By Jim Moore - January 2021
During the spring and summer months of the year 2019, as in most prior years, there were hundreds of bees, wasps, flower flies, and other flower loving insects coming and going and visiting all the many blooming flowers around our home. From sunrise to sunset the humming sound of these pollinators never ceased. Following after these were their predators: dragonflies, damselflies, robber flies, and spiders too! And hunting the spiders were spider wasps. From the first crocus flowers of early spring, to frosty days of autumn still producing scores of Gaillardia blooms, there they were. On many cold autumn mornings I would find bumble bees on the flowers waiting for sun to warm up their bodies before they resume their chores and return to their colonies.
Then came the year 2020, and the humming of these pollinators never arose. I saw just one queen bumble bee visiting a crocus flower, and after that never an offspring. No bumble bees, no honey bees, no solitary bees, no flower flies, no wasps, not even the ever pesky yellow jackets. Gone also, or gone elsewhere, were the predators. Were the winter months any more harsh than previous winters? I do not think so. Pesticides? I never use them. Were the predatory critters over zealous in their hunting? They never were before. What happened I wondered? Our tomato and squash plants had to be hand pollinated throughout the season. I also wondered if there would be a recovery of these insects in the coming years. I had previously read online stories about massive insect population declines in many places around the world; was it happening here now? And so I returned to researching those news articles again.Recently within the last decade or so publicized research documenting the massive numerical decline in the total biomass of insects have been published. The total 'biomass' of insects simply refers to the estimated weight of all living insects on planet earth. Research documents the decline of the total biomass during the last 30 years at being close to 80%, and declining by 2.5% yearly! This includes land and aquatic insects. And it does not include biomass loss prior to these recent 30 years.
Many vertebrate animals, including birds, mammals, reptiles, amphibians, and fish, feed primarily upon insects; and upon other smaller vertebrate animals that feed primarily on insects. Many other vertebrate animals are food dependent on the seeds, fruit, and foliage of plants that depend solely on insect pollination. Thus, an 80% decline in the primary food source of so many vertebrate animals would have had a profoundly negative effect on the biomass (think population numbers) of these higher tiered animals. Unfortunately, the resultant decline in insect dependent vertebrate animals is also well documented.
The primary direct causes of this insect apocalypse are: habitat loss do to agriculture and urbanization, pesticides and herbicides, and man made artificial light.Historically, from times past, and especially today, the number one cause, by far, of insect biomass decline, and that of many dependent species, is the loss of habitat to agriculture and urbanization. The vast conversion of natural habitats to agriculture and urbanization has resulted in a dramatic loss of biodiversity in those landscapes. Certain insects that naturally feed on wild plant species, often multiply in mega-plagued like numbers on related crop species causing great economic loss.
Thus, the world wide used of pesticides. I will never forget what my Entomology professor once told our class, "All animals and plants are made of protoplasm; and pesticides and herbicides target protoplasm. Insects just die in mass quicker because they are so small." Perhaps, many of us older folks remember the 1962 book "Silent Spring" by Rachel Carlson, in which she documents the harm to birds via the use of the insect pesticide DDT.
Pesticide use is still necessary to ensure a stable food supply for human-kind, and to provide protection from insect transmitted diseases. But the loss in biomass of beneficial non-pest insect species, that perish as collateral damage, has greatly contributed to the loss of bottom tiered food biomass. Also, the potential loss of so many wild pollenating insects, such as bees, threatens the existence of many crops, and wild flora, dependent upon insect pollination.
A more recently discerned contributor to the collapse of insect biomass is the combined total of night time artificial light. Scientists are beginning to understand the profound, and negative effect that artificial light has on the biorhythms of nocturnal insects, especially flying insects. Many of us have seen the great variety of insects that are attracted to our porch lights, street lights, car headlamps, sometimes in great quantity. This is an unnatural attraction, and an interruption in the cycle of daylight, and the night-darkness in which nocturnal insects are adapted to. Unsuccessful mating, due to attraction to artificial light, is now considered to be another direct, and potentially serious, cause of nocturnal insect biomass decline. Many insect species produce hundreds, to thousands, of eggs per individual insect! Again, the nocturnal 'higher-ups' on the food chain also suffer food loss, and numerical decline.
The effect of regional, and global climate change on insect biomass, although not as direct and instantly damaging as the issues discussed above, will definitely pan out slowly over time as it has in ages past.The last ice age terminated a lot of flora, fauna, and habitat; but it did so very slowly. Currently our climate is in the last stages of the slow global warming trend that slowly terminated the last ice age. The current human caused decrease in surface flora and fauna biomass carbon, and the burning of bio-fuel carbon, releases extra CO-2 into the atmosphere which accelerates this naturally occurring warming trend. Carbon sequestration, or atmospheric carbon dioxide removal, is the very difficult human goal to halt global warming, without kick-starting the next ice age.
For folks living here in Lassen and Plumas counties, and everywhere else, I recommend the following practical suggestions: Convert your home landscapes into more Eco-friendly environments for both birds and insects. Plant more f'lowering' trees, shrubs, perennials, and annuals. Restrain using herbicides and pesticides around your homes. Convert outdoor lighting to motion-sensing lighting. Research online how to do these things, and even more. Also, read the online information on the Insect Apocalypse; since I have here only briefly discussed the issue.
One final thought: If all insects were to suddenly die off on the surface of planet Earth, their extinction would soon be followed, as a result, by most all other land based animals and plants. Such is the interdependency that is founded upon the biomass of more than a million distinct species of insects!
Postscript: In the year 2021 there was indeed a very small reappearance of pollinating insects, followed by even more in 2022.
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