Magicicada

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Magicicada
Magicicada septendecim

Magicicada septendecim

Systematics
Subordination : Risso cicadas (Cicadomorpha)
Superfamily : Cicadoidea
Family : Cicadas (Cicadidae)
Subfamily : Tibicininae
Tribe : Tibicinini
Genre : Magicicada
Scientific name
Magicicada
Davis , 1925
Distribution of the species of the genus Magicicada in the USA: green = distribution 17-year-old cicadas ; red = distribution of 13-year-old cicadas ; blue = M. neotredecim ; Yellow tones = areas of overlap
Magicicada septendecim
Hatching Magicicada
Population of periodic cicadas and their larval membranes ( exuvia )
Larval skin (exuvia)
Development of the old larva to a full insect
Sphecius speciosus is a predator specialized in singing cicadas
Bark cracks with egg nests
Damage caused by periodical cicadas deciduous trees in Baltimore
Plants with cicadas of Brood X.

The genus Magicicada belongs to the family of singing cicadas ( Cicadidae) within the order of the round-headed cicadas (Cicadomorpha). It comprises a total of seven species distributed in the eastern United States , including the species Magicicada neotredecim, which was newly described in 2000 .

The insects are also referred to as " periodic cicadas ", because these animals are mass occurrences locally at regular intervals, a "big event" in the USA. After the larvae have undergone a 13-year and 17-year development in the soil, the adult animals of a population hatch almost simultaneously. The transformation of the insects, the mating, oviposition and death take a total of only a few weeks. Some of the animals appear to such an extent that special garbage bins with the label “Drop-off for Cicadas only” are used to remove the dead cicadas at the end of June , in order to feed them to animals in zoos.

Distribution of the species

The genus Magicicada is only found in the eastern United States. While the species with a 17-year life cycle occur in the northern areas within this distribution area, those with a 13-year development time are native to the regions to the south, although there are overlaps. A total of seven species are known to date.

With a 17-year development cycle:

With a 13-year development cycle:

anatomy

The adult animals, between 20 and 33 millimeters in size, have black bodies and red complex eyes ( compound eyes ) that are clearly bulging at the sides . Like all singing cicadas, they have three point eyes ( ocelli ), which are arranged in a triangle on the forehead ( frons ). The antennae of the periodic cicadas that attach between the eyes are very short. They each consist of two thick base links and a five-link antenna bristle. The bubble-like bulging head shield, which is characterized by several transverse grooves and folds, is striking. The proboscis ( rostrum ) arises at the lower edge of the face and , when at rest, lies folded against the body between the hips ( coxa ).

In the resting position, the forewings are folded together like a roof, which is characteristic of cicadas. They always tower above the abdomen. The not very rich veining of the hyaline, membranous forewings is orange and differently distinct depending on the species. Parts of the veins near the wing tip are colored black and form an "M" or "W" shape. The females have a punctured abdomen with a long ovipositor . The abdomen of the males is bluntly rounded and is brightly colored with a species-specific, extensive orange color. Only they have drum organs ( tymbals ) which are located on the sides of the first abdominal segment behind the attachment of the hind wings. On the underside of the abdomen of both sexes there are paired auditory organs ( tympanals ).

The thighs ( femur ) of the front legs of adult animals are, in contrast to the normally shaped middle and rear legs, clearly thickened and thorny. The front legs of the larvae have developed into grave legs in adaptation to their underground way of life.

nutrition

Like all singing cicadas, the species of the genus Magicicada are phloem suckers . With the help of their proboscis, the adult animals prick the pathways of various woody plants and herbaceous plants - never sweet and sour grasses - and suck the sap, which is rich in sugar and nutrient salts . The subterranean larvae suck the sap from plant roots.

Vocalizations

Although all species of cicada emit sound or vibration waves for communication, only the males of the singing cicadas are able to produce sounds that can be heard by humans, as are the species of the Magicicada genus . For this they have their own organ, the "drum organ" (tymbal) at the beginning of the abdomen. By attaching muscles (sing muscles), records are made to vibrate in this organ. The abdomen of the cicadas is largely hollow thanks to large tracheal bubbles and ensures the necessary resonance . With the help of these organs, sounds in the range from 0.5 to 25 kilohertz can be generated with a volume of up to 84 dB . The females do not have a drum organ and consequently do not sing. In contrast, both sexes have auditory organs (tympanals) on the underside of the abdomen. The paired organs consist of a wafer-thin membrane that absorbs vibrations.

The singing of the males, the process of vocal expression is also known as stridulation , serves primarily to attract the females. The males usually gather in choirs in light tree tops by encouraging each other to sing. The females are attracted by the song. So cicadas of both sexes can be found in high numbers in the trees. A singing male registered by a nearby female increases the number of sounds. The females respond to the signals of the males with clicking their wings. The males are able to both hear and visually perceive the flapping of their wings. Finally, they form a duet from the male's song and the female's wing beats.

The songs of the male cicadas are species-specific and can be used to identify the species. In some cases, the species can only be identified by their songs, as some species hardly differ morphologically. The signals of the females, the clicking of their wings, are also species-specific.

Reproduction, Development and Life Cycle

The larvae live underground at a depth of up to 30 centimeters. The hemimetabolic insects go through five larval stages separated by moults, during which they gradually become more and more similar to the adult animal. They become gradually larger and larger and with increasing age, the systems for the wings and genital fittings increase. The adult larvae of the 5th instar work their way towards the surface of the earth in the spring of the 13th or 17th year. They create slim, cylindrical caves with a diameter of 1 to 1.5 centimeters. When the soil has reached a temperature of around 17.9 ° C, when the weather is favorable, usually between May and June, they leave the soil through a loophole and look for suitable places in the vegetation in the area. There they molt one last time to become a full insect. The newly hatched adult animals ( Imagines ) are initially soft and whitish. You need about four to six days until they are completely colored and the chitin shell is completely hardened. The larvae of a population hatch in very large numbers, sometimes with more than 370 individuals per square meter. The hatching of the adult animals of a population takes a total of about four to six weeks.

After the animals are fully mature, they start looking for a partner and finally mating . The insects only live a few weeks with the sole aim of reproducing. The males produce species-specific chants that combine to form entire choirs to attract females who are ready to mate. After mating, the males die. The females live a little longer to lay eggs. With the help of their laying spike, they drill about one centimeter long Y-shaped cracks in the bark of living branches. They lay up to 20 eggs in these “nests”. In total, a single female can lay around 600 eggs.

In late summer, six to ten weeks after oviposition, the embryonic development is complete and the first larval stage hatches. It falls to the ground. There it digs itself in and looks for suitable roots where it can suckle in order to begin its 13 or 17-year-old larval development here.

The periodic of the cicadas

All cicadas a kind and a life cycle (engl. As isolated in time and space "breeding" brood ), respectively. All types of the populations always appear at the specified intervals (every 13 or 17 years). The life cycles of one and the same species in different regions are not synchronized and can appear staggered in time. The "broods" are marked with Roman numerals. The "17-year-Brood I" specified by Marlatt (1898) for 1893 appeared for the last time in 2012 in Virginia and West Virginia . In 2007, the "17-year- Brood XIII " hatched in parts of Iowa , Illinois , Wisconsin , Michigan and Indiana . There are a total of 30 broods quantified in this way in the USA. The breeds I to XVII relate to cicadas with 17 years, the breeds XVIII to XXX to those having a 13-year development. In fact, only 15 broods are currently recorded.

There are various hypotheses about the appearance of the different breeds, the spatial relationships, interactions and species status . One assumption suggests that the larval stage of the northern cicadas with a development time of 17 years was extended in extremely cold times in order to split off new broods from the original one. In addition, several broods were often observed “out of sequence”, that is, they appeared earlier or later than expected. The use of molecular techniques also led to the assumption that switching life cycles or interposing additional broods may also lead to the emergence of new species. By switching on a four-year rhythm within the cicadas with a 17-year development, animals with a 13-year life cycle are to be produced. For example, the new species M. neotredecim is believed to have emerged from populations of M. septendecim through a change in life cycle from 17 to 13 years. The species status is still being discussed. The animals clearly differ in their song from the other species.

Overview of the populations

with a 17-year development cycle

with a 13-year development cycle

Biology and ecology

Enemies and parasites

In the first week after hatching, the abundant cicadas are a popular food for reptiles , birds , squirrels , cats, and other mammals . For these animals, however, the cicadas are not the main prey. An exception is the grave wasp Sphecius speciosus . It carries singing cicadas that have been paralyzed by stings as larval food in their brood chambers. According to the size of their prey, these insects, also known as "cicada killers", are themselves quite large and powerful.

Some animals are attacked by the fungus Massospora cicadina, which specializes in singing cicadas . The abdomen of the infected insect breaks open and shows a white color caused by the numerous spores . The fungus does not kill the cicada immediately; however, the infestation leads to infertility.

Survival strategies

Mass development is seen as a strategy for survival. Potential predators become oversaturated (“predator satiation”), so that enough cicadas always survive to preserve the species. The reproduction of the cicadas in intervals can also be explained by predator-prey relationships . Your enemies usually live in 2, 4 or 6 year rhythms. If the cycle lengths of the cicadas were twelve years, for example, the animals could be eaten by all predators that appear every 1, 2, 3, 4, 6 and 12 years. With a life cycle of 13 years, only those species that occur every year or every 13 years are predators. According to this, prime numbers (only divisible by one and itself) are to be regarded as favorable for reproduction intervals. The next largest prime number is 17; the cycle length in years of the species of the genus Magicicada distributed in the north of the USA .

Material cycles

Fertilization experiments in which the carcasses of cicadas were scattered on test areas in densities as they occur naturally, showed an increase in the ammonium and nitrate content of the soil up to three times over within 30 days. While the ammonium content quickly returned to its original level, the nitrate content, on the other hand, remained elevated over the long term. At the same time, the biomass of decomposers ( bacteria and fungi ) in the soil increased by an eighth. Plants also benefit from the flood of nutrients. Bluebells , such as B. Campanulastrum americanum , which grew on soil "fertilized" with cicada, contained more nitrogen and produced seeds nine percent larger. In this way, the nutrients are returned to the soil that they previously lost through the life activity of the cicadas.

Periodic cicadas and human

Even the natives of the New World observed the peculiar periodic return of the cicadas and integrated the phenomenon into their mythology . The Hopi Indians (Oraibi) living in Arizona interpreted the life cycle of the singing cicadas as a resurrection and gave them the power of immortality. Such supernatural powers were called kachina . These were given away in the form of carved dolls for religious instruction to children. One was called "Mahu" (cicada). She is worshiped in dances and ceremonies.

The first European settlers in Tennessee experienced a documented mass development of periodic cicadas for the first time in 1634. Since then, the mass increase in this population has been repeated regularly every 17 years, the next time in 2025. They are often incorrectly referred to as plagues. The sudden appearance of such numbers of insects was frightening and reminded the settlers of the migratory locust plagues in Europe. The term "periodic locust plague" has survived to this day, although the cicadas are not related to these insects.

The cicadas can cause damage to young trees and bushes in particular if too many animals suckle on the plant or too many egg clutches are deposited on them. Individual branches can break off or the trees are weakened as a whole, wither and in extreme cases die off. Ornamental trees such as dogwood and hickory and fruit trees such as apples , peaches and cherries are particularly affected . Conifers are generally not damaged. The effects of the larvae suckling on the roots are estimated to be minor. The damage can be of economic importance. Since this phenomenon only occurs every 13 or 17 years, the economic impact is likely to be minor.

In fact, the regular spectacle is a great attraction for tourists and journalists when the larvae crawl out of the ground around a tree with up to 40,000 holes. Periodic cicadas are completely harmless to animals and humans. They cannot sting or transmit disease.

Danger

The IUCN lists the following species as low risk / near threatened:

Others

In the USA, the “Periodic Cicadas ” are compared to the so-called “ Annual Cicadas ” or “ Dog Day Cicadas ”. These representatives of the singing cicadas (Cicadidae) of various genera, native to North America, have shorter life cycles between two and five years. Unlike the species of the genus Magicicada, they do not appear regularly with high numbers of individuals, but annually without any noticeable mass developments. The adult animals hatch in late summer, when Sirius , the very bright star (also known as the dog star) of the constellation Big Dog, stands in the night sky, which is what the English name refers to.

Sources and further information

credentials

Individual evidence

  1. ↑ a b c A.F. Sanborn: Periodical Cicadas: The Magic Cicada (Hemiptera, Tibicina, Magicicada ssp.). In: Denisia 4, 2002, NF 176: 225-230, ISBN 3-85474-077-8
  2. ↑ HS Dybas & DD Davis: A populations census of seventeen-year periodical cicadas (Homoptera: Cicadidae: Magicicada) . Ecology 43 (3): 432-444, 1962.
  3. ^ CL Marlatt: The periodical cicada. Bull. US Dept. Agri., Div. Entomol. Bull., 1907. 18:52
  4. ^ CL Marlatt: A new nomenclature for the broods of the periodical cicada. - Bull. US Dept. Agri., Div. Entomol. Bull. 71: 1, 1898.
  5. ^ RD Alexander & TE Moore: The evolutionary relationships of 17-year and 13-year cicada, and tree new species (Homoptera, Cicadiae, Magicicada). -Misc. Publ. Mus. Zool., Univ. Me. 121: 1. 1962.
  6. ^ DC Marshall & JR Cooley: Reproductive character displacement and speciation in periodical cicadas, with description of a new species, 13-year Magicicada neatredecim. - Evolution 54: 1313, 2000.
  7. ^ " Periodical Cicada - Brood V ". Forest Service . United States Department of Agriculture. April 15, 2016.
  8. ↑ Swarms of cicadas emerging in Midwest . May 20, 2007. 
  9. ↑ Brood XXII (13-year) The Baton Rouge Brood . National Geographic Society. Retrieved August 28, 2011.
  10. ^ R. Remane, E. Wachmann : Cicadas - get to know, observe - Naturbuch Verlag, Augsburg 1993, ISBN 3-89440-044-7
  11. ^ KS Williams & C. Simon: The ecology, behavior and evolution of periodical cicadas. Annual Review of Entomology 40: 269-295, 1995.
  12. ^ KS Williams, KG Smith & FM Stephen (1993). Emergence of 13-year periodical cicadas (Cicadidae, Magicicada): phenology, mortality, and predator satiation. Ecology 74 (4): 1143-1152, 1993.
  13. ↑ Numbers count in cicada life. Max Planck Society, April 29, 2002, archived from the original on October 1, 2007 ; Retrieved May 3, 2013 .
  14. ↑ L. Yang: Periodical cicadas as resource pulses in North American forests. Science, 306: 1565-1567, 2004.
  15. ↑ R. Achtziger & U. Nigmann: Cicadas in Mythology, Art and Folklore. In: Denisia 4, 2002, NF 176: 1-15. ISBN 3-85474-077-8
  16. ↑ H. Oldenberg: Some observations of swarms of strange insects and the mieschiefs done by them. - Phil. Trans. Lond. 1: 137, 1666.

further reading

  • JR Cooley & DC Marshall: Sexual signaling in periodical cicadas, Magicicada spp. (Hemiptera: Cicadidae). Behavior 138: 827-855, 2001.
  • DH Lane: The recognition concept of species applied in an analysis of putative hybridization in New Zealand cicadas of the genus Kikihia (Insecta: Hemiptera: Tibicinidae). In: M. Lambert and HG Spencer, eds. Speciation and the recognition concept: Theory and Application. (The Johns Hopkins University Press, Baltimore and London). Marlatt, CL 1923. The periodical cicada. USDA Bur. Entomol. Bull. 71: 1-183, 1995.
  • DC Marshall: Periodical cicada life-cycle variations, the historical emergence record, and the geographic stability of brood distributions. Annals of the Entomological Society of America. 94: 386-399, 2001.
  • A. Martin & C. Simon: Anomalous distribution of nuclear and mitochondrial DNA markers in periodical cicadas . Nature 336: 237-239, 1988.
  • A. Martin & C. Simon: Differing levels of among-population divergence in the mitochondrial DNA of periodical cicadas related to historical biogeography. Evolution 44: 1066-1080, 1990.
  • C. Simon: Evolution of 13- and 17-year periodical cicadas (Homoptera: Cicadidae). Bull. Entomol. Soc. At the. 34: 163-176, 1988.
  • C. Simon, J. Tang, S. Dalwadi, G. Staley, J. Deniega & T. Unnasch: Genetic evidence for assortative mating between 13-year cicadas and sympatric 17-year cicadas with 13-year life cycles provides support for allochronic speciation. Evolution 54: 1326-1336, 2000.

Web links

Commons : Magicicada  - collection of images, videos and audio files

Chants (mp3)

Videos (requires Windows Media Player)

This version was added to the list of articles worth reading on July 21, 2007 .