Rhinocyllus conicus | |
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Dorsal view of Rhinocyllus conicus | |
Lateral view of Rhinocyllus conicus | |
Scientific classification | |
Kingdom: | Animalia |
Phylum: | Arthropoda |
Class: | Insecta |
Order: | Coleoptera |
Family: | Curculionidae |
Genus: | Rhinocyllus |
Species: | R. conicus |
Binomial name | |
Rhinocyllus conicus (Frölich, 1792) | |
Synonyms | |
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Rhinocyllus conicus is a species of true weevil. It is best known as a controversial agent of biological pest control which has been used against noxious thistles in the genera Carduus , Cirsium , Onopordum , and Silybum .
The adult weevil is black and covered in a thin black and yellowish mottled coat of hairs. It is a short-snouted beetle up to 6 millimeters in total body length. The female lays over 100 eggs on or near the bracts of the thistle flower head. She covers the eggs with masticated plant tissue to protect them from predators. When the white larva emerges from its egg it burrows into the flower head and feeds on the flower parts and developing seeds. As it grows it deposits frass and chewed plant tissue on the walls of its chamber, producing a rigid protective shell in which it will pupate. Pupation takes up to two weeks and when the weevil emerges as an adult it remains inside the chamber for a few more weeks before tunneling out of the plant.
Damage to the plant occurs mainly from larval destruction of the flower head, which prevents seed production. Some larvae tunnel through the upper stem instead of chambering in a flower head; this can also be destructive to the plant. Adults do some damage as well when they feed on the foliage. Thistles which reproduce only via seed, such as musk thistle, are controlled well by this weevil and its seed head destroying larvae. Some thistles are able to reproduce vegetatively, and while they are impacted as well, they can sometimes survive.
This weevil is native to Eurasia and North Africa. It was first introduced to the United States for thistle biocontrol in 1969, and it is now widely established in that country. The weevil was found to be very effective in reducing the spread of invasive thistles, particularly musk thistle, but also welted, Italian, bull, milk, and other thistles. However, the weevil will also readily attack native thistles of genus Cirsium, [1] in some cases contributing to population decline. [2] It is for this reason that this weevil is no longer recommended for distribution as a biocontrol agent. Further releases of the weevil are prohibited in many areas.
Biological control or biocontrol is a method of controlling pests, such as insects, mites, weeds, and plant diseases, using other organisms. It relies on predation, parasitism, herbivory, or other natural mechanisms, but typically also involves an active human management role. It can be an important component of integrated pest management (IPM) programs.
Onopordum acanthium is a flowering plant in the family Asteraceae. It is native to Europe and Western Asia from the Iberian Peninsula east to Kazakhstan, and north to central Scandinavia, and widely naturalised elsewhere, with especially large populations present in the United States and Australia. It is a vigorous biennial plant with coarse, spiny leaves and conspicuous spiny-winged stems.
Cirsium arvense is a perennial species of flowering plant in the family Asteraceae, native throughout Europe and western Asia, northern Africa and widely introduced elsewhere. The standard English name in its native area is creeping thistle. It is also commonly known as Canada thistle and field thistle.
Centaurea solstitialis, the yellow star-thistle, is a species of thorny plant in the genus Centaurea, which is part of the family Asteraceae. A winter annual, it is native to the Mediterranean Basin region and invasive in many other places. It is also known as golden starthistle, yellow cockspur and St. Barnaby's thistle.
Bruchidius villosus is a species of bean weevil known by the common names broom seed beetle and Scotch broom bruchid. This beetle is used as an agent of biological pest control against the noxious weed known as Scotch broom.
Bangasternus fausti is a species of true weevil known as the broad-nosed seed head weevil. It is used as an agent of biological pest control against noxious knapweeds, particularly spotted knapweed, squarrose knapweed, and diffuse knapweed.
Cyphocleonus achates is a species of true weevil known as the knapweed root weevil. It is native to southern Europe and the Mediterranean and is used as an agent of biological pest control against noxious knapweeds, especially spotted knapweed. It has recently been spotted in India.
Larinus minutus is a species of true weevil known as the lesser knapweed flower weevil. It is used as an agent of biological pest control against noxious knapweeds, especially diffuse knapweed and spotted knapweed.
Larinus obtusus is a species of true weevil known as the blunt knapweed flower weevil. It is used as an agent of biological pest control against noxious knapweeds, especially spotted knapweed.
Metzneria paucipunctella is a species of moth known as the spotted knapweed seed head moth. It is used as an agent of biological pest control against noxious knapweeds, particularly spotted knapweed.
Chaetorellia australis is a species of tephritid fruit fly known as the yellow starthistle peacock fly. It is used as an agent of biological pest control against the noxious weed yellow starthistle.
Eustenopus villosus is a species of true weevil known as the yellow starthistle hairy weevil. It is used as an agent of biological pest control against the noxious weed yellow starthistle.
Larinus curtus is a species of true weevil known as the yellow starthistle flower weevil. It is native to Southern Italy, Southern Europe, the Middle East and the Caucasuses. It is used as an agent of biological pest control against the noxious weed yellow starthistle in the United States.
Cirsium undulatum is a species of thistle known by the common names wavyleaf thistle and gray thistle. It is native to much of central and western North America from British Columbia east to Manitoba and south as far as the State of Durango in Mexico. It has also been found outside of its native range as an introduced species.
Larinus planus is an insect of the Curculionidae family. They are oval shaped, dark brown or black, and about 5–10 millimetres long. While native to Europe, it is also common in North America. It feeds on floral buds, primarily of thistles, with the larvae stage being the most destructive to them. In North America, it has been used as a biocontrol agent. It is also known as Larinus carlinae.
Trichosirocalus horridus is a species of true weevils, native to Europe. It is a biological pest control agent that was introduced into the United States in 1974 to control exotic thistles, especially in the Cirsium and Carduus genera.
Cirsium vinaceum is a rare species of thistle known by the common name Sacramento Mountains thistle. It is endemic to Otero County, New Mexico, in the United States, where it is known only from the Sacramento Mountains. The plant can be found in six canyon systems in a southern section of this mountain range spanning about 32 kilometers. It is rare because it is limited to a specific type of mountain wetland which is both naturally uncommon and threatened by a number of forces. The plant was federally listed as threatened in 1987.
Hylobius transversovittatus is a species of weevil in the family Curculionidae. It is native to the Old World where both adults and larvae feed on purple loosestrife. This plant is regarded as an invasive species in North America and the weevil has been introduced into both the United States and Canada in an effort to control the plant.
Galerucella calmariensis is a species of leaf beetle in the family Chrysomelidae. It is commonly known as the black-margined loosestrife beetle and is native to Europe and Asia where both adults and larvae feed on purple loosestrife. It has been introduced in North America as a biological control agent for purple loosestrife.