Effects of colony food shortage on behavioral development in honey bees

Three experiments were conducted to explore the effects of severe food shortage on the control of two important and interrelated aspects of temporal division of labor in colonies of the honey bee (Apis mellifera): the size and age distribution of a colony's foraging force. The experiments were conducted with single-cohort colonies, composed entirely of young bees, allowing us to quickly distinguish the development of new (precocious) foragers from increases in activity of bees already competent to forage. In experiment 1, colony food shortage caused an acceleration of behavioral development; a significantly greater proportion of bees from starved colonies than from fed colonies became precocious foragers, and at significantly younger ages. Temporal aspects of this starvation effect were further explored in experiment 2 by feeding colonies that we initially starved, and starving colonies that we initially fed. There was a significant decrease in the number of new foragers in starved colonies that were fed, detected 1 day after feeding. There also was a significant increase in the number of new foragers in fed colonies that were starved, but only after a 2-day lag. These results suggest that colony nutritional status does affect long-term behavioral development, rather than only modulate the activity of bees already competent to forage. In experiment 3, we uncoupled the nutritional status of a colony from that of the individual colony members. The behavior of fed individuals in starved colonies was indistinguishable from that of bees in fed colonies, but significantly different from that of bees in starved colonies, in terms of both the number and age distribution of foragers. These results demonstrate that effects of starvation on temporal polyethism are not mediated by the most obvious possible worker-nest interaction: a direct interaction with colony food stores. This is consistent with previous findings suggesting the importance of worker-worker interactions in the regulation of temporal polyethism in honey bees as well as other social insects. Received: 17 April 1997 / Accepted after revision: 26 December 1997     

Insektizid-Auswirkungen auf Fließgewässer-Lebensgemeinschaften

Event-triggered sampling from a stream in agricultural terrain has revealed a level of contamination considerably higher than that which has generally been assumed, although only moderate amounts of insecticides had been washed away from the cultivated fields. Macroinvertebrate sampling carried out in parallel with the contamination measurements documented severe negative effects of the insecticide inputs on the aquatic community; 8 of the 11 species disappeared from the water for a period of 3 to 6 months. In field investigations, as well as inin situ bioassays,L. lunatus andG. pulex exhibited acute responses (drifting, mortality during drifting) which were seen to be significantly higher than those values noted at an uncontaminated control site as far as even 2000 m from the input site. In these bioassays, where the animals are confined in cages, the insecticide toxicity inG. pulex may be overestimated compared to the field data since the drifting behavior of this species normally helps it to avoid contamination.     

Reduced riparian zone width compromises aquatic macroinvertebrate communities in streams of southern Brazil

Recent changes in Brazilian legislation reduced the width of riparian forest buffer needed to be preserved in private properties from 30 to 15 m or less. The consequences of these modifications can be dramatic, mainly because riparian buffer width is an important parameter for riparian forest structure and functioning. Our study assessed whether (1) macroinvertebrate family richness and Ephemeroptera, Plecoptera, and Trichoptera (EPT) family richness decrease with reduced riparian buffer width; (2) taxonomic composition and functional feeding group (FFG) composition of macroinvertebrates vary with a reduced riparian buffer width; and (3) reduced riparian buffer width similarly influence the macroinvertebrate community in different stream substrates. We selected three fragments with different riparian buffer widths (>40, <30, and <15 m) in three streams (fourth and fifth orders) in the Sinos River watershed, southern Brazil. Our results show that on all substrate types, reducing the width of the riparian buffer altered neither the macroinvertebrate richness nor EPT richness. However, EPT richness was greater in the substrates stone and gravel than leaf litter, independent of riparian buffer width. There was a significant difference in macroinvertebrate composition among riparian buffer widths. The macroinvertebrate composition and FFG differed among substrates, independent of riparian buffer width. This study showed that riparian buffer widths <15 m altered the macroinvertebrate community. A width greater than 15 m is necessary to maintain the composition and trophic conditions of macroinvertebrate families similar to those found in reference states of conservation.     

Ecotoxicologial evaluation of wastewater ozonation based on detritus-detritivore interactions

Advanced oxidation technologies such as ozonation have been proposed to improve removal efficiency of micropollutants during wastewater treatment. In a meta-analysis of peer-reviewed literature, we found no ecotoxicological effects of wastewater ozonation on invertebrates (n = 82), but significant adverse effects on bacteria (n = 24) and fish (n = 5). As information on functional endpoints or trophic interactions is lacking, we applied a bioassay relating to leaf litter decomposition to fill this gap. Leaf discs exposed to ozone-treated wastewater with a high (1.04 mg O₃ (mg DOC)⁻¹, n = 49) ozone concentration were significantly preferred by an aquatic detritivore, Gammarus fossarum, over discs conditioned in wastewater not treated with ozone. This effect might have been mediated by reduced bacterial and elevated fungal biomass, and appears to be the first demonstration of wastewater ozonation impacts on invertebrates and an associated ecosystem process. In accordance with the food-choice trials, chemical analyses revealed significantly decreased concentrations of organic micropollutants in wastewater treated with ozone at high concentrations. Thus, food-choice trials as applied here hold promise to assess environmental effects of advanced oxidation technologies in wastewater treatment and appear to be a valuable complement to the ecotoxicological toolbox in general.     

Effects of nano-TiO(2) in combination with ambient UV-irradiation on a leaf shredding amphipod

Production and use of engineered nanoparticles, such as titanium dioxide nanoparticles (nTiO₂), is increasing worldwide, enhancing their probability to enter aquatic environments. However, direct effects of nTiO₂ as well as ecotoxicological consequences due to the interactions of nTiO₂ with environmental factors like ultraviolet (UV) irradiation on representatives of detrital food webs have not been assessed so far. Hence, the present study displayed for the first time adverse sublethal effects of nTiO₂ at concentrations as low as 0.2 mg L⁻¹ on the leaf shredding amphipod Gammarus fossarum both in presence and absence of ambient UV-irradiation following a 7-d exposure. In absence of UV-irradiation, however, the effects seemed to be driven by accumulation of nTiO₂ at the bottom of the test vessels to which the gammarids were potentially exposed. The adverse sublethal and lethal effects on gammarids caused by the combined application of nTiO₂ and ambient UV-irradiation are suggested to be driven by the formation of reactive oxygen species. In conclusion, both the accumulation of nTiO₂ at the bottom of the test vessel and the UV induced formation of reactive oxygen species clearly affected its ecotoxicity, which is recommended for consideration in the environmental risk assessment of nanoparticles.     

A Top-Down Regional Assessment of Urban Greenhouse Gas Emissions in Europe

This paper provides an account of urban greenhouse gas (GHG) emissions from 40 countries in Europe and examines covariates of emissions levels. We use a “top-down” analysis of emissions as spatially reported in the Emission Dataset for Global Atmospheric Research supplemented by Carbon Monitoring for Action from 1153 European cities larger than 50 000 population in 2000 (comprising >81 % of the total European urban population). Urban areas are defined spatially and demographically by the Global Rural Urban Mapping Project. We compare these results with “bottom-up” carbon accounting method results for cities in the region. Our results suggest that direct (Scopes 1 and 2) GHG emissions from urban areas range between 44 and 54 % of total anthropogenic emissions for the region. While individual urban GHG footprints vary from bottom-up studies, both the mean differences and the regional energy-related GHG emission share support previous findings. Correlation analysis indicates that the urban GHG emissions in Europe are mainly influenced by population size, density, and income and not by biophysical conditions. We argue that these data and methods of analysis are best used at the regional or higher scales.     

Integrating spatial support tools into strategic planning—SEA of the GMS North–South Economic Corridor Strategy and Action Plan

The GMS countries, supported by the Asian Development Bank, have adopted a holistic, multidimensional approach to strengthen infrastructural linkages and facilitate cross border trade through (i) the establishment of a trans-boundary road connecting two economic nodes across marginalised areas, followed by 2) facilitation of environmentally and socially sound investments in these newly connected areas as a means to develop livelihoods. The North–South Economic Corridor is currently in its second phase of development, with investment opportunities to be laid out in the NSEC Strategy and Action Plan (SAP). It targets the ecologically and culturally sensitive border area between PR China's Yunnan Province, Northern Lao PDR, and Thailand. A trans-boundary, cross-sectoral Strategic Environmental Assessment was conducted to support the respective governments in assessing potential environmental and social impacts, developing alternatives and mitigation options, and feeding the findings back into the SAP writing process. Given the spatial dimension of corridor development—both with regard to opportunities and risks—particular emphasis was put in the application of spatial modelling tools to help geographically locate and quantify impacts as a means to guide interventions and set priorities.     

Status and future of the forest health indicators program of the USA

For two decades, the US Department of Agriculture, Forest Service, has been charged with implementing a nationwide field-based forest health monitoring effort. Given its extensive nature, the monitoring program has been gradually implemented across forest health indicators and inventoried states. Currently, the Forest Service??s Forest Inventory and Analysis program has initiated forest health inventories in all states, and most forest health indicators are being documented in terms of sampling protocols, data management structures, and estimation procedures. Field data from most sample years and indicators are available on-line with numerous analytical examples published both internally and externally. This investment in national forest health monitoring has begun to yield dividends by allowing evaluation of state/regional forest health issues (e.g., pollution and invasive pests) and contributing substantially to national/international reporting efforts (e.g., National Report on Sustainability and US EPA Annual Greenhouse Gas Estimates). With the emerging threat of climate change, full national implementation and remeasurement of a forest health inventory should allow for more robust assessment of forest communities that are undergoing unprecedented changes, aiding future land management and policy decisions.