Vegetation features radiating from residential areas in response to livestock grazing were quantified for an arid steppe rangeland in the Keshiketeng Banner, Chifeng Prefecture, in northeastern Inner Mongolia in 2004 and 2006. The aim of this study was to estimate grazing impacts on the vegetation dynamics of these historical grazed ecosystems. Grazing intensities were classified as reference area (RA), light (LG), moderate (MG), and heavy (HG) according to the vegetation utilization across the study area. Rangelands were studied along a grazing gradient, where characteristics of plant communities, heights of dominant species, aboveground vertical structures, and belowground biomass were investigated. Along this grazing gradient, vegetation changed from the original dominant plant species Leymus chinensis (Trin.) Tzvel. to a semi-subshrub species Artemisia frigida Willd. when moving from the reference area (RA) to the region around the settlement. Canopy coverage, aboveground productivity, and the number of perennial species declined as one moved toward the residential area. Heights of five dominant species, except for Stipa grandis P. Smirn., declined with increased grazing intensity. Aboveground vertical structure in the RA treatment showed more resilience than the other treatments. There was no difference in root biomass in the top 1 m of soil (P. 0.05) between the RA treatment and the area immediately around settlement (HG treatment). Generally, we found that the intensity of grazing disturbance did not exceed the tolerance of the rangeland ecosystem within LG treatment. However, vegetative conditions in HG treatment became worse with increased grazing pressure. Rangelands in this arid steppe are under tremendous threat due to excessive forage utilization, which cannot be considered a sustainable practice. Resumen Las características de la vegetación en áreas residenciales en respuesta al pastoreo de ganado fueron cuantificadas en un pastizal estepario árido en Keshiketeng Banner, del noreste de Mongolia en 2004 y 2006. El objetivo de este estudio fue estimar los impactos del pastoreo en la dinámica de la vegetación de estos ecosistemas pastoreados históricamente. Las intensidades de pastoreo fueron clasificadas como un área de referencia (RA), ligero (LG), moderado (MG), y pesado (HG) según la utilización de la vegetación a trave´s del área de estudio. Los pastizales fueron estudiados a lo largo de un gradiente del pastoreo, donde las características de las comunidades de la planta, las alturas de las especies dominantes, sobre las estructuras verticales, y la biomasa subterránea se investigaron. A lo largo de este gradiente de pastoreo la vegetación cambió de la especie original dominante Leymus chinensis (Trin.) Tzvel. a un Artemisia frigida Willd. en la medida que se movía del RA a la región hasta el establecimiento de (HG). La cobertura del follaje, la productividad aérea y el número de especies perennes disminuyeron con el movimiento hacia el área residencial. Las alturas de cinco especies dominantes, a...

The aim of this research was to determine chemical composition and repellent and insecticidal activities of the essential oil of Kaempferia galanga L. rhizomes against the booklouse, Liposcelis bostrychophila Badonnel, and to isolate insecticidal or repellent constituents from the oil. The essential oil was obtained by hydrodistillation and analyzed by gas chromatography-mass spectrometry. Twenty-eight components of the oil were identified. The major compounds in the oil were ethyl-rho-methoxycinnamate (38.6%), ethyl cinnamate (23.2%), 1,8-cineole (11.5%), trans-cinnamaldehyde (5.3%), and borneol (5.2%). Based on bioactivity-guided fractionation, four active constituents were isolated from the oil and identified as 1,8-cineole, ethyl cinnamate, ethyl rho-methoxycinnamate, and trans-cinnamaldehyde. The essential oil exhibited contact toxicity against the booklouse with an LC50 value of 68.6 microg/cm2. Ethyl cinnamate (LC50 = 21.4 microg/cm2) exhibited stronger contact toxicity than ethyl rho-methoxycinnamate and trans-cinnamaldehyde (LC50 = 44.6 and 43.4 microg/cm2, respectively) while 1,8-cineole showed weak acute toxicity. The essential oil also possessed fumigant toxicity against the booklouse with a LC50 value of 1.5 mg/liter air. 1,8-Cineole and trans-cinnamaldehyde (LC50 = 1.1 and 1.3 mg/liter, respectively) possessed stronger fumigant toxicity against the booklouse than ethyl cinnamate and ethyl rho-methoxycinnamate (LC50 = 10.2 and 10.2 mg/liter air, respectively). trans-Cinnamaldehyde was strongly repellent to booklice, whereas ethyl cinnamate and ethyl rho-methoxycinnamate were weakly repellent and 1,8-cineole did not repel booklice. The results indicate that the essential oil and its constituent compounds have potential for development into natural insecticides or fumigants and repellents for control of insects in stored grains.

No abstract

The screening for repellency against the booklouse, Liposcelis bostrychophila (Badonnel), and the red flour beetle, Tribolium castaneum (Herbst), from 14 Chinese medicinal herbs showed that the essential oils of Curcuma longa L., Epimedium pubescens Maximouwicz, Lindera aggregate (Sims) Kostermans, Nardostachys chinensis Battandier, Schizonepeta tenuifolia Briquet, Zanthoxylum schinifolium Sieber et Zuccarini, and Z. officinale Roscoe exhibited strong repellency against L. bostrychophila and T. castaneum. A total of 35 components of the essential oil of E. pubescens were identified by gas chromatography and gas chromatography-mass spectrometry. Beta-Eudesmol (14.89%), alpha-pinene (13.38%), borneol (9.56%), (R)-carvone (7.89%), and menthol (7.45%) were the main components of the essential oil of E. pubescens. From the essential oil of E. pubescens, four monoterpenoids and one sesquiterpenoid were isolated by bioassay-guided fractionation. The compounds were identified alpha-pinene, borneol, menthol, carvone, and beta-eudesmol. (R) -carvone, menthol, borneol, and beta-eudesmol were strongly repellent against L. bostrychophila at concentration of 8.5 nl/cm2 after 2 h exposure whereas alpha-pinene exhibited moderate repellency. (R)-carvone exhibited stronger repellency against the booklouse than the positive control, N, N-diethyl-3-methylbenzamide (DEET). Moreover, (R)-carvone also possessed stronger repellency against T. castaneum than DEET. The other four constituents, menthol, borneol, and beta-eudesmol also showed repellency against the red flour beetles but weaker than DEET at lower concentrations.

Adverse effects of environmental toxicants to human health have traditionally been assayed using in vitro assays. Organ-on-chip (OOC) is a new platform that can bridge the gaps between in vitro assays (or 3D cell culture) and animal tests. Microenvironments, physical and biochemical stimuli, and adequate sensing and biosensing systems can be integrated into OOC devices to better recapitulate the in vivo tissue and organ behavior and metabolism. While OOCs have extensively been studied for drug toxicity screening, their implementation in environmental toxicology assays is minimal and has limitations. In this review, recent attempts of environmental toxicology assays using OOCs, including multiple-organs-on-chip, are summarized and compared with OOC-based drug toxicity screening. Requirements for further improvements are identified and potential solutions are suggested. Expected final online publication date for the Annual Review of Analytical Chemistry, Volume 14 is August 2021. Please see http://www.annualreviews.org/page/journal/pubdates for revised estimates.