| The yellow mealworm beetle (Tenebrio molitor) originated more than 150 million years ago, but their beetle ancestors go back to 350 million years ago, showing an impressive ability to adapt and survive to changing and quite different environments through such a large period of our planet. |
The order Coleoptera represents all known beetles and is arguably the group of animals with more species catalogued to date. The origin of the beetles is dated to the Carboniferous, a geological period of approximately 60 million years (My) that spanned from the end of the Devonian Period (about 358 My), to the beginning of the Permian Period (298 My).
The Carboniferous was geologically very active, as the supercontinent Pangaea came together by the late half of this period. Terrestrial life was well established. Amphibians were the dominant land vertebrates, of which one branch would eventually evolve into reptiles. In fact, the Carboniferous period is sometimes called the Age of Amphibians. Arthropods (of which insects and beetles belong) were also very common, and many were much larger than those of today, such as Meganeura. Vast swaths of forest covered the land, which would eventually be laid down and become the coal beds characteristic of the Carboniferous system.
Of the all the species of beetles known nowadays (> 400.000), approximately half of them are herbivorous, feeding on live plant material, and it is believed that they codiversified along with the evolution of the flowering plants (angiosperms) in terrestrial ecosystems. Most of these herbivorous beetles feed on live flowering plants (angiosperms) such as the Colorado potato beetle (Leptinotarsa decemlineata), or weevils (with their characteristic proboscis (large snout)), while the other half are detritivores, saprophages (feed on decomposing dead organic material) and mycophages. This huge diversity of beetles started at the late Carboniferous period, more than 300 million years ago!
Scientists have been conducting phylogenomic studies and found that herbivorous beetles were able to “incorporate” genes from bacteria and viruses that allowed the produce enzimes capable to degrade plant cell walls and digest cellulose, hemicelluloses and pectins (the most abundant source of carbohidrates on Earth), obtaining thus essential nutrients such as simple sugars and amino acids easy to assimilate. What an ingenious way to evolve, isn´t it?
The superfamily Tenebrionoidea, known as darkling beetles, is one of the largest beetle groups with approximately 34,000 described species, and is where the yellow mealworm beetle (Tenebrio molitor) belongs. Many of the species of this superfamily are detritivores/saprophages, while others eat also fungi. This superfamily originated in the late Triassic-early Jurassic period (around 200 My ago), when the climate was generally hot and dry, with many deserts in the interior of the supercontintent Pangea. In this period there was a huge mass extinction both at sea and land… but the ancestors of our Tenebrio managed to survive, fortunately!
The oldest beetle (now extinct) belonging to this superfamily is called Wuhua jurassica and was discovered in Daohugou (China). It is believed that lived in the middle Jurassic (174.1 to 161.5 My ago). We can certainly say that is the great-great-greaaaat-grandpa of our Tenebrio!
Definitely, the yellow mealworm beetle knows how to adapt and survive though time and that is why at Protiberia we are delighted to work with it!
References:
- Britannica: https://www.britannica.com/browse/Fossil-Geologic-Time
- Wang B, Zhang H. The oldest Tenebrionoidea (Coleoptera) from the Middle Jurassic of China. Journal of Paleontology. 2011;85(2):266-270. doi:10.1666/09-088.1
- D.D. McKenna et al. The evolution and genomic basis of beetle diversity, Proc. Natl. Acad. Sci. U.S.A. 116 (49) 24729-24737
