Beetles. I recently heard on Nature podcast (24 April 2008; sometimes work is super boring, and I’m sick of all my music) that beetles are contributing to global warming. North American forests are being pillaged by fungus-bearing Mountain Pine beetles, which render ruddy pine-trees that should be green. They are killing the trees, making the forests massive carbon repositories. Trees are our friends because they clean up carbon emissions for us, and can be climbed on. But these voracious Mountain Pine beetles infesting forests are killing our trees, which means less trees to clean up our carbon. Insult to injury: as the dead trees decay they release more carbon into the atmosphere. So now humans and coleopterans are major contributors to Global Warming. Researchers estimate (Kurz et al. 2008) that these beetles will have caused the release of almost a billion tons of CO2 into the atmosphere between Y2k and the year 2020 (hey, remember the big Y2k fiasco?). Dammit! It would be nice to be able to place a substantial amount of the blame for Global Warming on these dendrophagous coleopterans, absolving humans of their environmental sins. But humans are probably at least partly responsible for the current Mountain Pine beetle outbreak: their northward expansion is due in part to rising temperatures in recent years, and we’re the bastards that have been heating up the planet.
So beetles are already on the list. But apparently beetles have been eating fossils, too. Paleontologists recently identified thousands of dinosaur fossils that ‘bore’ (pun!) traces of beetle feeding activity (Britt et al. 2008). To quote from the abstract:
The traces include mandible marks, pits, and shallow bores on cortical bone, and deep, meandering furrows and tunnels (borings) on articular surfaces. The interiors of bones are intensely mined, and the cavities and borings are filled with fine bone fragments (insect frass). . . . Examination of more than 5,000 bones . . . shows insect traces on bone are common but overlooked and that many bones are substantially damaged by insect mining (Britt et al. 2008, my emphasis).So how much of the fossil record have these detrivores altered or destroyed? Hard to say, though I have not heard of any known cases of insect damage in the human fossil record. Oh, and “frass” is a funny word for insect excrement.
So what’s the take-home message here? It seems to me that too often beetles’ shortcomings are overlooked by their positive attributes: they’re an unforgivably speciose and evolutionarily ‘successful’ group (the great population geneticist JBS Haldane is credited to have said humans could easily divine that the Creator had “an inordinate fondness for beetles”); they released many great records and #1 singles; some of them like to play with poop, etc. But what are we to do with the ones that destroyed our fossils (arguably making paleontology more interesting) and are helping us microwave our planet? I do not think that drastic punitive action should be taken against the largest order of insects. But the next time you see a beetle, even if it’s not of the Mountain Pine or dermestid persuasion, you tell it, “Shame on you.”
Britt BB, Scheetz RD, Dangerfield A (2008) A Suite of Dermestid Beetle Traces on Dinosaur Bone from the Upper Jurassic Morrison Formation, Wyoming, USA. Ichnos 15(2):59 - 71
Kurz WA, Dymond CC, Stinson G, Rampley GJ, Neilson ET, Carroll AL, Ebata T, Safranyik L (2008) Mountain pine beetle and forest carbon feedback to climate change. Nature 452(7190):987-990