Biology of the Musk Thistle Head Weevil. The adults and larvae of the tortoise beetle feed on the leaves and skeletonize the plant. CABI Compendium: Status inferred from regional distribution. It is not a regulated pest in any country of introduction. > 10°C, Cold average temp. Musk thistle (nodding thistle). After pupation, the newly-minted adult lingers in its protective case for a while before exiting the flower. She covers the eggs with masticated plant tissue to … Ecology, 88(2):413-423., Sagliocco JL, Kwong RM, Morley T, 2012. They traveled to New Zealand in 1973, to Argentina in 1980, and to Australia in 1989. by Niechols JR, Andres LA, Beardsley JW, Geoden RD, Jackson CG]. North America has about 90 species of native thistle in the genus Cirsium (USDA, 2013). Acta Oecologica, 15(5):529-541, Turner CE, Pemberton RW, Rosenthal SS, 1987. musk thistle head weevil, led to its introduction in Oklahoma during 1991. Populations from Onopordumacanthium have also been described (Zwölfer and Harris 1984). To put things in perspective, with 400,000 species and counting, the beetle Order Coleoptera is the largest Order in Class Insecta (in fact, beetles are the largest Order of animals, period, accounting for a quarter of animal species). While they specialize on thistles in the genus Carduus, a lot depends on synchrony – lining up their reproductive schedule with the budding of the plants. Further details may be available for individual references in the Distribution Table Details section which can be selected by going to Generate Report. Wallingford, UK: CABI, Denton J, 2011. Environmental Entomology, 14(4):433-436, Harris P, 1981. Indeed, it appears that R. conicus lays more eggs on early capitula than the individual captulum can support, as in the native range parasitoids often kill a proportion of eggs; however, this over-laying of eggs can mean that capitula in the exotic range may wilt under the attack levels of R. conicus, leaving all larvae dead (Cullen and Sheppard, 2012). Washington, DC, USA: USDA Forest Service. Of these species, only R. oblongus is sympatric with R. conicus in the latter’s native range (Zwölfer and Harris, 1984), and may indeed be a subspecies (Klein and Seitz, 1994). by Julien, M. \McFadyen, R. \Cullen, J.]. Zoological Journal of the Linnean Society, 110(2):181-191, Laing JE, Heels PR, 1978. The two groups, temperate and Mediterranean, correspond to differences in climate, and differ in their phenology of oviposition and physical appearance:  the Mediterranean group starts to lay about a month earlier than the temperate group and generally has a narrower body shape, although there is individual variation and overlap between the two groups. In: Proceedings of the 28th New Zealand Weed and Pest Control Conference. (Maw, 1982), C. ownbeyi S.L. Acta Oecologica, 12(6):707-726, Sheppard AW, Cullen JM, Aeschlimann JP, 1994. It was assumed that the weevil would stick to its non-native targets, but by the mid-‘90’s, it was obvious that the NTRBs weren’t limiting themselves to exotic thistles. Wallingford, UK: CABI, CABI, Undated a. CABI Compendium: Status as determined by CABI editor. The economic benefits of R. conicus as a biological control agent against the exotic thistle Carduus nutans have been very significant in Canada, the USA and New Zealand. In: Biological control of invasive plants in the eastern United States [ed. Zwölfer and Harris (1984) stated that R. conicus ‘has been established in most parts of North America with a Carduus nutans problem’; C. nutans is known from nearly all of North America except 5 US states and 4 Canadian Provinces (USDA, 2013). It is a short-snouted beetle up to 6 millimeters in total body length. Economic impact assessment of Australian weed biological control. CABI is a registered EU trademark. A sixth species, R. inquilinus Gyll., described from Finland, appears to be a small individual of R. conicus (Zwölfer and Harris, 1984). Welsh (DePrenger-Levin et al., 2010) and C. hillii (Canby) Fernald (Sauer and Bradley, 2008). More work is needed to better understand the genetic patterns underlying these differences and to see if the different ecotypes show any degree of reproductive incompatibility. Desrochers A M, Bain J F, Warwick S I, 1988. In the words of the Germans/Dutch/Pennsylvania Dutch/Scandinavians (lots of people claim this saying), “We grow too soon old and too late smart” (or, in the words of Benjamin Franklin – “Life’s tragedy is that we get old too soon and wise too late.”). Biological control of plumeless thistle (Carduus acanthoides L.) in Argentina. Weed Science, 25(3):288-292, Goeden RD, Ricker DW, 1978. Please consider upgrading your browser to the latest version or installing a new browser. Berlin, Germany: Dr W. Junk, Cullen J, Sheppard AW, 2012. Imagine this bounty virtually wiped out by the Eurasian thistlehead weevil, Rhinocyllus conicus. It is by Mark Schwarzlander at University of Idaho. Pan-Pacific Entomologist, 62(4):329-332, Woodburn TL, 1996. Overall, R. conicus was less effective in Australia due to asynchrony with its host. Commonwealth Institute of Biological Control, 4:76-9, Hodgson JM, Rees NE, 1976. Melbourne, Australia: CSIRO Publishing, 184-189, Sauer SA, Bradley KL, 2008. Development from egg to adult takes about seven weeks, but may be shorter in Mediterranean climates. Rhinocyllus conicus is a weevil, native to Europe and western Asia, that has been introduced into several countries as a biological control agent for some exotic invasive thistle species (Boldt and Kok, 1982). Weed Science, 24(1):59-62, Jessep CT, 1975. R. conicus reduces seed production of the native North American thistle species it is able to attack (Turner et al., 1987; Louda, 1998). 110 (2), 181-191. Females lay between 100 and 200 eggs, two to five at a time, on the bracts of the developing thistle flower buds, and then top each egg with frass (bug poop) (alternatively, some sources say she caps the eggs with chewed-up plant material). > 10°C, coldest month < 0°C, dry summers), Continental climate with dry winter (Warm average temp. Based on the relative distribution and abundance of C. nutans in these other countries, the benefits to New Zealand resulting from the impacts of R. conicus are likely to be a similar order of magnitude to Australia, while in North America the benefits are likely to be very much higher, perhaps an order of magnitude higher or more. Plants Database. The known distribution of R. conicus does not perfectly match the distribution of its main host plants in its native range, which suggests some apparent gaps in its native range may simply be because the host has been recorded but the pest has not. Newly-hatched larvae dive into the flower head where, according to Wikipedia, they feed inside the receptacle on flower parts and developing seeds – one larva may consume as many as 25 seeds. In the Mediterranean region, where R. conicus also uses the hosts C. pycnocephalus, C. tenuiflorus and S. marianum, the hot dry summer means the hosts have a relatively early, but shorter flowering period, meaning R. conicus starts ovipositing earlier than in temperate regions, but only has time for one generation before their hosts stop flowering and adults need to seek aestivation sites. However, dispersal only takes place in spring and in the absence of suitable nearby hosts. Musk thistle is a biennial weed that reproduces only from seed. Despite their secretive lifestyle, the larvae are found by parasitoids. Thistle-head weevil (Rhinocyllus conicus); adult. The head weevil overwinters as an adult (Figure 3). This habit favors attack by R. conicus. 45 (4), 534-537. Introduction of a weevil for biological control of nodding thistle. Klein M, Seitz A, 1994. It was introduced to the United States in 1969, the same year the National Environmental Policy Act was crafted. Ecological effects of an insect introduced for the biological control of weeds. Weed Science, 45(4):534-537, Gassmann A, Kok L-T, 2002. The risks of the introduction and spread of R. conicus to other regions is limited, as it is specific to a few genera of host plants and has only left its native range through deliberate release as a biological control agent. The other four species in the genus Rhinocyllus also feed in the capitula of members of the tribe Cardueae (in the Asteraceae). Musk thistle and thistle head weevil: noxious weed and biological control By Kent Fothergill on May 26, 2011 • ( 1) Musk thistle along a Pemiscot County roadway. Flower heads contain multiple larvae, and the combined pupal chambers may form a large, hard mass. Musk thistle head with bracts consumed by some insect. In its exotic range R. conicus has also attracted parasitoids (Zwölfer and Harris, 1984; Wilson and Andres, 1986), but at quite low rates. On this basis, and given the genetic divergence between groups, Klein and Seitz (1994) argued that R. conicus has two subspecies. Plumeless thistle, Carduus acanthoides L., and musk thistle, CarduuS thoermeri Weinmann, potted plants were inoculated with eggs of Rhinocyllus conic We use cookies to enhance your experience on our website.By continuing to use our website, you are agreeing to our use of cookies. The insect, called the musk thistle seed head weevil, will greatly reduce the thistle population next year, said an Extension biological control specialist at the University of Missouri. 24 (4), 204. Weed Science. Natural enemies and population stability of the winter-annual Carduus pycnocephalus L. in Mediterranean Europe. At the edges of Russian thistle’s range, and when Russian thistle has finished blooming, the weevil showed a willingness to move to native thistles – in fact, it has been found in 22 of our 60-ish species of native Cirsium, some of them already rare. Mating takes place shortly thereafter, and by the time musk thistles begin to bolt, the females are ready to lay eggs. 5-Year Review: Summary and Evaluation. Turner et al. Slough, UK: Commonwealth Agricultural Bureaux. The head weevil can attack other thistles, including native species. Coleoptera, Curculionidae, Subfamily Hyperinae. These are R. oblongus Cap. Each female lays approximately 100 eggs. 5-Year Review: Summary and Evaluation. \BeardsleyJW, \Geoden, R. D. \Jackson, C. G.]., USDA-NRCS, 2013. What a journey! Populations of the weevil from south-west France were released against spear thistle Cirsium vulgare in the state of Victoria in Australia in 1989, but establishment has been poor since (Sagliocco et al., 2012). As a biological control agent it has proved more effective in temperate regions and this may be in part because the populations of the weevil introduced into these regions have a partial second generation. All weevils from both genera are believed to feed in the capitula of Asteraceae species. (1987) listed another twelve species of native Cirsium thistles in California from which R. conicus has been reared. In late summer and in autumn the adults seek overwintering sites away from their hosts. Native to Europe and western Asia, R. conicus has been deliberately introduced to Canada in 1968 (Harris and Zwölfer, 1971; Harris, 1984); South America in 1980 (Feldman, 1997); Australia in 1989 (Woodburn and Cullen, 1993; 1995); and New Zealand in 1973 (Jessep, 1975; 1981) as a biological control agent for thistles in the genera Carduus,Cirsium and Silybum. They also argued that the Mediterranean group matches the morphological descriptions and climatic distributions of R. oblongusCapiomont (1873) and therefore that the status of this species needs further consideration. Data source for updated system data added to species habitat list. Melbourne, Australia: DSIR/CSIRO. The BugLady found this pair of weevils while she was chasing Thistle tortoise beetles (clearly, it’s a weevil that gets a lot of mileage out of its food plant). Global Biodiversity Information Facility. They are dark/black in color, but freshly-emerged individuals are mottled with a coat of short black and yellowish hairs that makes them look like they’re dusted with pollen. 89. Dispersal of Rhinocyllus conicus for biocontrol of musk thistle. Zwölfer H, Harris P, 1984. More information about modern web browsers can be found at The biology of Canadian weeds. California, USA: University of California Division of Agriculture and Natural Resources, 248-251, Arnett AE, Louda SM, 2002. The four instars of larval development and pupation occur inside the capitulum. And, in the “Ain’t the Internet Grand” category, a Google search for “weevil on thistle” resulted in a quick ID. To date, more than 900,000 weevils have been collected and redistributed to 670 sites in Oklahoma. by Delfosse ES, Scott RR]. Populations from different regions and hosts have distinct host preference profiles and capacities to differentially exploit different thistle hosts (C. nutans, C. pycnocephalus, C. vulgare (Savi) Tenore and Silybum marianum Gaert.) Rondebosch, South Africa: University of Cape Town, 409-415, Woodburn TL, Cullen JM, 1993. It does not seem that R. conicus has managed to spread to new regions unaided. This weevil only has a partial second generation in more temperate climates (Gassmann and Kok, 2002); however, in Tennessee and Georgia, R. conicus was observed to complete one generation and then not feed on thistles until the following spring (Wiggins, 2013, personal communication). Of Asteraceae species et al 24 ( 4 ) BY-NC 3.0 US, Based on impact native... Also feed in the series winter ( Warm average temp Canada was successful... By Moran, V. C.\Hoffmann, J. 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