Macrogeographic population structuring in the cosmopolitan agricultural pest Bactrocera cucurbitae (Diptera: Tephritidae)

The macrogeographic population structure of the agricultural pest Bactrocera cucurbitae (Diptera: Tephritidae) was investigated in order to identify the geographic origin of the species and reconstruct its range expansion. Individuals of B. cucurbitae were collected from 25 worldwide‐distributed localities (n = 570) and genotyped at 13 microsatellite loci. The Bayesian clustering reveals that B. cucurbitae can be subdivided into five main groups corresponding to populations from (i) the African continent, (ii) La Réunion, (iii) Central Asia, (iv) East Asia and (v) Hawaii. The proportions of inter‐regional assignments and the higher values of genetic diversity in populations from Pakistan, India and Bangladesh suggest that B. cucurbitae originated in Central Asia and expanded its range to East Asia and Hawaii on one hand and to Africa and the islands of the Indian Ocean on the other. A number of outliers (10–19 specimens according to different clustering algorithms) show high levels of admixture (Q > 0.70) with populations from different regions and reveal complex patterns of inter‐regional gene flow. Anthropogenic transport is the most plausible promoter of this large‐scale dispersal. The introduction of individuals from geographically distant sources did not have a relevant role in the most recent African invasions, which originated from the expansion of local populations. These results could provide a useful background to better evaluate invasion risks and establish priorities for the management of this cosmopolitan agricultural pest.     

Ant community composition and functional traits in new grassland strips within agricultural landscapes

1. Ongoing intensification and fragmentation of European agricultural landscapes dramatically reduce biodiversity and associated functions. Enhancing perennial noncrop areas holds great potential to support ecosystem services such as ant‐mediated pest control.
2. To study the potential of newly established grassland strips to enhance ant diversity and associated functions, we used hand collection data and predation experiments to investigate differences in (a) ant community composition and (b) biocontrol‐related functional traits, and (c) natural pest control across habitats in cereal fields, old grasslands, and new grassland transects of three years of age.
3. Ant species diversity was similar between new and old grasslands, but significantly higher in new grasslands than in surrounding cereal fields. Contrary, ant community composition of new grasslands was more similar to cereal fields and distinct from the species pool of old grasslands. The functional trait space covered by the ant communities showed the same distribution between old and new grasslands. Pest control did not differ significantly between habitat types and therefore could not be linked to the prevalence of functional ant traits related to biocontrol services in new grasslands.
4. Our findings not only show trends of convergence between old and new grasslands, but also indicate that enhancing ant diversity through new grasslands takes longer than three years to provide comparable biodiversity and functionality.
5. Synthesis and applications: Newly established grasslands can increase ant species richness and abundance and provide a consistent amount of biocontrol services in agroecosystems. However, three years after their establishment, new grasslands were still dominated by common agrobiont ant species and lacked habitat specialists present in old grasslands, which require a constant supply of food resources and long colony establishment times. New grasslands represent a promising measure for enhancing agricultural landscapes but must be preserved in the longer term to promote biodiversity and resilience of associated ecosystem services.

     

北京市农业景观生态与美学质量空间评价

选择了重点反映农业景观生态与美学功能的生态系统功能、自然性、开阔与多样性、污染概率和整洁度等10个单一空间显性指数,基于田间调查和专家系统赋予其不同权重,构建了农业景观质量综合评价指标,并基于地理信息系统支持下的土地利用数据和利用遥感获得的植被指数,对北京市农业景观质量及其空间差异进行了评价.结果表明：北京市农业景观质量的区域差别较大,城区及小城镇边缘的农业景观质量最差,近郊外围及远郊区较好;北京市农业景观的优劣主要与地形和人为压力有关.基于空间信息技术和景观指数,在大尺度上构建的综合指标体系,对评价农业景观质量的空间差异具有重要意义.     

The good,the bad,and the future: Systematic review identifies best use of biomass to meet air quality and climate policies in California

California has large and diverse biomass resources and provides a pertinent example of how biomass use is changing and needs to change, in the face of climate mitigation policies. As in other areas of the world, California needs to optimize its use of biomass and waste to meet environmental and socioeconomic objectives. We used a systematic review to assess biomass use pathways in California and the associated impacts on climate and air quality. Biomass uses included the production of renewable fuels, electricity, biochar, compost, and other marketable products. For those biomass use pathways recently developed, information is available on the effects—usually beneficial—on greenhouse gas (GHG) emissions, and there is some, but less, published information on the effects on criteria pollutants. Our review identifies 34 biomass use pathways with beneficial impacts on either GHG or pollutant emissions, or both—the “good.” These included combustion of forest biomass for power and conversion of livestock-associated biomass to biogas by anaerobic digestion. The review identified 13 biomass use pathways with adverse impacts on GHG emissions, criteria pollutant emissions, or both—the “bad.” Wildfires are an example of one out of eight pathways which were found to be bad for both climate and air quality, while only two biomass use pathways reduced GHG emissions relative to an identified counterfactual but had adverse air quality impacts. Issues of high interest for the “future” included land management to reduce fire risk, future policies for the dairy industries, and full life-cycle analysis of biomass production and use.     

农业景观格局与麦蚜密度对其初寄生蜂与重寄生蜂种群及寄生率的影响

农业景观格局与过程能够强烈影响寄生蜂对寄主的寻找及寄生作用,寄主密度亦是影响寄生蜂分布的重要因素,然而农业景观的格局和寄主密度对寄生蜂寄生率的相互影响是一项值得研究的工作.在简单与复杂2种麦田农业景观结构下,调查了麦蚜的分布格局与2种寄主密度下麦蚜的初寄生率与重寄生率,分析了景观结构对麦蚜密度的影响、景观格局与麦蚜密度对寄生蜂寄生率与重寄生率的影响及交互作用.结果表明:景观结构的复杂性对麦蚜分布和寄生蜂初寄生率与重寄生率的影响均不明显,但寄主密度与景观结构的复杂性对寄生蜂的影响存在着明显的交互作用,寄主密度与寄生率呈正相关,寄主密度较低时烟蚜茧蜂为优势种,寄主密度较高时燕麦蚜茧蜂为优势种.麦蚜初寄生蜂与重寄生蜂对寄主密度的反应与其形态学、体型大小以及生活史特征相关,初寄生蜂与重寄生蜂的群落组成显著影响其对麦蚜的寄生率,而与景观结构的复杂性关系不大.     

黄土高原生物结皮对SCS-CN模型初损率的影响

水文模型是水文过程研究的有效工具,初损率(λ)是径流模型SCS-CN模型的参数,对模拟流域水文过程具有重要意义.为了确定生物结皮对λ的影响,提高该模型在黄土高原生物结皮广泛分布的退耕地的预测精度,本研究以陕西省定边县鹰窝山涧流域不同盖度的生物结皮坡面为对象,采用模拟降雨试验,分析土壤潜在最大入渗量(S)与实际入渗量(F...     

Fourteen polymorphic microsatellite loci in the field gudgeon,Gnathopogon elongatus elongatus

We isolated and characterized 14 polymorphic microsatellite loci for the field gudgeon, Gnathopogon elongatus elongatus, a popular freshwater species in streams including agricultural canals in Japan. The number of observed alleles for each locus ranged from 9 to 24, and the values of observed and expected heterozygosities ranged from 0.750 to 1.000 and from 0.832 to 0.953, respectively. These microsatellite markers will be useful for studies of population genetic structure and genetic variability of the field gudgeon.     

意愿价值评估法应用于农业生态补偿研究进展

农业生态补偿是支持和保护农业发展的重要政策激励手段,有关补偿标准的估算及计量方法研究始终是学术界讨论的热点。意愿价值评估法(CVM)是国际社会进行非市场价值评估最广泛采用的陈述偏好方法。由于在农业生态补偿领域应用时间不长,农业产业的弱质性及农民认知水平的差距,导致国内CVM的实证研究面临许多问题和困惑。阐明CVM方法的内涵与理论基础,全面系统地梳理国内外CVM在农业补偿领域的研究进展。以激励农户采纳农业清洁生产技术补偿意愿问卷调查为例,深入探讨CVM应用于农业生态补偿政策评估中存在的假想特性偏差、研究手段偏差及调查实施偏差等。提出通过合理的技术途径和对策措施规避可能的偏差,包括:明确计量模型适用范围、开展效度与信度检验、选择两种尺度评估及处理调查过程偏差的方法等,为破解CVM应用于国内农业生态补偿政策制定中的问题提供方法和思路借鉴。研究指出存在的不足与局限性,以期未来不断完善和拓展。     

长期施磷对黄壤旱地磷库变化及地表径流中磷浓度的影响

对贵州黄壤旱地进行采样以及盆栽试验,探索黄壤旱地磷库的变化及其对地表径流磷量的影响。结果表明,长期施磷后黄壤旱地无机磷占全磷的比例逐渐增高,Al-P、Fc-P和Ca-P积累的顺序为Fe-P>Al-P>Ca-P。长期施磷后黄壤旱地的有效磷和藻类可利用的总磷也不断积累,高磷（Olsen-P>25mg·kg^-1)旱地藻类可利用的总磷与Al-P、Fe-P和Ca-P的相关系数分别为0.859、0.903和0.650,Fc-P对藻类可利用磷量的影响起着最重要的作用。在模拟雨强为63.2mm·h^-1下,降雨30min后,低磷黄壤旱地（Olsen-P为4.62-15.9mg·kg^-1)径流中磷酸根磷含量仅为2.81-4.17μg·L^-1,生物有效性磷含量为0.723-0.876mg·L^-1;高磷黄壤旱地（Olsen-P)为29.4-59.2mg·kg^-1)径流中磷酸根磷含量达到0.026-0.714mg·L^-1,生物有效性磷含量增加到0.996-1.281mg·L^-1;高磷黄壤旱地地表径流磷量能加速水体富营养化的产生。