Pheromones and colonization: reassessment of the milkweed bug migration model (Heteroptera: Lygaeidae: Lygaeinae)

Summary. Research on insect migration has justifiably emphasized females – the so-called “oogenesis-flight syndrome”– since it is the females that place the eggs into new habitats. The large and small milkweed bugs, Oncopeltus fasciatus and Lygaeus kalmii, respectively, have featured prominently in studies of insect migration and sequestration of host plant toxins for chemical defense. Here we report that males of these species, and males of another well-studied lygaeine (Neacoryphus bicrucis), produce pheromones in glands usually considered to serve only a defensive role in Heteroptera (the metathoracic scent glands), and that these pheromones are exploited by a tachinid parasitoid as a host-finding kairomone. The pheromones are mixtures of C₆ and C₈ saturated and unsaturated esters reminiscent of lepidopteran pheromones, and the key compound of the O. fasciatus pheromone has now been correctly identified as (E)-2,7-octadienyl acetate. It is proposed that the concept of the oogenesis-flight syndrome for these kinds of insects should accommodate the role of males in the migration process. The hypothesis is presented that male-produced pheromones play a significant role in guiding colonization of new habitats in many heteropteran species. In addition, data are presented suggesting that there is a trade-off between the amount of pheromone produced by colonizing males and the host breadth of the species. Received 21 December 1998; accepted 15 February 1999.     

Temperature niche composition change inside and outside protected areas under climate warming

Conservation of biodiversity relies heavily on protected areas but their role and effectiveness under a warming climate is still debated. We estimated the climate-driven changes in the temperature niche compositions of bird communities inside and outside protected areas in southern Canada. We hypothesized that communities inside protected areas include a higher proportion of cold-dwelling species than communities outside protected areas. We also hypothesized that communities shift to warm-dwelling species more slowly inside protected areas than outside. To study community changes, we used large-scale and long-term (1997–2019) data from the Breeding Bird Survey of Canada. To describe the temperature niche compositions of bird communities, we calculated the community temperature index (CTI) annually for each community inside and outside protected areas. Generally, warm-dwelling species dominated communities with high CTI values. We modeled temporal changes in CTI as a function of protection status with linear mixed-effect models. We also determined which species contributed most to the temporal changes in CTI with a jackknife approach. As anticipated, CTI was lower inside protected areas than outside. However, contrary to our expectation, CTI increased faster over time inside than outside protected areas and warm-dwelling species contributed most to CTI change inside protected areas. These results highlight the ubiquitous impacts of climate warming. Currently, protected areas can aid cold-dwelling species by providing habitat, but as the climate warms, the communities’ temperature compositions inside protected areas quickly begin to resemble those outside protected areas, suggesting that protected areas delay the impacts of climate warming on cold-dwelling species.     

Exploring metapopulation-scale suppression alternatives for a global invader in a river network experiencing climate change

Invasive species can dramatically alter ecosystems, but eradication is difficult, and suppression is expensive once they are established. Uncertainties in the potential for expansion and impacts by an invader can lead to delayed and inadequate suppression, allowing for establishment. Metapopulation viability models can aid in planning strategies to improve responses to invaders and lessen invasive species’ impacts, which may be particularly important under climate change. We used a spatially explicit metapopulation viability model to explore suppression strategies for ecologically damaging invasive brown trout (Salmo trutta), established in the Colorado River and a tributary in Grand Canyon National Park. Our goals were to estimate the effectiveness of strategies targeting different life stages and subpopulations within a metapopulation; quantify the effectiveness of a rapid response to a new invasion relative to delaying action until establishment; and estimate whether future hydrology and temperature regimes related to climate change and reservoir management affect metapopulation viability and alter the optimal management response. Our models included scenarios targeting different life stages with spatially varying intensities of electrofishing, redd destruction, incentivized angler harvest, piscicides, and a weir. Quasi-extinction (QE) was obtainable only with metapopulation-wide suppression targeting multiple life stages. Brown trout population growth rates were most sensitive to changes in age 0 and large adult mortality. The duration of suppression needed to reach QE for a large established subpopulation was 12 years compared with 4 with a rapid response to a new invasion. Isolated subpopulations were vulnerable to suppression; however, connected tributary subpopulations enhanced metapopulation persistence by serving as climate refuges. Water shortages driving changes in reservoir storage and subsequent warming would cause brown trout declines, but metapopulation QE was achieved only through refocusing and increasing suppression. Our modeling approach improves understanding of invasive brown trout metapopulation dynamics, which could lead to more focused and effective invasive species suppression strategies and, ultimately, maintenance of populations of endemic fishes.     

Opportunities and challenges for Common Agricultural Policy reform to support the European Green Deal

The Common Agricultural Policy (CAP) is the European Union's main instrument for agricultural planning, with a new reform approved for 2023–2027. The CAP intends to align with the European Green Deal (EGD), a set of policy initiatives underpinning sustainable development and climate neutrality in the European Union (EU), but several flaws cast doubts about the compatibility of the objectives of these 2 policies. We reviewed recent literature on the potential of CAP environmental objectives for integration with the EGD: protection of biodiversity, climate change mitigation and adaptation, and sustainable management of natural resources. The CAP lacks appropriate planning measures, furthering instead risks to biodiversity and ecosystem services driven by landscape and biotic homogenization. Funding allocation mechanisms are not tailored to mitigate agricultural emissions, decreasing the efficiency of climate mitigation actions. The legislation subsidies farmers making extensive use of synthetic inputs without adequately supporting organic production, hindering the transition toward sustainable practices. We recommend proper control mechanisms be introduced in CAP Strategic Plans from each member state to ensure the EU is set on a sustainable production and consumption path. These include proportional assignment of funds to each CAP objective, quantitative targets to set goals and evidence-based interventions, and relevant indicators to facilitate effective monitoring of environmental performance. Both the CAP and the EGD should maintain ambitious environmental commitments in the face of crisis to avoid further degradation of the natural resources on which production systems stand.     

A systematic review of snake translocations to identify potential tactics for reducing postrelease effects

Advancements in the field of reintroduction biology are needed, but understanding of how to effectively conduct translocations, particularly with snakes, is lacking. We conducted a systematic review of snake translocation studies to identify potential tactics for reducing postrelease effects. We included studies on intentional, human-mediated, wild–wild, or captive–wild translocations to any location, regardless of motive or number of snakes translocated. Only studies that presented results for at least 1 of 4 outcomes (movement behavior, site fidelity, survival, or population establishment) were included. We systematically searched 4 databases for published studies and used 5 methods to search the gray literature. Our search and screening criteria yielded 121 data sources, representing 130 translocation cases. We quantified the association between 15 translocation tactics and short-term translocation outcomes by calculating odds ratios and used forest plots to display results. Snake translocations involved 47 species (from mainly 2 families), and most were motivated by research, were monitored for at least 6 months, occurred in North America, and took place from the 1990s onward. The odds of a positive snake translocation outcome were highest with release of captive reared or juvenile snakes, release of social groups together, delayed release, provision of environmental enrichment or social housing before release, or minimization of distance translocated. The odds of a positive outcome were lowest when snakes were released early in their active season. Our results do not demonstrate causation, but outcomes of snake translocation were associated with 8 tactics (4 of which were strongly correlated). In addition to targeted comparative studies, we recommend practitioners consider the possible influence of these tactics when planning snake translocations.     

矿区可持续发展的战略

指出了矿区可持续发展的城镇化、多元化产业、农业结构调整及生态农业、生态矿区(或绿色矿区)的四大战略。     

长江三角洲人口集聚与布局探讨

长江三角洲是我国重要的经济区域,是参与国际竞争、提高国际分工地位的代表地区,也是最主要的人口聚集区。随着国家贯彻落实科学发展观,推进人口分布、产业布局和经济环境在空间上的均衡发展,长三角在产业和人口方面的集聚效应将更加明显。从生态景观和经济发展的分析入手,开展了人口承载力和人口集聚的研究,大胆提出未来长三角人口集聚的规模以及在空间上的分布,同时提出建设六大都市圈和六大国际门户,形成网络化的城市空间布局,有效承接大量流入的人口和支撑产业的发展。     

南昌地域城市群的发育与发展思路

在全球化过程中,城市群是城市化过程中出现的一种特殊的城镇空间组织形式,通过对城市群的发展研究来探讨区域经济的发展是学术界一个新的研究领域和良好的动态趋势。在对城市群的基本概念、发展阶段进行分析的基础上,提出了南昌地域城市群形成发展的动力机制,并对南昌地域城市群进行了界定。最后在对南昌地域城市群进行SWOT分析的基础上,提出南昌地域城市群发展的战略对策。     

新疆黄萎病发病程度不同棉田土壤细菌群落结构差异分析

新疆棉区棉花黄萎病发生危害严重,提高该病的生态防控技术对实现棉花"化肥、农药"减施增效有重要意义.文章以阿克苏、石河子和库尔勒三地棉花黄萎病不同发生程度棉田土壤为研究对象,利用高通量测序技术对土壤细菌种群结构进行研究,并分析土壤理化性质与细菌多样性及种群结构的相关性,以期揭示棉田土壤的细菌群落结构差异及主要影响因子,为...     

Simulation and control strategy for the variational influent of WWTP

With the development of activated sludge model, the simulation software for the design and operation of wastewater treatment plant （WWTP） was produced and has been widely used. The dynamic change of the quality and flow of influent are major factors causing the unstable operation of wastewater treatment process. As a basic model, ASMI model was used for the simulation of activated sludge process, and double exponential model was selected for the simulation of secondary sedimentation tank. The influences of influent change to the aeration tank and secondary sedimentation tank were investigated, and the relationship among influent change, the quality of effluent and the level of sludge blanket in secondary sedimentation tank was established. On the basis of the simulation results, the operation of the WWTP could be adjusted under the dynamic change of the influent. Furthermore, the controlling strategy combined the feed-forward on the influent flow and the feedback on the level of sludge blanket in the secondary sedimentation tank was studied.