San Diego may soon have more rooftop green spaces and community gardens as part of a new campaign to boost the shrinking population of local bees, which serve as crucial pollinators needed to sustain agriculture and ecotourism.

The city is the largest in the nation to become a Bee City U.S., a designation that requires creating new habitats for pollinators, adopting policies that prevent habitat destruction and revising pest management plans to use pesticides only as a last resort.