Biological Control of Musk Thistle, Carduus Nutans, in South Dakota

Home , Agapanthia cardui, Carduus, Cochylis dubitana, Lixus cardui, Longitarsus testaceus, Tingis cardui

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Electronic Theses and Dissertations

1974

Dennis Morihara

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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

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IN SOUTH DAKOTA

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� >iAROt NG )PERKINS MARSHALL. I COASO.... C:\:O:d:tiP�f;i'.',"°�4 e�Ol#N I � I

'! DAY \� EOMUNOS I I

ZIEBACH -

BUTT E r. .... � P OTTER 11 F>UL• 1..... I I �OOtNGTOH MEADE �DEUEL.

I � <-' t-lA I NO I HAMLIN

BEADL.E LA I �- . BROOKINGS WRENCEI '--- I II. I

I.AKE MOODY PENNINGTON SANBORN I MINER 't.

AURORA C,IJSTER OA'J1$0NIHANSONIMC COOK I MIMNEl'iAHA

FALL RIVER HUTCHINSON

SENNETT TODD  SHANNON •

Fig. 1.-Counties in South Dakota with more than one Carduus nutans infestation that has been an herbicide, treated or would have been treated with if money were available. L. After J. Wrage (personal co�.rnunication ).

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 . In the

second summer, only few thistles were found in this area being replaced

largely by catnip, Neoeta catapia L. (J) The third area at Site A was

a narrow band of musk thistle approximately 2 x 20 m, growing along a

cornfield adjacent to the unoccupied farmstead . These thistles were 1 m

�;ere on�e, ta.l� �t �.:iturity ci.:-4d :;ubjected in the early swnmer of 1973 to

pesticide wind drift from the contiguous cornfield, which resulted in

permanent twisting of the stems, although the drift was not strong

enough to initiate any kind of kill .

Site B was a JO acre pasture, 10 miles west of Yankton and 1 mile

north of the Missouri River. The thistle· density of this pasture was

not as high as the densities of the stands of Site A, but the infested

area was much more extensive, covering about 5of, of the field. Tne

principal grasses of this pasture were: _ Sporob.olus cryptandrus (Torrey)

G�ey, �· inermis, £. japonicus Thunberg, Pea pratensis L., and

Pani01.1-m 'Wi.lcoxianum Vasey. The field was sprayed with herbicides twice

1974. with occurred on 14 June . ·in The first application, 2,4-JD,

About 20 of the musk thist1es remained alive. The second application 6

occurred between 24 July and 7 August. Virtually 10o% of the nusk

thistle were killed. Sampling was, thereafter, shifted to isolated

thistles in surrounding areas.

Releases of Rhinocyllus conicus.-On 24 May 1973, 1,000 E.• conicus weevils were released at Site A. Five hundred weevils were freed in area #1 and the remainder were released, between rain showers, in area #2. 'Ihese introductions constituted the only attempts at colonization of this insect in South Dakota.

Rhinocyllus conicus is an oligophagous insect which feeds on members of the subtribe Ca.rduinae, including Carduus, Cirsium, and

Silybum thistles. Tests which established the host range of this

w weevil were carried out from 1962 to 1967 by Z CJlfer (1967 and 1969).

on Fa��le� ovipo�tt, t:n the .sprine, t.h'3 thi.�t.l� h'?-ad�, covertn.e the eggs ( Fig. 2) with a crust of minute particles of the host plant which are cemented with .the a.id of an unknown liquid. These crusts form roundish yellow-brown plates which measure about 1.5 mm in diameter. Up to 20 or more eggs may be deposited on an individual flower head� 'Ihe eggs· hatch and the larvae burrow into the head through the bracts. Larvae feed on the seeds causing the heads to dry up prematurely. Pupation occurs in ovoid pupal cells within the head. The adults, the overwintering stage, f�ed on the peripheral tissues of the stem, peduncle, and leaves of their host plants. The damage caused by the adults is not considered important.

T'ne native geographical range of this insect includes the

Mediterranean region, central and eastern Europe, and western Asia. 8

Rhinocyllus conicus does not inhabit the en tire endemic range of distribution of its ma.in host plant , Q. nutans (Zw�lfer 1967).

Insect Survey.--Empirical insect surveys have been taken of specific host plants for various reasons. Weires and Chiang (197J) used such a list for integrated control of cabbage pests. Zw6lfer

(1965 and 1970) surveyed the phytophagous insect fauna of thistles in

Ell.rope to discover potential biological control agents . Goeden (1971), and Goeden and Ricker (1968) appraised the native fauna of southern

o California thistles. The Calif rnia studies revealed the relative absence of in sect injury in critical niches of the host plants prior to foreign recrui.tment of phytophagous species for biological control purposes.

Root (l97�) exa�i�ed spe��z divcr�ity �nd density w�th �3sp0ct to trophic levels, in his quantitative survey of 2 kinds of habitats of collards.

c The sampling techniques o.f e cologi al studies dictate the nature and accuracy of the entire study. In rrry work, .the wide variation in habitats of musk thistle, the absence of faunistic records of �· nutans

c a in South D:lkota, and the limited duration of this study, alled for broad, flexible procedure that would produce qualitative results on which to base more specific studies if necessary.

m Results fro my survey should reveal the success or failure of this initial introduction of R. conicus and at the same time divulge some· of the insect fauna of nr..isk thistle in South Dakota.

survey began following the release of B.• conicus. The A total of 9

29 samples were taken from the previously mentioned sites throughout

the summers of 197J and 1974. The collecting procedure for all samples

was kept as uniform as possible with a total of about 1.5 man hours

maintained for each. A single sample consisted typically of J

collecting methods: (1) suction sampling, (2) sweeping and hand

collecting, and (J) plant dissections. The rmisk thistles were chosen

arbitrarily for inspection and sampling. Supplementary hand

collections were taken fro� thistles, usually of roadside plants,

located near but not within the previously meritioned study sites.

Suction sampling. When stands were of appropriate size and

density to ensure.that only musk thistle insects were collected, a

D-Vac.®va cuum· sampler was employed. The 8" nozzle was used and the

was ru.:i.i machine foi: JO second:; sp�nuing abou C. J sec/plant. The

specimens were returned to the laboratory in the net in which they were

caught and were killed by freezing. Because.of the unworkably high

number of specimens collected by this method, only a fraction of the

total were pinned, identified, and used as data• Selection of specimens for identification was made in a manner to achieve a random

sample.

Sweeping and hand collecting. The more conspicuous insects were

first observed and then collected by this method. Approximately 20 specimens field trip were retrieved. per .

Dissections. �ore than 50 musk thistle plants were dissected throughout the entire study. This included the internal inspections of roots, stems, and flower heads and buds. Dissections were made in 10

the field. Plants displaying insect injury as well as healthy

looking thistles were selected.

Insects collected by sweeping, hand collecting, and dissections were either killed immediately, or returned alive to the laboratory, in the case of larvae and pupae, for rearing to the adult stage to simplify identification. Rearing was done on thistle bouquets in t gallon plastic ice cream containers, which were placed in rearing cabinets. Relative humidi�y, temperature, and day length were controlled according to the climatic averages of the appropriate month.

Identifications were made to the lowest possible taxon. The

South D:tkota State University Insect Collection and appropriate keys were used. Parasitic hymenopterans and other difficult ta:xa were sent to the Systematic Entomology Laboratory, U.S.D.A., Beltsville,

Maryland.

RE.SULTS AND DISCUSSION

Insect &irvey.--The species collected during the 2 summers of sampling are broken into 3 categories: (1) phytophagous insects

( Table 1), (2) insect parasites and predators ( Table J), and (3) saprophagous insects.

Table 2 represents the phytophagous insects of musk thistle in

from Zw8lfer (1965) and Coulson (1969) who Ellro�e and was derived dealt with finding potential biocontrol agents• My work includes any insect found on the plant. Thus, the differing criteria in the 11

respective lists should be kept in mind as comparisons are mad e .

Phytophagous Insects.--Table 1 lists 96 taxa representing 8

ord s, er 41 families, 68 genera, and 59 species. Of the 96 taxa, 10

occurred with a frequency of at least 0.21 and of these, 7 are

economically destructive. At no time chlring this study did any

population impose a destructive control level on thistles.

The gras shoppers were the most conspicuous group of phytophagous

species. These insects are general feeders and have little influence

in natural control of thistles since they also affect other plants in

the co:mrrD.lnity to varyi�g degrees. In addi tion, they are economic

pests. The heaviest infestation of orthopterans at Site B (Yankton)

occurred during August 1973· �uch of the foliage had been stripped,

e leaving the ro ette showed pr ference for the older plants s stage

relatively free of injury. Most of the damage occurred after and

, a negligible i e ce during seed dissemination thus, having nflu n on

thistle reproduction. One longhorned grasshopper was observed

stripping a thistle head of its bracts and plumes, however, this type

of da�ge was rare. No orthopterans are listed in Table 2, which

concentrates on insects that are potential biocontrol agents.

unim tance of the order en ptera biocontrol is The relative por H d in

habits. Table 2 shows only 1 species, indicated by their polyphagous

displays any kind of specificity. The Tingi§ cardui L., that host

is restricted to Carduus - Cirsium literature shows that I.• cardui

spp. but Coulson (1969) stated that this bug does not appear promising e Table 1.-Phytophagous ins cts collected from musk thi stle , Carduu s nutans , in South Dakota , 1973-1974.

Relative frequency Stages Plant Host Economic

e e . Insects in samples il collected association pr f rence status

Orthoptera Acrididae Melanonlus bivitatus (Say) 0.07 I,A Ec,L 0 e * 0 e M. differentialis (Thomas ) 0.07 A Ec,L 0 e E· femurrubrum (DeGeer ) 0.17 I,A Ec,L u 0 e !:I· sp. nidentified Q s * 0.14 I,A Ec,L * 2 unidentified spp. 0.17 I,A Ec,L Tettigoniidae * J unidentified spp. 0.21 I,A Ec,L,H Gryllidae Oecanthus nigricornis Saussure 0.17 I,A Ec,L 0 e 1 unidentified sp. 0.03 A

Thysanoptera 1 unidentified sp. 0.03 A Ee

e Hemipt ra a Mirid e 0 Adelnhocoris lineolatus (Goeze) 0.07 A Ec,H n Chlamydatus associatus (Uhler ) 0.03 A· Ee c n 0 Lopidea sp. O.OJ A Ee n Lygus lineolaris (Palisot de Beauvais) * 0.28 A 0 e Ec,H,S ...... n Plagiognathus politus. Uhler 0.07 E,I Ee c l\) Table 1.-( continued).

Poecilocansus lineatus (Fab.) 0.07 I,A Ee 0 e Ee Semium hirtum Reuter 0.03 A 0 n * en 5 ( 1 ) unidentified spp. 0.34 I,A Ee ' 0c Piesmatidae -I 0 n Piesma cinera (Say) _0.03 A Ec,H,L I Lygaeida.e CJ Geocoris uliginosus (Say) 0.03 A Ec,H c n )> i :A 1 unidentif ed sp. o. 03 A Ee 0 Coreidae )>-{ Lentocoris trivittatus (Say) 0.03 I,A Ec,H,L,S 0 e Vl Ortholomus 0.03 A Ee - n --{ sp. l> Pentatornidae· -I Chlorochroa uhleri Stal 0.03 A Ee fT1 0 n Cosmopepla bimaculata (Thomas) 0.10 I,A Ec,H , L c 0 n z Ellschistua euschistoides < (Vollenhoven) 0.1 I,A E ,H , 0 n rri 7 c L :::0 �· tristigmus (Say) 0.17 I,A Ec , H,L c n (f) -I -< Homoptera r Membra cidae m' Ceresa constans (Walker) 0.07 A Ee 0 n (Fabrieius) ::o, Stictocephala inermis 0.07 I,A Ee· 0 e >, Cercopidae � * 1 unidenti fied sp. 0 . 14 I Ec,S Cicadellidae * - Acera.tagallia uhleri (Van D.lzee ) 0.10 A Ee n Agallia quadripunctata (Provancher) O. OJ A Ee - ...... n \..t..) Table 1.--(continued).

Relative frequency St es Plant Ho st Economic a ag Insects in samples collected association preference sta.tu s

Agalliopsis novella Say 0.14 A Ee 0 n o 0.03 Deltocephalus signatifr ns Van D. A Ee - n Elymana sp. 0.03 A Ee 0 n Empoasca fabae(7) (Harris) 0.17 A Ee 0 e * Endria inimica (Say) . 0.28 I,A Ee 0 · e Graphocephala coccinea Forster 0.03 A Ee 0 n Latalus sp. 0.03 A Ee 0 n * Hacrosteles divisa (Uhler) 0.14 A Ee c e Neostele_s_ nE3glect.@._ Delong & Davidson 0.10 I,A Ee - n Paraphlepsius irroratus (Say) 0.17 I,A Ee 0 n Psammotettix sp. 0.03 A Ee - n Acanaloniidae Aca.nalonia bi vittata (Say) 0.03 A Ee 0 n Delphacidae 1 unidentified sp·. 0.07 I,A Ee - n Aphididae Aphis 2(?) spp. * 0.28 I,A Ee,S - e Rhopalosiphum sp. 0.07 I,A Ec,S - e

Coleoptera Buprestidae 1 unidentified sp. 0.03 I En Nitidulidae Conotelus sp. 0.03 A p 0 n Byturidae 1 unidentified sp. 0.03 I !-'. {::" Table 1. --(continued).

Relative frequency Stages Plant Host Economic a Insects in samples collected association preference status

Lepidoptera Papilionidae Papilio glaucus Linn. 0.03 A p 0 n a Nymph lidae ca d Vanessa r ui (Linn.) * 0. 37 I,A E�,L,P 0 e Geometridae 1 unidentified sp. 0. 03 I Ec,L Noctuidae Papaipema nebris (Guenae) 0. 14 I En,S 0 e * 2 unidentified spp. 0.07 A p Pterophoridae 1 unidentified sp. 0. 14 I En,S Pyralidae Hom.oeosoma electellum ( Hulst) 0.07 I En,H c e Tortricidae 1 unidentified sp. 0. 03 A p

d .3 unidentifie spp. (microlepidoptera) 0. 07 A p

I Di.ptera Tanyderidae 1 unidentified sp. 0. 03 A T 0 n Cecidomyiidae 1 unidentified sp. * 0. 24 A Syrphidae ) O.OJ A p - n f-' Mesograpta marginata (Say V\ Table 1. -( continued).

Relative frequency Stages Plant Host Economic a . es Insects in samp1 collected association preference status

Pedilidae Pedilus sp. 0. 03 A p 0 n E· labiatus Say 0. 07 A p 0 n Mordellidae Mordella sp. 0.10 I,A En,L,S,P n Nordellistena 4(?). spp. * 0. 14 A En,L,S,P n Melandryidae Anthobates trif aciatus :Melsh. 0.14 A p 0 n Chrysomelidae Chaetocnema confinis Crotch * 0. 14 A Ec,L 0 e Diabrotica lonsicornis (Say) * 0. 31 A p 0 e 12· undecimpunctata howardi Barber* 0. 07 A p 0 e �· verg:lfera Leconte 0. 10 A p 0 e Diachus auratus (Fabricius) 0. 03 A Ec,L 0 n

§Pit� cucumeris (Harris) . 0. 03. A Ec,L 0 e Leptinotarsa decemlineata (Say) 0.03 A Ec,L 0 e Longitarsus testaceus (?) · ) (!folsheimer ' 0. 03 A Ec,L t n Systena elongata (Fab.) 0. 03 A Ec,L 0 n S. frontalis (Fab.) 0. 07 A Ec,L 0 n Cllrculionidae Ceutorhynchu� aeratus Dietz 0. 03 A p 0 n Conotrachelus sp. 0. 03 A Ee 0 e

r-' °' Table 1.--(continued).

Rela.tive frequency Stages Plant Host E ono a c mic Inse cts in samples collected association preference status .

Tephritidae Euaresta bella (Loew) * 0.10 A En,H 0 n culta (Wiedeman) 0.07 Paracantha A En 0 n C hloropidae O�:rninella * 0.31 En,S 0 e spp. A Agromyzidae Cerodontha dorsalis (Lo�w) 0.03 A En,L 0 n .A.nthomyiidae * 0.17 A En 0 e Hylemya spp.

Hymenoptera Cimbicidae Cimbex americana Leach 0.03 A T 0 n Pteromalidae Mesopolobus nobilis (Walker) 0.03 . A T 0 n Halictidae Agropostemon texanus Cresson 0.03 A p - n

- A· sp. 0.03 A p n Halictus sp. 0.10 A p - n Lasioglossum spp. 0.24 A p - n 0.07 - n �sp .. A p Anthophoridae �elissodes agilis Cresson 0.03 A p t n 0.03 A p - n M· sp. t-' --.J Table 1.--(continued).

Relative frequency Stages Plant Host Economic Insects in samplesa collected association preference status

Apidae 0.07 0 Apis mellif era Linn. A p e 0 Me�abombus fervidus (Fab.) 0.03 A p n �· pennsylvanicus (DeGeer) 0.07 A p 0 n c Pyrobornbus griseocollis (DeGeer) 0. 07 A p n

a= # of samples in which sp. appeared/29 samples. E=Eggs,. I=Irnmatures, and A=Adults. Ec=Ectophagous, En=Endophagous, R=Roots, S=Stems, L=Leaves, P=Pollen an d H=Flowerheads an d buds. -=no information, o=other plants or polyphagous,. c=compositae, an d t=thistles. e=economic sp. and n=non-economic sp. *=occurred at both.Site s A and B.

� co Table 2.--Phytophagous insects reported from musk thistle, Carduus nutans, in Ell.rope.

Relative Source frequen cy Plant Host of Insects in samples Stages association specificity record

Hemiptera Hiridae Lygus pratensis L. 0 0 z ru Pla�iognathus arbusto m F. 0 0 z Tingidae Tingis cardui L. c I,A Ec',S,L t z Lygaeidae Lygaeus �uestris L. 0 0 z Coreidae Coreus marginatus L. 0 0 z Pentatomidae Carpocoris rudicus Poda c I,A Ec,S,L 0 z Dolycori.li baccarum L. c I,A Ec,S, L 0 z Ehrydema oleraceum L. 0 0 .z Odontotarsus. Eurpureolineatus Rss. 0 0 z

Hornoptera Aphididae Capitophorus carduinus v.d.G. c Ec,S,L t z eu Dactynotus (Uromelan) aen s HRL. c Ec,S,L t z Unidentified spp. c Ec,S,L 0 z

C oleo ptera Mordellidae Unidentified spp. I En,R,S 0 z r' c '° Alleculidae Unidentified sp. 0 0 z Tabl e 2. -- ( continu ed) .

Rel ative Source frequency Plant Host of Insects in samples Stages as sociati on speci fi ci ty record

Anobiida e Lasiod erma redtenbacheri Bach. c I En,H t z Scarabaeidae Oxythyrea funesta Poda 0 0 z o P to si a hungaria Hbst. 0 0 z Tropinota hirta Poda 0 0 z Cerambycidae Agapanthia cardui L. c A Ec,S,L 0 z A· dahli R. c A Ec ,S,L t( ? ) z h_. villosoviridescens Deg. c A Ec ,S,L t z Chrysomelidae Cassida deflorata Suffr. c I,A Ec,L c c Q. �biginosa· Muell . c I,A Ec,S,L t z Q. vibex L. c I,A Ec,L c · C 0 Cryptocephalu s seri ceus L. 0 z Galeru ca tanaceti (L.) c I,A Ec,L c c Psyl liodes sp. 0 0 z a m a f.· ch l co er Illig c I,A .Ec,L t c Sphaeroderma tes tac eu m L. c I,A En,Ec,S,L t z Platys tomida e Pl atystom a sp. 0 0 z

Curculionidae Api on (Q. ) (?) cardu orum Kirb. c I,A En,Ec,R,S,L t z A· (Q. ) onopordi Kirb . c A Ec,S,L t z A· ( Ce atapi o ) pi si F. c N r n 0 Table 2.-- ( continued ) .

Relative Sou rce frequency Plant Host of Insects in samples Stages association specificity record

t Ceuthorhyncus horrisus Panz. c A Ec ,s, t z .Q.. (Hadroplontus ) litura (F. ) I,A En,Ec,S.L t c g,. trimaculatus F. c A Ec,S,L t z Cleonu s 2iger Scop. c I,A En,Ec,R,S,L t z �Ji comata Boh. I 0 c li· sp . 0 0 z Larinus carlinae 01. c A Ec , H t z I,A z 1.• jaceae F. c En ,Ec ,H t k• scolyraj. 01. c A Ec ,H t z 1_. sturnus Schall. c I,A En,Ec ,H t c ,z k· alP-:irus L. c I,A En,Ec ,R,S,L 0 z Lixus cardui 01. c A Ec,S,L t z 1.• elongatus Goeze c I,A En,Ec,R,S,L t z 0 �· .junci Boh. 0 z Rhinocyllu s conicus Froel. c I,A En,Ec ,H t z Leopidoptera Nymphalidae

f.yrameis cardui L. · c I Ec ,L,S t z Gelechiidae Li ta acuminatella Sire. c I En,L t z Limacodidae Cochylis dubitana Hb. I En,H z Q. posterana z. c I En,H t z 0 1 unidentified sp. c I En,H z

N ....., Table 2.-(continued ).

Relative Source r H f equen cy Plant ost of · Inse cts in samples Stages associ ation specificity record

a.e Pyralid 0 Homoeosoma binaevellum Hb. I En,H 0 z Ii· nebulellum D. & S. c I En,H 0 z �·:yeloi s cribrumella Hb. c I En,R,S;H c c,z !i• sp. I En,H c Olethreutida.e Epiblemma sp. I En,S,H c Oecophoridae Agonopter;oc arenella Schiff. c I Ec , S ,L t z fl· subprooingu ella Stt. c I Eh ,L t z Cnephasiella incertana Tr . 0 0 z Cnephsia spp. 0 0 z S. c t M?i blema scutulan D. & I En,R,S, H z Coleophoridae I En,L t z Coleophora therinella Tngstr. c Cosmpterygidae · Pyroderces argyrogrannnos z. 0 I En,H 0 z

Diptera Cecidomyiidae unidentified spp. c I En,H 0 z Syrphidae e Ch ilosia chryso coma (Mg. ) I En,S,H c c,z Chilosia spp . c I En,R,S t( ?)

l\) l\) Table 2.--( continued ).

Relative Source re Host of f quency Plant Insects in samples Stages association specificity record

Tephritidae Chaetostomella onotrophes Loew c I En,H t z Tephriti s (?) heiseri Frfld. c I En,H t z 1· hyo s cyanii L. c I En,H t z Urophora solstitialis L. c I En,H t z i_yphosia rniliaria Schrk c I En,H t z

O=Occasionally and C=Common. !=Immature and A=AdUlt. e En=Endophagous, Ec=Ectophagous, R=Roots, S=Stel'lls, L=Leav s and H=Flowerheads and buds. o==polyphagous, c=Compositae and t=thistles. C=Coul son (1969 ) and Z=Zw8lfer (1965 ).

l\) \,.\) 24

for biocontrol because it does not breed on thi stles. The mo st frequ ently collected bu g on the South Dakota thi stles was Lygus lineola ri s ( Pali sot de Beauvois ) , or the tarni shed plant bug. This

common insect takes sap from more than 50 e conomi c plants besides many weeds and grasses (Met calf et al . 1962 ) .

Endria inimica ( Say ) (Homoptera ) , the painted leafhopper , appeared from May to Au gust at both Si tes . It is a vector of aster yellows (no symptoms were seen on thistles ) and wheat streak mo saic. The only homopterans li s ted in Table 2 are the aphids. The aphids probably show the hi ghest degree of ho st specifi city in thi s generally polyphagous

order . The South Inkota aphid populations became frequent in late Ju ly

- •. e and Au gu st at Si te A area #1 A high p rcentage of the plants support-

e ad colcnies -...�th t nding o.nts.. HcwcYer 1 preda t�.o� .g.nd pa!'asiti �� 1·r�re

w damaging heavy , keeping the individual colonies far belo densities.

The attendant ants are not listed in the tables becau se of their omni vorou s habits and relative unimp ortance in direct exploitati on of the weed. One European species of aphid , Dactynotus . aeneus Hille Ri s Lam

sts (Coulson 1969 ). bers , has undergone screening te

ra ) family coll e cted in the Eur p ea The large st beetl e (Coleopte o n surveys wa s the Curculionida e. Many of thes e weevils have coeval ved

and some restri ction to th � r host plants . Eight with thistle s show e

us in the larval stages. Altho of the 18 ·weevils are endophago ugh they g enerally display the same feeding habi ts , a clo ser e.xamination reveals

incidence in diversifi cation of food ni ches , the high degree of

an brought about by long associations with their pl t hosts (ZwBlf er 25

'\_

1970). To the contrary , the largest beetle family collected in my

study wa s the ectophagous Chrysomelidae. Diabroti ca longi corni s ( Say ) ,

the northern corn rootworm , occurred the mo st frequently. The adults ,

the only stage collected , were taken from July to September and are

seri ous economi c pests. No damage wa s effected on the thi stles as these beetles were found only on the flowers , probably feeding on the pollen. Mordellidae were well repres ented in both tables. Although not a common group in s. Dak . , rrio rdelli stena spp . were collected from both sites. Harri s and Zwolfer (1968) reported a !i• sp . in the pith of

Cirsium vulgare ( Savi ) Tenore.

Four species of Lepi doptera were found to do significant amounts of damage to individual weeds , al though none occurred in large enough

as a common , num1J ers to affect . the -..; eed popu.la ti0r.s ��- 1-� 0l c. Th"' rnc st

Vanessa cardui L. , the painted lady , threatened soyb ean and sunflower crops in eastern S. Da. k. ·in 1973· Homoeosom.a electellum ( Huls t ) , the sunflower moth , is a pest in the north central counties of S. Dak . wh ere many sunflowers are . grown . Papaiperna nebri·s (Gu en�e ) , the stalk borer, wa s found within the stalks of corn that grew along area #J as well as within thi stle stems. An unidentified Pterophoridae , possibly

Ril ey , wa s reared the arti choke plume moth , Platyptila carduidactyl a from field collected thi stle stems and heads • . Thu s, none of the moth spe ci es mentioned are truly desirable although they are able to infli ct severe darnage to their thi stle hosts.

Of the Diptera , a frequently occurring unidentified speci es of

m both sites from Hay to July. adult Ceci domyiidae was recovered fro 26

Thi s could possibly be Dasyneura gibsoni Felt , the larvae of whi ch

feed on developing seeds in the heads of Canada thi stle ( Detmers 1927

and Nearman 1973 )_. Osci nella spp . (Chloropidae ) were also recovered

from both sites throughout the summers . The family Tephritidae was

poorly represented in Tabl e 1, wh en compared to th e proportion

represented in Table 2. More than half of the &lropean dipterans are

fruit flies with endophagous , specifi c habits . Th e number of

specificity tests condu cted with merribers of tephritids ( Coulson 1969 )

indi cate its potential for biocontrol purposes. As with the other

orders , the South l)lkota flies show a polyphagous habit and those

present at both sites are common species.

All phytophagous hyrnenopterans taken were pollen collectors . Of

these, the hali ctids, Lasiordossum spp. , were most numerou s. 'thes e

connnon bees were the only ones to occur at both sites. No phytophagous

insects of Hymenoptera are li sted in Table J as the general habi ts of

thi s group are useless from the standpoint of controlling weeds .

ast of the 75+ species of insects ( ca. 4J% ) collected in At le 32

Europe are endophagous as immatures . Th ese insects generally occurred wi th a greater frequ ency and diversifi cation of food ni ches ( Zw8lfer

-1970 ) than their counterpart Coleopt_era and Lepidoptera relatives in

South Dakota . Of the taxa in Table 1, 11 have been indi cated in the

rature to have endophagous habits , however , I have only been able lite _

to observe directly J species di splaying endophagou s habits , viz , f.· nebris , 1!.• electellum, and 1 unidentified pterophori d. The 3 species

e of moths represent about 3% of the 96 taxa in Tabl 1. 27

Twenty-two out of the 96 taxa in Table 1 occurred at both sites.

Of these, 21 are common insects with polyphagou s feeding habits.

There does not app ear to be a characteri stic insect fauna of musk thistle, the taxa of Table l reflecting more or less the fauna of the local community than anything el se.

Forty-two out of the 96 taxa occurred with relative frequencies of 0.03, i.e. , found in only 1 sample. Although they are li sted as phytophagous insects of thi stles with feeding habits indi cated , these should be considered rare or possibly transi ent animals.

Entomophagou s Insects.--Resident populations of entomophagous insects are more likely to play a role in determining the density levels of an establi shed species rather than preventing a large populn.tion cf artif�cially int!"odnced inse�t.s from becoming establi shed.

They act as density dependent factors , and will become of less in�ortance as their host · populati ons approach zero {Lack 1954 ).

Of the parasiti c Hymenoptera listed in Table J, 4 have been

cu personal communi cation ) . associated with R· coni s (W.W. Surles ,

Th ese are : Blacus sp. , Bracon sp. , Hvssopu s benefactor (Crawford ) , . and Eurytoma sp. However, none of these are confirmed parasitoids.

ects. --Although the saprophagou s group is Saprophagous Ins

m energy cycles of the c?mmuni ty , it is ommitted extremely i portant in from detailed di scussion. The issu e of weed reproduction is normally not affected by thi s group whi ch is primarily involved 'With de- composition.

coni cus. -Adult were released on 24 May Rhinoc;yl lu s weevils Table 3�--Parasiti c and predaceous insects collected from musk thi stle, Carduu s nu tans , in South Dakota , 1973-1974.

Relative Hosts frequency,. or Si tes . Insects in sa.mpl es a. · Stages preyb collected

Odonata Coenagrionidae l unidentified sp. 0. 03 A Nosquitoes , midges B and other small insects

H a emipter Anthocoridae Orius insidiosus (Say) 0.21 A Aphi ds and other A,B soft bodied insects and their eggs

Phymatidae Phvmata pennsylva.nnica americana lv�elin. 0.21 A · Wide variety A,B Reduvi.idae Sinea diaderna ( Fab. ) 0.10 A,I Aphids and other A insects Neuroptera Chrysopidae unid nt e sp. 1 e ifi d 0.31 A,I ,E Aphids A,B Hemerobiidae 1 unidentified sp. 0. 03 I. Aphids B

Coleoptera Carabidae Mi crolestes nigrinus }1annerheim 0. 03 A Bark insects N A � Table ).--(continued ).

ve Relati Hosts fre uen y or Sites q c b Insects in samplesa Stages prey collected

Histeridae Atholu s sp . O. OJ· A B Cl eridae Phylloba.enus humerali s (Say) 0.10 A Xyl ophagous insects A £.• pallidipennis (Say) 0.10 A Xylophagous insects A Coccinellidae Col eomegilla maculata lengi 0.10 Timberlake A Aphids , s cale A,B insects and mites Hippoda.mia convergens Gu erin-Meneville 0.17 A,I Aphids , scale A,B insects and others !!• tredecimpunctata (Say ) 0.17 A,I Aphids , scale A,B insects and others · 0 Scymnu s sp. .24 A,I Aphids , sea.le A insects and mi tes s . 0. 03 Stethorus p A Mites A Meloidae 1 uni�entified sp. O. OJ I Bees , grasshoppers B

Diptera a. Cer topogonida.e 1 unidentified sp. 0.14 A A,B Therevidae Psilocephala fronta.li s Cole 0.10 A Insect larvae in sand , B earth or decaying wood l\) '° · Table ).--(continued ).

Relative Ho sts frequency or Sites Insects a b in samples Stages prey collected

e Asilida DioEmi tes sp . O.OJ A Wide variety B Promachu s sp. O.OJ A Wide variety A Empididae Drapetis sp. 0.07 A S�ll diptera A,B 2 unidentified spp. 0.07 A Small diptera A Doli chopodidae Medetera vittata Van DJ.zee O.OJ A Wood boring beetles B ll• veles Loew 0.07 A Wood boring beetles A Syrphidae Allograpta obligua (Say) 0.14 A Aphids l A �yrphus americanus (Wiedemann ) O.OJ A Aphids A Chloropidae spp. ., ' Thaumaton�1.a 0.17 A Root aphids A Muscidae irritans (L. ) 0.0 Haematobia 3 A Vertebrates B Tachinidae 0 2 unidentified spp . .10 A Insects A Hymenoptera Braconidae O.OJ Apanteles sp. A Lepidopterous larvae A Apha.ereta sp. O.OJ A Diptera Aspilota sp. O.OJ A Di.ptera Blacus sp. O.OJ A Bracon spp. 0.07 A \.A) 0 Table J. -(continued ) .

Relative Hosts frequency or Sites b Insects in sampl esa Stages prey collected

Chelonus sp. 0.07 A Lepidopterous larvae A .Q.. seri ceus ( Say ) O.OJ A Lepidopterous larvae B Onius sp. 0.07 A Diptera Orgilus sp. 0.03 A Ichneurmnonidae (7) Trachysphyru s sp. O.OJ A Lepidopterous larvae B

n · 1 unide tifi ed sp. O.OJ A A Mymaridae Polynema 0. 07 sp. A Homoptera A Elllophidae Aprostoc8tu s sp. O.OJ. A (?) Coleoptera A Hori smenus carolinensi s Burks 0. 03 A Probably small larvae A in cases or leaf mines Hys sopus benefactor (Crawford ) 0. 03 A Petrova comstockiana A (Fern. ) (pitch twig moth ) Tetrasti chu s sp. 0.10 A Coleoptera , diptera A,B or lepidoptera 1 bruchophagi G han 0.07 · a A Hymenoptera A 1 unidentified sp. 0.03 A Encyrtid ae Anagyrus sp. 0.03 A A Copidosoma sp. 0.03 A scale insects B Pteromalidae Catalaccus cvanoideus Burks 0.03 A Eurytomidae Eurytoma sp. 0.03 A � Table ).--(continued ).

e at . Hosts R l : ve ' frequenc:r or b Sites a Insects in sample.s Stages prey .collected

Cynipidae Pseudeu coila sp . 0.10 A Diptera a Ceraphronidae Ceraphron sp. O. OJ A Diapriidae Belyta sp. 0.03 A Dip�era S celi onidae rfa crotelei a sp. 0.03 A (?) Orthoptera Telenomus sp. 0.07 A Insect egg parasite Platygastridae Amblya spi s sp . 0. 07 A (?) Diptera Chrysididae 1 unidentified sp. 0. 03 A Hymenopterous larvae A Forrni cidae ( ey) O l� A Wide variety Conomyrma. insana Buckl .l b Pompilidae unidentified sp. 0.03 A 1 Spiders A Sphecidae Alys son sp. 0.03 A (?) Planthop pers A Hali ctidae d s sp. 0.07 Spheco e A Hali ctidae B Aphidiidae L;ys iEhl ebus sp. 0.03 A Aphids a=# of samples in whi ch sp. appeared/29 samples. b=As reported in the literature. a=Site A and Si B. b= te \.Al N .E=Eggs, I=Immat ures , and A=Adul ts. 33

19?3· Oviposition and mining occurred qui te noti ceably throughout

the fi rst and second areas of Site A. Oviposition began before 31

. May and mining before 8 June. Dissecti ons of thi stle heads in mid

Au gu st yi elded · empty pupal cells except for a single live adult which

wa s recovered from its pupai cell on 14 August at area #2 , 82 days

after the release. Dispersion appeared to be greater at. area #1 and

fewer dead adults were found at area #2 • . All B.• 9oni cus activity

occurred in the sunnner of its release. There was no trace of thi s

populati on the following surmner .

The cause( s ) of thi s failure to establi sh are unknown. Studi es

in Vi rginia ( Kok 1974 ) indi cated early spring (1'�ay ) releases were

ire more effecti than la te summer releases. Kok al so stated that

locali zed dense thi stle stands appear to be mo re suitable for

colonizati on than extensive stands , probably due to less dispersal of

the weevil. Both these measures were applied in the South Dakota

introduction.

Rhinocyllus coni cus has a wide geographi cal range in furope

whi ch indi cates rather broad ecological tolerances. _Comparisons of

se of central and eastern climati c diagrams of s. Dak. with tho

:Ehrope ( Fig. 3) suggest tha t ecotypes from selected areas might be

the best adapted populations . Of course , these diag�ams are crude

comparisons as the habitat of the weevil popula tions are greatly

i.e. , influenced by th e immediate surroundings of the environment ,

of es, k , etc. the temperature inside plants or on the surface leav bar

ai r (Andrewartha may be quite different from that of the surrounding 35

and Bi rch 1954 ). However , preliminary deci sions concerning weevil collecting areas must be made upon considerations such as these.

Sill-1MARY

Biologi cal control ha s met with many successes but only a fraction of the introduced natural enemies become established and only a smaller proportion of those establi shed provide compl ete control. However, complete control is not always necessary. }fu sk thi stle is a likely candidate of biocontrol because of its relatively weak competitive habits , its lack of natural enemies in s. Dak. , and its ability to invade areas wh ere it is economically unfeasible to spra:t•

The population of B.• coni cus released in May 1973 did not establi sh despite signs of oviposition , mining , and pupation. No direct cause can be accounted for thi s failure.

The insect survey of Q• nutans suggests tha t the weed does not possess a distinct fauna but more or less reflects the local fauna of the community. Compari sons with the ID.i.ropean phytophagou s insects

hly te reveal that :musk thi stle in s. tak. has not been thoroug exploi d by endemi c insects. 36

ACKNOWLEOOEMENTS

This study was financed by USDA Agr. Res. Ser. No . 12-14-100-9935

(33).

I thank Dr. &iward U. Balsbaugh , Jr. for his assi stance in all phases of thi s study. Dr. Robert J. Wal strom receives my appreciation for introducing me to the graduate program in Entomology at South Dakota

State Universi ty. I also wish to thank Mr. Isaac Larson for the use of his land. I give a big ki ss to Cynthi a Mo rihara who helped me get out of bed in the morning. 37

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