Free-flight phonotaxis in a parasitoid fly: behavioural thresholds, relative attraction and susceptibility to noise

 The phonotactic capacity of tachinid flies to acoustically detect and localize a sound source simulating their cricket host was investigated in a large flight room. Acoustic measurements were performed to estimate the actual stimulus delivered to the flies, revealing highly heterogeneous sound fields. When presented with a simulated cricket song in red or infrared light conditions, the flies readily flew to the sound source and landed on it. Behavioural phonotactic thresholds were established as a function of carrier frequency and were found to coincide well with the frequency of the host's natural song (4.5–5.2 kHz). Experiments revealed that the same range of frequencies is preferentially attractive to the free-flying flies, and that the reliability of signal detection in the presence of noise is best at behaviourally relevant frequencies. Received: 23 February 2000 / Accepted in revised form: 6 June 2000     

The vulnerability context of a savanna area in Mozambique: household drought coping strategies and responses to economic change

In this paper, we investigate the ways in which climate stressors and economic changes related to liberalisation alter the local vulnerability context. Household and key informant data from two villages in Mozambique are analysed. First, we explore how changes such as increased market integration, altered systems of agricultural support, land tenure change and privatisation of agro-industries may affect factors important for response capacity, including access to local natural resources, employment opportunities, and household labour and capital. Next, we investigate how people related to the market while coping with the 2002–2003 drought. The study reveals that there had been an increase in informal trade and casual employment opportunities; however, market relations were very unfavourable and as the drought intensified, smallholders were locked into activities that barely secured economic survival and which sometimes endangered long-term response capacity. Only a few large-scale farmers had the capital and skills necessary to negotiate a good market position in urban markets, thus securing future incomes. Inequality, social sustainability, vulnerability and natural resource use are all closely linked in the savannas. Hence, both climate change adaptation policies and sustainability measures need to target vulnerability context and the social and environmental stressors shaping it.     

Microarthropod communities as a tool to assess soil quality and biodiversity: a new approach in Italy

Traditional approaches to soil quality evaluation were based on the use of physical, chemical and microbiological indicators. Recently, new methods, based on soil microarthropods have been proposed for soil quality evaluation. Soil microarthropods have been shown to respond sensitively to land management practices and to be correlated with beneficial soil functions. In Italy, a new approach (called QBS index) based on the types of edaphic microarthropods has been proposed to assess soil biological quality. The QBS index is based on microarthropod groups present in a soil sample. Each type found in the sample receives a score from 1 to 20 (eco-morphological index, EMI), according to its adaptation to soil environment. The QBS index sums up these scores, thereby characterizing the microarthropod community of the sample being studied. QBS has been applied on a range of soil types and land uses in Italy, its validity evaluated for assessing biological quality of soil in different situations. This paper describes the QBS methods and presents three applications of the proposed methodology.     

From conflicts to wise practice agreement and national strategy: cooperative learning and coastal stewardship in estuarine floodplain management,Tweed River,eastern Australia

Appropriate information, participatory processes and wise practice agreements are key elements in reducing conflicts over the use and management of coastal resources. In this work we describe the evolution of a cooperative learning approach to coastal floodplain management, incorporating these elements. Government-encouraged drainage of coastal floodplains in eastern Australia caused accelerated oxidation of acid sulfate soils and export of diffuse acidic drainage into streams. Major impacts on infrastructure, ecology, fisheries and aquaculture resulted. In the Tweed River estuary, in 1987, all gilled organisms were killed by acid discharge from floodplain canelands. This generated major conflicts between fishers, environmentalists and sugarcane producers. The cooperative learning partnership that evolved, involving cane farmers, local government, and researchers, has produced better strategies for managing sulfidic estuarine areas and mitigating impacts on downstream ecosystems. These underpinned mandatory best practice management guidelines for the NSW sugar industry. Increases in productivity and decreases in acid discharge have resulted. Fish kills on the Tweed and elsewhere also generated broader, parallel whole-of-government approaches that led to Australia's national strategy for managing coastal acid sulfate soils and the rapid adoption of information and strategies across Australia.     

Fostering coastal resilience to climate change vulnerability in Bangladesh,Brazil, Cameroon and Uruguay: a cross-country comparison

This paper describes a comparative study of four different cases on vulnerability, hazards and adaptive capacity to climate threats in coastal areas and communities in four developing countries: Bangladesh, Brazil, Cameroon and Uruguay. Coastal areas are vulnerable to sea-level rise (SLR), storm surges and flooding due to their (i) exposure, (ii) concentration of settlements, many of which occupied by less advantaged groups and (iii) the concentration of assets and services seen in these areas. The objective of the paper is twofold: (i) to evaluate current evidence of coastal vulnerability and adaptive capacity and (ii) to compare adaptation strategies being implemented in a sample of developing countries, focusing on successful ones. The followed approach for the case evaluation is based on (i) documenting observed threats and damages, (ii) using indicators of physical and socioeconomic vulnerability and adaptive capacity status and (iii) selecting examples of successful responses. Major conclusions based on cross-case comparison are (a) the studied countries show different vulnerability, adaptive capacity and implementation of responses, (b) innovative community-based (CBA) and ecosystem-based adaptation (EbA) and (c) early warning systems are key approaches and tools to foster climate resilience. A recommendation to foster the resilience of coastal communities and services is that efforts in innovative adaptation strategies to sea-level rise should be intensified and integrated with climate risk management within the national adaption plans (NAPAs) in order to reduce the impacts of hazards.     

NUTGRANJA 2.0: a simple mass balance model to explore the effects of different management strategies on nitrogen and greenhouse gases losses and soil phosphorus changes in dairy farms

Farm nutrient management has been identified as one of the most important factors determining the economic and environmental performance of dairy cattle (Bos taurus) farming systems. Given the environmental problems associated with dairy farms, such as emissions of greenhouse gases (GHG), and the complex interaction between farm management, environment and genetics, there is a need to develop robust tools which enable scientists and policy makers to study all these interactions. This paper describes the development of a simple model called NUTGRANJA 2.0 to evaluate GHG emissions and nitrogen (N) and phosphorus (P) losses from dairy farms. NUTGRANJA 2.0 is an empirical mass-balance model developed in order to simulate the main transfers and flows of N and P through the different stages of the dairy farm management. A model sensitivity test was carried out to explore some of the sensitivities of the model in relation to the simulation of GHG and N emissions. This test indicated that both management (e.g. milk yield per cow, annual fertiliser N rate) and site-specific factors (e.g. % clover (Trifolium) in the sward, soil type, and % land slope) had a large effect on most of the model state variables studied (e.g. GHG and N losses).     

Response of the bird cherry-oat aphid (Rhopalosiphum padi) to climate change in relation to its pest status, vectoring potential and function in a crop-vector-virus pathosystem

Global climate change threatens world food production via direct effects on plant growth and alterations to pest and pathogen prevalence and distribution. Complex relationships between host plant, pest, pathogen and environment create uncertainty particularly involving vector-borne diseases. We attempt to improve the understanding of the effects of climate change via a detailed review of one crop-vector-pathogen system.The bird cherry-oat aphid, Rhopalosiphum padi, is a global pest of cereals and vector of yellow dwarf viruses that cause significant crop losses in cereals. R. padi exhibits both sexual and parthenogenetic reproduction, alternating between crops and other host plants. In Australia, only parthenogenesis occurs due to the absence of the primary host, thus the aphid continuously cycles from grasses to cereals, allowing for continuous virus acquisition and transmission.We have reviewed the potential impact of future climate projections on R. padi population dynamics, persistence, abundance, dispersal and migration events as well as the interactions between vector, virus, crop and environment, all of which are critical to the behaviour and development of the vector and its ability to transmit the virus. We identify a number of knowledge gaps that currently limit efforts to determine how this pathosystem will function in a future climate.     

The development of new environmental policies and processes in response to a crisis: the case of the multiple barrier approach for safe drinking water

While new environmental policies and procedures often are developed incrementally, they can also result from crises or other significant events. In situations where policies and procedures are introduced in response to a crisis, questions about the strengths and weaknesses of existing mechanisms, and the extent to which they can be used to address concerns, may be ignored. This paper explores the complexities of introducing new policies and processes where planning systems and procedures already exist. Drinking water source protection policies that are being developed in response to the tragic events in Walkerton, Ontario, Canada serve as the context for the inquiry. Three case study watersheds were selected to reflect the diversity of municipal jurisdictions and water supply systems in Ontario. A content analysis was undertaken on regulatory and non-regulatory policy documents to determine the extent to which they addressed elements of the multi-barrier approach for drinking water safety. Findings from the research reveal considerable evidence of the multi-barrier approach in the policy and guiding documents analyzed. Policy development in response to a crisis can advance progress on the issue of drinking water safety and coincide with emerging governance strategies. Policy effectiveness may be enhanced by considering existing policies as well as contextual and jurisdictional differences.     

Economic feasibility of adapting crop enterprises to future climate change: a case study of flexible scheduling and irrigation for representative farms in Flathead Valley,Montana, USA

Future climate change directly impacts crop agriculture by altering temperature and precipitation regimes, crop yields, crop enterprise net returns, and net farm income. Most previous studies assess the potential impacts of agricultural adaptation to climate change on crop yields. This study attempts to evaluate the potential impacts of crop producers’ adaptation to future climate change on crop yield, crop enterprise net returns, and net farm income in Flathead Valley, Montana, USA. Crop enterprises refer to the combinations of inputs (e.g., land, labor, and capital) and field operations used to produce a crop. Two crop enterprise adaptations are evaluated: flexible scheduling of field operations; and crop irrigation. All crop yields are simulated using the Environmental Policy Integrated Climate (EPIC) model. Net farm income is assessed for small and large representative farms and two soils in the study area. Results show that average crop yields in the future period (2006–2050) without adaptation are between 7% and 48% lower than in the historical period (1960–2005). Flexible scheduling of the operations used in crop enterprises does not appear to be an economically efficient form of crop enterprise adaptation because it does not improve crop yields and crop enterprise net returns in the future period. With irrigation, crop yields are generally higher for all crop enterprises and crop enterprise net returns increase for the canola and alfalfa enterprises but decrease for all other assessed crop enterprises relative to no adaptation. Overall, average crop enterprise net return in the future period is 45% lower with than without irrigation. Net farm income decreases for both the large and small representative farms with both flexible scheduling and irrigation. Results indicate that flexible scheduling and irrigation adaptation are unlikely to reduce the potential adverse economic impacts of climate change on crop producers in Montana’s Flathead Valley.