Dryophthorinae

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Dryophthorinae
Sitophilus oryzae

Sitophilus oryzae

Systematics
Class : Insects (Insecta)
Order : Beetle (Coleoptera)
Subordination : Polyphaga
Superfamily : Curculionoidea
Family : Weevil (Curculionidae)
Subfamily : Dryophthorinae
Scientific name
Dryophthorinae
Schönherr , 1825

The Dryophthorinae are a subfamily of beetles within the family of weevils (Curculionidae). In the past, they were viewed by numerous systematics as an independent family. The subfamily includes numerous particularly large and conspicuous species, including some of the largest weevils ever, reaching four inches in length. Some species are dreaded pests. About 1200 species are known worldwide. In Central Europe, only two species live in the wild, as well as some storage pests in houses.

features

They are predominantly elongated, cylindrically shaped species, whose pronotum is at least as long as it is wide and about the width of the elytra . The head carries the trunk (anatomically: rostrum) that is characteristic of the superfamily, an extension of the head capsule with the mouthparts at the tip. The trunk of the Dryophthorinae is usually cylindrical, less often flattened, and of moderate length (neither noticeably long nor noticeably short) and straight or slightly curved. The subfamily differs from related lines of the weevils mainly in the construction of the mouthparts and antennae. The structure of the labium is characteristic of the mouthparts . Of the three sections of the labium that are normally formed in the beetles, the weevils only have two, called the prementum and postmentum . In the Dryophthorinae the prementum is retracted into the head capsule and is not visible from below. The special design of the antennas is easier to see. These are kneeled, i.e. H. the base phalanx ( scapus ) is elongated and the rest of the antennae rests on it at a clear angle. In the Dryophthorinae the antennae is not three-limbed, as is usual with the weevils, but four-limbed, in that the last limb of the flagellum is enlarged and attached to the limb. The front links of the club are very compact and the club is shortened towards the end. As a result, the club appears to be divided into two parts, with a basal, shiny section and a distal, matt section, the three links of which are difficult to see. Accordingly, the antennae flagella does not consist of seven, as usual, but at most six members. In numerous species it is shortened even further. In the tribe Dryophthorini it consists z. B. only of four members.

The wing covers of the Dryophthorinae usually have clear rows of dots or stripes. Often they are shortened at the end so that the last tergite of the abdomen is exposed, it is then referred to as pygidium . The animals are mostly black or red-brown in color, many species are black with a conspicuous aposematic or warning sign made of red or yellow dots and ribbons. Scales and hairs are different, from densely scaled to almost bald. The structure of the feet ( tarsi ) is also characteristic . The last tarsal link of the Dryophthorinae is usually pulled forward in the middle between the claws like a lobe. The species of the Dryophthorini tribe are also noticeable in that the fourth limb, which is otherwise shortened and barely visible in the weevils, is elongated in them.

The larvae of the Dryophthorinae are predominantly of the typical shape of the weevil larvae; with the exception of the head capsule, they are slightly sclerotized , legless and slightly curved towards the abdomen. A special shape of the abdomen is typical of the subfamily. Here, segments four to six are markedly widened, while those behind are small and narrowed.

Way of life

The species of the subfamily dryophthorinae are conspicuously on monocots ( monocots specialized), only a few species of dicots known. Most of the world's species live on palm trees (Arecaceae). Most types of grass or sour grass ( sedges ) can be found in the temperate latitudes . The genus of the grain beetle ( Sitophilus ) specializes in grass seeds, including cereal grains, and has been spread around the world as a storage pest. The real grain beetle ( Sitophilus granarius ) is not known to be found in the wild. The small tribe Dryophthorini, which includes the most original representatives of the subfamily, lives differently, drilling in rotten wood or wooden mulm.

Within the subfamily, bacteria have been identified as intracellular symbionts of numerous species. The bacteria live in special cells called bacteriocytes that surround the midgut. They provide their host with essential nutrients that the host cannot synthesize itself. The bacterium is no longer viable outside the cells. Some, such as the rice grain beetle Sitophilus oryzae, carry a representative of the Alpha Proteobacteria and the Wolbachia genus belonging to the Gammaproteobacteria in the same cells , which means that (in addition to the nuclear and mitochondrial genomes) four genomes of different origins are detected in one cell.

Economic importance

Some Dryophthorinae are feared pests. The species of the genus Sitophilus are pests of all types of grain and have been carried off by humans with supplies worldwide. Rhynchophorus ferrugineus and Rhynchophorus palmae occur on economically important palm species that can cause them to die. The species have now been carried away almost worldwide and can hardly be combated. The species of the genus Cosmopolites (which has the worldwide spread in the name) are feared pests in banana crops. Other species are harmful to sugar cane and bamboo.

Systematics

The Dryophthorinae are mainly considered to be a relatively basal branch of the “higher” weevils, which comprise the families (or subfamilies) with kneeling antennae. The monophyly of the line is hardly doubted by any systematist due to the special construction of antennae and mouthparts as autapomorphies . Whether they deserve the status of an independent family or should better be treated as a subfamily of a broad family Curculionidae is still a matter of dispute.

The Dryophthorinae are divided into five tribes:

Scientific synonym for Dryophthorinae is Rhynchophorinae. The Dryophthorinae were formerly considered to belong to the Cossoninae, with which they share the way of life in wood.

Individual evidence

  1. ^ Rolf G. Oberprieler, Adriana E. Marvaldi, Robert S. Anderson: Weevils, weevils, weevils everywhere. Zootaxa, 1668, pp. 491-520, 2007
  2. ↑ Brenda M. May (1994): An introduction in the immature stages of Australian Curculionoidea. In: Elwood C. Zimmerman: Australian Weevils (Coleoptera: Curculionoidea): Brentidae, Eurhynchidae, Apionidae and a Chapter on Immature Stages by Brenda May (Australian Weevils Series) (Volume II). CSIRO Publishing.
  3. ↑ Robert S. Anderson (2002): The Dryophthoridae of Costa Rica and Panama: checklist with keys, new synonymy and descriptions of new species of Cactophagus, Mesocordylus, Metamasius and Rhodobaenus (Coleoptera; Curculionidae) Zootaxa 80: 1-94.
  4. ^ Dryophthoridae of Costa Rica and Panama
  5. ↑ A. Moya, R. Gil, A. Latorre (2009): The evolutionary history of symbiotic associations among bacteria and their animal hosts: a model. In: Clinical Microbiology and Infection , Volume 15, Supplement 1: 11-13.
  6. ↑ Abdelaziz Heddi, Anne-Marie Grenier, Chaqué Khatchadourian, Hubert Charles, Paul Nardon (1999): Four intracellular genomes direct weevil biology: Nuclear, mitochondrial, principal endosymbiont, and Wolbachia. Proceedings of the National Academy of Sciences of the USA, vol. 96 no.12: 6814-6819 doi : 10.1073 / pnas.96.12.6814
  7. ↑ Adriana E. Marvaldi, Andera S. Sequeira, Charles W. O'Brien, Brian D. Farrell (2002): Molecular and Morphological Phylogenetics of Weevils (Coleoptera, Curculionoidea): Do Niche Shifts Accompany Diversification? Systematic Biology 51 (5): 761-785. doi : 10.1080 / 10635150290102465
  8. ↑ Patrice Bouchard, Yves Bousquet, Anthony E. Davies, Miguel A. Alonso-Zarazaga, John F. Lawrence, Chris HC Lyal, Alfred F. Newton, Chris AM Reid, Michael Schmitt, S. Adam Ślipiński, Andrew BT Smith: Family -group names in Coleoptera (Insecta). ZooKeys, 88, pp. 1-972, 2011 doi : 10.3897 / zookeys.88.807

Web links

Commons : Dryophthoridae  - Collection of images, videos and audio files