Weevils are
beetle
Beetles are insects that form the Taxonomic rank, order Coleoptera (), in the superorder Holometabola. Their front pair of wings are hardened into wing-cases, elytra, distinguishing them from most other insects. The Coleoptera, with about 40 ...
s belonging to the
superfamily
SUPERFAMILY is a database and search platform of structural and functional annotation for all proteins and genomes. It classifies amino acid sequences into known structural domains, especially into SCOP superfamilies. Domains are functional, str ...
Curculionoidea, known for their elongated snouts. They are usually small – less than in length – and
herbivorous
A herbivore is an animal anatomically and physiologically evolved to feed on plants, especially upon vascular tissues such as foliage, fruits or seeds, as the main component of its diet. These more broadly also encompass animals that eat n ...
. Approximately 97,000 species of weevils are known. They belong to several families, with most of them in the family
Curculionidae
The Curculionidae are a family of weevils, commonly called snout beetles or true weevils. 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.
Th ...
(the
true weevil
The Curculionidae are a family of weevils, commonly called snout beetles or true weevils. 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
...
s). It also includes
bark beetles
A bark beetle is the common name for the subfamily of beetles Scolytinae. Previously, this was considered a distinct Family (biology), family (Scolytidae), but is now understood to be a specialized clade of the "true weevil" family (Curculioni ...
, which while morphologically dissimilar to other weevils in lacking the distinctive snout, is a subfamily of Curculionidae. Some other beetles, although not closely related, bear the name "weevil", such as the
leaf beetle
The beetle family Chrysomelidae, commonly known as leaf beetles, includes over 37,000 (and probably at least 50,000) species in more than 2,500 genera, making it one of the largest and most commonly encountered of all beetle families. Numerous s ...
subfamily
Bruchinae
The bean weevils or seed beetles are a subfamily (Bruchinae) of weevils, which in turn are a subset of beetles. The Bruchinae now placed in the family Chrysomelidae, though they have historically been treated as a separate family. The subfamily ...
, known as "bean weevils", or the
biscuit weevil (''Stegobium paniceum''), which belongs to the family
Ptinidae
Ptinidae is a family of beetles in the superfamily Bostrichoidea. There are at least 220 genera and 2,200 described species in Ptinidae worldwide. The family includes spider beetles and deathwatch beetle, as well as the Cigarette beetle, cigare ...
.
Many weevils are considered pests because of their ability to damage and kill crops. The grain or
wheat weevil
The wheat weevil (''Sitophilus granarius''), also known as the grain weevil or granary weevil, is an insect that feeds on cereal grains, and is a common pest in many places. It can cause significant damage to harvested stored grains, and may drast ...
(''Sitophilus granarius'') damages stored
grain
A grain is a small, hard, dry fruit (caryopsis) – with or without an attached husk, hull layer – harvested for human or animal consumption. A grain crop is a grain-producing plant. The two main types of commercial grain crops are cereals and ...
, as does the
maize weevil
The maize weevil (''Sitophilus zeamais''), known in the United States as the greater rice weevil, is a species of beetle in the family Curculionidae. It can be found in numerous tropical areas around the world, and in the United States, and is a m ...
(''Sitophilus zeamais''), among others. The
boll weevil
The boll weevil (''Anthonomus grandis'') is a species of beetle in the family Curculionidae. The boll weevil
feeds on cotton buds and flowers. Thought to be native to Central Mexico, it migrated into the United States from Mexico in the late 19 ...
(''Anthonomus grandis'') attacks
cotton
Cotton (), first recorded in ancient India, is a soft, fluffy staple fiber that grows in a boll, or protective case, around the seeds of the cotton plants of the genus '' Gossypium'' in the mallow family Malvaceae. The fiber is almost pure ...
crops; it lays its eggs inside cotton bolls and the larvae eat their way out. Other weevils are used for biological control of invasive plants.
A weevil's
rostrum
Rostrum may refer to:
* Any kind of a platform for a speaker:
**dais
**pulpit
** podium
* Rostrum (anatomy), a beak, or anatomical structure resembling a beak, as in the mouthparts of many sucking insects
* Rostrum (ship), a form of bow on naval ...
, or elongated snout, hosts chewing
mouthparts instead of the piercing mouthparts that
proboscis
A proboscis () is an elongated appendage from the head of an animal, either a vertebrate or an invertebrate. In invertebrates, the term usually refers to tubular arthropod mouthparts, mouthparts used for feeding and sucking. In vertebrates, a pr ...
-possessing insects are known for. The mouthparts are often used to excavate tunnels into grains. In more derived weevils, the rostrum has a groove in which the weevil can fold the first segment of its antennae.
Most weevils have the ability to fly (including pest species such as the
rice weevil
The rice weevil (''Sitophilus oryzae'') is a stored product Pest (organism), pest which attacks seeds of several crops, including wheat, rice, and maize.
Description
The adults are usually between long, with a long snout. The body color appears ...
), though a significant number are flightless, such as the genus ''
Otiorhynchus
''Otiorhynchus'' (sometimes misspelled as ''Otiorrhynchus'') is a large genus of weevils in the family Curculionidae. Many species of the genus, particularly the black vine weevil (''O. sulcatus'') and the strawberry root weevil (''O. ovatus'') ...
'', and others can jump.
One species of weevil, ''
Austroplatypus incompertus'', exhibits
eusociality
Eusociality ( Greek 'good' and social) is the highest level of organization of sociality. It is defined by the following characteristics: cooperative brood care (including care of offspring from other individuals), overlapping generations wit ...
, one of the few insects outside the
Hymenoptera
Hymenoptera is a large order of insects, comprising the sawflies, wasps, bees, and ants. Over 150,000 living species of Hymenoptera have been described, in addition to over 2,000 extinct ones. Many of the species are parasitic.
Females typi ...
and the
Isoptera
Termites are a group of detritophagous eusocial cockroaches which consume a variety of decaying plant material, generally in the form of wood, leaf litter, and soil humus. They are distinguished by their moniliform antennae and the soft-bo ...
to do so.
Taxonomy and phylogeny
Because so many species exist in such diversity, the higher classification of weevils is in a state of flux. They are generally divided into two major divisions, the Orthoceri or primitive weevils, and the Gonatoceri or true weevils (
Curculionidae
The Curculionidae are a family of weevils, commonly called snout beetles or true weevils. 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.
Th ...
).
E. C. Zimmerman proposed a third division, the Heteromorphi, for several intermediate forms. Primitive weevils are distinguished by having straight antennae, while true weevils have elbowed (geniculate) antennae. The elbow occurs at the end of the
scape (first antennal segment) in true weevils, and the scape is usually much longer than the other antennal segments. Some exceptions occur, such as
Nanophyini, primitive weevils with long scapes and geniculate antennae, while among the true weevils,
Gonipterinae and ''
Ramphus'' have short scapes and little or no "elbow".
A 1995 classification system to family level was provided by Kuschel, with updates from Marvaldi ''et al.'' in 2002,
and was achieved using
phylogenetic
In biology, phylogenetics () is the study of the evolutionary history of life using observable characteristics of organisms (or genes), which is known as phylogenetic inference. It infers the relationship among organisms based on empirical dat ...
analyses. The accepted families were the primitive weevils,
Anthribidae
Anthribidae is a family of beetle
Beetles are insects that form the Taxonomic rank, order Coleoptera (), in the superorder Holometabola. Their front pair of wings are hardened into wing-cases, elytra, distinguishing them from most other i ...
,
Attelabidae
The Attelabidae is a widespread family of weevils. They are among the primitive weevils, because of their straight antennae, which are inserted near the base of the rostrum. The prothorax is much narrower than the base of the elytra on the abdo ...
,
Belidae
Belidae is a family of weevils, called belids or primitive weevils because they have straight antennae, unlike the "true weevils" or Curculionidae which have geniculate (elbowed) antennae. They are sometimes known as " cycad weevils", but this pr ...
,
Brentidae
Brentidae is a cosmopolitan distribution, cosmopolitan family of primarily xylophagy, xylophagous beetles also known as straight-snouted weevils; they have sometimes been called "primitive weevils", but this name also applies to taxa such as the ...
,
Caridae
Caridae is a small Gondwanan family of weevils. They are considered part of the primitive weevil group, because they have straight rather than geniculate (elbowed) antennae. The insertion of the antennae on the rostrum cannot be seen from above ...
, and
Nemonychidae
Nemonychidae is a small family of weevils, placed within the ''primitive weevil'' group because they have straight rather than geniculate (elbowed) antennae. They are often called pine flower weevils. As in the Anthribidae, the labrum appears ...
, and the true weevils
Curculionidae
The Curculionidae are a family of weevils, commonly called snout beetles or true weevils. 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.
Th ...
. Most other weevil families were demoted to subfamilies or tribes. Further work resulted in the elevation of
Cimberididae
Nemonychidae is a small family of weevils, placed within the ''primitive weevil'' group because they have straight rather than geniculate (elbowed) antennae. They are often called pine flower weevils. As in the Anthribidae, the labrum appears a ...
to family from placement as a subfamily of Nemonychidae in 2017
and the recognition of the
Cretaceous
The Cretaceous ( ) is a geological period that lasted from about 143.1 to 66 mya (unit), million years ago (Mya). It is the third and final period of the Mesozoic Era (geology), Era, as well as the longest. At around 77.1 million years, it is the ...
age family
Mesophyletidae
Mesophyletidae is an extinct family of weevils known from a number of genera preserved in Cretaceous amber. The family was first described as a subfamily in the extant family Caridae, and subsequently raised to family status in 2018.
Distribut ...
in 2018 from
Burmese amber
Burmese amber, also known as Burmite or Kachin amber, is amber from the Hukawng Valley in northern Myanmar. The amber is dated to around 100 million years ago, during the latest Albian to earliest Cenomanian ages of the mid-Cretaceous period. Th ...
.
The oldest weevils date to the Middle-Late Jurassic boundary, found in the
Karabastau Formation
The Karabastau Formation () is a geological formation and lagerstätte in the Karatau Mountains of southern Kazakhstan whose strata date to the Middle to Late Jurassic. It is an important locality for insect fossils that has been studied since ...
of Kazakhstan, the
Shar-Teg locality of Mongolia, the
Daohugou
The Haifanggou Formation (), also known as the Jiulongshan Formation (), is a fossil-bearing rock deposit located near Daohugou () village of Ningcheng County, in Inner Mongolia, northeastern China.
The formation consists of coarse conglomerates ...
locality in Inner Mongolia, China, and the
Talbragar site in Australia. The extinct family
Obrieniidae, with species dating from the
Ladinian
The Ladinian is a stage and age in the Middle Triassic series or epoch. It spans the time between Ma and ~237 Ma (million years ago). The Ladinian was preceded by the Anisian and succeeded by the Carnian (part of the Upper or Late Triassic ...
stage of the
Triassic
The Triassic ( ; sometimes symbolized 🝈) is a geologic period and system which spans 50.5 million years from the end of the Permian Period 251.902 million years ago ( Mya), to the beginning of the Jurassic Period 201.4 Mya. The Triassic is t ...
through to tentatively the
Oxfordian, have sometimes been considered weevils. Genera of the family have only been found in three formations in
Kazakhstan
Kazakhstan, officially the Republic of Kazakhstan, is a landlocked country primarily in Central Asia, with a European Kazakhstan, small portion in Eastern Europe. It borders Russia to the Kazakhstan–Russia border, north and west, China to th ...
, with most named in 1993.
However, their phylogenetic position is contested, with others considering it part of
Archostemata
The Archostemata are the smallest suborder of beetles, consisting of 50 living species in five families and over 200 described fossil species. They are an ancient lineage with a number of primitive characteristics. Antenna (biology), Antennae may ...
.
The interfamilial relationships of Curculionoidea have been generally well resolved.
The phylogeny
A phylogenetic tree or phylogeny is a graphical representation which shows the evolutionary history between a set of species or Taxon, taxa during a specific time.Felsenstein J. (2004). ''Inferring Phylogenies'' Sinauer Associates: Sunderland, M ...
by Li et al. (2023) based on phylogenomic data is suggested below:[
]
Families
* Anthribidae
Anthribidae is a family of beetle
Beetles are insects that form the Taxonomic rank, order Coleoptera (), in the superorder Holometabola. Their front pair of wings are hardened into wing-cases, elytra, distinguishing them from most other i ...
—fungus weevils
* Attelabidae
The Attelabidae is a widespread family of weevils. They are among the primitive weevils, because of their straight antennae, which are inserted near the base of the rostrum. The prothorax is much narrower than the base of the elytra on the abdo ...
—leaf rolling weevils
* Belidae
Belidae is a family of weevils, called belids or primitive weevils because they have straight antennae, unlike the "true weevils" or Curculionidae which have geniculate (elbowed) antennae. They are sometimes known as " cycad weevils", but this pr ...
—primitive weevils
* Brentidae
Brentidae is a cosmopolitan distribution, cosmopolitan family of primarily xylophagy, xylophagous beetles also known as straight-snouted weevils; they have sometimes been called "primitive weevils", but this name also applies to taxa such as the ...
—straight snout weevils
* Caridae
Caridae is a small Gondwanan family of weevils. They are considered part of the primitive weevil group, because they have straight rather than geniculate (elbowed) antennae. The insertion of the antennae on the rostrum cannot be seen from above ...
* Cimberididae
Nemonychidae is a small family of weevils, placed within the ''primitive weevil'' group because they have straight rather than geniculate (elbowed) antennae. They are often called pine flower weevils. As in the Anthribidae, the labrum appears a ...
* Curculionidae
The Curculionidae are a family of weevils, commonly called snout beetles or true weevils. 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.
Th ...
—true weevils
* Mesophyletidae
Mesophyletidae is an extinct family of weevils known from a number of genera preserved in Cretaceous amber. The family was first described as a subfamily in the extant family Caridae, and subsequently raised to family status in 2018.
Distribut ...
* Nemonychidae
Nemonychidae is a small family of weevils, placed within the ''primitive weevil'' group because they have straight rather than geniculate (elbowed) antennae. They are often called pine flower weevils. As in the Anthribidae, the labrum appears ...
—pine flower weevils
* ? Obrieniidae
Sexual dimorphism
'' Rhopalapion longirostre'' exhibits an extreme case of sexual dimorphism
Sexual dimorphism is the condition where sexes of the same species exhibit different Morphology (biology), morphological characteristics, including characteristics not directly involved in reproduction. The condition occurs in most dioecy, di ...
. The female rostrum
Rostrum may refer to:
* Any kind of a platform for a speaker:
**dais
**pulpit
** podium
* Rostrum (anatomy), a beak, or anatomical structure resembling a beak, as in the mouthparts of many sucking insects
* Rostrum (ship), a form of bow on naval ...
is twice as long and its surface is smoother than in the male. The female bores egg channels into the buds of '' Alcea rosea''. Thus, the dimorphism is not attributed to sexual selection. It is a response to ecological demands of egg deposition.
Another example of extreme dimorphism in weevils is that of the New Zealand giraffe weevil
The New Zealand giraffe weevil, ''Lasiorhynchus barbicornis'', is a Brentidae, straight-snouted weevil in the subfamily Brentinae, endemism, endemic to New Zealand. ''L. barbicornis'' is New Zealand's longest beetle, and shows extreme sexual di ...
. Males measure up to and females , although there is an extreme range of body sizes in both sexes.
References
Further reading
* Bright, Donald E.; Bouchard, Patrice (2008)
''Coleoptera, Curculionidae, Entiminae: Weevils of Canada and Alaska Volume 2''
Insects and Arachnids of Canada Series, Part 25. Ottawa: NRC Research Press. .
External links
*
{{DEFAULTSORT:Weevil
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