Distribution of Rhinocyllus conicus in Rocky Mountain National Park Figure 4. 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. Additional index words: Biological control. and C. horridulum Michaux, and significant reductions in seed numbers of both species occurred during 2008. I found a few of these Short-snouted Weevils on Wilford Bridge on Monday, this I think is Rhinocyllus conicus. Area studied for presence of Rhinocyllus conicus Figure 3. A black weevil with a tessellated pattern of pale pubescence on the elytra. Identification difficulty. Weed and Pest Control Conference: 205–206. Thistles which reproduce only via seed, such as musk thistle, are controlled well by this weevil and its seed head destroying larvae. Rhinocyllus conicus has the greatest temporal overlap with the dominant tephritid fl y Paracantha culta (Louda 1998). Developing larvae feed on the receptacle and the young seeds, reduc-ing or preventing the production of viable seeds. Description . Length: 4 to 7 mm. 6 nutans (Harris 2005), however, six weevil larvae in one C. vinaceum flower head was the largest number found at Silver Springs (Sivinski 2007). Thank you. The weevil Rhinocyllus conicus Froeh., introduced to control exotic thistles, has exhibited an increase in host range as well as continuing geographic expansion. Each female lays about 100 to 200 eggs on the bracts of thistle heads. They are lovely little Weevils and are about 4-7mm in length. 1990). Selected survey tracks in the study area showing where weevils we were present and absent from thistle habitats Figure 5. A head weevil (Rhinocyllus conicus Froel., Coleoptera: Curculionidae) was selected for introduction into Canada and the United States for biological control of Carduus species (2, 3, 4, 10). collected in south-eastern Italy were released in See Canyon, California, in 1973 for the biological control of Italian thistle (Carduus pycnocephalus). Adults do some damage as well when they feed on the foliage. However, it was suspected that the phenology of the two seed predators issuchthattheyco-occuratacriticaltimefor U.solstitialis,whichcouldlimitthefly’sability tobuilduphighpopulations. The weevil also has become established in Missouri (Puttier et al. INTRODUCTION Thistles in the genus Carduus hav e been the target of classical biological control programs in several coun­ tries, including Argentina, Australia, Canada, New Zealand, and the United States (3). The adults overwinter on the ground in litter and can be found in the spring on musk thistle heads, where they lay their eggs. 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. Cirsium vinaceum flower head with three Rhinocyllus conicus egg sites. Herbicidal effect on Rhinocyllus conicus Froet., a thistle head weevil, was studied by examining the mortality, emergence rates and weights of weevils Rhinocyllus conicus (Frölich, 1792) on Carduus, Centaurea, Cirsium gall. Proceedings of the 28th N.Z. RHINOCYLLUS Germar, 1817. Rhinocyllus conicus is a species of true weevil. Rhinocyllus conicus Froel. They are associated with Thistles, the larvae develop in the flower heads. May, B.M. They are supposed to be a Southern species, but it appears they are heading North. 1978), Nebraska (McCarty and Lamp 1982), Kentucky (Townsend et al. Some larvae tunnel through the upper stem instead of chambering in a flower head; this can also be destructive to the plant. Rhinocyllus conicus Froel. Rhinocyllus conicus (Froelich, 1792) Synonyms . We tested whether the distribution of R. conicus was related to elevation by performing 2 separate studies. musk thistle seed production. In 25–30 days, the larvae pupate and the pupae develop into adults in 8–14 days. Rhinocyllus conicus Froel. CURCULIONIDAE Latreille, 1802. RHINOCYLLINI Lacordaire, 1863. Larvae develop in the flower head and consume the seed as it develops. Jessep, C.T. The rostrum is very short. It is by Kansas Department of Agriculture . 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). We examined the presence of the exotic weevil Rhinocyllus conicus Fröelich on native thistles at high elevations in the Rocky Mountains of Colorado. Some larvae tunnel through the upper stem instead of chambering in a flower head; this can also be destructive to the plant. 1993: Larvae of Curculionoidea (Insecta: Coleoptera): a systematic overview. Field data on the incidence and increase of this weevil at this colonisation site are presented. thistles in North America suggests at least 8 lessons for future biological control efforts. Includes mostly rare and very local species, only Larinus carlinae and Rhinocyllus conicus being widespread in the south. 1975: Introduction of a weevil for biological control of nodding thistle. … lus conicus, was introduced from Eurasia to control musk thistle by reducing seed pro-duction. 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. Habitat. Rhinocyllus conicus (Frölich, 1792) Suborder: Superfamily: Family: Subfamily: Tribe: Genus: POLYPHAGA Emery, 1886. us, overall, the strategies of the herbivores in this fl oral guild are By feeding on re-ceptacle tissue, its larvae prevent development of some or … Abstract. This weevil was introduced into Kansas by the Department of Agriculture to aid in the control of musk thistle. The effect of the red imported fire ant, Solenopsis invicta Buren, on Rhinocyllus conicus Froelich in a musk thistle, Carduus nutans L., biological control program was evaluated in laboratory and field trials in pastures in middle Georgia in 1999 and 2000. 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. The adult weevil is black and covered in a thin black and yellowish mottled coat of hairs. Rhinocyllus conicus Rhinocyllus conicus Species; Additional images; Click here to support NatureSpot by making a donation - small or large - your gift is very much appreciated. Between 1992 and 1996, the frequency of weevil damage to native thistles consistently increased, reaching 16 to 77 percent of flowerheads per plant. Abstract. Pupation in the receptacle. Rhinocyllus conicus (Froehlich) (Coleoptera: Curculionidae). Musk thistles that were infested with lower densities of T. horridus larvae (<20 per plant) also produced multiple stems that were usually shorter than uninfested thistles. Thistles which reproduce only via seed, such as musk thistle, are controlled well by this weevil and its seed head destroying larvae. Adults do some damage as well when they feed on the foliage. Rhinocyllus conicus was initially released and established in Virginia in 1969 where it successfully controlled musk thistle after six years (Kok and Surles 1974). Image 5512294 is of musk thistle head weevil (Rhinocyllus conicus ) adult(s). CURCULIONOIDEA Latreille, 1802 . 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 is a species of true weevil. 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. LIXINAE Schönherr, 1823. INTRODUCTION Thistles in the genus Carduus have been the target of classical biological control programs in several coun-tries, including Argentina, Australia, Canada, New Zealand, and the United States (3). Adult R. conicus are dark brown in color and 10 to 15 mm long. The effect of the red imported fire ant, Solenopsis invicta Buren, on Rhinocyllus conicus Froelich in a musk thistle, Carduus nutans L., biological c The late season flowers produce seeds with Eggs hatch in 6 to 9 days and newly hatched larvae feed through the bracts into the receptacle. Larvae of R. conicus completed development in heads of the native species C. carolinianum (Walter) Fernald and Schubert. 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. Adult Rhinocyllus conicus Fröelich on a thistle Photo by: Julia Hicks Figure 2. Adults of Rhinocyllus conicus (Froel.) Presence of the exotic weevil (Rhinocyllus conicus Fröelich) at high elevations in the Rocky Mountains of Colorado Western North American Naturalist , Dec 2014 Julia J. Hicks , Susan W. Beatty , … Rhinocyllus conicus on native species in the northcentral USAprovides the opportunity to experimentally evaluate factors that might help predict non-target host plant use, magni- tude of direct impact with transference, and indirect effects mediated by trophic interac-tions. structural damage by rhinocyllus conicus (coleoptera: curculionidae) within the flowerheads of nodding thistle - volume 116 issue 10 - j. d. shorthouse, r. g. lalonde Abstract Rhinocyllus conicus is a flowerhead weevil deliberately introduced into the USA for the biological control of invasive exotic thistles in the genus Carduus.This study documents the course and magnitude of the weevil population expansion onto nontarget host plants. 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. (Col.: Curculionidae) larvae feeding within the capitula of Carduus thistles may reduce production of viable seeds. horridus on Rhinocyllus conicus (Coleoptera: Curculionidae) ... conicus adults developed from T. horridus-infested thistles. Additional index words: Biological control. 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.. 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. Curculio conicus Froelich, 1792; Curculio thaumaturgus Rossi, 1794; References . 1984; Kelly et al. Establishment in NewZealand of all three biocontrol agents is well documented (Jessep 1975,1989b;Harmanetal.1996;Hayes2007). 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