What Bug Is That? The guide to Australian insect families.

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Curculionidae Latreille, 1802

Overview

The classification of Curculionidae has improved slightly since the publication of the 1st Edition of The Insects of Australia (Britton 1970), but there are still many problems, and there are no workable keys to the many subfamilies and tribes. In the scheme presented here Curculionidae is recognized in the broadest sense following Kuschel (in press), except for the exclusion of the exotic Ithyceridae. Both Thompson (1992) and Zimmerman (in press) gave family rank to the subfamilies Rhynchophorine and Erirhininae, and Thompson also considers Platypodinae to form a distinct family, as does Wood (1978, 1986). Most of the subfamily concepts of Kuschel and Zimmerman are recognized here. Kuschel combined most of them into a greatly enlarged Brachycerinae (Adelognatha in the broad sense) and Curculioninae (most other subfamilies), as well as the traditional Rhynchophorinae, Cossinae, Scolytinae and Platypodinae.  

The Entiminae, commonly referred to as the Adelognatha, are characterised by having a relatively short, stout rostrum, a conspicuous scar on the outer surface of each mandible (left by the detachment of a tooth used by the adult to escape from the pupal cell), concealed maxillae, and soil-dwelling larvae which often feed on roots. Polydrosines include the brightly coloured clown weevils ( Pantorhytes ) of Papua New Guinea, one species of which extends into North Qld, and also a number of introduced pests, such as Otiorhynchus , Asynonychus cervinus (Fuller's rose weevil), Graphognathus leucoloma (whitefringed weevil), Sitona discoideus , and Phlyctinus callosus (garden weevil). Entiminae differ in having more elongate eyes and a rounded prothoracic lobe behind each eye. Leptopius , called wattle pigs, are very common and some have become pests of sugar cane and fruit trees. The fossil remains of their large pupal cases are often encountered in S.A. and W.A. (Lea 1925).

The Aterpinae include the diamond beetle or Botany Bay weevil ( Chrysolopus spectabilis ), a spectacular green or blue species, whose larvae may destroy young Acacia trees. Rhadinosomus (Rhadinosominae) are extremely elongate weevils, which have each elytron terminating in an acute process. The Amycterinae is a large subfamily of robust, ground-dwelling weevils, which have a very short rostrum, very large, chisel-like mandibles, and in some cases ( Phalidura ) a pair of forceps at the abdominal apex in the male. Amycterines are confined to Australia and feed on a variety of monocotyledonous plants, especially Poaceae and Liliaceae, the larvae living in the soil and feeding on underground stems, crowns, tubers or rhizomes (A. T. Howden 1986). Species of Gonipterus and Oxyops (Gonipterinae) are unusual in having an external, foliage-feeding, slug-like larva; G. scutellatus was accidentally introduced into New Zealand, Africa and South America, where it has become a pest of eucalypts. The Diabathrariinae includes Strongylorhinus ochraceus , whose larvae live gregariously in large galls on eucalypts.

The subfamily Rhytirhininae includes species of Aphela , which live on beaches associated with dune vegetation, as well as two pests imported from southern South America, the vegetable weevil ( Listroderes difficilis ) and the Argentine stem weevil ( Listronotus bonariensis ). Molytinae is a large group including two of our most impressive weevils, Orthorhinus cylindrirostris , the elephant beetle, and Eurhamphus fasciculatus (Plate 4, I), a large and rare species the larvae of which tunnel into the wood of hoop pine ( Araucaria cunninghamii ). Also included are Tranes , which have large eyes, almost meeting beneath the head, and are associated with the cones of cycads and flower stalks of Xanthorrhoea , and members of the Phrynixini, which feed in fern fronds and have many relatives in New Zealand. Our main representative of Cleoninae is Lixus mastersi , while Magdalidinae includes species of Saccolaemus , which have truncate elytra and an exposed, horizontal pygidium. Within the Erirhininae are a number of aquatic weevils, which have a ventral plastron in the adult and various respiratory adaptations in the larva. Included is Cyrtobagous salviniae , which was introduced from Brazil to control salvinia (Calder and Sands 1985a). Rhynchaeninae are very small, distinctive species with enlarged hind femora used in jumping; the larvae are leaf miners.

Members of the large subfamily Cryptorhynchinae are typically rather long-legged weevils with a long, backwardly directed rostrum, which is usually received into a channel formed between the fore coxae and often terminating in a receptacle on the mesosternum. Psepholax are unusual in having a much shorter rostrum and resembling bark beetles (Scolytinae) in general form. The genus Melanterius includes a large number of species which attack the seed pods of Acacia . Tentegia are unusual in that their larvae subsist on dung pellets of wallabies and kangaroos (Macropodidae), which are placed by the adults in excavations beneath logs (Wassell 1966). Other notable examples are the mango seed weevil, Sternochaetus mangiferae , and Axionicus insignis , which breeds in the seed pods of kurrajong ( Brachychiton populneum ). The Zygopinae are very long-legged tropical weevils with large, contiguous eyes. Both Baridinae and Ceutorhynchinae have a small, exposed pygidium and mesepimera which are visible from above between the pronotum and elytral humeri. Cossoninae is a large subfamily world-wide, but is primarily tropical in distribution. They are relatively small, elongate weevils, with a short rostrum, widely separated fore coxae and usually a curved spine at the tibial apex; larvae and adults may be found beneath the bark of rotten logs. There are not many named Australian species, but many remain to be described. The Rhynchophorinae are usually characterised by having an exposed pygidium and a shiny antennal club, which is pubescent at the apex only. Trigonotarsus rugosus is a large, wood-boring species. Rhabdoscelus obscurus and Cosmopolites sordidus are pests of sugar cane and bananas, respectively, while Sitophilus granarius , S. oryzae , and S. zeamais are important stored products pests.
The subfamilies Scolytinae and Platypodinae are often treated as separate families, mainly on the basis of the extremely short rostrum and associated differences in the tentorium and mandibular articulations (Wood 1978, 1986). Platypodines and some of the more derived scolytines also have narrow tarsi and lack the lobed 3rd segment characteristic of most weevils. Scolytinae are usually referred to as bark beetles, because the majority of them construct galleries in the phloem layer beneath the bark of living or dead trunks, branches or twigs, and have characteristic gallery patterns resulting from the tunneling of larvae away from the oviposition sites in the brood gallery; some species, like Coccotrypes dactyliperda , however, are seed feeders. Species of Xyleborus and some related genera and all members of the Platypodinae bore into sapwood and heartwood and feed on yeast-like ambrosia fungi (Ascomycetes: Endomycetales), which grow on the tunnel walls and are transported and cultured by the beetles; these are often called ambrosia beetles, shot-hole borers or pinhole borers. Several Northern Hemisphere scolytines have been accidentally introduced into Australia. These include Scolytus multistriatus which transmits Dutch elm disease; Ips grandicollis , which damages pine plantations (Morgan 1967); Hylastes ater and Hylurgus ligniperda . Two common platypodines are Crossotarsus omnivorus and Platypus subgranosus .


Description

Highly variable in form, but usually moderately to strongly convex, robust, heavily sclerotised and often clothed with scales or bristles. Head always more or less produced in front of eyes to form rostrum, which is usually much longer than broad; antennae always geniculate with long scape and more or less compact club; labrum absent; maxillae reduced, with short, rigid palps; gular sutures fused; penultimate tarsal segment minute and concealed at base of lobed 3rd segment, except in Platypodinae.

Larvae more or less C-shaped and very lightly sclerotised, with minute antennae and robust mandibles. Most groups of curculionids are phytophagous, with the larvae almost always feeding internally in plant tissue of various kinds, and the rostrum is thought to have evolved as a means of boring into plant tissue to form an egg cavity. Some weevil groups, like Cossoninae and Cryptorhynchinae, utilise rotten wood or bark, and Platypodinae and some Scolytinae feed on ambrosia fungi.

  • Catasarcus impressipennis

  • Leptopius colossus

  • Curculionidae

  • Neochetina bruchi; water hyacinth weevil

  • Sitophilus granarius

  • Leptopius sp.

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