Many plants show significant biological activity against pests due to their unique chemical constituents. It is important to identify effective constituents for their development and utilization as botanical pesticides. Our previous study showed that Artemisia lavandulaefolia essential oil had biological activity against Plutella xylostella. Here, we isolated and identified the constituents of essential oil from A. lavandulaefolia by silica gel column chromatography. The main constituents identified were eucalyptol and caryophyllene oxide, and they were confirmed by gas chromatography–mass spectrometry (GC–MS). Eucalyptol and caryophyllene oxide showed strong contact toxicity against P. xylostella larvae after 24 h of application (Median lethal dose, LD₅₀ = 76.97 μL/mL and 20.71 mg/mL. Furthermore, the two active constituents against P. xylostella adults showed significant fumigant activity (Mmedian lethal concentration, LC₅₀ = 3.25 μL/L and 1.06 mg/L, respectively. Finally, we measured the detoxification enzymes and acetylcholinesterase of the larvae treated with active constituents. The eucalyptol-treated larvae displayed enhanced carboxylesterase (CarE) and glutathione-S-transferase (GST) activities in an in vivo experiment, but it was lower for acetylcholinesterase (AchE) activity. The activities of the CarE and GST significantly decreased when exposed to caryophyllene oxide. In general, the two active constituents, eucalyptol and caryophyllene oxide, showed high insecticidal activity, which demonstrates their potential to be used as natural insecticides.

Post-harvest diseases of mango reduce fruit quality and cause severe yield losses with completely unmarketable fruits. The most common diseases of mangos are anthracnose (Colletotrichum gloeosporioides). In this study, the antibacterial activities of essential oils from Artemisia scoparia, Artemisia lavandulaefolia, and Artemisia annua against C. gloeosporioides were tested. The results showed that the essential oil of A. scoparia was more effective by the agar diffusion method; the EC₅₀ value was 9.32 µL/mL. The inhibition rate was 100%, at a concentration of 10 μL/mL, through the spore germination method. The morphological changes of the mycelium were observed by scanning electron microscopy (SEM), the mycelia treated with essential oils showed shrinking, deformity, fracture, and dryness through SEM. A. scoparia essential oil was inoculated in vivo and subjected to paroxysm testing under natural conditions. A. scoparia had significantly inhibitory activity, and the inhibition rate was 66.23% in vivo inoculation tests after 10 days. The inhibition rate was 92.06% in the paroxysm test under natural conditions after 15 days. Finally, A. acoparia essential oil was analyzed by gas chromatography-mass spectrometry. The main compounds were 2-ethenyl-Naphthalene (23.5%), 2,4-pentadiynyl-Benzene (11.8%), 1,2-dimethoxy-4-(2-propenyl)-Benzene (10.0%), β-Pinene (8.0%), and 1-methyl-4-(1-methylethyl)-1,4-Cyclohexadiene (6.3%). The results have revealed the potential use of A. scoparia essential oil against post-harvest fungal pathogens C. gloeosporioides.

Plutella xylostella (L.) is one of the most serious pests of cruciferous vegetables. Our previous work demonstrated that the essential oil of Artemisia lavandulaefolia DC. exhibits promising insecticidal activities against P. xylostella. This study further characterizes the key components that are responsible for the insecticidal effect. In total, 47 compounds (96.52% of the total compounds) were identified from the total oil using GC-MS, and the major compounds were eucalyptol (21.57%), D(+)-camphor (17.33%), (-)-4-terpineol (9.96%) and caryophyllene oxide (10.96%). Among them, (-)-4-terpineol showed significantly larvicidal and fumigant activities against P. xylostella. The LD₅₀ of (-)-4-terpineol was 43.15 mg/mL at 12 h and 31.22 mg/mL at 24 h for 3rd instar larvae, and the LC₅₀ for adults was 8.34 mg/mL at 12 h and 7.35 mg/mL at 24 h. In addition, the adults treated with (-)-4-terpineol showed varying degrees of inhibitory activity toward glutathione S-transferase, catalase, acetylcholinesterase and Na⁺/K⁺-ATPase at different post-treatment intervals and concentrations. The results indicate that (-)-4-terpineol has promising insecticidal activities against P. xylostella, and it has good inhibitory effects on the four enzymes of P. xylostella adults.

The fall armyworm (Spodoptera frugiperda) is a significant agricultural pest with a broad host range and adaptability, posing challenges to pest management worldwide. To elucidate the molecular mechanisms underpinning their development and resilience, we performed a comprehensive transcriptomic analysis across nine developmental stages, spanning from the first instar larvae to adult forms. Utilizing differential expression analysis and time-series clustering, we identified 6834 differentially expressed genes (DEGs), uncovering key stage-specific expression patterns. Notably, 3072 stage-specific genes (SSGs) were defined using the Tau index, highlighting their roles in development and physiological adaptation. Functional enrichment revealed that the sixth instar stage prioritizes pathways related to growth and tissue remodeling, while adult males emphasize reproductive and sensory functions. Furthermore, we characterized 104 cytochrome P450 (P450) genes, showcasing distinct temporal expression patterns critical for detoxification and metabolic processes. A tandem array of P450 genes on chromosome 13 was identified, suggesting a coordinated mechanism enhancing insecticide resistance. Our findings highlight the complex genetic regulation that facilitates the developmental transitions and adaptive capabilities of S. frugiperda. These insights offer potential molecular targets for innovative pest management strategies aimed at mitigating the widespread impact of this pest.

Thiamethoxam is the main neonicotinoid insecticide used for controlling Riptortus pedestris (Fabricius) (Hemiptera: Alydidae). However, sublethal concentration stress may induce intergenerational transcriptional memory, leading to transcriptional patterns that may contribute to the intergenerational accumulation of metabolic tolerance, and evaluating only the toxicity of the current generation would underestimate the long-term risk. Therefore, this study investigated the effect of parental exposure on the expression of detoxification enzyme genes in offspring. Using transcriptome sequencing, we systematically identified three detoxification enzyme gene families (cytochrome P450 monooxygenases (CYPs), carboxylesterases (CCEs), and glutathione S-transferases (GSTs)) in R. pedestris and compared their differential expression patterns between the parental and filial generations after thiamethoxam treatment at three sublethal concentrations (LC₁₀, LC₃₀, and LC₅₀). In the parental generation, a Theta family GST was consistently upregulated, while in the filial generation, detoxification genes were predominantly downregulated, and the genes upregulated in the parents were not also upregulated in the offspring. Comparisons of parents and offspring at the same concentration revealed that the medium concentration induced the highest number of intergenerationally upregulated genes, exhibiting a non-linear response pattern. These results indicate that parental exposure to sublethal thiamethoxam leaves an intergenerational transcriptional imprint in the offspring, and the transmission pattern involves transcriptional reprogramming rather than simple replication of the parental response, the mechanism of which remains to be determined. This study provides transcriptomic evidence for understanding the metabolic adaptation and intergenerational resistance evolution of R. pedestris to thiamethoxam, offering important reference value for field resistance monitoring and rational insecticide application.

The fall armyworm (Spodoptera frugiperda) is a significant agricultural pest with a broad host range and adaptability, posing challenges to pest management worldwide. To elucidate the molecular mechanisms underpinning their development and resilience, we performed a comprehensive transcriptomic analysis across nine developmental stages, spanning from the 1st instar larvae to adult forms. Utilizing differential expression analysis and time-series clustering, we identified 6,834 differentially expressed genes (DEGs), uncovering key stage-specific expression patterns. Notably, 3,072 stage-specific genes (SSGs) were defined using the Tau index, highlighting their roles in development and physiological adaptation. Functional enrichment revealed that the 6th instar stage prioritizes pathways related to growth and tissue remodeling, while adult males emphasize reproductive and sensory functions. Furthermore, we characterized 104 cytochrome P450 (P450) genes, showcasing distinct temporal expression patterns critical for detoxification and metabolic processes. A tandem array of P450 genes on chromosome 13 was identified, suggesting a coordinated mechanism enhancing insecticide resistance. Our findings shed light on the complex genetic regulation that facilitates the developmental transitions and adaptive capabilities of S. frugiperda. These insights offer potential molecular targets for innovative pest management strategies aimed at mitigating the widespread impact of this pest.