South Dakota State University Open PRAIRIE: Open Public Research Access Institutional Repository and Information Exchange Electronic Theses and Dissertations 1974 Biological Control of Musk Thistle, Carduus Nutans, in South Dakota Dennis Morihara Follow this and additional works at: https://openprairie.sdstate.edu/etd Recommended Citation Morihara, Dennis, "Biological Control of Musk Thistle, Carduus Nutans, in South Dakota" (1974). Electronic Theses and Dissertations. 4737. https://openprairie.sdstate.edu/etd/4737 This Thesis - Open Access is brought to you for free and open access by Open PRAIRIE: Open Public Research Access Institutional Repository and Information Exchange. It has been accepted for inclusion in Electronic Theses and Dissertations by an authorized administrator of Open PRAIRIE: Open Public Research Access Institutional Repository and Information Exchange. For more information, please contact [email protected]. BIOLOGICAL CONTROL OF MUSK THISTLE, CARWUS NUTANS, IN SOUTH DAKOTA BY DENNIS MORI!Ii\RA A thesis submitted in partial fulfillment of the requirements for the degree l"la.ster of Science, Major in Entomology, South Dakota State University . 1974 RSITY UBRA�'i' TA STATE UNIVE SOUTH DAKO JU ) BIOLOGICAL CONTROL OF MIJSK THISTLE, CARJlJUS NUTANS, IN SOUTH DAKOTA .··"''�· · This thesis is approved as a creditable and independent investigation by a candidate for the degree, l'.LB.ster of Science, and is acceptable as meeting the thesis requirements for this degree. Acceptance of this thesis does not imply that the conclusions reached by the candidate are necessarily the conclusions of the major department. Thesis Advifer/ !l Date Head, Entbtlology-Zoology Department Date TABLE OF CONTENTS Page INTROilJCTION............................................... 1 METHODS AND l-'T..ATERIALS. • •• • •• • • • • • •• • •• •• • • •• • • • • • •• • • • • • •• • 4 Study Sites••••••••••••••••••••••••••••••••••••••••••••• 4 Releases of Rhinocvllus conicus••••••••• •••••••••••••••• 6 Insect Stlrvey•••• • •••••••••••• •••••••• · •.•................ 8 RESULTS AND DISCUSSION..................................... 10 Insect Su.rvey••••••••••••••• _ .... ... ... .. .. ..... .. ... ... 10 Phytophagous Insects•••••••••••••••••••••••••••••••••••• i1 Entomophagous Insects••••••••••••••••••••••••••••••••••• 27 ......... ............. ....... ... ......" .. '".� Saprophagcus Inseo.�s . 2?I Rhinocyllus conicus• ••••••••••••••••••••••••••••. •••••••• 27 Sill1Il·1!A.R.Y •••••••••••••.•••••••••••••••••••. • ••••••·• • • • • • •• •• • • • 35 ACKNOWLEIXH1ENTS............................................ J6 LITERATURE CITED........................................... 37 LIST OF FIGURES Figure Page 1 Counties in South Dakota with more than one Carduus nutans infestation that has been treated or would have been treated with an herbicide, if money were. available ••••••• •••••••• ••••• •••••• ••• • •• ••.• • •· •. ..... 2 2 An adult Rhinocyllus conicus with crust covered eggs on the· bracts of Ca:rduus nutans................. 7 J Comparison of mean monthly precipi ta.tion and temperature between Sioux Falls, South Dakota and Chernovisy, W. Ukraine............................... J4 LIST OF TABLES Table Page 1 Phytophagous insects collected from musk thistle, Carduus nutan�, in South Dakota, 1973-1974 ••••••••••• 12 2 Phytophagous insects reported from musk thistle, Carduus nu tans, in Europe............................ 19 J Parasitic and predaceous insect s collected from musk thistle, Carduus nut�ns, in South Dakota, 1973-1974�. 28 1 INTRODUCTION Carduus nutans L., musk or nodding thistle, is generally regarded as a serious threat that has not yet reached its potential limits of spread in North J\merican pastureland (Mu ligan and Frankton 19'4, -l Flee7 ood 1964 ). This undesirable Compositae was introduced into the east coast of North �'lterican Elrope the late 1800's (Stuckey from in - • . ce and For yth 19Sl) It has only re ntly become a problem in the l1idwest (McCarty 1964). l_n South Dakota, economic infestations occur in southern portions of the state (Fig. 1). ,1 1969, ?1itsk thistle, a (Doing jt al. I � Stuc and For. · h 19�1 ) can only reproduce by seed, therefore, any y 7 . method which can p_revent this from happening will reduce the problem. However, interference with the thistle's normal development may cause this biennial to behave as a short lived perennial. Plants grazed or sprayed in the spring may produce several new short stems in the same season. Three different growth stages may be present simultaneously which makes control of _Q. nutans more difficul·t than that of a strictly annual or biennial weed (Doing e. -1969 ). Feldman et al. (1968) and J . '..!/ . w a McCarty et al. (1969) did ork in Nebraska, which showed th t correct timing is important in herbicide application on this weed since the rosette stage is most vulnerab1e and weed destruction must occur before seed production. Treatments must be made over extensive areas where this thistle occurs to prevent influx of seeds (Carlson 1968). Finally, the thistle's ability to infest inaccessible areas (Harris and Zw�lfer 19'71) where cultural methods and herbicide application� MARSHALL. >iAROtNG e�Ol#N I )PERKINS I COASO.... C:\:O:d:tiP�f;i'.',"°�4 � I '! DAY \� EOMUNOS I I ZIEBACH - ..... � P OTTER 11 F>UL• 1..... BUTT r E I I �OOtNGTOH �DEUEL. MEADE I � <-' I t-lANO I HAMLIN BEADL.E BROOKINGS I �- . '--- I II. I LAWRENCEI I.AKE MOODY SANBORN I MINER PENNINGTON 't. AURORA COOK I MIMNEl'iAHA C,IJSTER OA'J1$0NIHANSONIMC HUTCHINSON FALL RIVER SENNETT TODD SHANNON • infestation that Fig. 1.-Counties in South Dakota with more than one Carduus nutans an herbicide, money were available. has been treated or would have been treated with if personal co�.rnunication ). After L. J. Wrage ( N' J u are impractical and economically nfeasible adds to the problem. Nost of our weeds are ·.introduced species whose natural enemies are not found in their new home areas. Lack of natural enemies leads cu to increased densities which do not oc r in native areas (!nuns 1929). Thus, .Q. nutans is a prime candidate for a biological control program in North America. Several introductions of a seed destroying weevil, Rhinocyllus coni cu s Froelich, have be�n ma.de with varying degrees of success. In California, R· conicus has been introduced to attack Italian thistles, �· pycnocephalus L., and milk thistles, Silybum marianum (L.) (Hawkes et al. 1972, Goeden and Ricker 1974). Kok (1974) and Surles et al. (1974) reported success of establishment of the weevil on musk thistle in Virginia. Pro:rrn.sing results in Canada by iiarris and Zwillft:.L.. (1971) indicated that R· conio1s may help in reducing seed production of both .Q.• nutans and g. acanthoides L., welted thistle. w In the summer of 1973, 1,000 E.• conicus eevils were released on This paper deals ·with that popula i musk thistle in South Dakota. t on . as well as the other insects associated with the weed. The resultant survey. supplies information on biotic factors such as interspecific competition, predation, and parasitism as such factors may influence the subsequent success or failure of this weevil as a biological control agent in South Dakota. Surveys of insects on musk thistle in Ellrope also are compared. The comparative su1dy yields insights into species di-:rnrsity and niche specialization 1·rithin the musk e - nse thistl i ct assuciation. 4 METHODS AND �u\TERIALS Carduus nutans may be distinguished from other thistles as over follows: heads nodding , usually solitary mostly 2.5 cm in diameter; stems usually without spiny wings for some di stance below the heads; bracts contracting abruptly into a narrow, oblong base and tapering at the tip into a strong spine ; middle and outer bracts strongly reflexed at the contraction, from 1.8 to 2.6 cm long and J to 9 mm in width just a�ove the contraction; flowers always purple (Milligan and Frankton 1954). e In east rn Nebras�a, nmsk thistle behaves as a biennial, but may a be a winter annual or an annual under f avor ble conditions. Generally, the seedlings emerge in the early spring or in the fall. However, in years of abundant rainfall during the summer, they may germinate m throughout the growing season. Ste el ongation starts in early May from the overwintered rosette plant. The first heads bloom in early �� June and seed dissemination begins two weeks la�er (Feldman et al. 1968 ). If Exact distribution records in North America are unknown, however, the U.S.D.A. Biological/ . Control of Weeds Laboratory, Albany, California, is in the process of obtaining such information. Economic j infestations ocpur as far west as Ida.ho ( Higgins 1974). .. ..m in southeastern South Dakota were used Studv Sites -Tr sites in this study. Both sites supported unusually dense infestations of Q. nutans, and were chosen on that basis. was ne Site A located at an unoccupied farrnstea.d in Min haha County, 2 mi les s.W. of Crooks. This site was composed of 3 distinct 5 infestations of musk thistle: (1) the first stand of thistles was approximately 2 x 9 m surrounded by Siberian el m, Ulmus pumila L., Conyza canadensis (L .) Cronquist (mare's tail) and a Bromus sp., probably Il· inermis Leysser. The thistles in this area stood 2+ m tall at maturity . (2) The second area, J x J m, was composed of musk thistles shaded throughout the day by Fraxinus pennsylvanica Marshall and Acer negundo L. The thistles in this area had been knocked down at an undetermined date early in the first surmner of the study