Vanishing Butterflies and Dying Bees
The European Environment Agency just published a study about butterflies in Europe. It shows that from 1990 to today, over a period of 20 years, the butterfly population was reduced by 50%. The reasons for this disappearance are increased agriculture, and the overall reduction of wild meadows. Mono-cultures, intensification of farming, and lack of sustainable practices leads to a dramatic loss of grassland biodiversity. Butterflies are a major contributor to biodiversity. They feed primarily on nectar from flowers, and they get nourishment from pollen, tree sap, rotting fruit, dung, and decaying flesh. They have a crucial ecological function for plants, because they carry flower pollen, occasionally over great distances, from one plant to another. Some butterfly species have migration patterns like birds, for instance the monarch butterfly, which travels yearly from Mexico to Canada, over a distance of 2500 to 3000 miles.
Butterflies also have symbiotic and parasitic relationships with other insects, for instance ants. They go through four stages in their life-cycle: egg, caterpillar, then pupa, which is the stage where the caterpillar stops to wander around, anchors itself to a leaf, and begins the metamorphosis into the adult butterfly. This miraculous process of change produces an insect that has 6 legs, and four wings. We often assume that butterflies have just two wings, but this is incorrect: They have 4 wings that can move independently from each other, thereby giving them the ability to precisely steer their flight patterns, even though it looks as if they move erratically through the air – the typical butterfly motion.
Butterflies are not the only insects under distress. Bees pollinate about 70 to 80 percent of the world’s agricultural crops, like apples, celery, cucumbers, asparagus, onions, cauliflower, carrots, cranberries, and almonds. All these fruits and vegetables relay on bees for reproduction, but the bees are dying. We are witnessing a dramatic reduction in the bee population worldwide. Between 2006 and 2011, approximately 30% of bees have disappeared, due to a problem termed “Colony Collapse Disorder”, or CCD. This happens for a variety of reasons: The wide-spread use of pesticides, new types of diseases and parasites, and environmental stress, like loss of habitat, contaminated water, or shifting weather patterns due to global warming.
We are in the midst of an ecological catastrophe. Insect population collapse will devastate agriculture worldwide. In the ecological interconnectedness of nature, bees and butterflies build crucial links between the world of insects and plants. An overall population decrease of bees worldwide by 30%, and butterflies by 50% over 20 years, is the sign of an ecological disaster in the making. These devastating changes can most likely not be solved by simple solutions, but can only be addressed by more systemic shifts. We have to change our relationship to nature, and we have to learn how to respect the deep interconnectedness that constitutes the natural cycles that support us. It is time that we begin to pay attention, but how do we shift the focus of the public to these devastating findings?
Update Sept 2014: A new study reveals that a gene mutation explains some of the monarch butterfly migration mystery. This gene changed the strength of the wing muscles. Here is a quote from Reuters:
(Reuters) – The 3,000-mile (4,800-km) mass migration of monarch butterflies in North America is one of the insect world’s fantastic feats, with millions embarking on the arduous journey from as far north as Canada down into Mexico and the California coast each autumn.
Scientists who scoured the genome of these colorful insects offered new insight on Wednesday into this annual airborne adventure. They pinpointed a single gene related to flight muscle efficiency that plays a major role in the monarch butterfly’s migration.
Their study, published in the journal Nature, also identified the gene behind the butterfly’s striking orange-and-black coloration.
“I find it amazing that these little butterflies live for months and fly thousands of miles to perform this annual migration,” said one the researchers, University of Chicago professor of ecology and evolution Marcus Kronforst.
“Our study shows that monarchs have been doing this every year for millions of years. There is nothing else like this on the planet,” Kronforst added.
The number of migrating monarchs has plummeted in recent years. Kronforst said while an estimated one billion monarch butterflies migrated to Mexico in 1996, that number stood at about 35 million this past winter. Threats to them include habitat loss due to human activities, pesticides that kill milkweed and climate change, experts say.
While mainly a North American species, monarch populations also can be found in Central America, South America and elsewhere. Those outside North America do not migrate.
The researchers carried out genome sequences on 92 monarch butterflies from around the world including non-migratory ones as well as on nine butterflies from closely related species. To study the genetic basis for migration, they compared the genetic blueprint of migratory monarchs to those that do not migrate.
“One gene really stood out from everything else in the genome,” Kronforst said.
It was a gene related to collagen, the main ingredient in connective tissue, that was essential for flight muscle function. The researchers were surprised to find the gene was less active, not more active, in migratory butterflies. So rather than making them big, powerful fliers the gene favored enhanced flight efficiency.
“An analogy might be the difference between marathon runners (migrating butterflies) and sprinters,” Kronforst said.
Shuai Zhan, a biologist at the Shanghai Institutes for Biological Sciences, said the study determined that the species originated in North America, contradicting the hypothesis that monarchs evolved from tropical ancestors.
(Dunham, Will. 2014. “Gene Plays Key Role in Monarch Butterfly’s Miraculous Migration.” Reuters. http://www.reuters.com/article/2014/10/01/us-science-butterfly-idUSKCN0HQ4MM20141001 (October 2, 2014).)