内蒙古黄土丘陵沟壑区生态系统健康评价

采用指标体系评价法,按自然指标体系,从生态系统活力、组织结构、系统服务功能和土壤健康等方面,以内蒙古黄土丘陵沟壑区为研究对象,分别选择原生植被区、人工恢复治理区、退化未治理区等3个样区,对其生态系统健康状况进行分析和评价,提出了适合于该区域的生态系统健康评价指标体系和权重体系,建立了适合于该区域的生态系统健康评价指数、评价模型和指标分级标准。最后,从自然生态学角度,结合研究区的实际情况,对该区域的生态系统健康恢复途径、生态系统管理和可持续发展策略提出了一些具有针对性的建议和措施,并对生态系统健康评价的进一步研究进行了展望。     

Effects of an integrated rice-crayfish farming system on soil organic carbon,enzyme activity,and microbial diversity in waterlogged paddy soil

A 10-year (2005–2015) field experiment was conducted to study the effects of an integrated rice-crayfish (CR) model on soil organic carbon, enzyme activity, and microbial diversity at soil depths of 0–10?cm, 10–20?cm, 20–30?cm, and 30–40?cm. Compared with a mid-season rice monoculture (MR) model, total organic carbon (TOC), particle organic carbon (POC), and water-soluble organic carbon (WSOC) were significantly higher in the 0–40?cm soil layers, and the content of microbial biomass carbon (MBC) was significantly higher in the 30–40?cm soil layer in the CR model. The ratios of WSOC to TOC and POC to TOC in the 0–40?cm soil layers in CR model exhibited an increasing trend, whereas the ratio of MBC to TOC in the 0–30?cm layers exhibited a decreasing trend with respect to that of the MR model, however, these differences were not statistically significant. The activity of soil invertase, acid phosphatase, and urease in the 0–40?cm soil layers in the CR model exhibited a decreasing trend with respect to that of the MR model, and the activity of urease in the 10–20?cm soil layer in the CR model was significantly lower than that in the MR model. Compared with the MR model, the CR model significantly enhanced the carbon utilization capacity of soil microbes, and the richness index, dominance index, and diversity index of the soil microbial community in the 20–30?cm layer, whereas it significantly decreased the number of dominant soil microorganism species and the carbon utilization capacity of soil microbes in the 0–10?cm layer. Soil organic carbon and its active components had a significant direct correlation with the microbial diversity index, and significantly positive correlations with invertase, urease, and acid phosphatase. With respect to the soil microbial diversity index, soil organic carbon and its active components had a closer relationship with soil enzyme activity.     

Concentration and ecological risk of heavy metal in street dusts of Eslamshahr,Iran

This study was done to evaluate heavy metal concentrations in street dust samples, to compare measured concentrations in samples to background concentrations in order to make evaluations for pollution indices, and to describe the quality of street dust in the studied area in relation to pollution. A total of 30 cumulative samples were collected from the streets of Eslamshahr City. Concentrations of heavy metals were determined using an Inductively Coupled Plasma-Optical Emission Spectrometry (ICP-OES). Results determined mean concentrations (mg/kg) of the heavy metals Cd, Cr, Cu, Ni, Pb, and Zn, in collected samples of street dust as 0.34, 35.1, 239, 42.4, 71.3, and 573, respectively. I_geo values for Cd and Cr, Cu, Ni, Pb, and Zn showed level of moderately polluted, unpolluted, moderately to strongly polluted, unpolluted, moderately polluted and moderately to strongly polluted, respectively. The pattern of total metal concentrations in the studied area was ranked as follows: Zn and Cu>Pb>Cd>Ni>Cr. The highest values for the monomial potential ecological risk (E_r) were observed for Cd (114). The mean level of RI for the studied soil samples was 192 (91.3–244), which is classed as presenting a strong potential ecological risk.     

Mate‐searching behavior in the invasive German wasp,Vespula germanica,in Patagonia

In order to increase the probability of reproduction, social insects can adopt various mate‐finding strategies, such as increasing densities of males at specific locations, and/or visual and chemical cues that attract the opposite sex. In field and laboratory studies we investigated strategies used by the invasive eusocial wasp Vespula germanica (Fabricius) (Hymenoptera: Vespidae). In tethered flight assays, we established contrasting flight patterns in females and males that may partly explain how related individuals distribute spatially during the mating period. We also determined experimentally, in the field and in the laboratory via olfactometer assays, that gynes produce airborne pheromonal cues that attract drones and are important during mate location. Our field trials also suggest that visual cues play a role in mate location. We conclude that in addition to aspects of the social biology of the species, an efficient mate‐location strategy can partly explain the invasion success of the species. Tools to mitigate the damage caused by yellowjackets may be developed by focusing on reproductive castes, in addition to workers.     

Lethal and behavioral sublethal side effects of thiamethoxam on the predator Harmonia axyridis

Thiamethoxam (TMX) is one of the most effective neonicotinoid insecticides for the control of green peach aphid, Myzus persicae (Sulzer) (Hemiptera: Aphididae), and various side effects can be expected in its natural enemies. The multicolored Asian lady beetle or harlequin ladybird, Harmonia axyridis (Pallas) (Coleoptera: Coccinellidae), is an important predator against M. persicae in greenhouses and fields. In this study, we evaluated the toxicity of TMX to H. axyridis and the effect on the functional response of this predator to M. persicae through three routes of exposure. Acute toxicity bioassays indicated that LC₅₀ values of TMX on H. axyridis through direct residual contact (‘contact’), systemic application (‘systemic’), and leaf‐dip treatment (‘leaf‐dip’) were 18.99, 21.26, and 15.39 mg a.i. l^?1, respectively. The hazard quotient indicated a potential hazard of this agrochemical regardless of the exposure routes. The mortality caused by the lowest rate, 2 mg a.i. l^?1, was not significantly different compared with the control group. For the three routes of sublethal TMX exposure, the type‐II functional response was a good fit to the prey consumption of H. axyridis. Predation was most affected by leaf‐dip treatment, followed by contact and systemic treatments, which had similar effect. For all exposure routes, the predation capacity of the predator recovered quickly after transfer to untreated cabbage leaves. Thiamethoxam applied systemically was the least toxic to H. axyridis and did not affect the functional response of the predator. However, the sublethal effects of TMX through both contact and leaf‐dip application may reduce the population growth of H. axyridis and consequently impair the biological control of M. persicae by this predator. These results illustrate that the assessment of potential effects of TMX on H. axyridis is crucial to develop effective integrated pest management programs for M. persicae in China.     

Weed seed granivory by carabid beetles and crickets for biological control of weeds in commercial lowbush blueberry fields

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