Ground Beetle

Common Name: Ground Beetle, Black Ground Beetle, Common Black Ground Beetle – Beetle, as insect, is of Old English origin as bitula from bitan a verb meaning “to bite”. This eventually devolved to bityl in Middle English, with the same pronunciation as the current spelling. Beetle can also mean a heavy wooden mallet in which case it is derived from the Old English bietel, which is derived from the verb “to beat”, as in Beatles [1]

Scientific Name: Pterostichus spp – The genus name is a combination of the Greek words pteron meaning “wing” and stichon meaning “divided by lines”. This refers to the pattern of parallel grooves that extend along the thicken wings called elytra (Greek meaning “sheath”) that cover and protect the dorsal side of beetles. The abbreviated spp signifies species pluralis and is used to refer to a genus and all of its species. There are 150 species of Pterostichus in North America. [2]

Potpourri: While it may seem that there could be nothing more mundane than a common black ground beetle, they are an important capstone species as apex predators of the detritus-covered soil that serves as the font for almost anything that grows. They are ubiquitous, also implied by mundane, which can mean worldly in addition to commonplace. Beetles comprise the order Coleoptera, the largest order in Kingdom Animalia, and make up about a third of all insects. There are some 300,000 species of beetles globally of which about ten percent are indigenous to North America. Coleoptera is a direct Latin translation of the Greek koleooptera meaning “sheathed wings”. The most distinctive features of beetles are the hard, rigid anterior wings called elytra that are not used for flight but sheath and protect the underlying delicate membranous flight wings. [3] Darwin is frequently credited with the observation that “The Creator would appear as endowed with a passion for stars, on the one hand, and for beetles on the other, for the simple reason that there are nearly 300,000 species of beetle known, and perhaps more, as compared with somewhat less than 9,000 species of birds and a little over 10,000 species of mammals.” The quote is properly attributed to the Neo-Darwinist J. B. S. Haldane. [4]

Beetles are prolific in part because they have carved out unique and surprisingly innovative niches in the tangled web of diverse ecosystems. They come in many shapes and sizes to suit the specifics of their subsistence profile. Tiger beetles are close cousins of ground beetles that chase down their prey at high speed over open ground. Tumblebug scarabs roll up balls of dung as hatcheries and first home for their progeny. Lady bird beetles are divinely benign (called cows of the Virgin Mary in France) for devouring aphids that suck plant fluids and destroy crops. Japanese beetles are an invasive blight to any gardener seeking to specialize in roses or fruit trees. Carrion beetles finish off the carcasses of anything too small or unpalatable to larger predators. Blister beetles exude toxins to protect their eggs from being eaten, named for its effects on the flesh of humans. Ground beetles are the generalists of the lot, living quiet lives under logs, rocks, and wet leaves of the forest. Turn over any log and you are likely to find one or more.

Ground beetles comprise the family Carabidae and are therefore also known as carab beetles or simply carabids. The family name is from the Greek word karabos, originally a type of crab which probably carried over to ground beetles due to the similarity of the hardened outer shell, which serves as an armored shield. Both crab and beetle shells are held together with chitin, an organic polymer that is also the main structural component of most fungi and many algae. Chitin is underappreciated as an important biological compound relative to cellulose, the primary structural component of plant cell walls. Both are polysaccharides, comprised of a string of many (poly) sugars (saccharides). The saccharide of choice for both chitin and cellulose is glucose, better known for its role as animal blood sugar, joined end to end with oxygen bonds. About one half of all carbon that comprises earth’s organic life, sometimes referred to as the biosphere, is cellulose. This amounts to one exagram (10 with 18 zeroes) of carbon that is processed and degraded annually, the mass of a mid-sized asteroid. Chitin differs from cellulose in structure only in having one side-bonded acetyl molecule and is only slightly less abundant as a carbon repository. [5]

Ground beetles also proliferate due to physiological attributes that promote adaptability. The most obvious design feature is the hardened, protective carapace they develop as adults, a property of all beetles. Box turtles live long lives due to the coevolution of a similar structure that wards off all but the most determined assaults. Beetles are attacked by fewer predators than other insects. [6] But there is more to beetles than an “intelligent” design. A study of the response of ground beetles to a combination of abiotic factors such as temperature and humidity and biotic factors such as competition and parasites revealed three distinct advantages: (1) Ground beetles are eurytopic, meaning that they can withstand a wide range of environmental conditions; (2) Ground beetles are adventurous rovers that seek out and colonize new areas; (3) Ground beetles are omnivorous and will consume anything edible. [7] But, as Michael Pollan points out in The Omnivore’s Dilemma, there is some danger in food selections due to toxins and a balance of different nutrients is required. Ground beetle experiments have demonstrated an innate selectivity that accounts for overall nutrition. Beetles fed a pretreatment diet lacking protein subsequently sought out protein-rich foods. A similar behavior was found with lipid or fat nutrient levels.[8]

Of the 3,000 plus carabids in North America, most are voracious predators, both as larvae and as adults. The family Carabidae is in the suborder Adephaga, which literally means glutenous in Greek. With strong jaws for crushing, they are surprisingly fast and agile. The larvae even have two claws at the end of each of their six legs called urogomfi (literally tail-tooth in Greek) for grasping writhing prey. Ground beetle consumption is prodigious. They can eat over twice their body weight in a single day. In the beetle version of the classic movie Cool Hand Luke in which Paul Newman eats 50 hard-boiled eggs, this would equate to fifty repetitions or 2,500 eggs. This gustatory act, which would seem to violate the laws of physiology and maybe physics as well is empowered in part by the manner in which food is consumed. Ground beetles regurgitate digestive fluids that partially decompose the crushed carcass to facilitate ingestion as a partially liquified meal, a behavior they share with spiders. And what do they eat? Basically, anything organic that is smaller than they are, which typically consists mainly of invertebrates such as worms, mollusks, and the larvae of other insects (including caterpillars and cockroaches). [9]

Because of their ubiquity and dining habits, ground beetles are generally good for agriculture, the science (and art) of farming. This is because they consume many things that are bad for agriculture. Crop pests are more frequently remediated with pesticides. Since chemicals that kill tend to be toxic to other living things that cohabit the targeted areas, applying them can also adversely affect the ground beetle population. As a case in point, a field experiment was conducted in Britain to measure the effects of pesticides applied to rid cabbage patches of the maggots (larvae) of the cabbage root fly. The surprising result was that the cabbage fields to which the chemical was applied suffered more maggot damage than those unsprayed as control. Investigation revealed that over 30 species of beetle ate the eggs and larvae of the offending predator and that the pesticide reduced their number to the extent that more root flies survived. [10] Two of the laws proposed by Barry Commoner, the father of ecology, are “Nature knows best,” and “Everything is connected to everything else.” Ground beetles are proof positive, and studies of cultivation practices have been conducted to determine best practices. These have shown that deep tillage depletes ground beetle population whereas reduced tillage with organic fertilization and green manuring promotes them. [11]

Most ground beetles look alike. In fact, the photograph above may very well be a bessbug, a similar beetle that lives in the same rotting log habitat but does not compete with ground beetles since bessbugs consume decaying wood and are not predatory. Even entomologists that specialize in beetles have trouble telling them apart. The obscure French entomologist René Jeannel (1879 – 1965) spent most of his life studying the speciation of nearly identical cave beetles. After a career of detailed research, he discovered that one of the most reliable identification tools to distinguish one beetle from another was the shape of the male reproductive organ called aedeagus from the Greek aidoia meaning genitals. This practice has continued to the present; it is a relatively common practice for biologists to use both male and female genitalia as a key indicator of species.

Beetle aedeagi generally consist of a capsule-shaped organ from which an inflatable sac extends like a windsock. The extended “penis” is studded with bristles and spines, which must have some purpose as beetles are bisexual and intercourse is de rigueur for procreation. The current hypotheses is that male beetle semen contains chemicals that influence female sexual behavior and that this effect is enhanced by being directly transferred to the blood via spine puncture wounds. Recent experiments employed a micro laser gun to remove some male penal spines to form a test group to compare with a fully-spined control group. The end result was that females impregnated with the fully spined group produced more offspring. The presence of spines on the male sexual appendage is not as outlandish as it sounds. Spines (made of keratin, like hair) are also found on many primates and rodents and there is evidence based on residual DNA that they were they were at some point present on Homo sapiens. [12] So beetles do matter after all.

Footnote: No article on beetles would be complete without reference to the origins of the name of the inimitable Beatles. John, Paul, and George started out as the Quarry Men without a drummer in Liverpool in the late 1950’s. As they gradually developed the sound for which they are so well known today, they decided they needed a more memorable stage name. John is quoted as saying that he was “just thinking about what a good name the Crickets (Buddy Holly’s band) would be for an English group when the idea of beetles came into my head”. He is also credited with changing the spelling to Beatles “to make is look more like beat music, just as a joke”. The original spelling was Beatals. After a short experiment with Long John and the Silver Beatals, presumably to sound more like Buddy Holly and the Crickets with a literary flourish, Beatals became simply Beatles and the rest is history. [13]

References:

1. Webster’s Third New International Dictionary of the English Language, Unabridged, Merriam Webster Co, Philippines, 1971, p 197.

2. Marshall, S. Insects. Their Natural History and Diversity, Firefly Books, Buffalo New York, 2006, pp 258-259, 287.

3. Milne, L. and M. The National Audubon Society Field Guide to Insects and Spiders, Alfred A. Knopf, New York, 1980, pp 533-621.

4. Haldane, J.B.S. What is life? The Layman’s View of Nature, L. Drummond, London. 1949, p 258 (Verified on paper by Stephen Goranson at Duke University)

5. Voet, D. and J. Biochemistry, John Wiley and Sons, New York, 1990, pp 255-257.

6. Gressitt, J. L. “Coleoptera” Encyclopedia Britannica Micropedia, Volume 4 pp 828-837 William and Helen Benton, publisher, University of Chicago. 1974.

7. Thiele, H. “Carabid Beetles in Their Environments. A Study on Habitat Selection by Adaptations in Physiology and Behavior”. Science August 1978, Volume 201 Issue 4357.

8. Mayntz, D. et al “Nutrient-Specific Foraging in Invertebrate Predators” Science 7 January 2005, Volume 307 Number 5706

9. Goncalves, M. “Relationship Between Time and Beetles in Mata de Cocal” Review of Brazilian Meteorology, Volume 32, Number 4, October 2017. https://www.scielo.br/j/rbmet/a/kJPLKtB3gLTdfTcMB9vM4Vd/?lang=pt

10. Nardi, J. Life in the Soil, University of Chicago Press, Chicago, Illinois, 2007, pp 136-138

11. Kromp, B. “Carabid beetles in sustainable agriculture: a review on pest control efficacy, cultivation impacts and enhancement” Agriculture, Ecosystems, and Environment, Volume 74, Issues 1-3, June 1999 pp 187-228 https://www.sciencedirect.com/science/article/abs/pii/S0167880999000377?via%3Dihub

12. Schilthuizen, M. Nature’s Nether Regions, What the Sex Lives of Bugs, Birds, and Beasts Tell Us About Evolution, Biodiversity, and Ourselves. Penguin House, New York, 2014, pp 28-31, and pp 150-157.

13. Spitz, B. The Beatles, Little, Brown and Company, New York, 2005. pp 175, 181, 196.

Many-Headed Slime

Common Name: Many-headed slime, Grape cluster slime, Slime mold – The many branches that radiate outward from the site of initial growth form clusters at food sources consumed as sustenance. The overall appearance is one of many small nodes that are metaphorically compared to heads.

Scientific Name: Physarum polycephalum – The genus name is from the Greek physarion, meaning small bellows, which may refer to the characteristic pulsating growth which appears to surge as if wind-driven. The species name from Greek poly meaning many and kephalikos (Latin cephalicus) meaning head.[1] The translation literally means many-headed.

Potpourri: Slime molds were saddled with one of the most pejorative names in biology. The Animal Kingdom’s most despicable attribute of slime is sometimes applied to humans as the penultimate insult. The Fungi Kingdom’s worst form is mold, destroyer of agricultural crops and promoter of human respiratory disease. Even so, slime mold is an apt name in describing an unusual form of life. Slime molds bridge the gap between animals and fungi in transitioning from a mold-like spore that then germanites into an amoeba-like animalcule that moves like Lewis Carrol’s “slithy toves”. The onerous task of organizing living things into a comprehensible structure has been a work in progress for centuries. With DNA replacing appearance as its organizing principle, phylogenetics has upended the historical hierarchical taxonomy of Carolinas Linnaeus. This transition is just beginning. Placing slime mold into its proper niche in the web of living things on the TBD list. For now, it is classified as a protist.

Numerous attempts have been made by intellectually curious, sapient humans to impose order on the entangled complexity of their surroundings. Schemes based on geographical locale, patterns of fruits and seeds, and gross morphology were all found to be impractical for field application. Linnaeus had the insightful idea of using sex as the organizational principal for plants, forming 26 categories based on the numbers and arrangement of the (all important) male stamens. Calling them vegetable letters he correlated stamen arrangements to the alphabet as a mnemonic. Praeludia Sponsaliorum Plantarum (Prelude to the Betrothal of Plants) was published in 1730, which garnered international interest that was both supportive and dismissive. Linnaeus forged ahead, and, based on the premise that “Minerals grow; Plants grow and live; Animals grow, live, and have feeling” settled on three kingdoms as his foundation. [2] The inclusion of inanimate rocks as an integral part of the tree of life is testimony to the ignorance of the times.

On December 13, 1735, the first edition of Linnaeus’s Systema Naturae (System of Nature) went on sale in Leyden, Netherlands with a section on the Mineral Kingdom and the Animal Kingdom to supplement the extant alphabetic Plant Kingdom. Minerals were dived into three categories named Petrae for simple stones, Minerae for simple stone mixtures, and Fossilia for aggregate rocky particles (that may or may not have an impression of an animal or plant); the system never made it into the work of Charles Lyell, who correctly classified sedimentary, metamorphic and igneous as the three types of rocks. [3] The Animal Kingdom was to have far reaching impact on the future of biology. Linnaeus devised the canonical format Kingdom, Class, Order, Genus, and Species to establish the first enduring method to catalogue living things into what became known as taxonomy. He identified six classes of animals with 549 species: Quadrupeds (which included the Order Anthropomorpha and thus two-legged humans); Birds; Amphibians; Fish; Insects; and a final class as catchall named Vermes that included everything from reptiles to squid. A seventh group was tacked on at the end named Paradoxa for those animals that were missing from the rankings, as the semi-animal slime mold would have been.

Some twenty kilometers south of Leyden lay Delft, the home of Antonie van Leeuwenhoek, the unlikely father of microbiology. As the owner of a fabric shop, the need for an improved method of magnification to inspect thread quality essential to the drapery business led him to the field of lens grinding, at which he excelled. In fabricating the first practical microscope, he was able to penetrate the heretofore unseen and unknown domain of the minuscule. An investigation of pond water yielded the presence of moving objects which he (correctly) interpreted to be animalcules. Over the course of the next century, as Leeuwenhoek’s hypothesis gained credence, the idea that these ubiquitous simple organisms must represent the origins of life gave rise to the term Protozoa, literally “fist life”. In the modern era, biology has yielded its operating system in the form of DNA coding for protein synthesis. Fungi were added to the kingdom count in the late 20^th century (long after rocks had been expelled) but there were still outliers. This gave rise to Kingdom Protista, implying the same notion of first-ness for those living things that were neither animals, nor plants, nor fungi. In addition to the slime molds, protists are inclusive of the animal/plant Euglenoids which are mobile photosynthesis factories, and brown algae aquatic Chrysophytes like kelp. [4]

It is tempting to think of slime mold as an evolutionary alternative that was successful enough to survive but not sufficient for mutation and expansion to higher levels of organization. Slime molds have been referred to as Dr. Jeckel and Mr. Hyde due to similar extremes of form and behavior that a single individual might manifest. [5] The slime mold life cycle starts with a wind-blown spore that germinates under appropriate environmental conditions of temperature, water, and nutrients. Slime mold spores form one of two structures: a blob called a myxamoeba that can divide making multiple copies; or a body called a swarm cell that has a flagellum at one end for locomotion. The sexual union of two compatible myxamoebas or two compatible swarm cells yields a fertilized egg cell or zygote. Individual zygotes fuse into a multi-nucleus structure called a plasmodium that surges back and forth in search of food, the mysterious surging mass occasionally seen on woodland jaunts. When the food runs out or if conditions otherwise deteriorate, fruiting bodies are erected and new spores are ejected to comprise the next generation.[6] Thus, a slime mold can be considered as fungus, plant, or animal according to what stage is considered central. Like the ancient parable of the blind men and the elephant, which is like a snake if one first encounters the trunk but like a spear if one encounters the tusk, slime molds are different things to different people.

Slime molds have traditionally been categorized as myxomycetes from the Greek myxa meaning nasal slime and mykes meaning fungus, a name first applied in 1654. For the next 300 years, fungi were part of the Kingdom Plantae in the Phylum Thallophyta, a collective for primitive plants which also included lichens and algae. Even with sequestration of fungi as the separate kingdom Eumycota, slime molds were considered an integral member. Only recently were they relegated to Kingdom Protista. There are currently about 1,000 species of slime mold taxonomically categorized in 5 orders, 14 families, and 62 genera. [7] Fuligo septica is the best. known of the slime molds. Commonly called either scrambled egg or dog vomit slime (according to age and color) it often grows on garden mulch and can get quite large; a world record F. septica was recorded in Texas in 2016 that was 30 inches long and 22 inches wide. [8] Physarum polycephalum has recently gained the reputation as the slime mold of science due to its demonstrated ability to make what seem to be intelligent choices about the location of food sources and the best way to access them. This is of some interest to developing a better understanding the evolution of cooperation among individual organisms, such as that of social insects like ants and bees.

A scientific experiment conducted at Japan’s Hokkaido University in 2000 found that P. polycephalum was capable of determining the shortest path through a maze that connected two caches of oat flakes, a slime mold favorite.[9] The award of an Ig Nobel prize recognizing this unusual and thought-provoking experiment garnered international slime mold stardom. Ten years later, researchers followed up on the maze trial with a map simulating Tokyo and its many train terminals marked by oat flakes. The objective was to determine if many-headed slime could find the best network route between them. The result, after only 26 hours of probing growth, was nearly identical to the extant Tokyo rail system, which presumably was the most efficient in practice and took decades to build. [10] The notion that slime molds could apparently make intelligent decisions led inevitably to media hype before settling down to the scientific underpinnings in recent years.

Slime mold replicating the train system of Tokyo (Reference 10)

The New York Times proclaimed the wisdom of slime in 2012, noting that it behaved as though it were “extremely intelligent” in creating networks that optimized the transport of nutrients. To promote interest for an American audience, a map of the United States was created with oat flakes marking 20 urban centers with slime mold propagating outward from the simulated location of New York City. The resultant connections nearly replicated the interstate highway system in four separate trials. [11] Broadcast media followed up this somewhat scientific finding with a report that slime mold could “solve problems even though it doesn’t have a brain” and had 720 sexes instead of only the boring two. [12] (Since slime molds don’t have bathrooms or sports teams, their social issues should be manageable). Research on the mechanisms employed by slime molds to locate and exploit food along the most favorable paths continues. The physical process is thought to be similar to the movement of fluids in the intestines, known as peristalsis, with slime mold tubes containing cytoplasmic fluid that surges and retracts in reaction to food quantity and quality. [13] From the perspective of a neurologist, the selection process is called emergence and is similar to the scouting methods used by ants to locate the best nesting site and bees to locate the best food source. In the case of slime molds, tubes are sent in all directions as “scouts” and retracting the unsuccessful paths to flow fully in the food direction. [14] An experiment to evaluate slime mold food preferences is not unlikely.

References:

1. Webster’s Third New International Dictionary of the English Language Unabridged, G. & C. Merriam Company, Philippines, 1971.

2. Roberts, J. Every Living Thing, Random House, New York 2024, pp 45-95.

3. Cazeau, C, Hatcher, R. and Siemankowski, F. Physical Geology, Principles, Processes and Problems, Harper and Row New York 1976, pp 6-11.

4. Starr. C. and Taggart, R. Biology, Wadsworth Publishing Company, Belmont, California, 1989, pp 62, 600-609.

5.Lincoff, G. The Audubon Field Guide to North American Mushrooms, Alfred A. Knopf, New York, 1981, pp 843-854.

6. Kendrick, B. The Fifth Kingdom, Focus Publishing, Newburyport, Massachusetts, 2000. P 10.

7. Keller, H. Everhart, S. and Kilgore, C. “The Myxomycetes: Nature’s Quick-Chage Artists” American Scientist, Volume 112, September-October 2024 pp 352-359.

8. Keller, H, “World Record Myxomycete Fuligo septica Fruiting Body (Aethalium)” Fungi Volume 9 Number 2, September 2016 pp 6-11.

9. Nakagaki, T. et al. “Intelligence: Maze-solving by an amoeboid organism”. Nature. 28 September 2000 Volume 407 Number 6803 page 470.

10. Wogan T. “Ride the Slime Mold Express” Science 21 January 2010.

11. Adamatzky, A and Ilachinski, A, “The Wisdom of Slime” New York Times, 12 May 2012.

12. Zaugg J. “The ‘blob’: Paris zoo unveils unusual organism which can heal itself and has 720 sexes”. CNN. 17 October 2019.

13. Alim, K et al. “Random network peristalsis in Physarum polycephalum organizes fluid flows across an individual”. Proceedings of the National Academy of Science USA. 29 July 2013 Volume 110 Number 33. pp 13306–11.

14. Sapolsky, R. Determined, A Science of Life without Free Will, Penguin Press, New York, 2023, pp 154-166.