Metarhizium fungi are pathogens of arthropods, with several early-diverged species infecting lizards or mushrooms. Most Metarhizium species are also beneficial plant symbionts, and they mainly colonize rhizosphere and rhizoplane with some strains colonizing leaves and stems. The development of Metarhizium and plant association commence either by the attachment of spores to roots or rhizosphere colonization. Rhizosphere hyphae are further attracted to roots by nutrient-rich root exudates, facilitating rhizoplane colonization. Both undifferentiated and differentiated (characterized by appressorial formation) hyphae can penetrate between root epidermal cells, with sporadical colonization. Plant-derived reactive oxygen species play a crucial role in limiting root cell colonization by Metarhizium. Metarhizium utilizes plant-derived sugars and fatty acids for the growth while transferring insect-derived nitrogen to the plants. Additionally, Metarhizium facilitates plant’s utilization of environmental phosphorus, zinc, and iron via increasing the bioavailability of these nutrients. Metarhizium colonization can improve plant resistance to herbivores, microbial pathogens, and abiotic stresses. Given their versatile benefits to plants, Metarhizium has been developed as insecticides, fertilizers, and plant immunity promoters. In addition to terrestrial ecosystems, recent studies report that Metarhizium also inhabits aquatic and wetland ecosystems, which could further enhance the understanding of their biology and ecology and widen their applications.

The detection rate of imidacloprid (IMI) in agro-products are increasing annually, posing negative effects on food safety and human health. A sensitive and portable dual-mode lateral flow immunoassay (LFIA) method, combined with the smartphone, has been established to monitor the IMI residues in agro-products. Optimal detection conditions were achieved with 0.4 mg/mL of IMI coating antigen and 4 μg/mL of IMI monoclonal antibody. The limit of detection (LOD) for qualitative analysis with naked-eye observation was determined to be 25 ng/mL. For quantitative analysis, 20% inhibition concentration (IC₂₀) was found to be 2.55 ng/mL, with a linear range (IC₂₀–IC₈₀) of 2.55–26.94 ng/mL. The recoveries and relative standard deviation (RSD) were in the ranges of 90.4%–103.2% and 2.0%–11.7%, respectively. There was a strong agreement between the results obtained from the established method and those from UHPLC-MS/MS, with the slope and coefficient of determination (R²) reaching to 1.091 and 0.9837, respectively. Overall, the proposed dual-mode LFIA method provides an efficient approach for on-site detection of IMI in agro-products.

Gut bacteria profoundly influence the physiology and ecology of insects. They may enter the hemocoel after the Bacillus thuringiensis (Bt) toxin impairs the midgut of larvae, potentially leading to sepsis. In our study, we found that antibiotic treatment, which led to a reduction in intestinal bacteria, significantly decreased the susceptibility of fall armyworm (FAW) larvae to the Vip3Aa19 protein. The 16S rRNA sequencing was conducted to analyze the gut microbiota associated with antibiotic treatment and the virulence of Vip3Aa19, and Enterococcus mundtii, Enterococcus faecalis, Enterococcus gallinarum, and Enterococcus casseliflavus were identified. Further studies indicated that E. mundtii and E. gallinarum, particularly the supernatants of these four Enterococcus species, exert a synergistic effect on the insecticidal capacity of Vip3Aa19 proteins. We selected three metabolites from the identified compounds produced by Enterococcus species and investigated their toxicity against FAW larvae. The results revealed that methyl indole-3-acetate, 3-methyloxindole, and 4-ethyl-2-methoxyphenol not only act as gastric poisons but also induce the death of hemocytes, which can accelerate the onset of septicemia. Our findings illuminate the significant role of insect gut microbiota and their metabolites in the context of Bt Vip3Aa19-killing pressure, providing insights into the importance of septicemia mediated by Bt toxins.

The fall armyworm, Spodoptera frugiperda, is a highly invasive pest that poses severe threats to food crop production worldwide. Several methods have been applied to control fall armyworm infestations, including egg parasitoids, chemical insecticides, and transgenic crops expressing Bacillus thuringiensis (Bt) toxins. However, the currently available control methods are either poorly effective or facing challenges such as resistance development and environmental concerns. The rapidly evolving molecular tools of genetic engineering, particularly clustered regularly interspaced short palindromic repeats (CRISPR)/CRISPR-associated (Cas), have been increasingly utilized in recent years in attempts to develop novel pest management strategies and genetically resistant crops. CRISPR/Cas-based genome editing offers a precise and efficient molecular tool that has been used successfully in several functional genomic studies of the fall armyworm over the last few years. In this review, we summarize recent progress in using CRISPR/Cas for precise genome editing of the fall armyworm, enabling the targeted modification of key genes essential for the survival and propagation of the pest. The potential of the CRISPR/Cas system to develop insect-resistant crops and pest management approaches that can be integrated into the current management strategies of the pest is discussed.

Fumigants are broad-spectrum pesticides that exhibit multi-site activity and are effective against various pests including fungi, bacteria, insects, nematodes, weeds, and rodents. These chemicals are characterized by small molecular weights, low boiling points, and high vapor pressures. Because of their unique physical and chemical properties, fumigants demonstrate excellent efficacy in pest control through robust diffusion, distribution, and penetration abilities, coupled with specialized fumigation techniques. Although predominantly utilized in soil and grain fumigation, their applications also extend to quarantine and commodity fumigation. This article reviews the mechanisms of action of both traditional and emerging fumigants, such as methyl bromide, chloropicrin, phosphine, allyl isothiocyanate, dimethyl disulfide, sulfuryl fluoride, ethanedinitrile, ethyl formate, and ethylicin. The objective is to provide a theoretical foundation for ongoing research and the development of fumigants and their applications.

Rice black-streaked dwarf virus disease (RBSDVD) poses a severe threat to rice production in China. Currently, the resistance levels of rice varieties to this disease are evaluated based on the incidence rate, which is a singular criterion that fails to capture the nuanced differences among cultivars with similar resistance levels. This study reveals a positive correlation between the severity of RBSDVD and the degree of plant dwarfing. We propose a refined evaluation method using the plant dwarfing index (PDI) to assess the resistance of different rice varieties. By analyzing the incidence rates and PDIs of four rice varieties with varying resistance levels after inoculation, we found that the PDI more accurately reflects the differences in disease severity among the varieties compared to the incidence rate. This PDI-based method for evaluating RBSDVD severity provides a scientific quantitative tool for future rice breeding and resistance mechanism studies.

Asian pear fire blight, caused by Erwinia pyrifoliae, is a devastating disease affecting pear trees. Effective integrated management of this disease depends on the timely and accurate detection and removal of diseased trees within orchards. Here, we developed four highly sensitive and specific monoclonal antibodies (MAbs) against E. pyrifoliae using isolated E. pyrifoliae as the immunogen and then established two serological techniques, dot enzyme-linked immunosorbent assay (dot-ELISA) and colloidal gold immunochromatographic strip (CGICS) assay, for detecting E. pyrifoliae using the obtained MAbs as detection antibodies. Both dot-ELISA and CGICS can detect eight different E. pyrifoliae strains from China and have no cross-reactivity with other 11 tested plant control bacteria. Furthermore, dot-ELISA and CGICS can detect E. pyrifoliae in bacterial suspensions diluted up to 7.81 × 10³ CFU/mL and 3.91 × 10³ CFU/mL, respectively, which were about 4 and 8 times more sensitive than conventional polymerase chain reaction (PCR). Additionally, CGICS was capable of detecting E. pyrifoliae in pear leaf homogenates diluted up to 1:10240 (w/v, g/mL). The detection results of 20 blinded pear tissue samples using both serological techniques were consistent with those obtained from PCR. Therefore, we conclude that these two newly developed techniques are suitable for large-scale detection of E. pyrifoliae in pear orchards.