The present work, focusing on the theme of food production and consumption in urban areas, analyses the relationships among three factors: city, human well-being and ecosystems. A case study was carried out addressing the quantification of the potential of rooftop vegetable production in the city of Bologna (Italy) as related to its citizens’ needs. Besides the contribution to food security of the city, the potential benefits to urban biodiversity and ecosystem service provision were estimated. The methodology consisted of: 1) experimental trials of potential productivity of simplified soil- less systems in rooftop gardens (RTGs); 2) detection of all flat roofs and roof-terraces and quantification of the potential surfaces that could be converted into RTGs; 3) identification of the city’s vegetable requirements, based on population and diet data; 4) calculation of the proportion of vegetable require- ment that could be satisfied by local RTG production; 5) identification of other benefits (improvement of urban biodi- versity through the creation of green corridors and estimation of carbon sequestration) associated with the increased area of urban green infrastructure (GI). According to the present study, RTGs could provide more than 12,000 t year−1 vegeta- bles to Bologna, satisfying 77 % of the inhabitants’ require- ments. The study also advances hypotheses for the implementation of biodiversity roofs enabling the connection of biodiversity rich areas across and close to the city: these would form a network of green corridors of over 94 km length with a density of about 0.67 km km−2

As part of an environmental risk assessment study of exotic natural enemies used in inundative biological control, life-history characteristics of Harmonia axyridis (Pallas), Hippodamia variegata (Goeze) and Adalia bipunctata (L.) (Col., Coccinellidae) were quantified under laboratory conditions at 25°C on Myzus persicae (Sulzer) as prey. Comparative studies showed significant differences among pre-adult development times: H. axyridis developed slower ( X ¼ 19.8 days) than H. variegata ( X ¼ 18.1 days) and A. bipunctata ( X ¼ 18.4 days). Differences were also evident in the duration of egg, larval and pupal stages. No measurable differences among the three species were found for fecundity, oviposition rate and adult longevity. Harmonia axyridis exhibited the longest pre-oviposition ( X ¼ 7.4 days) and interoviposition ( X ¼ 3.6 days) periods and the shortest oviposition period ( X ¼ 13.7 days). The Bieri model was used to describe age-specific fecundity for the three species of coccinellids. The intrinsic rate of increase (r m ), net reproductive rate (R 0 ) and mean generation time (T) were higher for H. variegata (r m ¼ 0.114, R 0 ¼ 52.75, T ¼ 41.88 days) than for H. axyridis (r m ¼ 0.089, R 0 ¼ 26.27, T ¼ 38.81 days) or A. bipunctata (r m ¼ 0.081, R 0 ¼ 18.49, T ¼ 40.06 days). Our findings show that the biological traits of H. axyridis do not seem to be factors that may contribute to the invasiveness of this coccinellid.

Abstract:In recent years, urban agriculture has been asserting its relevance as part of a vibrant and diverse food system due to its small scale, its focus on nutrition, its contribution to food security, its employment opportunities, and its role in community building and social mobility. Urban agriculture may also be a tool to re-appropriate a range of abandoned or unused irregular spaces within the city, including flowerbeds, roundabouts, terraces, balconies and rooftops. Consistently, all spaces that present a lack of identity may be converted to urban agriculture areas and, more specifically, to urban horticulture as a way to strengthen resilience and sustainability. The goal of this paper is to analyse current practices in the requalification of vacant areas as urban gardens with the aim of building communities and improving landscapes and life quality. To do so, the city of Bologna (Italy) was used as a case study. Four types of vacant areas were identified as places for implementing urban gardens: flowerbeds along streets and squares, balconies and rooftops, abandoned buildings and abandoned neighbourhoods. Six case studies representing this variety of vacant areas were identified and evaluated by collecting primary data (i.e., field work, participant observations and interviews) and performing a SWOT analysis. For most cases, urban horticulture improved the image and quality of the areas as well as bringing numerous social benefits in terms of life quality, food access and social interaction among participants. Strong differences in some aspects were found between top-down and bottom-up initiatives, being the later preferable for the engagement of citizens. Policy-making might focus on participatory and transparent planning, long-term actions, food safety and economic development.

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