About 1,000 demonstrators, some dressed as ears of corn and others as tomatoes, held a protest yesterday in San Diego on the opening day of a biotechnology trade show. Shannon Service of Boulder, Colo., who was in a monarch butterfly costume, said, “The biotech industry is conducting a real-time experiment with our biosphere. They don’t know the results, they can’t possibly know the results.” Organizers of the protest had hoped for several thousand participants. As many as 15,000 people are expected to attend the four-day trade show. Meanwhile, anti-biotech sentiment continues to grow in Japan, which has experienced three recalls in less than a month of snack foods containing unapproved genetically engineered potatoes.