One of my strongest memories of summers past, despite my lack of affection for insects in general, is the steady buzzing of bees and fluttering of butterflies in my mom’s garden. These sounds and visions, along with the heat and abundance of time to play outside, were simply what made up “summer” as I knew it. Adults, as we age, have a tendency to romanticize the “good old days,” yet the truth is – in some ways – things have indeed changed for the worse. In a major environmental shift now recognized officially by the White House, we are witnessing catastrophic and accelerating declines in the honeybee and butterfly populations. Furthermore, strange illnesses are increasingly reducing specific bat and bird populations. What are the causes of these changes? And why should we care?
The Washington Post notes, “…over the past five years, winter losses of commercial honeybee colonies have averaged roughly 30 percent. A consortium of universities and research laboratories announced last week that beekeepers lost 42.1 percent of their colonies between April 2014 and 2015, an 8 percent spike from the previous year, and that the number of summer deaths exceeded winter deaths for the first time since the survey began in 2010.” Additionally, the monarch butterfly population now covers only a small fraction of the forest area in Mexico compared with their activity twenty years ago. Little brown bats, at one time the most common bat species in the U.S., are dying off by the thousands, affected by the fungal “White Nose Syndrome.” Mortality rates are greater than 90% in many states. Finally, we are hearing more and more about large-scale bird flock deaths – in some cases, up to thousands at one time. Most recently, sea birds along the California coast up to the Pacific Northwest have been dying in increasing numbers.
Why are we seeing these dramatic population shifts in such a short period of time? Scientific evidence points to several potential causes. Initial concern centered on increased exposure to pesticides, though more recently, a complex multifactorial answer is emerging – one that has direct relevance for human health. Possibly related to climate change, a variety of infectious agents (parasites, viruses, bacteria and fungi) are killing the animals and insects noted above. Circularly, some of the treatments used to limit these infestations are making things worse. Loss of botanical food sources and habitats are some of the indirect sources of deaths, and each loss of population is compounding the others. What we have is a complicated cyclical impact of change in climate conditions (air and water temperatures, pollution, effect on food sources) leading to new infectious agents affecting immune health, and the treatments themselves potentially causing further harm to natural immune system repair mechanisms. Does this sound vaguely familiar?
Concern related to the massive deaths of these species has historically centered on the impact on our economic well-being. It is estimated that, through direct affects on pollination and crop development, the loss of bees, birds, bats and butterflies could cost the US roughly $15 billion a year. While the direct costs involved are substantial and deserve our attention, what is especially eerie is that notion that the increase in health morbidities we are witnessing, particularly in children (e.g., immune and inflammatory disorders), may be caused by the exact same sequence of events described above. Activists have pointed out that climate change will potentially affect human health via an increase in vector-borne infectious diseases, like Lyme disease or malaria. However, little attention has been paid to how subtle shifts in direct viral, bacterial, fungal and parasitic pathogens will alter the human gut microbiome and its ability to modulate immune function and detoxification. Disruption in the human microbiome, connected to environmental toxins, then worsened by the overuse of antibiotics, could be seen as the human model of what we’re witnessing in bats, bees, butterflies and birds.
What can we do? We must devote resources to better understanding the complex infectious etiologies of catastrophic species death. Reversing true root causes, if climate change is the major culprit, is essential but will take time. Today, we must develop safe and effective ways to protect these species, perhaps through microbiome modulation (using probiotics, for example, to change microbiota balance). Probiotics for bats, anyone? In fact, researchers have not only used metagenomic methods to sequence the bat microbiome, they have found some bats are resistant to White Nose syndrome, perhaps due to variations in microbiota on their skin. Similar work is being done in bees, demonstrating a relationship between levels and types of probiotic organisms and hive health. Perhaps we can learn something from these experiences that would be adaptable to human health concerns. Ultimately, addressing the needs of the birds and the bees (and the bats and butterflies) is a win-win situation for all of us.
(originally written for the Deirdre Imus Environmental Health Center)
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