Plant essential oils, as biological pesticides, have been reviewed from several perspectives and play a key role in chemical ecology. However, plant essential oils show rapid degradation and vulnerability during actual usage. In this study, we conducted a detailed analysis of the compounds present in the essential oils of A. stechmanniana using gas chromatography–mass spectrometry (GC-MS). The results showed seventeen terpenoid compounds in the A. stechmanniana oil, with four major terpenoid compounds, i.e., eucalyptol (15.84%), (+)-2-Bornanone (16.92%), 1-(1,2,3-Trimethyl-cyclopent-2-enyl)-ethanone (25.63%), and (-)-Spathulenol (16.38%), in addition to an amount of the other terpenoid compounds (25.26%). Indoor toxicity assays were used to evaluate the insecticidal activity of Artemisia stechmanniana essential oil against Aphis gossypii, Frankliniella occidentalis, and Bactericera gobica in Lycium barbarum. The LC₅₀/LD₅₀ values of A. stechmanniana essential oils against A. gossypii, F. occidentalis, and B. gobica were 5.39 mg/mL, 0.34 mg/L, and 1.40 μg/insect, respectively, all of which were highly efficient compared with azadirachtin essential oil. Interestingly, A. stechmanniana essential oil embedded in β-cyclodextrin (microencapsule) remained for only 21 days, whereas pure essential oils remained for only 5 days. A field efficacy assay with the A. stechmanniana microencapsule (AM) and doses at three concentrations was conducted in Lycium barbarum, revealing that the insecticidal activities of AM showed high efficiency, maintained a significant control efficacy at all concentrations tested, and remained for 21 days. Our study identified terpenoid compounds from untapped Artemisia plants and designed a novel method against pests using a new biopesticide on L. barbarum.

Megalurothrips usitatus (Bagnall) is one of the most important pests harming alfalfa (Medicago sativa L.) in Ningxia. In the field, Orius strigicollis (Poppius) is abundant. It has a high search efficiency and consumption rate of prey on a wide range of thrips and is often used as a biological control agent for these insects. To understand the predatory function and biological control potential of O. strigicollis on M. usitatus, the predatory ability of adults of O. strigicollis on second-instar larvae and adults of M. usitatus was measured under indoor conditions, and the Holling II and Hassell–Varley models were fitted to calculate the predatory function response, search efficiency, intraspecific interference, and predation preference of O. strigicollis on second-instar larvae and adults of M. usitatus. Our results showed that the predatory ability of O. strigicollis on second-instar larvae of M. usitatus was 78.62, and the theoretical maximum daily predation was 76.92. The predatory ability of O. strigicollis on adults of M. usitatus was 52.79, and the theoretical maximum daily predation was 52.62. The daily predation of O. strigicollis was positively correlated with prey density and negatively correlated with search efficiency. The rate of predatory action on prey decreased with an increasing O. strigicollis density, while the intensity of apportioned competition increased with an increasing O. strigicollis density. The results of the prey preference experiment showed that the preference of O. strigicollis for second-instar larvae of M. usitatus was significantly higher than for adults of M. usitatus. In conclusion, the indoor experiment data can provide an effective reference for the use of O. strigicollis to control M. usitatus infestation, providing an important biological control agent for controlling M. sativa thrips.

The laboratory toxicity and physiological effects of three biopesticides—the entomopathogenic fungus Beauveria bassiana, the biocontrol bacterium Bacillus safensis, and the botanical insecticide Artemisia ordosica essential oil—were evaluated against Megalurothrips usitatus, a major pest of alfalfa. All three biopesticides caused concentration-dependent mortality in M. usitatus. Among them, B. bassiana showed the highest corrected mortality (88.42%) and the shortest median lethal time (LT₅₀ = 4.51 days), indicating strong insecticidal activity. The median lethal concentration (LC₅₀) values at 7 days post-treatment were 4.48 × 10⁵ CFU/mL for B. bassiana, 1.67 × 10⁵ CFU/mL for B. safensis, and 2.907 mg/L for A. ordosica essential oil. Moreover, exposure to high concentrations of each agent significantly altered the activities of the protective enzyme peroxidase (POD) and the detoxifying enzyme glutathione S-transferase (GST). Our study supports the use of these biopesticides for thrips management and provides a scientific basis for the eco-friendly and sustainable control of alfalfa pests.

Compared with single insecticides, insecticide mixtures can enhance efficacy, broaden the spectrum of activity, and potentially delay resistance evolution in Aphis gossypii. However, their sublethal and intergenerational effects remain poorly understood. Here, the life table analysis was used to evaluate the effects of mixture treatments prepared from sublethal (LC₂₀) and low-lethal (LC₅₀) doses of nitenpyram, pymetrozine, and beta-cypermethrin on the directly exposed F₀ generation of A. gossypii and its effects on the F₁ progeny. Total protein, free amino acid, and vitellogenin (Vg) contents were measured, and the sequence and expression of Vg and vitellogenin receptor (VgR) genes were analyzed. Exposure to the mixture treatments significantly reduced longevity and fecundity in both generations while increasing total protein and free amino acid contents. Domain prediction confirmed the conserved structural features of AgVg and AgVgR, and phylogenetic analysis showed that both clustered with homologs from closely related aphid species. RT-qPCR further revealed that the mixture treatments significantly suppressed AgVg and AgVgR expression. In conclusion, exposure to the mixture treatments affects both directly exposed individuals and their progeny, providing a basis for evaluating the ecological consequences of insecticide mixtures and optimizing their use within integrated pest management strategies for A. gossypii.