climatic factors: Precipitation of Wettest Month (bio13), Mean Temperature of Warmest Quarter (bio10), and Temperature Seasonality (bio4). Under the current status, the total suitable region of M. signata is 252,276.71 × 104 km2. In addition to its native Asia, this pest has potentially suitable areas in Oceania, South America, North America, and Africa. In the future, with climate change, the suitable area of M. signata will expand to high-latitude areas and inland areas. This study found that by the 2070s, under the SSP5-8.5 climate scenario, the change in the potentially suitable area of this insect is the largest. By identifying the potentially suitable areas and key climatic factors of M. signata, we can provide theoretical and technical support to the government, enabling them to more effectively formulate strategies to deal with the spread, outbreak, and invasion of M. signata. [ABSTRACT FROM AUTHOR]

The prophenoloxidase (PPO) activation and Toll antimicrobial peptide synthesis pathways are two critical immune responses in the insect immune system. The activation of these pathways is mediated by the cascade of serine proteases, which is negatively regulated by serpins. In this study, we identified a typical serpin, BmSerpin-4, in silkworms, whose expression was dramatically up-regulated in the fat body and hemocytes after bacterial infections. The pre-injection of recombinant BmSerpin-4 remarkably decreased the antibacterial activity of the hemolymph and the expression of the antimicrobial peptides (AMPs) gloverin-3, cecropin-D, cecropin-E, and moricin in the fat body under Micrococcus luteus and Yersinia pseudotuberculosis serotype O: 3 (YP III) infection. Meanwhile, the inhibition of systemic melanization, PO activity, and PPO activation by BmSerpin-4 was also observed. Hemolymph proteinase 1 (HP1), serine protease 2 (SP2), HP6, and SP21 were predicted as the candidate target serine proteases for BmSerpin-4 through the analysis of residues adjacent to the scissile bond and comparisons of orthologous genes in Manduca sexta. This suggests that HP1, SP2, HP6, and SP21 might be essential in the activation of the serine protease cascade in both the Toll and PPO pathways in silkworms. Our study provided a comprehensive characterization of BmSerpin-4 and clues for the further dissection of silkworm PPO and Toll activation signaling. [ABSTRACT FROM AUTHOR]

Chemosensory proteins (CSPs) are highly efficient carry tools to bind and deliver hydrophobic compounds, which play an important role in the chemosensory process in insects. The diamondback moth, Plutella xylostella L. (Lepidoptera: Plutellidae), is a cosmopolitan pest that attacks cruciferous crops. However, the detailed physiological functions of CSPs in P. xylostella remain limited to date. Here, we identified a typical CSP, named Pxyl CSP18, in P. xylostella and investigated its expression patterns and binding properties of volatiles. PxylCSP18 was highly expressed in antennae and head (without antennae), and the expression level in the male antennae of P. xylostella was obviously higher than that in the female antennae. Moreover, Pxyl CSP18 has a relatively broad binding spectrum. Fluorescence competitive binding assays showed that Pxyl CSP18 had strong binding abilities with 14 plant volatiles (Ki < 10 μM) that were repellent or attractive to P. xylostella. Notably, Pxyl CSP18 had no significant binding affinity to (Z)-11-hexadecenal, (Z)-11-hexadecenyl acetate, and (Z)-11-hexadecenyl alcolol, which are the pheromone components of P. xylostella. The attractive effects of trans-2-hexen-1-ol and isopropyl isothiocyanate to male adults and the attractive effects of isopropyl isothiocyanate and the repellent effects of linalool to female adults were significantly decreased after knocked down the expression of PxylCSP18. Our results revealed that Pxyl CSP18 might play an important role in host plant detection, avoidance of unsuitable hosts, and selection of oviposition sites; however, it does not participate in mating behavior. Overall, these results extended our knowledge on the CSP-related functions, which provided insightful information about CSP-targeted insecticides. [ABSTRACT FROM AUTHOR]

Compared to other insects, the pea aphid Acyrthosiphon pisum has a reduced immune system with an absence of genes coding for a lot of immunity‐related molecules. Notably, nitric oxide synthase (NOS), which catalyses the synthesis of nitric oxide (NO), is present in the pea aphid. However, the role of NO in the immune system of pea aphid remains unclear. In this study, we explored the role of NO in the defence of the pea aphid against bacterial infections and found that the NOS gene of the pea aphid responded to an immune challenge, with the expression of ApNOS observably upregulated after bacterial infections. Knockdown of ApNOS using RNA interference or inhibition of NOS activity increased the number of live bacterial cells in aphids and the mortality of aphids after bacterial infection. Conversely, the increase in NO level in aphids using NO donor inhibited the bacterial growth, increased the survival of bacteria‐infected aphids, and upregulated immune genes, such as Toll pathway and phagocytosis related genes. Thus, NO promotes immune responses and plays an important role in the immune system of pea aphid. [ABSTRACT FROM AUTHOR]

MicroRNA-17-5p (miR-17-5p) has previously been reported to play an important role in tumor development and progression. However, it functions differently regarding different kinds of malignant tumor, and its role and mechanism in gastric cancer (GC) still lacks investigation. In this study, we detected the relationship between miR-17-5p and the development of GC by qRT-PCR, and it turned out that the level of miR-17-5p was significantly higher in GC patients than that in normal controls, and the aberrant expression of miR-17-5p was correlated with lymph node metastasis. After that, we examined the effect of miR-17-5p taking on the proliferation, apoptosis, migration and invasion of GC cells and the underlying mechanism. Experiments indicated that knockdown of miR-17-5p inhibited the proliferation, invasion and migration, while promoting apoptosis of SGC7901 cells. Early Growth Response 2 (EGR2) protein or mRNA levels were downregulated or upregulated after overexpression or knockdown of miR-17-5p, respectively. By using dual luciferase assay and Western blot, we identified EGR2 as a functional target of miR-17-5p. As far as we know, this could be the first study to demonstrate that miR-17-5p is associated with tumor stage of GC and that it could possibly become a new therapeutic method for the treatment of GC.