Rhinocyllus conicus is a species of true weevil. Rhinocyllus conicus is a species of true weevil. … Developing larvae feed on the receptacle and the young seeds, reduc-ing or preventing the production of viable seeds. 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.. A black weevil with a tessellated pattern of pale pubescence on the elytra. Area studied for presence of Rhinocyllus conicus Figure 3. 1984; Kelly et al. However, it was suspected that the phenology of the two seed predators issuchthattheyco-occuratacriticaltimefor U.solstitialis,whichcouldlimitthefly’sability tobuilduphighpopulations. lus conicus, was introduced from Eurasia to control musk thistle by reducing seed pro-duction. Rhinocyllus conicus larvae often co-occur with maggots of P. gentilis and compete with the native fly for the food resource in flower heads of C. vinaceum. This weevil was introduced into Kansas by the Department of Agriculture to aid in the control of musk thistle. Establishment and Efficacy of Rhinocyllus conicus Froelich (Coleoptera: Curculionidae) in Controlling Carduus nutans L. In North Carolina R. C. McDonald and A. O. Robbing Musk thistle, Cardmis nutans L., has become a serious weed pest in North Carolina since its accidental introduction in contaminated hay from the Midwest during drought periods in the late 1980's. They are lovely little Weevils and are about 4-7mm in length. By feeding on re-ceptacle tissue, its larvae prevent development of some or … musk thistle seed production. Larvae of R. conicus completed development in heads of the native species C. carolinianum (Walter) Fernald and Schubert. Between 1992 and 1996, the frequency of weevil damage to native thistles consistently increased, reaching 16 to 77 percent of flowerheads per plant. Adult Rhinocyllus conicus Fröelich on a thistle Photo by: Julia Hicks Figure 2. Jessep, C.T. Cirsium vinaceum flower head with three Rhinocyllus conicus egg sites. Curculio conicus Froelich, 1792; Curculio thaumaturgus Rossi, 1794; References . Proceedings of the 28th N.Z. Description . Of our five species of Lixus, four are probably extinct while the recently discovered L. scabricollis has spread rapidly around the coasts of England and Wales. The weevils can reduce seed production by near-ly 80%, but they are attracted more to earlier blooming rather than later blooming flowers. Rhinocyllus conicus (Frölich, 1792) Suborder: Superfamily: Family: Subfamily: Tribe: Genus: POLYPHAGA Emery, 1886. thistles in North America suggests at least 8 lessons for future biological control efforts. Rhinocyllus conicus was initially released and established in Virginia in 1969 where it successfully controlled musk thistle after six years (Kok and Surles 1974). The adult weevil is black and covered in a thin black and yellowish mottled coat of hairs. Rhinocyllus conicus has been widely used as a biocontrol agent of musk thistle in the USA (Surles et al., 1974, Kok and Surles, ... After 6–8 days, the eggs hatch and the larvae emerge and feed on the receptacle tissue, preventing seed formation. Rhinocyllus conicus Froel. Pupation in the receptacle. Includes mostly rare and very local species, only Larinus carlinae and Rhinocyllus conicus being widespread in the south. 1990). RHINOCYLLUS Germar, 1817. Rhinocyllus conicus (Froehlich) tribe,(Coleoptera: Curcu-lionoidae), nodding (musk) thistle receptacle weevil, is (Paynter known to attack different athistle species but displays a clear preference for nodding thistle, Carduus nutans L. (Zwölfer asand Harris, 1984). Distribution of Rhinocyllus conicus in Rocky Mountain National Park Figure 4. Field data on the incidence and increase of this weevil at this colonisation site are presented. CURCULIONOIDEA Latreille, 1802 . The weevil Rhinocyllus conicus Froeh., introduced to control exotic thistles, has exhibited an increase in host range as well as continuing geographic expansion. Rhinocyllus conicus has the greatest temporal overlap with the dominant tephritid fl y Paracantha culta (Louda 1998). The larvae of R. conicus feed in the receptacles and thereby prevent the production of viable seeds, with each larva destroying approximately 28 seeds (Popay et al. CURCULIONIDAE Latreille, 1802. 1993: Larvae of Curculionoidea (Insecta: Coleoptera): a systematic overview. Rhinocyllus conicus- Insights to Improve Predictability and Minimize Risk of Biological Control of Weeds S. M. LOUDA School of Biological Sciences, University of Nebraska, Lincoln, Nebraska 68588, USA Abstract A review of information on the release of Rhinocyllus conicusto control of Carduus spp. Herbicidal effect on Rhinocyllus conicus Froet., a thistle head weevil, was studied by examining the mortality, emergence rates and weights of weevils one or more weevil larvae live in the receptacle, feeding on callus tissue that is induced by their activities; according to Redfern & Shirley the receptacle also sclerifies. Rhinocyllus conicus Froel. Rhinocyllus conicus Froel. Rhinocyllus conicus (Froehlich) (Coleoptera: Curculionidae). Thirty Italian thistle (Carduus pycnocephalus) plants produced a total of 7735 (mean 285) flower heads, which potentially contained about 25 000 seeds, from mid-April to late August 1980, at See Canyon, San Luis Obispo County, California, the initial colonization site where Rhinocyllus conicus was introduced for the control of the weed. We examined the presence of the exotic weevil Rhinocyllus conicus Fröelich on native thistles at high elevations in the Rocky Mountains of Colorado. The weevil also has become established in Missouri (Puttier et al. LIXINAE Schönherr, 1823. us, overall, the strategies of the herbivores in this fl oral guild are 6 nutans (Harris 2005), however, six weevil larvae in one C. vinaceum flower head was the largest number found at Silver Springs (Sivinski 2007). We tested whether the distribution of R. conicus was related to elevation by performing 2 separate studies. Some larvae tunnel through the upper stem instead of chambering in a flower head; this can also be destructive to the plant. collected in south-eastern Italy were released in See Canyon, California, in 1973 for the biological control of Italian thistle (Carduus pycnocephalus). The adults overwinter on the ground in litter and can be found in the spring on musk thistle heads, where they lay their eggs. The rostrum is very short. 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