As urban areas and land-use constraints grow, there is increasing interest in utilizing urban spaces for food production. Several studies have uncovered significant potential for urban growing to supplement production of fruit and vegetables, focusing on one or two cities as case studies, whilst others have assessed the global scale potential. Here, we provide a national-scale analysis of the horticultural production potential of urban green spaces, which is a relevant scale for agri-food and urban development policy making using Great Britain (GB) as a case study. Urban green spaces available for horticultural production across GB are identified and potential yields quantified based on three production options. The distribution of urban green spaces within 26 urban towns and cities across GB are then examined to understand the productive potential compared to their total extent and populations. Urban green spaces in GB, at their upper limit, have the capacity to support production that is 8× greater than current domestic production of fruit and vegetables. This amounts to 38% of current domestic production and imports combined, or >400% if exotic fruits and vegetables less suited to GB growing conditions are excluded. Most urban green spaces nationally are found to fall within a small number of categories, with private residential gardens and amenity spaces making up the majority of space. By examining towns and cities across GB in further detail, we find that the area of green space does not vary greatly between urban conurbations of different sizes, and all are found to have substantial potential to meet the dietary needs of the local urban population. This study highlights that national policies can be suitably developed to support urban agriculture and that making use of urban green spaces for food production could help to enhance the resilience of the national-scale food system to shocks in import pathways, or disruptions to domestic production and distribution.

Results of dose response bioassays 'in vivo' used to characterise the phenotypic response of pyrethroid resistant S. avenae in comparison to susceptible S. avenae, and two other cereal aphids, the rose-grain aphid (Metopholophium dirhodum) and the bird-cherry – oat aphid (Rhopalosiphum padi), are used to measure levels of pyrethroid resistance. Aphid pests on cereals in the British Isles are predominantly controlled by pyrethroid insecticides, especially since the implementation of the recent ban on neonicotinoid seed treatments on all outdoor crops. Resistance to pyrethroids has been detected in one of the main aphid pests, the grain aphid (Sitobion avenae), probably brought on by the sustained use of these pyrethroid sprays to control cereal aphids, which can transmit plant viruses, especially Barley Yellow Dwarf Virus (BYDV). The withdrawal of several insecticide compounds (e.g. pirimicarb, dimethoate, chlorpyrifos and the aforesaid neonicotinoids) for cereal aphid control will probably increase the selection pressure, leading to increased levels of resistance in S. avenae, and, potentially, the evolution of resistance in other cereal aphid species. In this article we present the results of dose response bioassays 'in vivo' used to characterise the phenotypic response of pyrethroid resistant S. avenae in comparison to susceptible S. avenae, and two other cereal aphids, the rosegrain aphid (Metopholophium dirhodum) and the bird-cherry– oat aphid (Rhopalosiphum padi), in order to measure levels of pyrethroid resistance. At present, little is known about the extent of pyrethroid resistance in S. avenae beyond the UK and in other cereal aphids. It therefore becomes increasingly important to monitor these pests to inform crop management decisions in light of the recent loss of other insecticides. The unintended consequences of the rapid withdrawal of insecticides, together with a failure to prepare and install alternative products and control approaches in advance, will probably ultimately lead to the loss of effectiveness of insecticidal compounds like pyrethroids.

The EU Green Deal requires the reduction in pesticides and fertilisers in food crop production, whilst the sustainable development goals require reductions in food loss and food waste. In a complex and interacting system like the food system, these goals are difficult to coordinate. Here, we show an approach using Bayesian network modelling for decision support. Bayesian networks are important tools for modelling complex systems which may develop emergent behaviour and for providing quantitative comparisons for different candidate policies, approaches or interventions under the Integrating Decision Support System paradigm. Using lettuce as an exemplar crop, we demonstrate that expected food loss changes under different agricultural input reduction and integrated pest management combinations can be quantified to aid decision making for growers.