HOLOTYPE

March 28, 2016 by · Leave a Comment 

Holotypus m [von *holo-, griech. typos = Prägung, Typ], das von einem Autor bei der Beschreibung einer neuen Art festgelegte (designierte) „typische“ Individuum (Typus-Verfahren der taxonomischen Nomenklatur).

Nach den erst im 20. Jahrhundert strenger festgelegten internationalen Nomenklaturregeln muß es ein einzelnes, entsprechend gekennzeichnetes Exemplar sein. Bei Sexualdimorphismus kann entweder nur das Männchen oder nur das Weibchen der Holotypus sein; das „typische“, Individuum des anderen Geschlechts gilt dann als Allotypus.

In Zweifelsfällen gelten nicht die Angaben in der Artbeschreibung, sondern die tatsächlich am Holotypus feststellbaren Merkmale. Auch gilt der Holotypus weiterhin, wenn später festgestellt werden sollte, daß er aus einer für die gesamte Art gar nicht typisch aussehenden Population stammt. Er soll wegen dieser großen Bedeutung für Nachuntersuchungen in öffentlich zugänglichen Sammlungen verwahrt (deponiert) sein, in der Regel in großen Museen. auct., Belegexemplar, Paratypus, Typus.

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A holotype is a single physical example (or illustration) of an organism, known to have been used when the species (or lower-ranked taxon) was formally described. It is either the single such physical example (or illustration) or one of several such, but explicitly designated as the holotype. Under the International Code of Zoological Nomenclature (ICZN), a holotype is one of several kinds of name-bearing types. In the International Code of Nomenclature for algae, fungi, and plants (ICN) and ICZN the definitions of types are similar in intent but not identical in terminology or underlying concept.

For example, the holotype for the beetle “Lucanus formosus” is a preserved specimen of that species, held by the Muséum National d’Histoire Naturelle (MNHN) at Paris. An isotype is a duplicate of the holotype, and is often made for plants, where holotype and isotypes are often pieces from the same individual plant.

A holotype is not necessarily ‘typical’ of that taxon, although ideally it should be. Sometimes just a fragment of an organism is the holotype, particularly in the case of a fossil. For example, the holotype of Pelorosaurus (Duriatitan) humerocristatus, a large herbivorous dinosaur from the early Jurassic period, is a fossil leg bone stored at the Natural History Museum in London (NHM). Even if a better specimen is subsequently found, the holotype is not superseded.

HOLOTYPE Lucanus formosus DIDIER 1925

HOLOTYPE “Lucanus formosus DIDIER 1925″

 

REFERENCES:

1999 Spektrum Akademischer Verlag, Heidelberg;
2012 Antoine Mantilleri

Where the male and female symbols came from…

May 30, 2015 by · Leave a Comment 

Representing two planets, iron, copper and a couple of Olympian gods, the classical symbols for male and female pack a lot of meaning into a few squiggly lines.

The symbols themselves are ancient, and the associations they make date back to the dawn of civilization. The ancients, after observing how the movements of heavenly bodies like the Sun and planets heralded a corresponding change in events on our planet, eventually came to believe that there was a causal relationship. Logically, then, ancient scholars began to study the heavens in order to better predict, and prepare for, the future. They also came to associate different heavenly bodies with their powerful gods- Mercury, Venus, Mars, Zeus (Jupiter) and Cronus (Saturn).

male and female

Each heavenly body, along with its god, was also associated with a particular metal. So, for example, the Sun (Helios) was associated with gold (note: in truth, the Sun is white in the human visual spectrum, not yellow); Mars (in Greek, Thouros) was associated with the hard, red metal used to make weapons, iron; and Venus (in Greek, Phosphorus) with the softer metal that can turn green, copper.

Writing about these metals, the Greeks would refer to them by their respective gods’ names, and then as now, these were spelled with a combination of letters; after awhile, a type of shorthand arose; for example, relevant to Mars (Thouros) and Venus (Phosphorus):

Mars (Thouros) and Venus (Phosphorus)In medieval times, European alchemists relied on these shorthand symbols, which were retained through the Enlightenment and used by such notables as Carolus Linnaeus (the father of modern taxonomy who made binomial nomenclature popular), to refer to such metals in his 1735 work Systema Naturae.

Linnaeus was also the first to use these signs in a biological context in his dissertation Plantae hybridae (1751), where he used the symbol for Venus to denote a female parent of a hybrid plant and the symbol for Mars to denote a male parent.

Linnaeus continued to use the symbols for the purpose of distinguishing male and female, and by 1753’s Species Plantarum, he was using the symbols freely [1]
Following in Linnaeus’ footsteps, other botanists incorporated the symbolism, as did scientists from other fields including zoology, human biology and, eventually, genetics.

Modern geneticists no longer use these familiar symbols and instead rely on a square (for male) and circle (for female):

Modern GeneticsThis symbolism was developed by Pliny Earle, a doctor with the Bloomingdale Asylum for the Insane in New York in 1845 while explaining the inheritance of color blindness:

For the purpose of clearly illustrating the prevalence of this physiological peculiarity in the family, I have prepared the subjoined genealogical chart. Males are represented by squares and females by circles.

While it is not entirely clear why Earle deviated from the classical symbols, one explanation was later given by Royal Society Member, Edward Nettleship, who claimed that Earle had been “unable to get any printer’s symbols capable of use . . . except those employed in printing music.”

This post has been republished with permission from TodayIFoundOut.com. Image by Daniel Chloe Blanchfield under Creative Commons license.

How to collect beetles for DNA studies?

March 29, 2015 by · Leave a Comment 

Preserving beetles for DNA studies is easy, but a few rules need to be followed.

You will first need to decide which specimens to preserve. It is ideal to have two or more specimens of a species preserved, so that the extra specimens can serve as backups in case the first specimen fails to yield good DNA. Also, because the specimen from which DNA sequences will be obtained serves as the voucher, it is important to choose the gender that contains the key morphological characters for distinguishing species. This will allow the DNA data to be properly associated with the morphological data, type specimens, etc. For Bembidion, males contain the most diagnostic characters, and so males should be preferentially preserved for DNA. The general rule of thumb is that whatever gender is best for a holotype is the gender you should choose for DNA preservation.

Exactly how a specimen should be preserved depends upon the materials you have available. I use one of two preservation methods: in 95-100% ethanol, or in silica gel. One of the most important things that both of these do is to remove water from the beetle’s tissue, which prevents nasty enzymes from destroying the DNA. Here are some procedures I use to ensure high-quality DNA.

Ethanol preservation
95-100% ethanol is ideal; lower concentration doesn’t work as well. Drop the live beetles into ethanol. Make sure there aren’t too many beetles in the vial; ideally there is at least four times as much ethanol as there is beetle mass. The vial on the left below will have well-preserved DNA; the vial on the right is too tightly packed with beetles, and the DNA won’t be as high quality.

Charge of ethanol

right charge of ethanol

Once the beetles have all died, it is ideal to pour off the ethanol and replace it with fresh ethanol. If you can’t do that right away, that’s OK; but you should change the ethanol in the next day or two. If you can change the ethanol again a few weeks later, that would be even better.

It can also help a great deal to open the body of the beetle up so that ethanol can penetrate, especially if the specimen is large or has a very thick cuticle. When I collect, I usually open up one or two specimens this way (and preserve a few other specimens whole, without opening them up), to ensure that at least those specimens will have excellent DNA. The simplest way to do this is to hold the specimen between the thumb and forefinger in one hand, such that the abdomen is exposed, and take forceps and gently pull the abdomen slightly off, as shown below. It is best if you don’t take the abdomen off completely; that way, the abdomen is kept associated with the forebody.

dissection

dissection of the beetle

The advantage of a dissection like this is the specimen can then have the soft tissue removed for DNA extraction, and the rest of the body is in great shape for a morphological specimen. If I want an even better morphological specimen (for example, for a holotype), after the dissection I pull off the soft tissue and put it into ethanol, and put the body into sawdust and ethyl acetate (with labels to associate the two pieces, of course).

Finally, the specimen should be kept as cool as possible; if you can keep it in a fridge, or a non-defrosting freezer, the DNA will be better preserved.

Thus, the ideal is to:

  •     use 95-100% ethanol
  •     don’t put too many beetles in each vial
  •     change the ethanol twice
  •     open up the specimen slightly to allow the ethanol to penetrate
    (optional – will improve DNA quality but if other steps are  followed the DNA will still be OK)
  •     keep the specimens cool

While this is the ideal approach, most specimens will be well preserved if you just do the first three of these. Certainly, if you can only manage the first three of these, that is much better than no specimen at all.

If you don’t have 95-100% ethanol, an alternative that I have used successfully is to boil the live beetle in water for 30 seconds, and preserve it in 80% ethanol. The DNA seems to be OK in 80% ethanol for at least a few weeks if it is boiled first.

Silica gel
Another approach is to preserve specimens with silica gel. This yields very good DNA, but very brittle specimens that break in pieces.

Prepare each vial in advance by filling it half-full of dried silica gel. It is ideal to use indicating silica gel that changes color when it absorbs water; this allows you to see if the silica gel is still good, as it must be very dry to work well. (If it has changed color because it has absorbed water, you can dry it out by baking it in an oven.) Put a cotton plug on top of the silica gel to hold the silica gel in place in the vial. (Without the cotton plug, the silica gel will roll around and destroy the specimen.) Tighten the lid, and the vial is ready for use.

silica gel

right amount of silica gel

To preserve a specimen, open up the prepared vial, and put one to three live specimens in the top of the vial, above the cotton plug. Add whatever label you wish to use, and then close the lid tightly. The silica gel will dry out the beetle and preserve the DNA.

Vials
I use clear plastic vials with screw-top lids that contain an O-ring for a tighter seal. Here’s what they look like:

vials

different sizes of vials

The larger vial is about 65 mm long (with the lid on) by 15 mm wide, and is available from Sarstedt (their catalogue number 60.542.007). The smaller vial is 46 mm long by 11 mm wide, and is available from USA Scientific (their catalogue number 1420-9700).

UPDATE: Kip Will notes that he uses a slightly different procedures for the much larger beetles he works on. He twists them at the prothorax-mesothorax junction and break them open there so the ethanol can penetrate. For the larger specimens he changes the ethanol three times. If they are >25mm then he puts a leg or two separately into ethanol.

Written by David Maddison

Why beetles have “hard” elytra?

March 6, 2015 by · Leave a Comment 

One of the most important features of Coleoptera is their ‘elytra’, the hard exoskeletal which covers their wings. The ‘elytra’ helps to protect the beetle but also has many other functions, too. Some beetles trap moisture in their wings and the elytra protects it from drying in heat and wind, this means the beetles can travel across arid deserts without dehydrating. Other Coleoptera can live under water because they can store air in their wings, which is again protected by the elytra. Coleoptera (beetles) are most probably the most versatile creatures on earth. The beetles exoskeleton is made up of numerous plates called sclerites (a hardened body part), separated by thin sutures. This design creates the armoured defenses of the beetle while maintaining flexibility.

Beetle_description

The morphology of a fiddler beetle

Scientists interested in cuticle structure[1] have examined cuticle from the elytra of the red flour beetle, Tribolium castaneum. The elytra have two proteins in large amounts that are not present in the membranous hindwings. These proteins are associated with hard cuticle both in the elytra and elsewhere on the beetle. The cuticle of the elytra becomes hard and rigid from extensive crosslinking, or chemical connections between the protein strands. This evidence from red flour beetle suggests that in the evolutionary past, an ancestor of modern beetles had a mutation caused proteins for cuticle crosslinking to be expressed in the forewings. The up regulation of two cuticle genes in the forewings may be a key to the evolution of elytra.

The elytra are not used for flight, but tend to cover the hind part of the body and protect the second pair of wings. The elytra must be raised in order to move the hind flight wings. A beetles flight wings are crossed with veins and are folded after landing, often along these veins, and are stored below the elytra.

Cerambycid_beetle_open_elytra_s

Cerymbycid beetle ready for takeoff [3]

In some beetles, the ability to fly has been lost. These include the ground beetles (family Carabidae) and some ‘true weevils’ (family Curculionidae), but also some desert and cave-dwelling species of other families. Many of these species have the two elytra fused together, forming a solid shield over the abdomen. In a few beetle families, both the ability to fly and the elytra have been lost, with the best known example being the glow-worms of the family Phengodidae, in which the females are larviform (where the females in the adult stage of metamorphosis resemble the larvae to various degrees) throughout their lives.

“Nature is replete with examples of layered-structure materials that are evolved through billions of years to provide high performance. Insect elytra (a portion of the exoskeleton) have evoked worldwide research attention and are believed to serve as fuselages and wings of natural aircraft. This work focuses on the relationship between structure, mechanical behavior, and failure mechanisms of the elytra. We report a failure-mode-optimization (FMO) mechanism that can explain elytra’s mechanical behaviors. We show initial evidence that this mechanism makes bio-structures of low-strength materials strong and ductile that can effectively resist shear forces and crack growth. A bio-inspired design of a joint by using the FMO mechanism has been proved by experiments to have a potential to increase the interface shear strength as high as about 2.5 times. The FMO mechanism, which is based on the new concept of property-structure synergetic coupling proposed in this work, offer some thoughts to deal with the notoriously difficult problem of interface strength and to reduce catastrophic failure events.” [2]

REFERENCES:

[1] Mi Young Noh, Karl J. Kramer, Subbaratnam Muthukrishnan, Michael R. Kanost, Richard W. Beeman, Yasuyuki Arakane. Two major cuticular proteins are required for assembly of horizontal laminae and vertical pore canals in rigid cuticle of Tribolium castaneum. Insect Biochemistry and Molecular Biology. 53: 22-29.

[2] Fan, J.; Chen, B.; Gao, Z.; Xiang, C. 2005. Mechanisms in Failure Prevention of Bio-Materials and Bio-Structures. Mechanics of Advanced Materials and Structures. 12(3): 229-237.

[3] Species 2000 & ITIS Catalogue of Life

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Why do entomologists kill insects?

February 27, 2015 by · Leave a Comment 

A non-taxonomist’s perspective…

Admittedly, this isn’t really a direct user submission per se, but it’s a question which comes up in the entomological world enough to warrant a discussion. Collecting of insects is not controversial amongst entomologists, but seems to strike a chord with many people who are interested in entomology. There’s the perception that entomologists are like big-game hunters and kill insects simply as trophies. Some of the comments regarding this topic can be quite… passionate …and there’s been a lot of heated discussion about why people collect and kill insects.

Anti-collecting comments from Facebook Entomology group, posted under undergraduate collections.
First three easily legible comments were chosen:

User 1: “I live with insects and large animals, so shut up man. I don’t kill flies and mosqitos, nor wasps and roaches. Dna is perishable (or degradable, i don’t know english very well) and certainly no scientist will take dna from theese collections. You are hiding sadism by science. Also, I do not mean the extinction of species, but of higher value of this life in comparison to the attainment of a degree or other useless social conventions. And anyway, I’m sorry to give you this terrible news, but the dna you can get by collecting animals already dead.”

User 2: “You might also want to consider taking photos of butterflies as a recording system, rather than killing and pinning them. You could also educate yourself in the trending decline of butterfly species worldwide? Collecting for scientific purposes is one thing, but to promote the collecting and killing of butterflies as a pastime is abhorrent.”

User 3: “In this page they don’t understand. They said it’s not impossible to find them already dead in “natural way” but it’s too difficult, so they kill’em, probably thinking themselves like gods, only due to their study.”

The reality is a bit different from the perceptions of the posters above. Insects are collected for many reasons, and killed for many more. Taxonomists, the entomologists who describe new species and classify life into systematic groups, often bear the brunt of the blame for insect-killing. Consequently, there’s been a lot of discussion on the internet by taxonomists who explain why collecting is essential to science. Many people are concerned that scientists are helping lead to the destruction of insect species, however the few specimens that scientists do collect for research purposes are not contributing to species loss. A much more pertinent threat to insects is habitat loss and degradation. The posts we linked to are our favorites which explain why killing insects is essential to preserving them, as paradoxical as it may seem. While taxonomists have done an excellent job of discussing why they collect insects, there’s been a lot less attention to why insects need killed in the course of education, pest control, and research…and that’s what we want to mention in this post. We want to discuss the reasons entomologists kill insects in order to further the understanding of their biology among the public, to insure the survival of our agricultural systems, insure our own survival, and so we can further our understanding of their biology.

Why discuss insect killing?

Although we love insects, we’ve always been a bit uncomfortable with entomology as a field. Insect biology is extremely cool, because Lovecraftian or Kafka-esque biology comes standard with most species. Some insects eat their own mothers, while others will essentially age backwards to escape starvation. The majority of insects change into completely different creatures when they turn into adults. They’re so far removed from anything we can identify with, that you can spend hours at a time reading about their biology. Whereas most people have golf magazines by the toilet, Joe’s current reading material is about a group of caddisflies which lay their eggs in the arms of a sea star. Most entomologists are this way, and many of our conversations with our colleagues and co-workers revolve around this sort of stuff because everybody we’ve ever worked with has been as passionate about insect biology as we are. However, a lot of entomologists (ourselves included) must research new ways to kill insects even though we love them as organisms.

So … contrary to what some posters above have said we love insects, but we also research new ways to kill them.
Why do we do this?

1.) Entomologists need collections to educate the public

Nancy with a Malaysian Jungle Nymph.

Nancy with a Malaysian Jungle Nymph.

In order to reduce the chances of introducing invasive species, there are many restrictions to owning live insects. The University of Georgia, where Joe and Nancy obtained their Master’s degrees, (and where Nancy is still working) recently received permits to have and rear exotic insects. The process to obtain the permits was painstaking and specialty rearing facilities had to be obtained. The only other place in the Eastern United States to have these permits is the Smithsonian museum.,

Public outreach with preserved specimens.

Public outreach with preserved specimens.

In contrast to live collections, preserved insects are often for sale and there are fewer laws pertaining to the possession and selling of these items. Therefore, with these artfully done collections, we can captivate the curiosity and wonder of children and the public. We can make people who had been fearful, disinterested, or disenchanted with insects become curious, astounded with their natural beauty, and wonder about their remarkable biology. With collections, it is possible for us, as educators and scientists, to visit rural schools in Georgia, USA and show children what insects in rural Africa look like. And while some of this can be done with photography, having someone see with their own eyes a physical specimen the size of their head cannot be replaced by mere images.

2.) Entomologists protect our food supply

Bt cotton

Farming Bt cotton

Everybody needs to eat. Agriculture is the cornerstone of civilization, and by 2100 we’re going to need to be a lot better at agriculture because there may be as many as 11 billion people on this planet. Unfortunately, agriculture is also extremely inefficient. For every 100 lbs of food which could potentially be harvested, only about 30 lbs is used by consumers. Some of this is waste, but a lot of this is pest damage.

As an agricultural scientist, Joe looks at the situation like this: Of 100 lbs of food grown around the world, 70 lbs of it is lost along the way on average. Of those 70 lbs, 35 lbs of that is lost in the field before harvest. If every farmer stopped all pest control measures, that number would increase to 70 lbs of food lost before harvest. Without any additional increases in efficiency between field and table, the amount of land needed for agriculture would explode…and that would not be a good situation.

Our biggest animal competitors for food, fiber and shelter are insects. Insects attack food products at various points in the production chain. The examples which spring most readily to mind are those which attack plants in the field, but insects also attack food while it’s being stored. On average, pest and disease losses in the field are between 20 and 40% depending on the crop. In storage, 10-15% of the crop can be lost to pests and the value of the harvest can be dropped by up to 50% due to loss of quality. Complete losses of some crops aren’t uncommon either. Insect infestation also leads to other problems by encouraging the growth of mold that produces aflatoxins, so the losses due to infestation can lead to larger losses due to a loss of quality. While this secondary problem might sound minor, aflatoxins are among the most carcinogenic substances known and are thus one of the biggest and most persistent public health challenges.

Damage to raspberry by D. suzukii. Arrows indicate maggots.

Damage to raspberry by D. suzukii. Arrows indicate maggots. (LINK)

To give one very specific example…you might have noticed the increase price and decreased quality of summer berries this year. That’s because a recent invasive species, Drosophila suzukii, has been scaling its way up the eastern United States. Although it has been in Hawaii since the late 1980’s, by 2010 the fly had been spotted in North and South Carolina, Louisana and Utah in addition to Michigan and Wisconsin. D. suzukii deposits its eggs in summer berries like blueberries, raspberries, and blackberries. The maggots eat the flesh of the fruit, but seem to leave unnoticeable damage until the berry is broken into which exposes many the little wriggling maggots. As you can imagine, this makes the fruit unmarketable. In 2008 alone this fly was responsible for $500 million worth of damage, and some farmers lost 80% of their crop. It’s possible that other countries will refuse to buy our fruit out of fear of accidentally introducing this pest, so there are economic consequences beyond yield loss. In order to protect the livelihoods of these farmers, someone has to figure out how to manage this pest and lots of research has gone into understanding its basic biology.

Agricultural scientists work towards solving these problems by developing better tools for controlling insects. In some cases, insects can be controlled by making the environment really tough to live in through the use of biological controls. In some cases, this isn’t a feasible option and insects need to be controlled through other means. Either way, if we didn’t control insects there would likely be widespread starvation or exorbitant food prices.

3.) Entomologists protect human health

Anopheles gambiae, a mosquito responsible for more human suffering than war.  James D. Ganthany, via Wikimedia commons.

Anopheles gambiae, a mosquito responsible for more human suffering than war.
James D. Ganthany, via Wikimedia commons.

Diseases spread by insects are another huge problem for public health, mostly in developing countries. Every year almost a quarter-billion people contract malaria, and well over half a million die worldwide from the disease. In areas where the disease is found, it can affect every conceivable aspect of life from how people make money to how many children they have. It may be difficult to believe, but malaria was in the US as late as the 1940s. In the year 1934, there were 140,000 cases…and the disease was effectively gone from the US by the early 1950s. A combination of a convenient climate, a good economy, pesticide sprays, and habitat elimination facilitated this. Vector control continues to be an extremely important component of public health measures, because we continue to see malaria imported into the US from travelers.

The story of malaria is an important one, because it demonstrates how important vector control is for maintaining a healthy population. Worldwide, over half the population is at risk for contracting a vector-borne disease. The US is no different, although we are relatively fortunate to have the resources to fight these diseases and a climate which makes them easy to combat. Keeping the populations of disease vectors down is really important. In short, medical entomologists work to reduce human suffering by killing insects.

4.) Killing insects is essential to studying biological function

Pan trapping is often used to identify arthropod presence in a given area. Here, pan traps are being used to survey for oceanic island arthropod biodiversity

Pan trapping is often used to identify arthropod presence in a given area. Here, pan traps are being used to survey for oceanic island arthropod biodiversity (LINK)

This last one is admittedly the purpose of killing insects which the posters above were talking about. Collecting insects is essential for documenting their presence for a number of reasons. Many insects (as discussed in our first post) are simply too small to see, and a lot of collection methods kill the insects during the course of collection. In addition, a lot of important insect parts need to be extracted for species-level identification. Often the methods required for this aren’t possible to perform on live insects, and when they are they often injure the insects anyways. The posts written by taxonomists give more details about these methods.

There are a lot of research methods which require live field collected insects. Sometimes, you’re interested in biological characteristics of insects in the real world and captive reared insects just can’t be used to answer those questions. Other times, the insects you’re interested in may be impossible or impractical to rear in captivity. Bee research is a good example of this sort of limitation, there are a lot of bee species which can’t be reared in captivity. In bee research, researchers are often interested in real-world responses and this necessitates the capture of live insects from the field. Questions about presence, life history, abundance, and seasonality are all most effectively answered through collection techniques that kill the insects, but otherwise these questions, like questions about native pollinators, could not be answered.

The Bottom Line?

Entomologists are uncomfortable killing insects, and we don’t take it lightly. If we did, we wouldn’t be very good at our jobs. Most entomologists are deeply concerned about environmental issues, and have thought long and hard about why we’re doing what we’re doing. There are a lot of protocols in place to make sure our experiments don’t result in the extinction of species…and we’re constantly working to make public health and agricultural practices more sustainable in the long-term. Although it may seem paradoxical, wise management of insects for public health and agriculture is an environmental concern, and most entomological conservation research would not be possible without killing insects.

Co-Written by Joe Ballenger and Nancy Miorelli

Lucanus wemckeni SCHENK, 2006

March 11, 2014 by · Leave a Comment 

Lucanus wemckeni SCHENK, 2006

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Lucanus liuyei HUANG & CHEN, 2010

March 8, 2014 by · Leave a Comment 

Lucanus liuyei ssp. incert HUANG & CHEN, 2013

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What are ‘good species’?

March 6, 2014 by · Leave a Comment 

Recently in TREE, Mallet [1,2], argued for an operational, concept-free definition of species as ‘genotypic clusters’, asserting ’that species are man-made groupings’ [2]. However, Mallet resorts to the traditional notion of ‘good’ species for final arbitration regarding what degree of variation is appropriate for the species-level taxon.

This is a poor species definition for two reasons. As an operational definition it leaves us with no means for dealing with the great complexities of biological systems of descent. Moreover, the decision as to what constitutes species-level variation is based on an essentialistic perspective offered by a ‘good taxonomist’s or naturalist’s definition’ [1].

If species are, in Mallet’s operational terms, ‘groups that remain recognizable in sympatry because of the morphological gaps between them’ [2], it is important to realize that they are nothing more than the sum of the operations that serve to identify them [3,4]. We are left with the arbitrary decision of how large these gaps must be and what frequency of intermediates would lead us to accept two species rather than one. These difficulties are problematic for the diagnosis of a ‘species’ under any definition or concept, due to the fuzzy nature of groups resulting from, or participating in, the evolutionary process (i.e. natural groups).

However, they are more severe for a concept-free definition because we have no theoretical guideline with which to sort variation into hypotheses about natural groups. A conceptfree definition of species as ‘genotypic clusters’ must also deal with the discrete morphological variation manifest, for example, between genders of many plants and animals. These are ‘genotypic clusters’ of sorts. However, neither today, nor in Darwin’s time, do biologists wittingly hypothesize different species for different genders. Without an ontological context with which to sort variation in biological systems, we find ourselves perplexed by situations as straightforward as sexual dimorphism.

In stark contrast to his purely operational definition, Mallet alludes to such an ontological framework by reference to ‘good’ species [2]. But what are ‘good’ species? Mallet endorses the traditional position that, in the most difficult cases, the ultimate authority of the existence of ‘good’ species is the taxonomist or naturalist.

The implication of this deference to the taxonomist is that ‘good’ species exist, but that their essential nature is hidden; a taxonomist’s contribution is to reveal ‘good’ species through description, case by case. Thus, the notion that ‘good’ species can be revealed to us by taxonomic authorities is  steeped in the essentialistic outlook that Mallet [1,2] (and others [5]) seek to condemn. Furthermore, the definition of a species becomes ‘a group of organisms that is recognized as a ‘good’ species by the taxonomist or naturalist.’

This is obviously undesirable. Although taxonomists may point to groups that they believe exist, species will only have objective value if the general properties of ‘good’ species (the species taxon) are revealed to the rest of us. Whereas a purely operational definition causes us to forego the question, ‘what is the nature of the group that we might call species?’, asserting the existence of ‘good’ species (even if we knew their properties) demands that all groups of organisms, that we might call species, exist in the same ways. A definition that results in one or both of these outcomes should be avoided, particularly in studies of speciation where we are interested in all the natural groups produced by a pluralistic process of evolution. It is a step forward for students of speciation to acknowledge that different sorts of natural groups have valid claims to the term ‘species’ [6,7].

Similarly, it is regressive to undermine the notion that the species taxon (whatever natural group we choose for it to designate) has underlying properties that make it worth studying. One possible solution is provided by a nominalistic approach [6-9], which formulates a species definition explicitly while retaining the ontological meaning that a purely operational definition leaves behind. Such a definition would embody a statement of the necessary and sufficient properties for the diagnosis of species in any particular case. The important distinction between a nominalistic definition and Mallet’s is that our avenue of inquiry would lead us to explore the nature and evolution of natural groups (as opposed to some notion of a ‘good’ species), with or without a coextensive relationship between such groups and ‘good’ species (whatever they are!).

Kerry L. Shaw
Dept of Organismic and Evolutionary Biology, Harvard University, 16 Divinity Avenue, Cambridge, MA 02138, USA


References
[1] Mallet, J. (1995) Trends Ecol. Evol. 10,294-299
[2] Mallet, J. (1995) Trends Ecol. Evol. 10, 490-491
[3] Hull, D.L. (1968) Syst. Zoo/. 17,438-457
[4] Baum, D.A. and Donoghue, M.J. (1995) Syst. Bot. 20, 560-573
[5] Mayr, E. (1982) The Growth of Biological Thought, Belknap
[6] de Queiroz, K. and Donoghue, M.J. (1990) Cladistics 4, 317-338
[7] de Queiroz, K. (1994) Syst. Biol. 43, 497-510
[8] Popper, K.R. (1966) The Open Society and its Enemies (5th edn), Princeton University Press
[9] Baum, D.A. and Shaw, K.L. (1995) in Experimental and Molecular Approaches to Plant  Biosystematics
(Hoch, PC. and Stephenson, A.G., eds), pp. 289-303, Missouri Botanical Garden

Plants And The Human Brain

February 7, 2014 by · Leave a Comment 

Why humans think like insects…

Similarities between human and insect brains could be the reason why humans are attracted to plant-derived chemicals, such as tea, coffee, tobacco and drugs, according to a new book.

Professor David Kennedy, of Northumbria University, Newcastle, believes his new book, Plants and the Human Brain, answers the question as to why are affected by .

Despite many studies into how plant-derived chemicals interact with the and affect our behaviour, mood, mental and physical functions, there has been little research into why these chemicals have these effects at all.

Professor Kennedy, Director of Northumbria University’s Brain Performance and Nutrition Research Centre, believes that similarities between human and insect brains can explain why humans are affected by and, in some cases, attracted to plant-derived chemicals.

Professor Kennedy states that human brains are fundamentally just a more complex version of the insect brain, with many striking similarities and patterns of behaviour. These include the use of exactly the same neurotransmitters, receptors and physiological processes.

PlantsBrain

He explained: “Plants evolved to interact with the brains of insects, their closest neighbours, in order to survive, by attracting them for pollination, or repelling them or dissuading them from eating . Therefore, plant chemicals that have evolved to target the brains of insects then have the same effects on the human brain.

“Humans have a long and close relationship with plant-derived chemicals that alter brain function. Most of us reach for a cup of tea or coffee in the morning, many smoke tobacco; a few consume heavyweight drugs such as cocaine, morphine or cannabis.

“If you give the chemicals we think of as social drugs to insects, the change in behaviour is often strikingly similar to that seen in humans. For instance, caffeine and amphetamine make insects more active and less sleepy, LSD makes them confused, cocaine makes bees dance, and morphine kills insect pain. And all of these chemicals also stop insects from eating plant tissue and prove fatal to them at higher doses.”

Professor Kennedy’s book, published by Oxford University Press, explains some of the similarities in the genetics of plants and humans and how these similarities impact on human mental function.

“This book as a whole is novel because it is the first time anyone has tried to answer the question of ‘why’ rather than ‘how’ plant chemicals affect the human brain and behaviour,” said Professor Kennedy.

“Plants and humans share about 3,000 ancestral genes, which underlie a host of unexpected similarities.

“For example, plants synthesise and use most of the ‘neuro-chemicals’ that are found in the human brain, sometimes in concert with similar receptors that allow the chemicals to relay messages. The two also share the same communication processes within cells, and this factor in particular may provide the avenue for the brain performance and health benefits seen after we eat fruit and vegetables.

“We are not as different from plants as we would like to think, and our brains are, in most respects, the same as an insect brain – albeit much more complex.”

More information: Plants and the Human Brain, by David O. Kennedy is published by Oxford University Press and will be released on February 7th in the USA and during March in the UK.

Lucanus choui HUANG & CHEN, 2013

February 5, 2014 by · Leave a Comment 

Lucanus choui HUANG & CHEN, 2013
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Lucanus hewenjiae HUANG & CHEN, 2013

February 5, 2014 by · Leave a Comment 

Lucanus hewenjiae HUANG & CHEN, 2013

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Fossil Big-Headed Flies

January 25, 2014 by · Leave a Comment 

Scientists led by Dr. Bruce Archibald of Simon Fraser University have discovered three extinct species of big-headed flies that lived in what is modern North America during the early Eocene period, between 52 and 49 million years ago.

Fossil Fly

Modern big-headed fly shows its round head covered by compound eyes. (© Nikola Rahmé)

“Big-headed flies are a group of bizarre insects whose round heads are almost entirely covered by their bulging compound eyes, which they use to hunt for mainly leafhoppers and planthoppers, renowned common garden insect pests,” Dr. Archibald said.

The three new species belong to the living family Pipunculidae, which includes more than 1,300 species found worldwide.

“One fossil, Metanephrocerus belgardeae, is well-enough preserved to name as a new species,” Dr. Archibald said.

“It is named in honor of its finder, Azure Rain Belgarde, a student at the Paschal Sherman Indian School, who uncovered it on a field trip to the fossil deposits at Republic, Washington state.”

The other two unnamed, more enigmatic species are described from less complete fossils uncovered at Quilchena in southern British Columbia.

Fossil Fly

Newly discovered species of fossil big-headed fly named “Metanephrocerus belgardeae” (© Simon Fraser University)

 “The newly discovered species were preserved in Eocene epoch fossil beds that are 49 to 52 million years old, which is about 12 to 15 million years after the extinction of the dinosaurs. This great extinction event also disrupted forests in which the dinosaurs had lived, with mostly low diversity and greatly disrupted food webs for millions of years,” said Dr. Archibald, who is the lead author of a paper published in the Canadian Entomologist.

By the time of these flies in the Eocene, however, forests had diversified again, but this time with many new kinds of flowering plants that are familiar to us today, such as birches, maples, and many others.

Along with these new, rich forests came an expanding diversity of pollinators and herbivorous insects, and with them, diversification of their insect predators, including these big-headed flies.

“With these new discoveries, we see that the early history of these oddly shaped insect predators provides a part of the puzzle revealing the broad ecological-evolutionary revolution of expanding predator-prey relationships and increasing biodiversity during the formation of new ecosystems,” Dr. Archibald said.

Archibald SB et al. Early Eocene big headed flies (Diptera: Pipunculidae) from the Okanagan Highlands, western North America. The Canadian Entomologist, published online January 03, 2014; doi: 10.4039/tce.2013.79 Scie-News.com

BLACK LIST

September 8, 2013 by · Leave a Comment 

International “BLACK LIST”

Information about untrustworthy persons for buying, selling and trading insects

Coming-Soon

Goliath Birdeater – Theraphosa blondi LATREILLE, 1804

August 13, 2013 by · Leave a Comment 

The Goliath birdeater (Theraphosa blondi) is a spider belonging to the tarantula family, Theraphosidae. It is considered to be the second largest spider in the world (by leg-span, it is second to the giant huntsman spider), and it may be the largest by mass. It is also called the Goliath bird-eating spider; the practice of calling Theraphosids “bird-eating” derives from an early 18th-century copper engraving by Maria Sybilla Merian that shows one eating a hummingbird, but the term is inaccurate as they do not primarily prey on birds.[1]

Theraphosa blondi LATREILLE, 1804

Theraphosa blondi LATREILLE, 1804 (© F.Stumpe)

 Theraphosa blondi is native to the rain forest regions of northern South America. Wild Goliath birdeaters are a deep-burrowing species, found commonly in marshy or swampy areas, usually living in burrows that they have dug or which have been abandoned by other burrowing creatures. Females always mate and sometimes end up eating their mates. Females mature in 3 to 4 years and have an average life span of 15 to 25 years. Males die soon after maturity and have a lifespan of three to six years. Colors range from dark to light brown with faint markings on the legs. Birdeaters have hair on their bodies, abdomens, and legs. The female lays anywhere from 100 to 200 eggs, which hatch into spiderlings within two months.

Theraphosa blondi LATREILLE, 1804

Theraphosa blondi LATREILLE, 1804

Theraphosa blondi LATREILLE, 1804

Theraphosa blondi LATREILLE, 1804 (© F.Stumpe)

These spiders can have a leg span of up to 30 cm (12 in) and can weigh over 170 g (6.0 oz). Birdeaters are one of the few tarantula species that lack tibial spurs, located on the first pair of legs of most adult males. Like all tarantulas, they have fangs large enough to break the skin of a human (1.9–3.8 cm or 0.75–1.5 in). They carry venom in their fangs and have been known to bite when threatened, but the venom is relatively harmless and its effects are comparable to those of a wasp’s sting. Tarantulas generally bite humans only in self-defense, and these bites do not always result in envenomation (known as a “dry bite”). Also, when threatened, they rub their abdomen with their hind legs and release hairs that are a severe irritant to the skin and mucous membranes.

Theraphosa blondi LATREILLE, 1804

Theraphosa blondi LATREILLE, 1804 (© F.Stumpe)

Despite its name, the Goliath birdeater does not normally eat birds. As with other tarantulas, their diet consists primarily of insects, rodents, frogs and birds. However, because of its naturally large size, it is not uncommon for this species to kill and consume a variety of vertebrates. In the wild, larger species of tarantula have been seen feeding on rodents, frogs, lizards, bats, and even venomous snakes.

Theraphosa blondi LATREILLE, 1804

Theraphosa blondi LATREILLE, 1804 (© F.Stumpe)

In captivity, the Goliath birdeater’s staple diet should consist of cockroaches (generally the Dubia cockroach, Blaptica dubia). Spiderlings and juveniles can be fed crickets or cockroaches that do not exceed the body length of the individual. Feeding of mice is discouraged because of the risk of injury to the tarantula.

Literature:

[1] HERZIG, Volker, KING, Glenn F. 2013. The Neurotoxic Mode of Action of Venoms from the Spider Family Theraphosidae”. Nentwig, Wolfgang. Spider Ecophysiology. p. 203. ISBN 3643229891

 

Invasive Ladybugs – Secrets Of Their Success

May 30, 2013 by · Leave a Comment 

Not everyone has what it takes to be a successful invader. Most species that find their way to foreign lands starve, get eaten or otherwise fail to establish themselves in significant numbers. But every so often an organism thrives so well in its new terrain, that it ends up trampling much of the native flora and fauna. Harmonia axyridis – the harlequin ladybug – is one such formidable conqueror. Native to Asia, the ladybug (or ladybird if you prefer*) was deliberately introduced into Europe and North America during the 20th Century as a form of chemical-free pest control. I’m sure it seemed like a great idea at the time; Harmonia axyridis are voracious consumers of plant-plaguing aphids, and they’re darn cute by insect standards. What could possibly go wrong? Alas, as with many such introductions, the Asian ladybugs proved to be too much of a good thing, outcompeting equally adorable native ladybugs and then setting their sites on our fruit, including (gasp!) our wine grapes. Clearly, they’re a menace. But an impressive menace nonetheless. What’s their secret? Do they eat faster? Breed faster? Con the native ladybugs out of their lunch money?

Ladybugs

One thing the harlequin ladybug has going for it is its ability to defend against a wide range of pathogenic microorganisms. This is useful when encountering unfamiliar microbes outside one’s native range (when in Rome, it’s best not to be too susceptible to Rome’s germs). But a recent study in Science suggests that the invasive harlequins may also be aided by another species, a single-celled parasitic fungus that functions as a biological weapon against native ladybugs.

Something you should know about ladybugs in general – they often eat the eggs and larvae of competing ladybug species. For the harlequin ladybugs dining on native species’ young, this serves as both a nourishing snack and a means of reducing future competitors. But for native species partaking in little harlequins, the meal can be fatal. It was previously thought that the invasive ladybugs infused their eggs with a toxin to protect against this kind of predation. The metabolite harmonine (unique to the harlequins, and a contributor to their microbial resistance) was the likely cause of such interspecies poisonings. But when the authors injected native species Coccinella septempunctata (aka the seven-spot ladybug) with synthetic harmonine nothing happened. So much for that idea.

Coccinella septempunctata - (© Strt)

Coccinella septempunctata – (© Strt)

While scrutinizing the harlequin hemolymph (bug blood) for other possible culprits, the researchers found that it was teeming with a parasitic fungus of the Nosema genus. Hearty harlequins seemed unfazed by this fungus. It lounged around their blood in inactive spore form. But the less well-protected seven-spot ladybugs were easily taken down by the microbe, at least in the laboratory. Those injected with fungus isolated from the harlequin blood died within two weeks, while ladybugs dosed with a cell-free version of the hemolymph (i.e., no fungus present) survived the ordeal unscathed.

Harmonia axyridis - Harlequin lady beetle (© Strt)

Harmonia axyridis – Harlequin lady beetle (© Strt)

If these latest findings accurately reflect what goes on in the wild, this could mean that the harlequin ladybug owes its dominance to the combination of harboring and yet being resistant to an otherwise deadly parasite. Haven’t we seen this before somewhere? One obvious analogy is that of human invaders wiping out the locals by bringing along their homegrown germs. But for me the ladybugs brought to mind smaller organisms – bacteria. Soil dwelling bacteria are the original manufacturers of antibiotic drugs, and they developed these chemical weapons to eliminate nearby competitors and thus secure their food supply. In order to deploy such weapons, the bacteria had to protect themselves against these same chemicals, and so we also got antibiotic resistance genes as part of the package (less ideal for our species, but it’s working out quite well for the bacteria). Of course harlequin ladybugs aren’t making their own fungus, but there is some evidence that the spores are transmitted from parent to egg, and the whole arrangement seems strangely symbiotic. (Disclaimer: this is purely my speculation, not anything actually proposed in the article.)

And, as with bacteria-borne antibiotics, there may be something useful for us in this too. While the authors note that harmonine may not be the specific agent keeping the harlequin’s fungal residents in check, the compound has been shown to inhibit a variety of microbes, including those responsible for human ailments like tuberculosis and malaria. But if you’re trying to get rid of aphids, you might want to stick with soapy water.

* Entomologists would prefer that you prefer “ladybird” as these insect aren’t proper “bugs”, but I’m not that picky.
Alex Reshanov

Giant weta – a kind of huge cricket or grasshopper

March 31, 2012 by · Leave a Comment 

Fortunately for most of us this terrifying looking critter is only found on New Zealand, tough break Kiwis.

The ugly bugger is a giant weta, a kind of huge cricket or grasshopper. The giant wetas are supposed to have come about due to New Zealand’s lack of land mammals, until humans arrived there. A phenomenon known as island gigantism meant that some ugly invertebrates filled the space in the food chain by the lack of land mammals, so the wetas evolved into 50g crickets over 10cm long filling a similar role to what mice do in the rest of the world.

Giant wetas are vegetarian, but they can still give you a nasty bite if they don’t like the look of you.
(by Edgar Allan)

Giant weta – A kind of huge cricket or grasshopper

Titanus giganteus LINNAEUS, 1771 – A real “Titan”

March 31, 2012 by · Leave a Comment 

We’ll kick things off with this monster, it’s a Titan beetle.
The biggest Cerambycidae – Titanus giganteus LINNAEUS, 1771.

Titanus giganteus LINNAEUS, 1771

The Titan is one of the world’s largest beetles and is found in the South American rainforests, it grows up to 15cm (6 in) long. The insect’s ferocious looking mandibles are said to be strong enough to snap through pencils, quite what they’re used for is a mystery, as the adult beetles don’t actually eat. All the adults do is fly around looking for a mate. The larvae are extremely difficult to find, but bore holes in trees suggest that the juvenile Titan is a two-inch-thick, foot-long maggot. (by Edgar Allan)

Titanus giganteus LINNAEUS, 1771 – the face view

Titanus giganteus LINNAEUS, 1771 – the face view

Titanus giganteus LINNAEUS, 1771 – body view – 169 mm – a real giant

Titanus giganteus LINNAEUS, 1771 – total body length – 169 mm

Home forest for Titanus giganteus – The Amazon Rainforest

The light trap in the night – catching the “Titan”

The light trap in the night – catching the “Titan”

“King of Wasps” found in Indonesia

March 29, 2012 by · Leave a Comment 

Two-and-a-half inch monster has jaws longer than its legs…

A new species of wasp discovered on the Indonesian island Sulawesi is two-and-a-half inches long, and has jaws so vast that its discoverer admits, ‘I don’t know how it can walk.’ Lynn Kimsey, professor of entomology at the University of California, Davis, says ‘Its jaws are so large that they wrap up either side of the head when closed. When the jaws are open they are actually longer than the male’s front legs.’

King of Wasps - male with giant jaws

Kimsey discovered the warrior wasp on the Mekongga Mountains in southeastern Sulawesi. She says its enormous size and ferocity makes it like ‘the Komodo Dragon of wasps’. ‘I’m going to name it Garuda, after the national symbol of Indonesia,’ Kimsey said. Garuda – known as ‘King of Birds’ – is a powerful mythical warrior that’s part human and part eagle, boasts a large wingspan, martial prowess and breakneck speed. ‘The first time I saw the wasp I knew it was something really unusual,’ said Kimsey. ‘I had never seen anything like this species of Dalara. We don’t know anything about the biology of these wasps. They are only known from southwestern Sulawesi.’

King of Wasps - impressive male

Kimsey believes that the wasp’s huge jaws could be used in defence and for mating, allowing a male to hold a female in position. ‘The large jaws probably play a role in defense and reproduction,’ she said. ‘In another species in the genus the males hang out in the nest entrance. This serves to protect the nest from parasites and nest robbing, and for this he exacts payment from the female by mating with her every time she returns to the nest. So it’s a way of guaranteeing paternity. Additionally, the jaws are big enough to wrap around the females thorax and hold her during mating.’

Rob Waugh

‘King of Wasps’ found in Indonesia: Two-and-a-half inch monster has jaws longer than its legs

How many species are there?

March 24, 2012 by · Leave a Comment 

An interesting research note just came out in the American Naturalist by Hamilton and colleagues entitled quantifying uncertainty in estimation of tropical arthropod species richness. I retweeted a Science Daily twitter feed on this that had a terribly misleading opening line: “New calculations reveal that the number of species on Earth is likely to be in the order of several million rather than tens of millions“. This is, of course, absolute rubbish because the authors only looked at estimating tropical arthropod richness, not all species on Earth. The number of protists alone is probably > 4 million species, and there are an estimated > 1.5 fungi.

That whinge about crap reporting aside, this is what Hamilton and colleagues concluded:

  • using stochastic models, they predict medians of 3.7 million and 2.5 million tropical arthropod species globally
  • estimates of 30 million species or greater are predicted to have < 0.00001 probability
  • uncertainty in the proportion of canopy arthropod species that are beetles is the most influential parameter
  • in spite of 250 years of taxonomy and around 855000 species of arthropods already described, approximately 70 % await description

Interesting, but I didn’t give it much notice until New Scientist contacted me to get an assessment (their article will appear shortly). This is what I had to say:In general, I commend the authors for attempting to shed some mathematical light on the problem of species richness estimation. I believe that many species richness estimates are inflated for a number of taxa given the paucity of reasonable data with which to make extrapolations. I therefore support the notion that some estimates (e.g., > 30 million tropical arthropod species) are unrealistic.

That said, I believe that the approach potentially underestimates the influence of beta diversity on simple alpha diversity algorithms. Although they acknowledge that changing specialisation across a species’ range is possible (but could not correct for this), their algorithm completely ignores three MAJOR driver of biodiversity patterns: (1) the community of local competitors, (2) the community of local predators and (3) the biogeographical history of a particular ecosystem. These will shift enormously across a species’ range and impose a plethora of constraints that tend to promote speciation (i.e., greater number of niches).

Additionally, but related to the above, taking a single dataset from one island nation and extrapolating it to the entire tropical region is fraught with potential error. It makes for highly uncertain scientific predictions because it cannot capture all the nuances of species distributions elsewhere. Every biological community is different.

My overall conclusion is that while the algorithm provides some direction about the upward bias in existing estimates of arthropod species richness, their prediction is also likely to be far too conservative to be realistic. I would predict the ‘true’ species richness lies somewhere between their estimate of 2.5-3.7 million and existing estimates of > 30 million.

My other concerns include:

  1. It seems to me that the major assumption is the degree of specialisation – this is perhaps the most imprecise parameter and possibly prone to underestimation, especially in light of the high specialisation values observed for most tropical invertebrates.
  2. The sensitivity analysis is basic and does not take into account partial correlations. A multivariate ‘global’ sensitivity analysis using logistic regression is more robust (McCarthy et al. 1995. Biol Conserv 73:93-100); thus, I suspect that their rankings of parameter sensitivity are incorrect.
  3. I very much doubt the parameters in equation 1 (except number of herbivorous canopy beetles) followed uniform distributions. At the very least, I suspect these to be Poisson, log-Normal, Normal or beta (depending on type). The authors discuss this, but I disagree that the Pert is a good alternative distribution. For example, the proportional parameters (i.e., proportion of species that are beetles, the proportion of arthropods in the canopy, etc.) might in fact have a ‘central’ tendency much closer to an extreme between 0 and 1 under say, a beta distribution. Therefore, I believe that the authors have severely underestimated the variance (especially of high richness values), indicating that the upper confidence bounds are too conservative.

Why is any of this important for conservation? Without good estimates of species number and distribution, we have no idea how much we stand to lose/are losing as habitats are destroyed. This is essential information for predictive conservation biology, so we need to get it right. Good on Hamilton and colleagues for stepping in and moving the discipline forward. CJA Bradshaw

Literature:

Hamilton, A., Basset, Y., Benke, K., Grimbacher, P., Miller, S., Novotný, V., Samuelson, G., Stork, N., Weiblen, G., & Yen, J. (2010). Quantifying uncertainty in estimation of tropical arthropod species richness The American Naturalist, 176 (1), 90-95 DOI: 10.1086/652998

Insect of the year 2012

March 17, 2012 by · Leave a Comment 

Der Hirschkäfer – “Insekt des Jahres” 2012

 

(Lucanus cervus LINNAEUS, 1758) Bernhard Klausnitzer

Zusammenfassung: Der Hirschkäfer (Lucanus cervus LINNAEUS, 1758) wird als “Insekt des Jahres” 2012 vorgestellt. Eine kurze Übersicht zur Biologie wird vorgelegt, und auf die kulturgeschichtliche Bedeutung der Art wird hingewiesen.

Seit 1999 wird von einem Kuratorium das “Insekt des Jahres” erwählt. “Ein Hauptproblem für die Darstellung von Insekten in der Öffentlichkeit ist nach wie vor die Sympathiewerbung, denn spontan werden viele Insekten eher als lästig oder schädlich empfunden.” (DATHE 2008). Für das Jahr 2012 erhielt nun der Hirschkäfer (Lucanus cervus) den Titel und damit die Rolle eines “Botschafters für die Insekten”. Einen kurzen Überblick über den Hirschkäfer vermittelt der folgende Steckbrief des Hirschkäfers (nach KLAUSNITZER (2011), FRANCISCOLO (1997), KLAUSNITZER & SPRECHER-UEBERSAX (2008)).

Lucanus cervus ist mit Abstand der größte Käfer Mitteleuropas. Seine Körperlänge ist geschlechtsspezifisch verschieden. Die Männchen werden im Durchschnitt 35 – 75 mm, maximal 90 mm groß (gemessen mit den Oberkiefern), die Weibchen 25 – 45 mm. Beide Geschlechter kommen in sehr unterschiedlichen Größen vor, die von den Ernährungsbedingungen der Larven abhängen. Kleine Exemplare werden gelegentlich als “Rehkäfer” bezeichnet. Auffälligstes und namengebendes Kennzeichen sind die geweihartig ausgebildeten Oberkiefer der Männchen. Die Mandibeln der Weibchen sind viel kürzer.

Abbildung 1: Lucanus cervus - Geweihformen Männchen / Weibchen

Lucanus cervus – Mandibelformen

Flugzeit:
Mitte Juni bis Ende Juli, meist in der Dämmerung an lauen Abenden, brummen laut im Flug.
Verbreitete Laubholzbestände – besonders Eichenholz sind beliebte Habitate der Käfer.

Belebter Abendhimmel (© Thomas Kümmel)

Paarfindung:
Männ­chen und Weibchen brauchen für die Reifung der Spermien und Eier Baumsaft (der bestimmte Pilze enthält), weshalb sie entsprechende Wundstellen aufsuchen. Für die Aufnahme von Säften sind Un­terkiefer (Maxillen) und Unterlippe (La­bium) besonders ausgebildet, sie formen ein großes, gefiedertes, gegabeltes, gelb­liches “Pinselchen”. Kommentkämpfe der Männchen untereinander, an denen sich oft mehr als zwei Exemplare beteiligen sind keineswegs unüblich.

Lucanus cervus – Labium (© Halvor Bodin)

Lucanus cervus – Kommentkämpfe (© Albano Soares)

Kopulation:
Das Männchen stellt sich über das Weibchen, die Köpfe zeigen in die gleiche Richtung, die Mandibeln des Männchens hindern das Weibchen am Fortlaufen. Das Männchen bleibt in dieser Stellung unter Umständen meh­rere Tage, verteidigt Leckstelle und Weib­chen. Nimmt in dieser Zeit auch selbst Nahrung auf, indem es seine Mundwerk­zeuge zwischen den bogenförmigen weiblichen Mandibeln hindurchführt. Schließlich erfolgt die Kopula. Eine ei­genartige Besonderheit liegt im Bau des Penis mit einem auffällig langen dünnen Schlauch (Flagellum), der etwa 20 mm lang und in Ruhe spiralig aufgerollt ist.

Lucanus cervus – Kopulation by Heinz Rothacher

Lucanus cervus – “Liebe kann so schön sein”

Eiablage und Eier:
Das Weibchen gräbt sich nach Begattung in die Erde ein (0,30 – 0,50 m), um im Laufe von zwei Wochen in mehreren Aktionen seine 50 -100 Eier außen an morsche Wurzelstöcke, vor allem von Eichen, abzulegen. Die weißlich-gelben, leicht ovalen Eier haben einen Durchmesser von ca. 3,0 x 3,4 mm, ihr Gewicht beträgt ca. 0,02 g.

Lucanus cervus – Stadium I – Ei by Heinz Rothacher

Larven:
Nach etwa 14 Tagen schlüpfen die Larven, die sich zweimal häuten. Die drei Stadien unterscheiden sich in ihrer Größe erheblich, erreichen schließlich eine Länge von 100 -120 mm. Für ihre Entwicklung benötigen sie meist wohl fünf Jahre, es können aber auch sechs bis acht bis zur Verpuppung vergehen. Ein besonderes Kennzeichen ist das Vorhandensein eines Stridulationsorgans auf der Rückseite der Hüften der Mittelbeine (Pars stridens) und der Vorderseite der Trochanteren der Hinterbeine (Plectrum). Durch Reiben der beiden Teile gegeneinander können Töne erzeugt werden. Der Stridulationslaut besteht aus einem kurzen Knarren, das manchmal ein- bis zweimal wiederholt wird, die Frequenz erreicht maximal elf Kilohertz. Die Funktion der Lautäußerung ist noch nicht geklärt. Larven ernähren sich von mehr oder weniger in Zersetzung befindlichem, morschem, feuchtem, verpilztem Holz, das sie mit der Zeit zu Mulm umsetzen und abbauen.

Lucanus cervus – Larven © Universität Hohenheim

Puppe:
Die Larve fertigt während zwei bis drei Wochen aus Erde und Mulm einen bis faustgroßen (hühnereigroßen), ovalen, bis 20 mm dicken, innen mit Nahrungsbrei und Sekreten (fungizide und bakterizide Wirkungen) geglätteten und verfestigten Kokon an, der als Puppenwiege dient. Dieser liegt 15 -20 cm tief in der Erde in unmittelbarer Umgebung des Brutsubstrates. Der Kokon der männlichen Larve ist wesentlich größer, vor allem länger als derjenige der Weibchen. Es muss Platz bereitgestellt werden für die Mandibeln, die der geschlüpfte männliche Käfer im Gegensatz zur Puppe ausgestreckt hält (an den Puppen sind die Oberkiefer der Männchen nach der Bauchseite eingeschlagen). Nach etwa sechs Wochen schlüpfen die Käfer, bleiben über den Winter im Boden, den sie erst im Frühjahr verlassen.

Lucanus cervus – Puppe (© H. Rothacher)

Es ist nicht verwunderlich, dass der Hirschkäfer seit mindestens 2500 Jahren in vielfältiger Weise die Aufmerksamkeit des Menschen erregt hat (BODENHEIMER 1928, KLAUSNITZER 2002, SPRECHER & TARONI 2004). Lucanus cervus wurden magische Kräfte zugesprochen. Die Man­dibeln verkaufte man als Mittel gegen Zauberei. Ein Hirschkäferkopf in der Ta­sche soll Reichtum und Glück bringen. Am Hut oder in den Zöpfen getragen schützt er vor dem bösen Blick. Gelegent­lich wurden die Köpfe sogar als Amulette getragen. Selbst als Orakel waren sie gut. Wurde eine verlaufene Kuh gesucht, schüttelten die Hirten in der geschlosse­nen Hand die Käfermandibeln und be­fragten sie dabei. Nach dem Öffnen der Hand zeigte die rechte Mandibel die ent­scheidende Richtung an.

Früher wurde auch geglaubt, dass Hirschkäfer als “heilige Tiere” des ger­manischen Gottes Donar (Thor) Blitze anlocken können, weshalb sie nicht in Häuser gebracht werden durften. Diese (falsche) Annahme erscheint vielleicht durch die Lebensweise in einzelnen alten Eichen (Blitzeichen) erklärbar. Zahlrei­che Namen deuten auf diese Eigenschaft: Donarkäfer, Donnerkäfer, Donnerguggi, Donnergueg, Donnerguge, Donnerpup­pe, Hausbrenner, Feuerwurm, Feueran­zünder, Börner (Bedeutung wie Feuer­schröter), Köhler, Feuerschröter.

Den ersten Schritt in die Welt des My­thos machte der Hirschkäfer beim grie­chischen Dichter NIKANDER aus Kolo­phon (2. Jh. v. Chr.). In NIKANDERS „Ver­wandlungen” wird der Hirte Kerambos nach einem Streit mit den Nymphen dank ihrer magischen Kräfte in einen Hirschkäfer verwandelt. Kerambos, der Sohn des Euserion und einer Nymphe, war ein begabter und bei den Nymphen beliebter Sänger und der erste Sterb­liche, der Leier spielte. Es wird erwähnt, dass der Kopf des Käfers mit seinen Hörnern der aus Schildkrötenpanzer ge­fertigten Leier gleiche.

Der griechische Dichter ARISTOPHANES (448 -380 v. Chr.) erzählt in seiner Ko­mödie „Die Wolken”, Vers 761 – 763, von einem Kinderspiel, das im alten Grie­chenland verbreitet war und bei wel­chem Käfer an einen Faden gebunden wurden. Diese vor mehr als 2000 Jahren geschriebenen Worte erinnern an ein bis ins vergangene Jahrhundert in ländli­chen Gebieten Europas weit verbreitetes Kinderspiel, bei dem die Käfer an einem Bein mit einem Faden festgebunden und fliegen gelassen wurden. Dieses Spiel ist auf dem Titelblatt der „Abhandlungen von Insecten” von JACOB CHRISTIAN SCHÄFFER (1764-1779) abgebildet.

Hirschkäferlarven wurden auch geges­sen. Bei dem bei PLINIUS erwähnten cos­sus, einer Larve, die gemästet und ver­zehrt wurde, kommt am ehesten die Hirschkäferlarve in Frage. Ausgehend von der Verwendung als Nahrung und der angedeuteten kultischen Verehrung wurden auch dem Hirschkäfer verschie­denste Heilwirkungen zugeschrieben. Bei den Römern war es üblich, den Kin­dern Hirschkäferköpfe um den Hals zu hängen und zwar nicht als Spielzeug, sondern wegen ihrer Krankheiten ab­wehrenden Wirkung.

Der berühmte römische Schriftsteller GAIUS PLINIUS SECUNDUS (22 -79) erwähnt unsere Art und beginnt mit diesbezüglichen Akzenten, die später immer wiederholt und vertieft wurden: „Eine große Art Skarabäen, hat sehr lange Hörner, an deren Spitze zweispaltige Gabeln stehen, welche sie nach Belieben schließen und zum Kneipen verwenden können. Man hängt sie kleinen Kindern als Schutzmittel an den Hals.”

Im 1480 erschienenen Medizin- und Kräuterbuch „Ortus Sanitatis” des Frankfurter Stadtarztes JOHANNES WONNECKE VON CAUB ist Folgendes über den Hirschkäfer zu finden: “Gegend Abend fliegen sie zahlreich mit großem Geräusch umher. Sie haben große medizinisch benutzte Hörner, die Furchen und Zähne tragen sowie glänzen und die sie wie Zangen benutzen.” Der Verfasser des 1603 erschienenen „Theriotropheum Silesiae” (Der Schlesische Tiergarten) CASPAR SCHWENCKFELD (1563-1609) empfiehlt, den Hirschkäfer in Öl gegen Ohrenschmerzen zu verwenden und die „Hörner” kleinen Kindern gegen das Bettnässen um den Hals zu hängen.

Hirschkäfer spielen auch in der Heraldik (Wappenkunde) eine gewisse Rolle, und es gibt eine Fülle von bildlichen Darstellungen – Hirschkäfer sind einziger Inhalt oder Element vieler Kunstwerke. Besonders hervorzuheben sind zwei bedeutende Werke von ALBRECHT DÜRER (1471 – 1528), „Maria mit den vielen Tieren” von 1503 und „Anbetung der heiligen drei Könige” von 1504, die beide einen Hirschkäfer zeigen. Dank ihm wird der Hirschkäfer erstmals sogar Hauptsujet auf einem Gemälde. Die berühmte Einzeldarstellung aus dem Jahre 1505 (Aquarell und Deckfarben auf Papier) zeigt ein prächtiges Hirschkäfermännchen in zauberhaft natürlicher Haltung und wurde später von zahlreichen Künstlern kopiert. Hirschkäfer erscheinen auch auf den prächtigen handkolorierten Stichen der „Monatlich herausgegebenen Insecten Belustigung” aus dem Jahr 1749 von AUGUST JOHANN RöSEL VON ROSENHOF (1705-1759).

Der Monatlich herausgegebenen Insecten Belustigung

Bei WILHELM BUSCH (1832-1908) wim­melt es von Käferdarstellungen. In „Hänschen Däumling” kommen drei Kä­fer vor, ein Maikäfer, ein Nashornkäfer und ein Hirschkäfer, die mit dem Häns­chen Met trinken bis der Hirschkäfer die­sen schließlich zu einem Ameisenhaufen trägt. Auch die Bildergeschichtensamm­lung “Schnurrdiburr oder die Bienen” enthält Darstellungen von Bockkäfern, Nashornkäfern, Hirschkäfern und Maikä­fern.

Hirschkäfer sind auch auf Keramik zu finden, etwa auf einer prächtigen Porzel­lanplatte aus Straßburger Fayence und auf Meißner Porzellan aus der Hand von JOHANN JOACHIM KÄNDLER (1706-1775). Auf einem Solitaire Service der Manufak­tur Frankenthal mit von MARIA SIBYLLA MERIAN inspirierten Zeichnungen ist ein Hirschkäfer mit geöffneten Elytren ge­malt. Eine andere Figur aus der Meißner Manufaktur stellt einen rot ge­fiederten Eichelhäher auf einem Stück Baumstamm dar, der sich mit dem Schnabel gegen einen großen, den Stamm heraufkletternden Hirschkäfer verteidigt.

Hirschkäfer sind mehrfach als Motiv von Postwertzeichen verwendet worden. Unser einheimischer Lucanus cervus wurde 1963 von der Post der DDR und 1993 von der Deutschen Post verwendet. Selten ist seine Präsenz auf Münzen: die einzigen auf der Welt sind wahrscheinlich diejenigen aus Polen zu zwanzig und zwei Zloty.

2 zł 1997 – Jelonek rogacz (łac. Lucanus cervus)

20 zł 1997 – Jelonek rogacz (łac. Lucanus cervus)

Es ist sicher deutlich geworden, dass der Hirschkäfer die Menschen seit vielen Jahr­hunderten interessiert und beschäftigt hat. So wie wir die Spuren des Hirschkä­fers über 2000 Jahre in der Literatur zu­rückverfolgen können, möge er auch noch mindestens weitere 2000 Jahre sei­ne Spuren darin hinterlassen, aber nicht in der paläozoologischen Literatur!

Es wird immer Bestrebungen geben, den Hirschkäfer vor dem Aussterben zu be­wahren, da viele Menschen ein großes Verantwortungsgefühl haben. Mit jeder ausgestorbenen Art wird eine Evolutionslinie abgeschnitten, und das ist un­wiederbringlich. Hirschkäfer sind nur ein Beispiel. Die Achtung vor der Natur muss immer Vorrang haben. Auch unsere En­kel und Urenkel brauchen die Vielfalt einer reichen Pflanzen- und Tierwelt, deshalb müssen wir alles daran setzen, diese zu erhalten! Schließlich sollen sie dem größten heimischen Käfer nicht nur im Bilderbuch oder in Museen begegnen.


Literatur:

BODENHEIMER, F. S. 1928. Materialien zur Ge­schichte der Entomologie bis LINNE. Bd. 1 und 2. Berlin.

DATHE, H. H. 2008. Zum zehnten Mal ein Insekt des Jahres: Insekten erweisen sich auch in die­ser Aktion als erfolgreiche Tiergruppe. Ento­mologische Nachrichten und Berichte 52 (1): 1-3.

FRANCISCOLO, M. E. 1997. Coleoptera, Lucanidae. Fauna d’Italia 35: 1-228.

KLAUSNITZER, B. 2002. Wunderwelt der Käfer. 2. Auflage. 238 S. Spektrum Akademischer Ver­lag Heidelberg, Berlin.

KLAUSNITZER, B. 2011. Der Hirschkäfer Lucanus cervus, Insekt des Jahres 2012. Deutschland Österreich Schweiz. Faltblatt, Kuratorium In­sekt des Jahres.

KLAUSNITZER, B. & SPRECHER-UEBERSAX, E. 2008. Die Hirschkäfer oder Schröter (Lucanidae). 4., stark bearbeitete Auflage. Die Neue Brehm-Bü­cherei Nr. 551, 161 S. Westarp Wissenschaf­ten, Hohenwarsleben.

SPRECHER, E. & TARONI, G. 2004. Lucanus cervus depictus. 160 S. Giorgio Taroni Editore, Como.