One hundred twenty-five million years ago, the earth exploded with a kaleidoscope of color with the rapid evolution of flowering plants, the angiosperms. The explosion coincided with the rapid increase and diversification of bee species, the new artists of the landscapes. This presented Darwin with a special difficulty for his view of gradual evolution, his “abominable mystery”. Darwin eventually explained this adaptive radiation of plants and bees as a dialectical coevolutionary dance—coadaptation.
Bees have transformed the earth in geological time scales, but they continue to transform our landscapes today in timescales of decades, weeks, and hours by painting the hills and fields through their pollination activities. Honey bees pollinate about 1/3rd of the crops grown in the United States and, as a consequence, have shaped the agricultural industry. Honey bees are used because they are plentiful (up to 40,000 in a hive) and transportable. Crop pollination in the U.S. is “bees on wheels”: millions of colonies loaded onto trucks, transported sometimes thousands of miles, and dropped in fields needing pollination. Bees quickly relearn their new locations and begin foraging.
In California today, there are more than 400,000 hectares (each comprising of 280 trees) of almonds under cultivation. The total 112 million trees produce 3 trillion flowers (28,000 each), in turn producing 750 billion almonds—double the numbers from 30 years ago. The flowers are pollinated by 60 billion bees transported from across the U.S. After a flower is pollinated, its petals fall to the ground and, along with the fresh flowers, paint the Central Valley of California with a white and pink ribbon 600 km long that lasts about 4-6 weeks in the early spring.
About 335,000 hectares of alfalfa are grown in California. Fields of seed alfalfa, like almonds, extend up and down the Central Valley. Alfalfa seed production is totally dependent on bee pollination. Honey bees are reluctant to forage on the flowers because the reproductive parts are spring loaded and slap the forager on the head when the flower is first visited. The flowers lure them in with abundant nectar: 2,000kg of it per hectare. Hives of bees are placed in groups on the ground in the alfalfa fields. New flowers open in the morning and are deep purple in color. Once the flowers are pollinated, they rapidly senesce and turn pink. You can look across a field of alfalfa in the morning and see where the bees have been foraging near the hives. The field is painted with bands of purple and pink extending out from the groups of hives; bees pollinate the closest flowers first. The painting begins again the next morning with a new canvas of fresh flowers.
A new “abominable mystery” looms today. In 2006, beekeepers reported losing up to 90% of their colonies, with no explanation. Since then, they have continued to lose more than 850,000 of the 2.6 million commercial colonies every year, which equates to about a third. Around the same time, reports came in about the decline in native solitary bees worldwide. There are about 25,000 species of bees—most are solitary. Some species can only exist by exploiting specific species of plant and the plants are likewise totally dependent on them. People started asking “where have the bees gone?” Natural history surveys showed that their numbers and diversity are dwindling. What is causing this widespread plague on bees? Research money flowed. Every week a new “one thing” cause was found, only to be refuted and/or replaced by the next. Causes included parasites and diseases, insecticides, pesticides, herbicides, and habitat loss. Mark Winston in his wonderful book Bee Time called the decline of honeybees “death by a thousand cuts”.
Habitat destruction and indiscriminate use of chemicals have reduced populations of wild bees, perhaps sending some native plant and bee species into a new dialectic dance, a vortex of extinction. Rachel Carson warned in her 1962 book The Silent Spring of the consequence of indiscriminate use of chemicals and neglect for nature: the loss of the sounds of nature. Perhaps a new warning should be issued against the loss of the colors and artists of our landscapes.
Featured image by proxyminder via iStock.
Rachel Carson’s book is Silent Spring, no article.