Insects and Native Plants in the News

By Shirley Denton
Common Eastern Bumble Bee (Bombus impatiens) foraging on a Partridge Pea (Chamaecrista fasciculata) in Split Oak Forest WEA in Orange County. Photo by Valerie Anderson.

Two native insects have been in the news, and not in a good way. The first, the bumblebee, is an important native pollinator. The second, the lightning bug, needs native habitats. Neither is a single species, but together, they demonstrate the importance of maintaining healthy native plant ecosystems in balance with other environmental factors. Both demonstrate the importance of climate. Both demonstrate the importance of human behavior.
Fireflies in Maryland CC BY-NC-ND 2.0 by Robert Sullivan

The bumblebee study (published in Science) showed that populations in North America and Europe have plummeted as a result of increasingly extreme high temperatures. The number of areas populated by bumblebees has fallen 46 percent in North America and 17 percent in Europe. The data is not based on Florida. The researchers found that an increasing frequency of unusually hot days is increasing local extinction rates, reducing colonization and site occupancy, and decreasing species richness within regions, independent of land-use change or condition. As average temperatures continue to rise, bumble bees may be faced with an untenable increase in frequency of extreme hot temperatures which may exceed the tolerance limits of specific species and which may reduce the ranges of multiple species.
This study is reminiscent of studies of the honeybee, not native to North America, but important to many commercial crop species (also mostly not native to North America, but important to us humans). Honeybee declines have been associated with stresses some of which appear related climate change (others relate to land uses, use of pesticides, and agricultural practices).
Lightning bugs are quite different. These bugs rely on plants but plants don’t rely on them. They are not important as pollinators.  They are predominantly carnivores though adults of some species use nectar and pollen from plants. All of them rely on habitat structure (many like grassy moist settings). The mating rituals of many species rely on patterns of light, and having humans add nighttime light can mess up those rituals.
I don’t know about you, but I find these night blinkers entrancing and reminiscent of an almost forgotten past. I also remember an Ixia Chapter event when National Park Employees led us on a walk in the black dark – no flashlights allowed. The lightning bugs flitted among trees in a dark so dark that you could not see your feet. It was ethereal. I hope we don’t lose them.
A survey of 49 of the world’s firefly experts, published last month in BioScience, has identified the serious threats to fireflies: habitat loss, in almost all of the regions surveyed, artificial light (disturbs their mating rituals); pesticides (harms the insects and/or their invertebrate prey), and water pollution (species that have an aquatic stage). The report was not a census of the world’s firefly population. But it is “the very first time that experts have identified major threats are to fireflies in different parts of the world. Some species, however, appear to be doing well.
Insects rarely make the news. But the recent news is showing both the risks imposed by changes in climate, and the risks associated with other human behaviors (pesticide, night lights, habitat destruction, etc.). These are two very different types of insects. I’m guessing that they may be the tip of an iceberg.

KEY REFERENCES

US EPA, OCSPP . 2013. Colony Collapse Disorder. US EPA.
Lewis, S. M., c. H. Wong, A.C.S.Owens, C. Fallon. S. Jepsen, A. Thancharoen, C. Wu, R.D. Cock, M. Novák, T. López-Palafox, V. Khoo, J. M. Reed. 2020. A Global Perspective on Firefly Extinction Threats. Bioscience.
Soroye, P., T. Newbold and J. Kerr. Climate change contributes to widespread declines among bumble bees across continents. Science Vol: 367 (6478):685-688. https://science.sciencemag.org/content/367/6478/685.abstract

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