Vermont’s 17 food cooperatives are supporting a bill that would require the labeling of genetically modified foods. The co-ops said Tuesday that their member owners want to know which foods in their stores contain genetically modified organisms. A survey of 1,400 members and customers of City Market Onion River Co-op in Burlington last spring found that 95 percent favored such labeling. Last month, a bill requiring labels on genetically modified food cleared the Vermont House Agriculture Committee, but supporters say that even if the bill becomes law they expect it to be challenged in court by the biotech industry. The House Judiciary Committee is expected to consider the bill Thursday.