WELLFLEET — For years, ecologist and beekeeper John Portnoy has sold up to three varieties of honey at the Wellfleet Farmers Market — each made from the nectar of seasonal blooms, first black locust, then winterberry, and last, sweet pepperbush. But on a sunny Wednesday morning this month, his stand displayed only a couple of baskets of garlic and a carton of berries. The honey was missing — as it has been the entire summer.