Local food networks are stepping up to the plate in the Stewartry as the Covid-19 crisis escalates.With many residents self-isolating demand for home deliveries has rocketed.Major supermarkets have been swamped with mobile services often booked solid for weeks.Shoppers going online are being met with “no slots available” messages – sometimes into May.But the logjam has brought one dividend – a mini retail revolution at grassroots level.Jimmy Craig of Ballards Butchers in Castle Douglas has noticed the change – and stepped up his next-day delivery service in response.He said: “Since Covid-19 began demand for our home deliveries has quadrupled.