The fall armyworm (Spodoptera frugiperda) poses a substantial threat to many important crops worldwide, emphasizing the need to develop and implement advanced technologies for effective pest control. CRISPR/Cas9, derived from the bacterial adaptive immune system, is a prominent tool used for genome editing in living organisms. Due to its high specificity and adaptability, the CRISPR/Cas9 system has been used in various functional gene studies through gene knockout and applied in research to engineer phenotypes that may cause economical losses. The practical application of CRISPR/Cas9 in diverse insect orders has also provided opportunities for developing strategies for genetic pest control, such as gene drive and the precision-guided sterile insect technique (pgSIT). In this review, a comprehensive overview of the recent progress in the application of the CRISPR/Cas9 system for functional gene studies in S. frugiperda is presented. We outline the fundamental principles of applying CRISPR/Cas9 in S. frugiperda through embryonic microinjection and highlight the application of CRISPR/Cas9 in the study of genes associated with diverse biological aspects, including body color, insecticide resistance, olfactory behavior, sex determination, development, and RNAi. The ability of CRISPR/Cas9 technology to induce sterility, disrupt developmental stages, and influence mating behaviors illustrates its comprehensive roles in pest management strategies. Furthermore, this review addresses the limitations of the CRISPR/Cas9 system in studying gene function in S. frugiperda and explores its future potential as a promising tool for controlling this insect pest.

Environmental stresses diversely affect multiple processes related to the growth, development, and yield of many crops worldwide. In response, plants have developed numerous sophisticated defense mechanisms at the cellular and subcellular levels to react and adapt to biotic and abiotic stressors. RNA silencing, which is an innate immune mechanism, mediates sequence-specific gene expression regulation in higher eukaryotes. ARGONAUTE (AGO) proteins are essential components of the RNAinduced silencing complex (RISC). They bind to small noncoding RNAs (sRNAs) and target complementary RNAs, causing translational repression or triggering endonucleolytic cleavage pathways. In this review, we aim to illustrate the recently published molecular functions, regulatory mechanisms, and biological roles of AGO family proteins in model plants and cash crops, especially in the defense against diverse biotic and abiotic stresses, which could be helpful in crop improvement and stress tolerance in various plants.

The ongoing interplay among plants, insects, and bacteria underscores the intricate balance of defense mechanisms in ecosystems. Regurgitant bacteria directly/indirectly impact plant immune responses, but the underlying mechanism is unclear. Here, we focus on the interaction between regurgitant bacteria, diamondback moth (DBM), and plant. Six culturable bacteria were isolated from DBM gut regurgitant, including three Enterobacter strains (RB1-3), Micrococcus sp. (RB4), Staphylococcus haemolyticus (RB5), and Bacillus cereus (RB6). These RB strains suppressed genes related to jasmonic acid and glucosinolate signaling pathways but had little effect on salicylic acid signaling pathway genes in Arabidopsis thaliana wounds. RB1 and RB5 inhibited DBM development on A. thaliana but not on an artificial diet. RB1 and RB5 significantly suppressed GOX genes and proteins in DBMs. However, the Pxgox2 insect mutant strain inoculated with RB1 or RB5 did not significantly affect DBM feeding on A. thaliana compared to the wild type. Six RB have been functionally identified, with RB1 and RB5 negatively regulating GOX-mediated host adaptability. The deliberate addition of RB1 and RB5 can negatively affect DBM herbivory and fitness. Our study provides a molecular basis for the further application of RB for insect pest management by modulating insect–plant interactions.

Thrips are cosmopolitan agricultural pests and important vectors of plant viruses, and the increasing coexistence of multiple morphologically similar species has intensified the demand for species-specific molecular identification. However, traditional morphological identification and PCR assays using universal primers are often inadequate for mixed-species samples and field-adaptable application. In this study, we developed a species-specific molecular identification framework targeting a polymorphism-rich region of the mitochondrial cytochrome c oxidase subunit I (COI) gene, which is more time-efficient than sequencing-based COI DNA barcoding, for four economically important thrips species in southern China, including the globally invasive Frankliniella occidentalis. By aligning COI sequences, polymorphism-rich regions were identified and used to design four species-specific primer pairs, each containing a diagnostic 3′-terminal nucleotide. These primers were combined with a PBS-based DNA extraction workflow optimized for single-insect samples that minimizes dependence on column-based purification. The assay achieved a practical detection limit of 1 ng per reaction, demonstrated species-specific amplification, and maintained reproducible amplification at DNA inputs of ≥1 ng per reaction. Notably, PCR inhibition caused by crude extracts was effectively alleviated by fivefold dilution. Although the chemical identities of the inhibitors remain unknown, interspecific variation in inhibition strength was observed, with T. hawaiiensis exhibiting the strongest suppression, possibly due to differences in lysate composition. This integrated framework balances target specificity, operational simplicity, and dilution-mitigated inhibition, providing a field-adaptable tool for thrips species identification and invasive species monitoring. Moreover, it provides a species-specific molecular foundation for downstream integration with visual nucleic acid detection platforms, such as the CRISPR/Cas12a system, thereby facilitating the future development of portable molecular identification workflows for small agricultural pests.