The Curculionidae are the family of the "true" weevils (or "snout beetles"). They are one of the largest animal families, with 6,800 genera and 83,000[1] species described worldwide. They are the sister group to the family Brentidae.[2]
They include the bark beetles as the subfamily Scolytinae, which are modified in shape in accordance with their wood-boring lifestyle. They do not much resemble other weevils, so they were traditionally considered a distinct family, Scolytidae. The family also includes the ambrosia beetles, of which the present-day subfamily Platypodinae was formerly considered the distinct family Platypodidae.
They are recognized by their distinctive long snouts and geniculate antennae with small clubs; beyond that, curculionids have considerable diversity of form and size, with adult lengths ranging from 1 to 40 mm (0.04 to 1.57 in).
Weevils are almost entirely plant feeders, and most species are associated with a narrow range of hosts, in many cases only living on a single species. With so many species to classify and over 400 genera, the taxonomy of this family is quite complicated, and authors disagree on the number and placement of various subfamilies, tribes, and subtribes.
Although pesticide resistance hasn't historically been an issue with these insects, recently a mutation was discovered in association with the voltage-gated sodium channel in the species Sitophilus zeamais, indicating there is a lot to learn about how these insects adapt to changing environments.[3]
Many species of Weevils are common household and garden pests, but don't harm people, pets, or buildings. Their presence is more of a temporary nuisance. In tropical areas they have larger effects, specifically several species in the genera Conotrachelus and Copturus.[4] Recently, another species, Cylas formicarius has been observed with an increased amount of inbreeding suppression than is normal for the average population of weevils, both intraspecific and interspecific.[5]
The phylogeny of the group is complex; with so many species, a spirited debate exists about the relationships between subfamilies and genera. A 1997 analysis attempted to construct a phylogeny based mainly on larval characteristics.[6]
Recent work on the phylogenetic relationships in weevils mentions the two subfamily groups Adelognatha (short-nosed weevils, subfamily Entiminae) and Phanerognatha (long-nosed weevils, subfamilies of Curculionidae other than Entiminae) for the species of Curculionidae.[7]
Almost two dozen subfamilies are recognized by some authors even when merging those that are certainly invalid. Others, however, recognize a lesser number – the only subfamilies that are almost universally considered valid are the Baridinae, Cossoninae, Curculioninae, Cyclominae, Entiminae, Molytinae, Platypodinae, and Scolytinae. The various proposed taxonomic schemes typically recognize as many additional subfamilies again, but little agreement is seen between authorities about which. In particular, the delimitation of the Molytinae has proven difficult.
The timeline for current and extant weevil speciation and diversification is consistent with the radiation of gymnosperms during the Mesozoic period.[8]
The subfamilies considered valid by at least some authors today:
The Curculionidae are the family of the "true" weevils (or "snout beetles"). They are one of the largest animal families, with 6,800 genera and 83,000 species described worldwide. They are the sister group to the family Brentidae.
They include the bark beetles as the subfamily Scolytinae, which are modified in shape in accordance with their wood-boring lifestyle. They do not much resemble other weevils, so they were traditionally considered a distinct family, Scolytidae. The family also includes the ambrosia beetles, of which the present-day subfamily Platypodinae was formerly considered the distinct family Platypodidae.
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