When Disaster Has Struck….

It may turn out a boon for scientists

There are always some who benefit from wars, epidemics and other events that are generally seen as deleterious, in fact, disastrous. Take the historic eruption of Mt. Vesuvius in the year 79. It buried the city of Pompeii and its inhabitants under metres of ashes and in this way preserved the “activities” and details of the living conditions at the time of the disaster, which keep archaeologists busy to this day. Or think of the pharaoh Akhenaten’s home near modern day Amama, whose roof collapsed in 1353 BCE and trapped and preserved on its mud brick floor under dry conditions insects, which gave scientists a glimpse into the vermin people in those days shared their house with. Eva Panagiotakopulu et al. in 2010 identified grain weevils, flour beetles, mealworms, pupae of house and flesh flies from that site. Famous are also the disastrous falls of some animals into mud that subsequently froze and then preserved these creatures for thousands of years under conditions so excellent that even inner organs could be examined of specimens that were recovered and thawed.  

A disaster of a different kind (and of tremendous value to the palaeo-entomologist and evolutionary scientist) befell insects, spiders and other small creatures when a sticky drop of resin from a tree landed on them, trapped them and preserved them in what is now known as “amber”.  Some of the organisms known from such amber may have wandered into the stick secretion and trying to free themselves got more and more covered and ultimately embedded in it. Because of the specimens caught in this way, we know what groups of insects, spiders and other small creatures roamed the forests millions of years ago and how these species differed morphologically from those that now populate our forests. The reason for the excellent preservation is that the viscous resin not just entombs the trapped specimens, but that it prevents fungal rot and decay and ultimately, when hardened, conserves cellular and often even sub-cellular details remarkably well. Of the greatest interest, because of their rarity, are small vertebrates in amber. Numerous lizards, a young snake, tiny birds of the extinct Enantiornithes, baby dinosaurs, a small frog, all this and more, for instance, is available from 100 million year old Burmese amber. Amber washed up on Baltic Sea beaches is less old than Burmese amber (only ca. 40 million years) and unable to shed light on the assemblage of small vertebrates and invertebrates that shared the world 100 million years ago with the dinosaurs.

However, one of the most horrific disasters to befall Earth’s inhabitants are earthquakes and they must have accompanied the evolution of plants and animals “since the beginning”. This is why scientists of different disciplines have long been interested to find out, if there is something to be learnt from an animal’s behaviour prior to an earthquake. Anecdotal reports in support of such behaviours abound and date back to antiquity. But how reliable and verifiable are such reports and how long before an earthquake strikes do animals actually sense the event: minutes, hours, days?

There are apparently (long before the so-called P-wave that most animals would feel seconds before the strong and often highly destructive S-wave arrives) precursors that could occur days before the earthquake and such signals could involve tilting, groundwater changes and associated magnetic and electrical variations. There is experimental evidence that some animals are extremely sensitive to even the smallest tremors and vibrations (I’ve seen that in fish, spiders, etc.), but don’t such tremors occur very frequently without heralding an earthquake? That is, of course, very true and people would not have paid attention or remembered an animal’s unusual behaviour, unless there was indeed an earthquake and in “hindsight” one would associate an animal’ erratic behaviour with it. I was puzzled one day strolling along a lane on Hachijojima’s south coast, to see hundreds of dead earthworms, even though there hadn’t been any rain for days. I then thought that maybe the worms had been sensing slight earth tremors and were therefore leaving the soil. I waited for the next few days for an earthquake to happen (not at all a rare event on the volcanic island of Hachijojima), but it didn’t. Well, at least I could not feel it. 

© Dr V.B. Meyer-Rochow and http://www.bioforthebiobuff.wordpress.com, 2021.
Unauthorized use and/or duplication of this material without express and written permission from this site’s author and/or owner is strictly prohibited. Excerpts and links may be used, provided that full and clear credit is given to V.B Meyer-Rochow and http://www.bioforthebiobuff.wordpress.com with appropriate and specific direction to the original conten

Ants and their guests

Of which some behave very badly

I met Bert Hölldobler in 1972 at the 14 th International Congress of Entomology in Canberra, the capital of Australia. He then told me he was appointed to be professor at Harvard University.  Harvard University! A PhD-student at that time, I was surprised that a man as young as Bert would be a Harvard University Prof, but reading his studies on ants, I was no longer surprised.

There is no other insect group than the 10,000 or so species of ants in terms of different social behaviours and lifestyles: Ants are social insects; solitary species do not exist. In the all-female populations (as in bees, males only need to fertilize a virgin queen; after that they can die) different castes varying in size and appearance have different functions. Although no ant species is marine, there is an intertidal one (Polyrhachis sokolova) and one that scavenges food from inside a pitcher plant’s insect trap (Camponotus schmitzi). Some species collect seeds or feed on other insects and small vertebrates; some clean carcasses of birds and mammals and army-ants are famous for their raids, separated by temporary bivouacs constructed by and with the ants’ own bodies. Honeypot ants have castes so round and heavy with honey that they can no longer move, while ‘aphid-tending’ ants protect (and ‘milk’) their aphids like cattle. Well-known are also weaver ants Oecophylla smaragdina (with nests of sewn-together leaves) and fungus-growing leafcutter ants. There, too, are at least 35 ant species that keep slaves of other species.

Anyhow, Hölldobler’s work that intrigued me most, dealt with unwanted beetle guests in ant nests; guests that behaved badly and had devious ways to sneak into an ant colony and not get removed. For the little antlike staphylinid beetle Atemeles to enter the nest of a Formica ant, it smells and behaves like an ant. Its larva possesses the same smell as an ant larva and for this reason remains unattacked. The beetle larva also knows how to beg for food and when it taps the mouth of a passing ant, the ant responds with regurgitating a drop of fluid, which the beetle larva ingests. The ants do not prevent the beetle larva killing and devouring the ants’ babies, but continue to feed the cheat. However, the beetle larvae’s disguise is so perfect that they themselves are in danger to be eaten by another beetle larva: these beetles are cannibals! At the end of summer the beetle larva pupates, yielding an adult beetle in autumn. The Formica host ant colony, however, stops reproducing in winter and the new beetle generation would starve  – unless, and that’s what they’re doing, they emigrate to find a nest of a Myrmica species that has eggs and larvae throughout the winter. To get into a Myrmica nest, the adult beetle secretes from its abdomen an appeasement fluid, which turns the Myrmica guards into drugged ‘friends’. Once inside the Myrmica nest the beetles have enough food, mature sexually and in spring bid good-bye to the Myrmica host and seek a Formica nest again to start a new generation.

There are even “highwaymen” beetle species that locate the ants’ foraging trails by scent and then ambush ant workers, tickle their mouthparts and steel what they spit out of what they had in their crops. Of course, harmless ‘tenants’ like some mites or springtails also exist in an ant nest; yet, I bet there are still many more species of the bad guys that await discovery. But it takes a lot of patience and good eyesight to spot them: believe me I looked for them and failed.

© Dr V.B. Meyer-Rochow and http://www.bioforthebiobuff.wordpress.com, 2021.
Unauthorized use and/or duplication of this material without express and written permission from this site’s author and/or owner is strictly prohibited. Excerpts and links may be used, provided that full and clear credit is given to V.B Meyer-Rochow and http://www.bioforthebiobuff.wordpress.com with appropriate and specific direction to the original content.

You Never Sleep Alone

Mites as bed-mates and forensic indicators

When I moved into a wonderful flat on Hachijojima in Japan, I didn’t expect that some hungry bed bug had been waiting for a new victim! Terribly itchy red bites, some three in a row on my belly, made me suspect I was not alone in my bed. A few days later I saw the bug, known as Cimex lectularius. I moved from one tatami-room to the next, hoping the pest would not move with me. I was lucky  – until I had a visitor with her pussy cat. The latter had some fleas, which tasted my blood and once again left terribly itchy marks on my legs. Luckily, cat fleas don’t adapt to human hosts and mine eventually disappeared.

However, what almost certainly remained (and is actually present in virtually all beds, mattresses and beddings all over the world) must have been thousands of mites and various microscopic fungi. It has been estimated that a typical used mattress can be home to 100,000 to several millions of mites. In a British study published in 1995 a whole ‘zoo’ of mites was identified from a mattress. The dominant species was the so-called house dust mite with 95%; other species included Euroglyphus maynei (3%), Cheyletus tenuipilis (2%), Tarsonemus sp., Lepidoglyphus destructor, Acarus siro and the follicle mite Demodex folliculorum. In North America the house dust mite Dermatophagoides farina replaces the European Dermatophagoides pternoyssinus and in the tropics the Blomia tropicalis dust mite occurs.

The comforting fact is that the house dust mites in our beds and sheets are non-parasitic and do not transmit diseases. They can, however, cause allergies and (in genetically susceptible people) asthma attacks. Unfortunately, house dust mite sensitizations are a worldwide increasing phenomenon. After sensitization, re-exposures to mite allergens like the mites’ droppings, can initiate an immunoglobulin-dependent inflammatory antibody cascade that involves small proteins produced by white blood cells. What supports mite populations apart from an ample supply of dead human (or animal) skin cells, is warm and moist surroundings and a high co-occurrence with bed fungi, especially Aspergillus niger. Other common bed fungal genera noted were Penicillium, Rhizopus, Cladosporium, Alternaria, yeasts, and Rhodotorula. A dry, non-sweating body and an abstention to eat and drink while in bed should help to reduce fungal and mite bed co-occupant populations. But species and species compositions vary on different beds, linen, and blankets and can therefore indicate to a forensic expert which bed a person has slept in, if s/he has picked up some of that bed’s species. Just like insects, whose forensic potential I have highlighted in an earlier blog (The insect crown witness) mites can therefore help criminalistic sleuths. Sherlock Holmes, did he not know that?

The Turkish professors Rana Akyazı and Ayla Tüzün, however (as well as others elsewhere in the world), knew this very well and explain in their papers that each of the five stages of a decomposing corpse (fresh, bloat, active-, advanced- and dry decay) attracts different insect and mite species to the dead body. Mites occurring on humans like Demodex folliculorum and Sarcoptes scabieihominis survive for one or two weeks, respectively, on a dead human and can therefore sometimes provide a clue on the time of death. Other mite species arrive on the dead body together with the succession of flies or beetles that colonize the corpse. Since such succession waves have been studied since 1894 when P. Mégnin’s “La Faune des Cadavres” appeared, forensic acarologists (that is what mite experts are called) can reasonably accurately determine since when a corpse has been exposed to the environment. Since indoor mites have other preferences from outdoor mites, finding them on a dead body can provide important clues as to where a crime took place. Even a corpse submerged in water may not be totally free of mite ‘informants’, because aquatic mites could contaminate the body and impart some useful hints. If only Sir Arthur Conan Doyle and Sherlock Holmes’ Dr Watson had known all this!

© Dr V.B. Meyer-Rochow and http://www.bioforthebiobuff.wordpress.com, 2021.
Unauthorized use and/or duplication of this material without express and written permission from this site’s author and/or owner is strictly prohibited. Excerpts and links may be used, provided that full and clear credit is given to V.B Meyer-Rochow and http://www.bioforthebiobuff.wordpress.com with appropriate and specific direction to the original content.