Qingfeng Tang

Trehalase plays a crucial role in regulating various physiological activities in insects, such as energy metabolism and temperature stress tolerance; however, its function in the MED species of Bemisia tabaci remains poorly understood. This study systematically investigated the regulation of trehalose metabolism in B. tabaci MED using RNAi and pharmacological interventions. Developmental profiling revealed stage‐specific upregulation of trehalase genes BtTre and BtTPS1 , peaking in adults. Tissue‐specific expression showed BtTre1 and BtTPS1 were highest in the fat body, while BtTre2 was highest in the gut. RNAi targeting BtTre1 achieved 62.68% silencing efficiency, causing 34% downregulation of BtTPS1 suppressing trehalase activity, and disruping energy homeostasis, leading to significant stage‐dependent of 77% at 120 h. Validamycin treatment suppressed trehalase activity but increased trehalose content, whereas starvation induced the opposite effects, demonstrating metabolic plasticity. BtTre1 silencing in adults disrupted energy homeostasis more severely than in nymphs, suggesting a developmental vulnerability. These findings not only elucidate the essential role of trehalose metabolism in B. tabaci physiology but also identify BtTre1 as a promising RNAi target and confirm the significant inhibitory effect of validamycin on BtTre1 genes. The contrasting effects of pharmacological and nutritional perturbations provide insights into the design of combined control strategies.

Bactrocera dorsalis (Diptera: Tephritidae) is a highly invasive and destructive quarantine pests worldwide. To improved biological control efficiency, reduce chemical pesticides use, and optimise the application of Metarhizium anisopliae (Hypocreales: Clavicipitaceae) against B. dorsalis. This study evaluated the combined toxicity of M. anisopliae with deltamethrin and chlorpyrifos. The biocompatibility of M. anisopliae CQMa421 with these pesticides was assessed based on spore germination, mycelial growth, and sporulation. Additionally, the effects of combined treatments on detoxification enzyme and related gene expression in B. dorsalis were investigated. The results indicated that the virulence effect of M. anisopliae CQMa421 against B. dorsalis adults was time-dependent and dose-dependent. Deltamethrin showed good compatibility with M. anisopliae CQMa421, achieving 100% mortality at 1 × 10⁸ CFU/mL by 84 hours. Different concentrations of deltamethrin can promote the mycelial growth and sporulation of M. anisopliae CQMa421. The toxicity effect of deltamethrin and chlorpyrifos combined with M. anisopliae CQMa421 on B. dorsalis adults was better than that of single-agent treatment, and the co-toxicity factor of 5 mg/L deltamethrin and 1 × 10⁸ CFU/mL M. anisopliae CQMa421 was 24.81, which synergistically affected on B. dorsalis control. Enzyme activity assays and qRT-PCR results revealed that the combination treatment differentially activated and enhanced the activities of AChE, CarE, GST, CAT, and SOD. Meanwhile, BdCarE was significantly inhibited and upregulating BdGSTD7, BdGSTS1, BdCYP4ae1, BdPOD, BdPOD1, and BdCAT genes. In conclusion, the combination of deltamethrin and M. anisopliae CQMa421 enhanced the insecticidal efficacy against B. dorsalis, significantly affected the activity of related detoxification enzymes. Provided a robust basis for integrating biological and chemical control strategies to manage B. dorsalis more effectively.

The fall armyworm, Spodoptera frugiperda (J. E. Smith) (Lepidoptera: Noctuidae), is a highly destructive polyvorous pest with a wide host range and the ability to feed continuously with seasonal changes. This destructive pest significantly damages crops and can also utilize non-agricultural plants, such as weeds, as alternative hosts. However, the adaptation mechanisms of S. frugiperda when switching between crop and non-crop hosts remain poorly understood, posing challenges for effective monitoring and integrated pest management strategies. Therefore, this study aims to elucidate the adaptability of S. frugiperda to different host plants. Results showed that corn ( Zea mays L. ) was more suitable for the growth and development of S. frugiperda than wheat ( Triticum aestivum L. ) and goosegrass ( Eleusine indica ). Transcriptome analysis identified 699 genes differentially expressed when fed on corn, wheat, and goosegrass. The analysis indicated that the detoxification metabolic pathway may be related to host adaptability. We identified only one SfGSTs2 gene within the GST family and investigated its functional role across different developmental stages and tissues by analysing its spatial and temporal expression patterns. The SfGSTs2 gene expression in the midgut of larvae significantly decreased following RNA interference. Further, the dsRNA-fed larvae exhibited a decreased detoxification ability, higher mortality, and reduced larval weight. The findings highlight the crucial role of SfGSTs2 in host plant adaptation. Evaluating the feeding preferences of S. frugiperda is significant for controlling important agricultural pests.

The complete mitochondrial genome sequence of the Xylota coquilletti (Diptera: Syrphidae: Eristalinae: Xylotini) was sequenced and reported for the first time. The whole genome was 15,920 bp in length with the 37 classical eukaryotic mitochondrial genes and a control region. The nucleotide composition was included by 40.5% A, 39.6% T, 11.7% C, and 8.2% G, meaning that A + T (80.1%) was much greater than C + G (19.9%). It consisted of 22 transfer RNA genes (tRNAs), two ribosomal RNA genes (rRNAs), 13 protein-coding genes (PCGs), and a control region (CR). Phylogenetic analyses were performed using 13 PCGs and it was found that Xylota coquilletti was sister to Ferdinadea cupera. All this information could complement the mitochondrial data for a new tribe of Eristalinae.

Spodoptera frugiperda (J.E.Smith) (Lepidoptera: Noctuidae) is an invasive pest that ravaging crops in many provinces of China. In order to specifically control this invasive pest, understanding of the relationship between the insect and the hosts is necessary. In this study, we have compared the biological and nutritional indices of S. frugiperda by feeding it with five different host-plants (Zea mays, Triticum aestivum, Digitaria sanguinalis, Glycine max and Eleusine indica) under laboratory conditions. The biological and nutritional indices of Z. mays feeding S. frugiperda were the best. However, the pupa weight and fecundity of S. frugiperda fed with G. max and E. indica were significantly lower than those fed with other hosts, efficiency of conversion of digested food (ECD) and efficiency of conversion of ingested food (ECI) were also lower than others. The total phenol content of hosts was negatively correlated with the growth and nutrient accumulation of S. frugiperda, while the C/N content was positively correlated. When fed on different host plants, the biological and nutritional indices of S. frugiperda were different, but all of them could complete the life cycle. Therefore, S. frugiperda also has a tendency to feed on other hosts, especially plants with high C/N content, when Z. mays is insufficient.

Odorant-degrading enzymes (ODEs) play an important role in rapidly degrading and inactivating odorant molecules that have completed information transmission, as well as in maintaining the stability and sensitivity of insect olfactory sensing systems. Glutathione S-transferases (GSTs), as a group of ODEs, supposedly bear the ability to catalyze the conjugation of glutathione (GSH) and xenobiotic odorant molecules in the degrading process. However, there are few reports regarding the role of the GST genes of Sitophilus zeamais in the degrading process. Thus, we characterized 13 full-length genes encoding GST sequences from S. zeamais, of which only SzeaGSTd1 contained a high abundance in the antennae. Ligand-binding assays implied that SzeaGSTd1 was able to catalyze the conjugation of GSH with 2, 4-dinitrochlorobenzene (CDNB). We investigated whether recombinant SzeaGSTd1 bears the ability to degrade the volatile molecules of the host; among the host volatiles, and found capryl alcohol to be a suitable substrate for SzeaGSTd1. These results strongly suggest that SzeaGSTd1 probably plays a role in auxiliary host location by degrading the host volatiles of capryl alcohol and exhibits a potential biological function in the olfactory sensing system of S. zeamais. Knowledge of the potential functions of SzeaGSTd1 will provide new ideas for biological control strategies for S. zeamais.

Odorant-binding proteins (OBPs) are important in insect chemical communication. The objective of this research was to identify the functions of two OBPs in Sitophilus zeamais. qRT-PCR and western blot (WB) were performed to investigate the expression profiles at the transcript and protein levels, respectively. Fluorescence competitive binding assays were used to measure the ability of the OBPs to bind to host volatiles, and a Y-tube olfactometer was used to verify the results (attraction/no response) via behavioral experiments. The RNAi was used to verify the function by knocking down the ability of proteins to bind odorants. qRT-PCR showed the highest expression SzeaOBP1 and SzeaOBP28 at the low-instar larva (LL) and eclosion adult (EA) stages, respectively. WB showed that both SzeaOBP1 and SzeaOBP28 were highly expressed in the EA stage. Fluorescence competitive binding assays indicated that SzeaOBP1 exhibited extremely high binding affinity with cetanol. SzeaOBP28 exhibited a pronounced binding affinity for 4-hydroxy-3-methoxybenzaldehyde. The behavioral experiment showed that the adult S. zeamais responded strongly to 4-hydroxy-3-methoxybenzaldehyde and valeraldehyde from Sorghum bicolor. The RNAi knockdown individuals displayed behavioral differences between normal insects and dsRNA (SzeaOBP1)-treated insects. We infer that they both have functions in perception and recognition of host volatiles, whereas SzeaOBP28 may also have other functions.

Sensory neuron membrane proteins (SNMPs) play an important role in pheromone detection and are considered a component of pheromone reception in insects. However, the SNMPs of Sitophilus zeamais Motschulsky, an important pest of stored cereals, have not previously been reported. In this study, we report four SNMPs (named SzeaSNMP1a, SzeaSNMP1b, SzeaSNMP2a, and SzeaSNMP2b) from the antennal transcriptome of adult S. zeamais, including their full-length open reading frames. Sequence alignment and phylogenetic analysis suggest that these SzeaSNMPs have the general characteristics of SNMPs (two transmembrane domains and six conserved cysteine residues) and belong to two SNMP subgroups. To estimate the expression of SzeaSNMPs in different tissues, we performed quantitative real-time PCR. The SzeaSNMP1 genes (SzeaSNMP1a and SzeaSNMP1b) are mainly expressed in the antennae of males and females and weakly expressed in non-olfactory tissues such as legs and wings. In contrast, the SzeaSNMP2 (SzeaSNMP2a and SzeaSNMP2b) genes are highly expressed in male and female antennae, but we also detected relatively high levels of expression in non-olfactory tissues, especially SzeaSNMP2a in legs and wings.