WEEVIL

A 'weevil' is any beetle from the 'Curculionoidea' superfamily. They are usually small, less than 6 mm (¼ inch), and herbivorous. Due to the shape of their heads, weevils are commonly known as 'snout beetles'. There are over 60,000 species in several families, mostly in the family Curculionidae (the true weevils). Some other beetles, although not closely related, bear the name "weevil", such as the biscuit weevil (''Stegobium paniceum''), which belongs to the family Anobiidae.
Many weevils are damaging to crops. The grain or wheat weevil (''Sitophilus granarius'') damages stored grain. The boll weevil (''Anthonomus grandis'') attacks cotton crops. It lays its eggs inside unripe cotton bolls, and the young weevils eat their way out.
Weevils are often found in dry foods including nuts and seeds, cereal and grain products. In the domestic setting, they are most likely to be observed when opening a bag of flour although they will happily infest most types of grain including oats, barley and breakfast cereals. If ingested, ''E. coli'' infection and other various diseases can be contracted from weevils, depending on their diet.

Contents

Taxonomy

Phylogeny

Trivia

References

Gallery

Taxonomy

Because there are so many species and such diversity, the higher classification of weevils is in a state of flux. Weevils are generally divided into two major divisions, the Orthoceri or primitive weevils, and the Gonatoceri or true weevils (Curculionidae). Zimmerman proposed a third division, the Heteromorphi, for several intermediate forms ^[1]. 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. Nanophyini are primitive weevils (with very long trochanters) but have long scapes and geniculate antennae. From the true weevils, Gonipterinae and Ramphus have short scapes and little or no elbow.
The most recent classification system to family level was provided by Kuschel ^[2], with updates from Marvaldi ''et al.'' ^[3], and was achieved using phylogenetic analyses. The accepted families are the primitive weevils, Anthribidae, Attelabidae, Belidae, Brentidae, Caridae and Nemonychidae, and the true weevils Curculionidae. Most other weevil families were demoted to subfamilies or tribes. Weevil species radiation was shown to follow steps in plant evolution upon which the weevils feed.
Some of the features used to distinguish weevil families are:

Labrum visible as separate segment to clypeus	Anthribidae, Nemonychidae
Antennae elbowed	most Curculionidae, Nanophyini of Apioninae
Trochanters (segment between coxae and femora) as long or longer than coxae	Apioninae including Nanophyini
Fore tibia with comb of setae in apical groove opposite tarsal articulation	Belidae
Elytra striate (with longitudinal ridges or grooves)	Brentidae, Curculionidae, Rhinorhynchinae
Rostrum short and broad	Anthribidae, some Curculionidae (some Brachycerinae including ''Ithycerus'' (New York weevil), Scolytinae and Platypodinae).
Maxillary palps long and projecting (visible from above at tip of rostrum)	Anthribidae, Nemonychidae
Abdominal tergites 6 and 7 without spiracles	Caridae
Gular suture (on ventral part of head) single not double	Attelabidae, Brentidae, Curculionidae.

Phylogeny

A phylogeny of the Curculionoidea based on 18S ribosomal DNA and morphological data is suggested below:

Trivia

★ In the episode Evil Weevil of Courage the Cowardly Dog a weevil works as the butler for the Bagges, but actually wanted to suck Muriel and Eustace's blood.

★ In the movie captain Jack Aubrey (played by Russel Crowe) makes a joke about "choosing the lesser of two weevils".

★ In the book Crossroads of Twilight, book ten in The Wheel of Time series by Robert Jordan, concerns about weevils destroying stores of grain are frequent.

★ In the Hornblower Series by C. S. Forester, weevils are a common pest eating up the ship's biscuit supplies.

★ ''Zyzzyva'', a genus of tropical American weevils, is the last word in many English language dictionaries including The Official Scrabble Players Dictionary.

★ In the episode ''The Night of the Headless Woman'' of The Wild Wild West the episode's bad guy, Abdul Hassan plans to infest all western countries with giant boll weevils so that he can get rich supplying the West with cotton.

References

1. Australian weevils (Coleoptera: Curculionoidea). Volume 1. Orthoceri: Anthribidae to Attelabidae: the primitive weevils, E. C. Zimmerman, , , CSIRO, East Melbourne, 1994,
2. A phylogenetic classification of Curculionoidea to families and subfamilies, G. Kuschel, , , Memoirs of the Entomological Society of Washington, 1995
3. Molecular and morphological phylogenetics of weevils (Coleoptera, Curculionoidea): do niche shifts accompany diversification?, A. E. Marvaldi, A. S. Sequeira, C. W. O'Brien & B. D. Farrell, , , Systematic Biology, 2002

Gallery