Essential oils (EOs) are often the source of insecticidal substances of high efficiency and low toxicity. From gas chromatograph-mass spectrometer, column chromatography, and nuclear magnetic resonance spectra analyses, twenty terpenes were identified from the EOs of Artemisia nakaii. These comprised mostly monoterpenes (49.01%) and sesquiterpenes (50.76%). The terpenes at the highest concentrations in the EOs of A. nakaii were feropodin (200.46 ± 1.42 μg/ml), (+)-camphor (154.93 ± 9.72 μg/ml), β-selinene (57.73 ± 2.48 μg/ml), and 1,8-cineole (17.99 ± 1.06 μg/ml), calculated using area normalization and external standards. The EOs were tested for biological activity and showed strong fumigant toxicity and significant antifeedant activity against the larvae of Spodoptera litura. Furthermore, the monoterpenes 1,8-cineole and (+)-camphor displayed significant fumigant activity against S. litura, with LC50 values of 7.00 ± 0.85 and 18.16 ± 2.31 μl/L, respectively. Antifeedant activity of the sesquiterpenes feropodin and β-selinene was obvious, with EC50 values of 12.23 ± 2.60 and 10.46 ± 0.27 μg/cm2, respectively. The EOs and β-selinene were also found to inhibit acetylcholinesterase, with IC50 values of 37.75 ± 3.59 and 6.88 ± 0.48 μg/ml, respectively. These results suggest that monoterpenes and sesquiterpenes from the EOs of A. nakaii could potentially be applied as a botanical pesticides in the control of S. litura.

Summary The establishment of invasive species is widely recognised as a pivotal issue in the preservation of biodiversity. Salvia reflexa, a species native to the south‐central United States and Mexico, has been widely introduced in Argentina, Australia, New Zealand and Japan. In China, the first population of this plant was found growing adjacent to a grain depot in Shahai village, Jianping County, Liaoning Province, on 25 July 2007. Since the grain depot imported foodstuffs from regions where the plant is native, we infer that S. reflexa was introduced into China via imported foodstuff in the early to mid‐2000s. Based on field observations, at least seven populations of this plant were observed in north‐east China. The plants displayed vigorous growth in midsummer and produced prolific seeds to overcome the cold environment in winter. Salvia reflexa occurred in both dense monocultures and in mixed stands with native plants. In order to validate a system for recognising and categorising non‐native plants in China, the Australian Weed Risk Assessment system was used to assess the invasiveness status of 19 exotic and 16 native plants in north‐east China. Salvia reflexa exhibited a high score of 10, suggesting it is a potentially pernicious alien invasive plant. Although the current distribution of S. reflexa is restricted to Liaoning province and thus far has limited impact on local environments, local regulatory authorities should pay close attention to this plant and take measures to stop its expansion. This is the first time that an invasive plant from the Lamiaceae (mint family) has been documented from cold environments in China.

Aims: By studying the response of seed germination and seedling growth of invasive plants, Rorippa amphibia and Rorippa sylvestris, to temperature, the influence of temperature on the invasive ability of two species of Rorippa were further analyzed, which provided a theoretical basis for revealing the diffusion and invasion mechanism of two invasive plants in Rorippa. Study Design: Seed germination and seedling growth test of two invasive plants in Rorippa at different temperature was studied by means of laboratory culture. The germination percentage, germination index, germination potential of the seeds and the total leaf number, root length, lateral root number, biomass and root shoot ratio of seedlings were determined. Place and Duration of Study: Seeds were collected from the Shenyang Agricultural University of Liaoning Province in July 2018. Experiments were done in the College of Bioscience and Biotechnology, and conducted in April 2019 for a month. Methodology: The petri dish method was used at the experiment of seed germination. The seedling growth experiment was carried out by pot sowing. Results: At the seedling stage.R. amphibia has the strongest tolerance at 30°C, while the R. sylvestris does at 35°C. The low temperature is more beneficial to the accumulations of the seedlings, R. amphibia is the most tolerant at 25°C, and R. sylvestris is at 30°C at the seedling stage. Conclusion: The response of the seeds and seedlings of the two species to temperature was basically the same. Higher temperature promoted seed germination and inhibited seedling growth, while lower temperature inhibited seed germination. The response of seeds and seedlings of R. sylvestris to high temperature makes it more invasive in the process of global warming.

Invasive plants can change the soil ecological environment in the invasion area to adapt to their growth and reproduction through root exudates. Root exudates are the most direct manifestation of plant responses to external environmental changes, but there is a lack of studies on root exudates of invasive plants in the context of inevitable global warming and nitrogen deposition. In this research, we used widely targeted metabolomics to investigate Ambrosia trifida root exudates during seedling and maturity under warming and nitrogen deposition to reveal the possible mechanisms of A. trifida adaptation to climate change. The results showed that the organic acids increased under warming condition but decreased after nitrogen addition in the seedling stage. Phenolic acids increased greatly after nitrogen addition in the mature stage. Most phenolic acids were annotated in the phenylpropane metabolic pathway and tyrosine metabolism. Therefore, nitrogen deposition may increase the adaptability of A. trifida through root exudates, making it more invasive under global warming. The results provide new ideas for preventing and controlling the invasion of A. trifida under climate change.

Aims: Global warming and biological invasion are major environmental issues faced in the world. In the study, Rorippa amphibia, a perennial invasive clone plant in northern China, was used as a material to study the germination characteristics of the seeds at different temperatures. Study Design: Germination test of R. amphibia seeds at different temperature was studied by means of laboratory culture. The germination percentage, germination index, germination potential, bud height and root length of the seeds were determined. Place and Duration of Study: Samples were collected from the west side of the swimming pool of Shenyang Agricultural University of Liaoning Province in August 2017. Experiments were done in the College of Biological Science and Technology, between October 2017 and June 2018. Methodology: The petri dish method was used in the experiment. Fifty seeds were randomly selected and soaked in distilled water for 12h. The seeds were placed in a petri dish covered with double filter paper, cultured at 10℃, 15℃, 20℃, 25℃, 30℃, 35℃ and 40℃ in light incubators for 12h darkness and 12h light (4000lux), with 3 repeats per processing. Seed germination was based on Xu et al.; BJI, 22(3): 1-7, 2018; Article no.BJI.46966 2 embryo root breakthrough seed coat ≥ 1 mm. During the experiment, the numbers of seed germination were recorded every day, and the filter paper was kept moist until there was no new seed germination for 2 consecutive days, which was regarded as the end of germination. The numbers of seed germination should be counted regularly every day, and the beginning and duration of germination should be recorded. The germination rate, daily germination rate, germinating potential, germinating index and vigor index of R. amphibia seeds at different temperature were calculated by measuring bud height and radicle length on the 10th day after germination. Results: The temperature range of seed germination of R. amphibia was wide, which could germinate at 15 -40℃. Lower temperature delayed the peak period of seed germination at some extent and the germination rates of R. amphibia peak at 30 -35℃, which were 44.67% and 50% respectively. At 35℃, germination potential and germination index were 25.33% and 29.46, reaching the maximum value. Conclusion: The reason for the wide temperature range of seed germination and the low germination rate might be the candidate method for clonal plant population establishment in temperate zone. The higher germination rate of high temperature condition suggested that clone invasive plants in temperate regions were more invasive during global warming. Short Research Article