Entiminae

The Entiminae are a large subfamily in the weevil family Curculionidae, containing most of the short-nosed weevils, including such genera as Entimus, Otiorhynchus, Phyllobius, Sitona, and Pachyrrhynchus. In comparison with their stunning diversity, only a few of these weevils are notorious pests of major economic importance. Entimines are commonly encountered in the field, including urban environments, and abundant in entomological collections.

Entiminae
Central European Entiminae, with some anatomical details
Scientific classification Edit this classification
Domain: Eukaryota
Kingdom: Animalia
Phylum: Arthropoda
Class: Insecta
Order: Coleoptera
Infraorder: Cucujiformia
Family: Curculionidae
Subfamily: Entiminae
Schoenherr, 1826
Diversity
55 tribes
Dorsal views of the head of Compsus auricephalus (Eustylini) and Apodrosus quisqueyanus (Polydrusini) showing their deciduous processes. In Compsus auricephalus the deciduous processes are large and sickle-shaped, whereas in Apodrosus quisqueyanus these are very small.
Dorsal views of the head of Compsus auricephalus (Eustylini) and Apodrosus quisqueyanus (Polydrusini) showing their deciduous processes.
Frontal view of the head of Compsus auricephalus indicating the mandibular scar.
Head of Compsus auricephalus indicating mandibular scar.

Diversity

There are over 12,000 described species in the Entiminae subfamily worldwide, distributed in over 1,370 genera,[1] which total nearly 14,000 by more recent counts.[2] Most tribes are represented in only one biogeographic region of the world. The current classification within the subfamily has been recognized as artificial rather than reflecting natural groups.[1]

General morphology

Besides the shape of their broad and short rostrum, most entimines are easily recognized by the presence of a mandibular scar that appears when a deciduous process falls off the mandible, shortly after the emergence of the adult from the pupal stage.[3]

Ecology

In general, entimines tend to feed on a broad range of plants (polyphagous), but there are instances of oligophagy. In general, the larvae feed externally on roots in the soil and adults feed on foliage.[1][3] They also show preference for habitat or substrate rather than plant specificity.[1]

Entimine weevils are primarily associated with angiosperms, but there are also species recorded from gymnosperms. They feed on monocotyledoneous and a broad range of dicotyledoneous plants, including members of the families Fabaceae, Malvaceae, Rutaceae, Solanaceae, and many more.[1]

The most commonly seen/known species are usually those associated with vegetation, where there is a trend to find more abundance and less diversity in cultivated areas, whereas forested or less disturbed areas tend to have more diversity and less abundance; there is a lot of diversity represented in the soil and on leaf litter, which is often overlooked.[4]

The most effective method for collecting entimines from vegetation would be using a beating sheet or by manual collecting; for soil entimines the best method would be leaf litter sifting.

Biology

Entimines may lay eggs loosely on the substrate, or in clusters glued onto the vegetation[5] and do not use their rostrum to prepare their oviposition site.[1] Over 50 species of entimines have been reported as parthenogenetic.[1]

The integument of entimines can be black, reddish, orange and even metallic in coloration. Many species of Entiminae are covered by scales arranged in a broad variety of patterns. Those scales bear three dimensional photonic crystals[6] within their lumen, which makes the scales iridescent.[1]

Many species are flightless, which usually can be seen externally: the elytral shoulders (outer anterior corners of the elytra) are reduced to absent in apterous and brachypterous forms and well-developed in species with well-developed wings.

Three drawings: first one on the left, shoulders absent (outer corner of elytra straight); center, shoulders weakly developed (outer corner of elytra slightly curved); right, shoulders well-developed (outer corners of elytra prominent)
Variation on development of elytral shoulders in entimine weevils.

Tribes

The current tribal classification of Entiminae follows Alonso-Zarazaga & Lyal[7] for the most part, with a few updates by Bouchard et al.[8] The latest tribal addition is the Namaini Borovec & Meregalli.[9] Currently, there are 55 tribes recognized in the subfamily.

A key to identify tribes is presented by Legalov.[10]

References

  1. Marvaldi, A. E.; Lanteri, A. A.; del Río, M. G.; Oberprieler, R. G. (2014). "Entiminae Schoenherr, 1823.". In Leschen, R. and R. G. Beutel. (ed.). Handbook of Zoology, Arthropoda: Insecta: Coleoptera, Volume 3: Morphology and Systematics (Phytophaga). Berlin: De Gruyter. pp. 503–522.
  2. Yunakov, N. (2021). "3i taxonomic databases, Curculionidae, subfamily Entiminae | COL". www.catalogueoflife.org. doi:10.48580/d4sl-3f8. Retrieved 2021-12-20.
  3. Anderson, R. S.; Howden, A. T. (2002). "131 Curculionidae Latreille, 1802, XII Entiminae Schoenherr, 1823". In Arnett, R.H.; M.C. Thomas; P.E. Skelley; J.H. Frank (eds.). American Beetles. Vol. II: Polyphaga: Scarabaeoidea through Curculionoidea. Boca Raton, FL: CRC Press. pp. 722–815.
  4. Girón, Jennifer C. (2020-12-30). "Status of knowledge of the broad-nosed weevils of Colombia (Coleoptera, Curculionidae, Entiminae)". Neotropical Biology and Conservation. 15 (4): 583–674. doi:10.3897/neotropical.15.e59713. ISSN 2236-3777.
  5. Howden, A. T. (1995). "Structures related to oviposition in Curculionoidea". Memoirs of the Entomological Society of Washington. 14: 53–102.
  6. Seago, Ainsley E; Brady, Parrish; Vigneron, Jean-Pol; Schultz, Tom D (2009-04-06). "Gold bugs and beyond: a review of iridescence and structural colour mechanisms in beetles (Coleoptera)". Journal of the Royal Society Interface. 6 (suppl_2): S165–S184. doi:10.1098/rsif.2008.0354.focus. PMC 2586663. PMID 18957361.
  7. Alonso-Zarazaga, M. A.; Lyal, C. H. C. (1999). A world catalogue of families and genera of Curculionoidea (Insecta: Coleoptera) excluding Scolytidae and Platypodidae (PDF). Barcelona, Spain: Entomopraxis. pp. 315 pp via International Weevil Community.
  8. Bouchard, Patrice; Bousquet, Yves; Davies, Anthony; Alonso-Zarazaga, Miguel; Alonso-Zarazaga, Miguel; Lawrence, John; Lyal, Christopher; Newton, Alfred; Reid, Chris; Schmitt, Michael; Slipinski, Adam (2011-04-04). "Family-Group Names In Coleoptera (Insecta)". ZooKeys (88): 1–972. doi:10.3897/zookeys.88.807. ISSN 1313-2970. PMC 3088472. PMID 21594053.
  9. Meregalli, Massimo; Borovec, Roman; Cervella, Piero; Santovito, Alfredo; Toševski, Ivo; Ottati, Sara; Nakládal, Oto (2021-09-01). "The Namaini, a new weevil tribe with six new genera from South Africa (Coleoptera: Curculionidae: Entiminae)". Zoological Journal of the Linnean Society. 193 (1): 95–123. doi:10.1093/zoolinnean/zlaa142. ISSN 0024-4082.
  10. Legalov, A. A. (2020). "Annotated key to weevils of the world: Part 5 - Subfamily Entiminae (Curculionidae)" (PDF). Ukrainian Journal of Ecology. 10 (2): 332–346.

Further reading

  • Donald E. Bright, Patrice Bouchard. The Insects and Arachnids of Canada, Part 25: Coleoptera. Curculionidae. Entiminae. Weevils of Canada and Alaska. Vol. 2. Ottawa, NRC Research Press, 2008. ISBN 0-660-19400-7.
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