Romalea microptera
| Romalea microptera | ||||||||||||
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Romalea microptera |
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| Romalea | ||||||||||||
| Serville , 1831 | ||||||||||||
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| Romalea microptera | ||||||||||||
| ( Palisot de Beauvois , 1817) |
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Romalea microptera is a short- antennae insect fromthe Romaleidae family . It is the only species of the (monotypical) genus Romalea .
features
The animals reach a body length of 60 (males) to 80 millimeters (females) and a weight of 9 grams, making them one of the greatest short-antennae terrors. The body is quite sturdy while the legs remain thin. The wings are shortened and clearly shorter than the abdomen; the animals are not able to fly. The slow, awkward-looking movements have given the animals the common American name "Lubber" ("Lümmel").
The species is characterized by its warning color ( aposematism ) and thus indicates its toxicity to potential predators. It occurs in several color morphs, which can live next to each other anywhere within their range. The basic color of the light morph is dull yellow with black spots and drawing elements of different dimensions. The segment sections are colored black. The top of the head and thorax are mostly colored pale orange. The cover wings (Tegmina) are yellow with black spots, the (usually hidden) hind wings are bright red with a black border. The dark drawing elements can reach different dimensions, up to a black morph with only a few yellow spots; in this way they resemble the nymphs, from which they can be easily distinguished by the formation of the wings.
The color of the nymphs is very different from that of the adult animals, although their color does not allow any conclusions to be drawn about the color of the adults. As a rule, their basic color is black. On the back (dorsal) there is a conspicuous yellow, orange or red longitudinal stripe, other colored markings can appear on the edge of the pronotum , the abdominal segments and on the head.
Poisonous effect
Romalea microptera is poisonous in all stages . The Imagines also have dorsal Gifttdrüsen (converted stigmata on metathorax) with which they accompanied potential predators sibilance can hurl a toxic secretion; if necessary, they wrap themselves in the foamy secretion. The poison consists of phytochemicals ingested and sequestered with food in connection with self-synthesized substances. As a major exception among the poisonous insects, the species is able to use numerous plant substances from a wide variety of plant species, which means that the composition of the poison differs individually. In addition to various phenols, ketones and quinones, a main component of the poison is the sesquiterpenoid romallenone . In addition, other substances can be added; when eating leek species, sulfide-containing metabolites are also used.
In tests on 119 insectivorous bird and lizards from 21 species, all of them rejected or spat them out again; If they were swallowed, vomiting usually resulted. Even when observing in the habitat, the animals were usually ignored by insectivorous birds. The only known exception is the Louisiana strangler Lanius ludovicianus . This species of bird hunts the locusts and then impales them (typical for the species) on thorns; obviously the toxin is not stable long after the locust dies. The Louisiana strangler, however, only eats the head and abdomen and leaves the thorax with the poison glands lying around, while other grasshopper species like to eat it.
distribution
The range of Romalea microptera in North America is limited to an area in the southern and eastern United States along the Gulf Coast and the southernmost Atlantic coast. It occurs all over Florida , as well as Tennessee , Georgia , Alabama , Mississippi , Louisiana , Arkansas, and east Texas . It is the only species of the Romaleidae in this area. The somewhat similar Taeniopoda eques ("Horse Lubber") only lives in desert-like habitats further west. Both species can mate (with artificial contact) and produce viable offspring.
Life cycle
Romalea microptera develops one generation per year. Adults are long-lived and can be found almost all year round. Females lay their eggs in the summer months. The eggs are grouped in clusters of 30 to 80 each, which are enveloped in a foamy secretion. These are buried in moist soil by the female with the abdomen valves. A female can produce three to five clutches in the course of her life. The clutches overwinter, the nymphs hatch in March (in southern Florida as early as February). Like most relatives, the species has five nymph stages (rarely in females and, as an exception, six). Most animals reach the adult stage in July or August.
The species is an exception among the locusts in that the nymphs do not disperse after hatching, but stay together. This gregarious behavior is limited to a few species in grasshoppers. It is explained by the toxicity of the nymphs, because it means that potential predators avoid the others after contact with one animal. Further advantages (e.g. in thermoregulation) are speculated, but have not yet been proven. The animals usually separate themselves while eating during the day, they gather at night in elevated places, e.g. B. on bushes.
ecology
The species lives in humid to swampy habitats, preferably in open pine forests, cultivated land and weed vegetation, e.g. B. on roadsides and roadsides. In their diet it is predominantly a generalist ( polyphagous ) herbivore of herbaceous species with a preference for flowers and inflorescences. Known food plants are z. B. Cnidoscolus stimulosus (“Stinging Nettle”, Euphorbiaceae ), American pokeweed ( Phytolacca americana ), heart-leaved pike ( Pontederia cordata ), American lizard's tail ( Saururus cernuus ) and broad-leaved arrowweed ( Sagittaria latifolia ). By eating (young) citrus plants ( citrus ), they are considered economic pests and in many regions of Florida are usually fought with insecticides. Like many species of grasshopper, however, it is not a pure herbivore, but also accepts animal food when the opportunity arises. These are mainly dead, injured or freshly skinned prey. As with the plant species, poisonous species do not act as a deterrent.
Although they are well protected against predators due to their poisonous effects, they have numerous enemies. The most important antagonist is a parasitoid caterpillar fly (Fam. Tachinidae), Anisia serotina . In some populations, 60 to 90 percent of the animals are parasitized by this species. Other important parasitoids are Blaesoxipha opifera and Blaesoxipha hunter (Fam. Sarcophagidae, meat flies ). As is typical for almost all grasshopper species, there are no parasitoid hymenoptera species in this species either.
Taxonomy
Romalea microptera is the only species of the ( monotypical ) genus Romalea . The species was first described as Acridium micropterum by the French researcher Palisot de Beauvois. The older synonym Romalea guttata , under which the species is carried in many publications, has been suppressed by the Commission for Zoological Nomenclature as nomen oblitum (forgotten name).
supporting documents
literature
- John L Capinera, Clay Whitney Scherer, Jason Squitier: Grasshoppers of Florida . University Press of Florida, 2002, ISBN 0813024269 , p. 64 online (PDF; 96 kB)
- CW Scherer & JL Capinera: Eastern Lubber Grasshopper, Romalea microptera (Beauvois) (= guttata (Houttuyn)) (Insecta: Orthoptera: Acrididae). Document EENY-006 (IN132), University of Florida online
Individual evidence
- ↑ a b c d e f C. W. Scherer & JL Capinera: Eastern Lubber Grasshopper, Romalea microptera (Beauvois) (= guttata (Houttuyn)) (Insecta: Orthoptera: Acrididae). Document EENY-006 (IN132), University of Florida online
- ↑ a b c James T. Costa: The other insect societies. Harvard University Press, 2006. ISBN 978-0674021631 . p.82 ff.
- ↑ Reuven Yosef (1992): Predator exaptations and defensive adaptations in evolutionary balance: no defense is perfect. Evolutionary Ecology 6: 527-536.
- ↑ Timothy W. Stauffer, John D. Hatle, Douglas W. Whitman (2011): Divergent Egg Physiologies in Two Closely Related Grasshopper Species: Taeniopoda eques Versus Romalea microptera (Orthoptera: Romaleidae). Environmental Entomology 40 (1): 157-166. doi : 10.1603 / EN10200
- ^ Matthew L. Richardson, Peter F. Reagel, Robert F. Mitchell, Douglas W. Whitman (2012): Opportunistic Carnivory by Romalea microptera (Orthoptera: Acrididae). Annals of the Entomological Society of America 105 (1): 28-35. doi : 10.1603 / AN11057
- ↑ Orthoptera speciesfile online
- ↑ D. Keith McE. Kevan: Romalea guttata (Houttuyn), name change for well-known eastern lubber grasshopper (Orthoptera: Romaleidae). Entomological News 91: 139-140.
