South Dakota State University Open PRAIRIE: Open Public Research Access Institutional Repository and Information Exchange

Electronic Theses and Dissertations

1984

Host-plant Interactions of Diabrotica cristata (Coleoptera: Chrysomelidae) and Prairie Grasses in East-Central South Dakota

Niamoye D. Yaro

Follow this and additional works at: https://openprairie.sdstate.edu/etd

Recommended Citation Yaro, Niamoye D., "Host-plant Interactions of Diabrotica cristata (Coleoptera: Chrysomelidae) and Prairie Grasses in East-Central South Dakota" (1984). Electronic Theses and Dissertations. 4248. https://openprairie.sdstate.edu/etd/4248

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]. HOST-PLANT INTERACTIONS OF DIABROTICA CRISTATA (COLEOPTERA: CHRYSOMELIDAE) AND PRAIR IE GRASSES IN EAST-CENTRAL SOUTH DAKOTA

BY

NIAMOYE D. YARO

A thesis submi tted in partial ful fillment of the requirements for the degree Ma ster of Sci ence Major in Entomology South Dakota State University 1984 HOST-PLANT INTERACTIONS OF DIABROTICA CRISTATA (COLEOPTERA: CHRYSOMELIDAE) AND PRAIRIE GRASSES IN EAST-CENTRAL SOUTH DAKOTA

This thesis is approved as a credi table and independent investigation by a candidate for the degree , Master of Science , and is acceptable for meeting the thesis requi rements for this degree .

Acceptance of this thesis does not imply that the concl usions reached by the candidate are necessari ly the conclusions of the major department.

/ ,Tames L. Krysan 7 ' Date' L/Research Advi sor

Emmett R. Easton Date Major Advisor

Peter-wil� Date Assistant Professor

Mauri ce Horton , Head Date Pl ant Science Department ACKNOWLEDGEMENTS

I wi sh to pay special grati tude to my research advisor, Dr. James L. Krysan, for his advice and technical assistance that enabled me to carry out this research. I wish to express sincere appreciation

to Dr. Gera 1 d R. Sutter and the staff of the Northem Grain Insects

Research Laboratory ( NGIRL ) ( USDA ) , Brookings , SO, for providing the facilities to conduct this investi gation . Appreciation is extended to

Dr. Terry F. Branson ( NGI RL) for his personal interest in my wo rk and his advice in larval sampling technique. Appreciation is also extend­ ed to Ms. LeAn ne Dobratz for her assistance at odd hours . I am especially grateful to Dr. Emnett R. Easton , my major advisor for his hel p in the preparation of my thesis and his gui dance throughout my period of course work. I am also grateful to Dr. Peter

J. Wilkin for introducing me to Dr. Krysan and for his constructi ve remarks in the preparation of my thesis. I exp.ress sincere appreci­ ation to Dr. Maurice L. Horton , Head of the Plant Science Department and to the Plant Sci ence facul ty and staff for their ready assistance and frfendship. Thanks is also due to Dr. Paul Evenson of the Plant Science Department and to Dr. James R. Fisher an d Ms . Denise Hanson of the NGIRL for their hel p with the statisti cal analyses and computer

services. Thanks is also due to Dr. Gene Arnold for his help with the identification of the weed species mentioned in this thesis. Appreci­ ation is gi ven to al l of my friends who have contributed in a positive way.

i I extend grati tude to my husband, Dalla, fo r hi s patience and understanding duri ng my stay in Brooki ngs that was necessary for thi s study abroad. Deep appreciation is a 1 so extended to my parents and uncles for their encouragement and mora 1 support. Fi nanci a 1 support provided by the African-American In stitute was particularly appreci­ ated permitting me to complete this advanced training in the Uni ted

States.

ii TABLE OF CONTENTS

Chapter Page

1 INTRODUCTION. . . • . • 1

2 REVIEW OF LITERATURE. 4

Taxonomy • . . • 4

Biology and Distribution . 5

Life Cycle of NCR and WCR .. 6 Diapause .•• ..•• .•• .. . 6 Effect of Chi ll on Hatch of Eggs . 8 Diet and Oviposition. 9

Economi c Impact. . . . . 10 Sampl ing Methods 11

Control .• •. : . 15

3 DIABROTICA CRISTATA : HOST PLANTS AND OVIPOSITIONAL HABITs. • • . • . • 17 The Study Area . 18 Materials and Methods. 18

Descri ption and Pl acement of Emergence Cages. 19 Descri ption and Placement of Sticky Traps . . 19 Trap Hei ght . . • . . • ...... 22 Habitat of Adult D. cri stata ...... 23 Egg Laying Si te . -...... • . . . . 23 Determination of Ovipositi onal Preference and Collection of Eggs in the Laboratory. . . 24 Longevity of Q. cristata in the Laboratory . . 25.

Results ...... 26 Emergence Cages . 26 Trap Hei ghts ...... 26 Habitat of Adult D. cristata ... . 32 Egg Ovipositi on STtes 1n the Fi eld. 38 Laboratory Test ...... 38 ·Determination of Ovipositi onal Preference 40 Longevity of Adult Q. cri stata . 40 Di scussion .... 43

ii i TABLE OF CONTENTS (conti nued)

Chapter

4 THE RESPONSE OF D. CRISTATA (HARRIS) TO INDOLE, EUGENOL AND TWO tuGENOL DERIVATIVES . . • . . • 47

Materia 1 s and Methods. • • . • . . • . . • 48

Co 1 or Campa ri son. . . • . . • • . . . . 48 Compari son of Two Methods of Dispensing Attractants • ...... • • . . . 49 Attractant Experiment with NCR and WCR . 51

Resul ts. . . . • • . . • • . • . • • . . • . 52

Color Compari son. . • . . • • . • • • . . 52 Comparison of Two Methods of Dispensing Attractants • . . . • . • . • • . . • • 52 Experiment.Testi ng the Attractiveness of

Eugenol and Two of Its Analogs for -D. cristata. � ••....•...... • . 58 Experiment with NCR and WCR: Attractancy to Indole, Eugenol and Two Analogs of Eugenol . . • . . 62

Discussion • 68

5 CONCLUSION. • 71 LITERATURE CITED. 73

APPENDICES ..... 79

iv LIST OF TABLES

Table

1 Ranges of Diabrotica Species in the Vi rgifera Group Which Occur in the Uni ted States .... 7

2 Pe riod of Emergence of Adult Diabrotica cristata from Big Bluestem Grass Plots near Brookings , S6uth Dakota...... • . . . . . 27

3 Mean Catches of Adult Di abrotica cristata on Sticky Traps at Vari ous Dates from July 20 to August 1, 1983 in a Big Bl uestem Grass Plot near Brookings ...... 28

4 Mean Catches of Adult Di abrotica cristata on Sticky Traps at Di fferent He 1ghts on Date by Height Interaction duri ng July 20-August 1, 1983 , in a Big Bluestem Grass Pl ot near Brooki ngs , South Dakota ...... 29

Sa Mean Catches of Adult Di abrotica cristata on Sticky Traps at Variou� Dates from August 5-17 , 1983 , in Big Bluestem Grass Plot near Brookings , South Dakota ...... 31

5b Mean Catches of Adult D. cri stata on Sticky Traps at Diffe rent Heights from August 5- August 17 , 1983 , in a Big Bl uestem Grass· Plot at Brookings , South Dakota. • ...... 31

6 Mean Catches of Adult Diabrotica cri stata at Vari ous Dates , July 22-September 13 , 1983� in Three Grass Species Pl ots near Brookings , South Dakota...... 34 7 Mean Catches of Adul t Di abrotica cri stata on Sticky Traps Among Three Grass Spec1es by Date Interaction July 22-September 13 , 1983 , at Brooki ngs , South Dakota ...... 35

8 Mean Catches of Adul t Diabrotica cristata on Sticky Traps at Va�ious Dates from July 26- August 30 , 1984 , in Di fferent Grass Species Plots near Brookings , South Dakota. . . .. 36

v LIST OF TABLES (continued)

Tabl e

9 Mean Catches of Adult Diabrotica cristata on Sticky Traps Among Three Grass Spec1es on Date by Grass Species Interaction from July 26- August 30 , 1984 , at Brookings , South Dakota .. 37

10 Egg Occurrence of D. cri stata from Diffe rent Grass Species near-Brook1ngs , South Dakota in 1983 and 1984 ...... 39

11a The Pe rcentage of Ovi position of D. cristata in Three Ovipositional Med ia from August 18- Sep embe r 1, Under Laboratory Condi tions (20� -21° C and 70% Rh ) ...... 41

11b Mean Occurrence of Eggs Laid in Three Ovi positional Media in the Laboratory from August 18-September 1. 41

12 Longevity of Adu lt -D. -cristata Col lected from the Field from July 15-September 9, 1983 ... 42

13 Mean Catches of D. cristata by Date and Color Interaction in a-Big Bluestem Grass Pl ot near Brooki ngs , SO ...... 53

14 Mean Count of Male D. cristata at Various Dates to 2 Attractan ts and Con trol Wrapped with Cheese Cloth in a Big Bl uestem Grass Plot near Brookings , SO, in 1984 ...... 55

15 Mean Catches of Male D. cri stata on Date by Attractant Interaction for 3 Lures Exposed by Wrapping with Cheese Cl oth in a Big Bluestem Grass Plot near Brooki ngs , SO , in 1984 ..... 56 16a Mean Catches of Female D. cri stata on Sticky Traps Using 3 Lures Exposed by Wrapping with Cheese Cloth in a Big Bluestem Grass Plot near Brooki ngs , SO, in 1984 ...... 57 16b Mean Counts of Male D. cri stata at Various Dates Using Eugenol and Its Analogs Incorporated in Baited Sticky Traps in a Big Bluestem Grass Plot near Brooki ngs August 5-11, 1984 ..... 57

vi LIST OF TABLES (continued)

Table

17 Mean Catches of Male D. cri stata on Date by Attractant Interaction in a B1 g Bluestem Grass Pl ot near Brookings, SO, 1984 ...... 60

18 Mean Catches of Female- D. cristata on Date by Attractant In teraction Tn a Big Bluestem Grass Plot near Brooki ngs , SD, August 1984 ...... 61

19 Mean Counts of Femal e NCR at Various Dates on Di fferent Attractants from a Corn Field near Aurora (Brooki ngs County , SD) August 1984 .. 64

20 Mean Catches of Femal e NCR on Date by Attractant Interaction in a Corn Field near Aurora , 1984 65

2 1 Mean Catches of Male WCR by Date and Lure Interaction in a Corn Field near Aurora, August , 1984 .... . ·- ...... 66

22 Mean Catches of NCR and WCR on Unpainted Sticky Traps Bai ted with Di fferent Attractant Material s in a Corn Field at Aurora near Brooki ngs , SO (August 22-27 , 1984) ...... 67

vii LIST OF FIGURES

Figure Page

1 Emergence Cage . 20

2 Hal f gal lon mi lk carton trap design 21

3 Structure of eugenol and rel ated compoun ds ( from Ladd, 1984 ) ...... ; . . . . 50

vi ii LIST OF APPENDICES

Appendix

1 Weekl y Egg Counts of D. cri stata in Three Ovi positional Medical� Northern Grain Insect Laboratory , Brookings , SO - 1983 ...... 80

2 Freque ncies of Adult D. cristata on Three Di fferent Co lors of Sticky Traps in the Big Bluestem Grass Pl ot in 1984 ...... 81

3 Total Adult D. cri stata from 9 Sticky Traps Mixed with Attractant in a Bi g Bluestem Grass Pl ot near Brooki ngs , SO. (July 27-August 2, 1984 ) ...... 82

4 Total Adult D. cri stata Counts from 9 Sticky Traps Where Attractants Were Wrapped in Chee se Cloth in a Big Bl ues tem Grass Pl ot (July 1984) .. 83

5 Total Adult D. cri stata Counts from 16 Sticky Traps Bai ted-wi th Different Attractants in a Big Bluestem Grass Pl ot near Brookings , SO, August 1984 84 6 Frequencies of the Northern Corn Rootworm Captured on 20 Baited Sticky Traps in a Co rn Field near Aurora in August of 1984 ..... 85

7 Frequencies of the Western Co rn Rootworm Captured on 20 Baited Sticky Traps in a Corn Fi eld near Aurora in August, 1984 ...... 86

ix 1

CHAPTER 1

INTRODUCTION

This thesis concerns the biology of Di abrotica cristata

(Harris) (Coleoptera: Chrysomel idae) a smal l relatively inconspicuous beetle inhabi ting relict prai rie and grass lands in the Great Plains

Region of North America. Diabrotica cristata has been classified taxonomi ca11 y in the vi rgi fera group (Smi th and Lawrence , 1967) and is, therefore , closely related to several very important pest species incl uding Di abrotica vi rgi fe ra virgifera LeConte , the western corn rootwonn (WCR ), Diabroti ca virgifera � Krysan and Smi th , the

Mexi can corn rootworm (MCR) and Di abrotica barberi Smith and Lawrence , the northern corn rootworm (NCR). The genus Diabrotica (Chrysome­ lidae) is composed of three groups: fucata, virgifera and signifera

(Wi lcox , 1972 ). The virgi fera group not only incl udes the above pests as well· as D. cri stata, but al so Diabrotica longi cornis (Say ) a species whose range overlaps Q. barberi in the Central Plains (Neb­ raska south to Texas and Mexico). The larvae of al l of the Diabrotica species are root feeders whi le the adults feed on pol len, silks and the fl oral parts of plants. The WCR and the NCR are major pests of corn in the Mi dwest , whereas D. cristata and D. longi cornis have not been identified as corn pests. Q. cristata occupies rel ict prairies of the United States , northe rn Mexico east of the Rocky Mo untains and Canada (Smith, 1966)

(Wi esenborn and Krysa n, 1980). Pe rennial grasses are characteristic 2

features of relict prairies , and the larvae are believed to feed on the roots of native perennial grasses. Chi ttenden (1902 ) reported that a Mr. Pratt in 1899 observed D. cri stata attacking the blossoms of lima beans at Travilah, Maryl and, while Ki rk and Bal sbaugh (1975 ) reported the col l ection of adul ts of Q. cristata from Ci rsium �· thistle (composite); Amorpha canescens, lead plant (leguminosae); Rhus coriaria, smooth sumac (Anacardiaceae); Psoralea sp, scurfpea (legumi­ nasae) as we ll as from the ends of ears of corn. Dougl as (1929) al so

reported the col lection of D. cri stata from corn . Many adult Dia­ brotica species such as D. longi cornis and the WCR feed on and are closel y associated with cucurbi_ts , however, adult NCR's tend not to associ ate with cucurbi ts ( Krysan and Branson , 1982 ). D. cri stata is only occasional ly col l ected from cucurbits (J.L. Krysan , personal conmuni cation) even though the NCR and D. crista ta have simi 1 a r behaviors , wi th both species observed feeding on the fl ewe rs of a variety .of prairie forbs (Ludwig and Hi ll, 1975; Branson and Krysan ,

1981). Unlike the NCR , .Q_. longi cornis and Q. cristata , the adult WCR has not been obse rved feeding on the flowe rs of prai rie forbs .

In the laboratory .Q_. cri stata wi ll feed and develop as larvae when fed upon corn roots (Branson and Krysan 1981). Thi s fragment of information suggest that the NCR and Q. cri stata may share simi lar host plants under natural conditions in the fiel d. The fol lowing objectives were devel oped to test thi s hypothesis. 3

1. To determine the host plants of Q. cristata under

field conditions through the placement of eme rgence

cages over different grass species.

2. To determine through the empl oyment of sticky

traps the preferred resting , feeding or mating sites

of adult D. cristata in a habitat of mixed grasses.

3. To determine the longevity and ovipositi onal

preference of adul ts in the laboratory and field

respectively.

4. To investigate the response of adult Q. cristata to chemical attractants (indole, eugenol and eugenol

deri vati ves ) under field conditions .

Such studi es with Q cristata may reveal underlying bases fo r the association of these species with plants and hence provide clues to features which confer pest status on species of the vi rgi fera group. Such information could be useful in the development of pest management methods to suppress popul ations of an insect that could evolve into a future pest of grasses. 4

CHAPTER 2

REVIEW OF LITERATURE

Taxonomy

The genus Di abrotica (Chrysomel idea) bel ongs to the subfami ly

Ga lerucinae in the tribe Luperini , subtribe Diabroticina , section

Di abroticites (Wilcox, 1972). The WCR was descri bed by LeConte in

1868 and the NCR was described by Say in 1824 as Ga11 eruca 1 ongi ­ corn is. Since Say•s original specimens were lost, Smi th and Lawrence

(1967 ) desi gnated a neotype for Q. longicomi s. Smith and Lawrence

(1967 ) al so · recognized two subspecies namely, Q. longi corni s longi ­ co rnis of Say , and a new subspecies , Q. longi cornis barberi . Chi ang later ( 1973) reported th�t White in 1969 had recognized an eastern population of Q. longi corni s as di stinct from Q. longi cornis longi ­ co rnis. More recently, Krysan et. al . (1983) studied Di a brotica from two cruc.ial geographic areas : the eastern Great Plains and the mi d­

Atlantic and southern states. Their re sults revealed that D. longi­ comi s barberi and D. longi co rni s longicornis represented repro­ ductively isolated taxa . They reported that D. longi comis barberi Smith and Lawrence earl ier commonly referred to as the NCR was a synonym of Q. barberi . Smith (1967 ) wrote that Say in 1824 descri bed

Galleruca atripennis from materi al col l ected by the Long expedition to the state of 11Mi ssouri ". The original type series was lost so LeConte (1859) placed the neotype of the species in the genus Diabrotica.

Galleruca atripennis Say was a primary homonym of Gal l eruca atripenni s 5

Fabricius. The next avai lable name was cri st�ta ( Harri s ) 1837.

Harris (1837) descri bed the species now known· as Diabrotica cristata as fol lows : "Black, thorax rufous with a black disc and two impressed spots; elytra with the margin dil ated , a lateral elevated and an abbreviated impressed line . Length from 4.35 IT1Tl to 4.87 nm. ..

In addition to the development of keys fo r adult identifi ­ cation, various methods have been developed to distinguish between the eggs and larval stages of the species in the virgifera group. Atyeo et. al . (1964) illustrated the cha racteri stic scul pturing of egg chorions fo r the NCR and the WCR. Rowley and Peters ( 1972) in a scanning el ectron microscopy stu�y of the eggshel l of four species of Diabrotica : WCR� NCR, Q.. cristata and Q_. undecimpunctata howardi

Barber ( Southern corn rootworm: SCR the latter in the fucata group ) , found that the eggshell of Q_. cristata resembled that of the NCR more cl ose1 y than those of the other two species examined. Mendoza and

Pete rs (1964) furnished a key to separate the mature larvae of these species wh i le Guss and Krysan (1972 ) empl oyed the technique of poly­ acryami de gel electrophoresis to characterize the esterases of eggs of several Diabroti ca species.

Biology and Di stribution The genus Diabrotica is of neotropi cal origin ( Webster, 1895;

Smi th , 1966) . The only species of Di abrotica which overwinter where· freezing temperatures routinely occur are in the virgifera 6

group. The ranges of those species which occur in the Un i ted States of American ( U.S.A. ) are listed in Table 1 adapted from Krysan (1982).

Life Cycle of NCR and WCR

The NCR and WCR share a similar life cycle. Adult beetl es lay thei r eggs in the soil of corn fields and in other fields where weeds and flowering plants are present. They deposit eggs during the late summer and fa l l. Most eggs are laid in the fi rst 15.24 em of soil , although they al so have been found to depths of up to 38 em ( Kantack et. al . , 1977). The overwinteri ng eggs hatch in the northern areas of the U.S.A. such as in South Dako�a in June , and the larvae feed on the root system eating smal ler roots and tunnel ing into the larger ones.

Rootworms become ful l grown during July and pupate in cel ls in the soil . The adult beetles emerge in late July and continue to emerge unti l early September. The adults of WCR emerge a little later in the season than do the northern corn rootwonn adul ts.

Di apause

The WCR and the NCR are we11 known to be un i vo 1 tine ( one generation per year) , to have an egg diapause , and to overwinter in the soi1. Thus a donnancy scheme in the egg stage adapts these species for survival in the col d north. There is some evidence , al though indirect, that D. cristata has a 1 ife cycle similar to that of the WCR and the NCR. The seasonal pattern of col lection of adult 7

TABLE 1

Ranges of Diabrotica Species in the Virgifera Group Which Occur in the United States

Taxon Range Reference virgifera group D. cristata Canadian Provinces and the Smi th (1966 ) "[Harris) U.S. east of the Rocky Mountains south onto the plateau of Mexico

D. lemni scata Southwe stern U.S. south to Smi th (1966 ) LeConte Guatemala

D. longi cornis Neb., Col o., and Ar iz. Smi th and Tongicornis (Say) south to Durango , Mexico Lawrence (1967)

D. 1 ongi corn is Ontario Canada and Pa. Smith and barberi Smith and west to S. Dak. and south Lawrence (1967) Lawrence to Ark.

D. vi rgi fera Ohio and Mont. south Krysan et. al . vi-rgif era LeConte to Tex. and Durango , (1980 ) Mexico

Q. virgi fera � Okla. south to Central Krysan et. al . Krysan.and Sm1th Ameri ca (1980) 8

D. cristata in Kansas ( Greene , 1970 ) suggests that this species is uni vol tine. Observing that the eggs of D. cri stata did not hatch fo llowing oviposition after one month of incubation at 25° C, and that the embryonic stage was similar to the embryonic stage of the WCR and the NCR ( i.e. , an undifferentiated germ band ) , Krysan (1982 ) concluded that D. cristata underwent diapause in the egg stage .

Effect of Chi ll on Hatch of Eggs

Krysan ( 1982 ) ma intained the eggs of the WCR, NCR and Q.. cri stata at 25° C on moist , sterile blotter paper in plastic petri dishes for 2 weeks. He then c-hilled them at 7 � 1.5 ° C for a six week period. Fo11 ow i ng the remova 1 of the eggs from this 1 ower temperature they were incubated again at 15, 18 or 25° + 1° C. Krys�n

(1982 ) noticed that chilling had no significant effect on the per­ centage of WCR eggs that hatched and the rate of diapause development of WCR eggs was essential ly the same at 15, 18 and 25° C. Wi th the

NCR, Krysan ( 1982 ) found that the 1 anger the chi 11 ( up to 4 months), the higher the percentage of eggs that hatched. He al so noticed that chi 11 enhanced the hatch of eggs of Q. cri stata. These effects of chill on eclosion suggest that Q. cristata is more closely related to the NCR than it is to WCR. Th e WCR• s do not have a thenna1 optimum for diapause development whereas the optima for D. cri stata and NCR is closer to 7° C. 9

Diet and Ovi position

Laboratory rearing me thods for the WCR were developed in the

1960's to aid in the understanding of the biology of this pest.

Hami lton (1972) working wi th the SCR establ ished that a diet of pol len substitute and plant tissue to increase egg production was better than a diet consisting of only plant tissues. Guss et. al . (1976 ) al tered a dry diet previously formulated for the SCR. This alteration con­ sisted of gri nding the food into a fine powder then fo rmulating it into a pel let suitable for the WCR. The WCR females fed the Guss et. al (1976) altered dry diet laid 71% more eggs than beetles fed on fresh corn leaves. Ovi position_ by the WCR was affected not only by diet, but a1 so by ovi pes itio n a1 sites , temperature and photoperi ad. Guss et. al . ( 1976) studied the ovipositional preference media of the

WCR. Three substrates placed in the bottom of petri dishes (100 x 15 nm) consisted of: ( 1) wad of wh.i te gauze , ( 2) wad of gauze pain ted black, and (3) soil that was sifted through an 80 mesh screen. They al so evaluated three protective devices for the ovipositional media:

( a ) fluted steel , ( b ) redwood sticks , and ( c ) al uminum covered screens, as well as media without protect ive coveri ngs . Their tests indicated that adult WCR preferred to oviposit at covered media either in soil or in mo ist whi te gauze . Ki rk et. al . (1968) tested soil aggregate size in rel ation to ovipositional preference of the WCR and found that as the soil aggregate size increased, ovipositional prefer­ ence al so increased. They al so tested the ovipositional preference of the WCR to mo ist and dry sifted soil dishes and found that oviposition 10

was 9.3 times greater in the mo ist soil than in the dry. Mi hm and

Chi ang (1974) noted that the longevity of female beetles was greater

under laboratory conditions of 10° C than at wanner temperatures at

15° C. Female WCR reared by Hi ll (1975} had a mean longevity of 78.2

days and a mean fecun dity of 1,087 eggs laid for a total of 13 .5

cl utches. After a mean preo vipositional peri od of 12.2 days egg

laying commenced at a high level wi th one of the first of the four egg

cl utches being the largest. Branson and Johnson (1973) re ported a

mean preovipositional period of 14.3 days , a mean longevity of 94. 8

days , and a mean fecundity of 1,023 eggs. Hooten ( 1979) found a mean

longevity of 67 days and 60.5 days for WCR females that emerged from

eggs from Beresford and El kton , SO, WCR populations respectively.

Economic Impact Data are unavailable regarding the economic importance of Q.

cristata; however , considerable infonnation is avail able regarding the

economi c impact of WCR and the NCR. Apple ( 19 71) reduced average

larval populations of the NCR from 19.1 to 1.5 per root mass with the

insecticide carbofuran . The yield of corn was increased from 100.9 to

116 .3 bushel s per acre . He concluded that one NCR larva per root ma ss

provoked an ave rage yield reduction of 0.85 percent. Hill and Peters (1971) establ ished a relationship between yiel d loss and root damage

rating. Wi th a normal yiel d of 125 bu/acre , there was a re duction of

-5.8 bu/acre for every adjusted root damage rating unit on a scale from

1-6. Chiang et. al. (1980) indicated that a corn plant has an 11

extensive enough root system to sustain the rootwonns which re sult from a manual infestation of 600 to 1200 eggs/plant , and still produce a near nonnal yield. Yield was signifi cantly reduced only when the numbers of insects were· so large and the damage to corn root system so severe that the insects themsel ves suffered high mortal ity through competition for food. Branson et. al. (1980) investigated a uni fonn infestation with eggs of the WCR at different rates of eggs per 30.5 em of row. They found that the root damage rating was a more sensi­ tive measurement of rootworm damage than verti cal pulling wei ght , root lodging , goosenecki ng , plant stunting , or adult recovery. They reported that root damage ratings , unl ike vertical pulling weights, were independent of the size of the root system. Experiments have indicated a 1 oss of 10 to 30 percent of yi e1 d were corn ha s been picked by hand and wei ghed ( Burkhardt , 1972 ) .. The known pest Dia­ brotica have been estimated to cause some $1 bi 11 ion in damage per year in the USA ( Metcalf and Rhodes in Krysan and Branson 1982).

Sampl ing Methods Populati on measurement is estimated by absolute or re lative sampl ing methods .

The absol ute method of population determination samples the number of animals per unit .area. Its measurement involves counting the total number of animals in a uni t area of habitat sampled, with the total number of these units in the whole habitat of the population 12

also bei ng determined (Southwood , 1978} . Absol ute methods of sampl ing according to Southwood (op. cit. ) are seldom 100 percent effi cient but are more rel iable than relative methods. The accuracy of re lati ve methods can sometimes be corrected in various ways to provide more re liable density estimates . The biological interpretation of re l ative population estimates , however, is extremely diffi cult and their size is infl uenced by at least one of the fo l lowing fi ve factors

(Southwood, 1978) .

1. Changes in the actual numbers or population

changes.

2. Changes in the number-s of animal s in a particular

11phase11 where phase is defined as an insect age such

as the pre or post reproduct ive age .

3. Changes in activity (di urnal or nocturnal ).

4. Changes in the efficiency of a trap or the search­

i-ng method. 5. The responsiveness of a particular sex and species

to a trap stimul us.

Traps can be categori zed into those that catch insects at random and those that attract them in some way. Broadbent (Southwood , 1978) stated tha t the cylinder sticky trap was a good design , �ampl ing at random from the passing air. This trap consisted of a piece of plastic material which covered a length of stove pipe. They found that plastic materials yellow in color caught mo re aphids than white models , and whi te was a better color than black. 13

Guss et. al. ( 1983) constructed pheromone traps from blank flat ( plastic coated) milk cartons. When deployed the traps formed the shape of a vertically ori ented tri angle . Tangle Trap® ( Tanglefoot

Company , Grand Rapi ds, Michigan ) was used to coat the inner surface of cardboard blanks that were taken to the field and unfol ded.

Howe and Shaw ( 1972 ) empl oyed two sampl ing methods for corn rootwonn egg sampl ing consisting of a gol f course cup cutte r and a bulb setter. ·Chiang (1973) discussed earl ier methods used to sample a 11 of the 1 i fe stages of the corn rootworm. Foster et. a 1. ( 1979) studied the spatial di stribution of the eggs of the NCR. They found that 85 percent of the eggs in �he upper 20 em of soi l sampled were concentrated in the top 10 em. The base of corn plants and cracks in the soil were p refe rred oviposition sites. They concl uded that a sampl ing program should incl ude samples at the plant base and between rows to a depth of 10 em. Of five relative sampl ing methods eval uated with regard to variability and time , three of them were stati stical ly reliable ( Fo ster et. al ., 1979). The normal core method which empl oy­ ed a 5.4 em diameter core sampl er was the most efficient with regard to time , but a newly developed 11frame method .. wa s reconmended as· the mo st accurate. Bergman et. al. (1981) studied larval sampl ing of the corn rootwonns. Hein and Tol l efson (1984) showed egg and larval sampling to be highly variable and costl y.

The plant count method has al so been introduced, and sampl ing plans have been proposed for its use in adult corn rootwonn sampl ing

A• Q vQ?L.. i..,..· v� 14

(Lovett , 1975). The ear zone count, a subsample of the plant count was reconmended for use in adu1 t contra1 samp 1 i ng according to the

Un ion Carbide Corporation (Hein and Tol lefson , 1984). Sampl ing plans for plant counts, ear counts , and cyl indrical sticky traps were developed by Steffey et. al. (1982). They found that plant counts prov i ded the most precise estimate of beetle populations at the least cost. Foste r et. al . (1982 ) developed a sequential sampl ing plan for the plant count. In fiel ds where the adult corn rootworm population is bel ow the economic threshold, sampl ing must be re peated unti l the population exceeds the threshold or decl ines. Hein and Tollefson

(1984) compared eight rel ative trapping methods for their ability to sample populations of adult NCR and WCR. Two of the trapping tech­ niques , the unbai ted Pherocon® AM 1c trap (Zoecon Corp. , Phercon

Supply Servi ce , 975 Cal ifornia Avenue, Palo Al to, CA) and the ear level , cylindrical sticky trap were found to have the best adult corn rootwo rm . sampl ing characte ristics.

Studies on the fli ght and distribution of the WCR by Wi tkowski et. al . (1975) showed. that males and females were active at the same time of day at a height below 1.84 m. Traps placed in com field showed the WCR fl i ght heights to be as fol lows :

59 percent of beetles were taken at heights of 0.31-0.62 m,

32 percent of beetles were taken at heights of 0.92-1.22 m,

9 percent of beetl es were taken at heights of 1.54-1.84 m. 15

Howe et. al . ( 1963) placed vertical poles covered with adhe­

sive into corn fields at hei ghts above the ground of 0.92 m, 1.84 m,

2.76 m and 3.68 m. They found that most NCR were caught at heights be1 ow 1. 84 m.

Bartel t and Chiang (1977) indicated that traps placed at 0.3 m and 0.9 m heights above the groun d were most effective. Traps placed at 2m (tassel height) attracted very fe w beetles. Witkowski et. al .

(1975) determined that 91 percent of the WCR beetles were captured on non-ba ited verti cal yellow sticky traps below 1.2 m. Thi s indicated that most of the beetle activity occurred below the canopy height in corn fi el ds.

Ladd et. al . (1984) showed that the most effective combination of height and color for trapping NCR outside a corn fi eld was a ye llow

ba ited trap in a zone 0 to 0.25 m above the ground.

Control

Early control measures recommended fo r corn rootwonns con­ sisted of crop rotati�n, fall tillage , alteration of planting date

(early or la te) and the use of resistant hybrids (Tate and Bare ,

1946).

Crop rotation has long been assumed to interrupt the 1 ife cycle of the corn rootworm. Hill et. al . (1948) reported that crop. rotation effectively control led the NCR and the WCR in Nebraska. The studies of Branson and Ortman (1967, 1970, 1971) on the host range of

larvae of the WCR and the NCR respectively, which showed that the 16

species we re abl e to complete thei r life cycle on 13 of thei r 18 potential hosts , ·indicate care should be taken in the selection of crops in the rotation . Larvae were found in corn roots in the fi e 1 ds that had corn-soybe an-corn rotation ( Gou ld, 1971 ). A crop rotation failure to control NCR was noted by Bigger (1932). This was a three year rotation series that had two years of corn and one year of oat-sweet clover mixture . Hi s results indicated that more than one year of some othe r crop should be interposed between the successive corn crops for rootworm control .

The use of chemical s in rootworm control was fi rst establ i shed by Hill et. al . in Nebraska (1948) using the chlorinated hydroca rbon insecti cides. These compounds were very effective in rootworm control until 1959 when resi stance was noted in western corn roo tworm popula­ tion ( Bal l an d Weekman , 1962). Eventually, resistant populations were reported in South Dakota in 1962 ( Howe et. al ., 1963) an d they have al so appeared in surrounding states . By 1962 , diazinon an d phorate

( organo-phosphate compounds) were recommended as re placement chemi cal s for chlori nated hydrocarbon ( Ball, 1973). The cu.rrent rate and use of carbamates an d organophosphate compounds has provided effective corn rootworm control .

Recently the development of pest management strategies has res ulted in an increased effort to optimi ze sampl ing me thods for rootworms . These studies involve the use of sticky traps bai ted wi th pl ant deri vative 1 ures or attractants to mon itor corn rootwonn popu­ la tions to enable growers to arrive at a more re l iable pest management decision. 17

CHAPTER 3

DIABROT ICA CRI STATA : HOST PLANTS AND OV IPOSITIONAL HAB ITS

The host-plant relationships of the Chrysomel idae in the tri be

Luperini are crucial features which are diffi cult to study, compared wi th most othe r chrysomel ids, because their larvae feed underg round

( Wi lcox , 1972). Also the larvae and adults do not necessarily feed on the same or related plant species . The re lationships between Q_. cri stata an d its hosts have been only superficial ly pursued. There are some reports , however, regarding the presence of the adults among grasses on the rel ict prairies.- In the U.S.A. it is known to be associated with perennial grasses ( Smith , 1966). It has also been shown that the adults present on fl owers fed on pol len (J .L. Krysan , personal communication) . A survey for Q.. cristata adults on re li ct prai ries of Eastern South Dakota and Sou thwestern Minnesota has

re vealed .its presence on six fami lies of plants ( Wiesenborn an d

Krysan , 1980). This survey showed that Q.. cri stata frequented mo st,

but not al l, of the pl �n ts that were in flower. Very littl e, howev er,

is known about the host plants fed upon by the larvae of Q. cristata .

The purpose of this study was to inves tigate the rel ationships

between D. cris tata an d its habitat. Thi s is especially pertinent in

light of re cent biochemi cal systematic studies which show that D.

cristata and the NCR pest are as closely re l ated as are subspecies an d

sibl ing species in some insect groups (J .L. Krysan , person al corrmun i cati on ) . 18

THE STUDY AREA

Thi s study uti1 i zed 1 and owned by the South Dakota State

Un iversity Expe riment Station located 0.8 km north of the main campus

in no rthern Brooki ngs County , South Dakota. In contrast with native prairie, which is comprised of perennial grasses· and diverse forbs, the study area was composed of grass monocultures consisting of: (a )

An dropogon gerardi vitman (big bluestem) ; (b) Pani cum vi rga tum L.

(swi tch grass ), and (c) Bromus i nennis Leyss ( brome grass). The big bluestem consisted of a rectangular plot (ca 23 x 16 m) and the plants were arranged in 44 rows at i nterva1 s of 0. 5 m. Medi cago sativa L.

(alfal fa) was planted on the n{)rth side. The switch grass plot adjacent to the big bluestem was also rectan gular (ca 20 x 10 m) and the plants were arranged in 40 rows at intervals of 0.5 m. Each plant co nsisted of a square of sod of 0.6 m. The brome grass plot was 150 m

southeast of the above two p 1 ots. It was a squa re ( ca 82 x 82 m) , surrounded by a fence, and the plants were not arranged in rows . The big bl uestem and the swi tch grass heights we re ca 0.6 -1. 32 m during the study and can reaGh heights of 1.82 m, wh ile the brome grass when allo wed to grow to maturity hardly reaches 0.6 m in height.

MATERIALS AND METHODS

The fiel d aspects of this study was conducted from June through Septembe r in 1983 and 1984. The data were analyzed by the analysis of variance (ANOVA) and the means were sepa rated by the

Wa ll er Duncan K ratio t test. 19

Descri ption and Placement of Emergence Cages

De scription. The cages were pyramidal in shape ( Figure 1).

The triangular faces were (1.19 m x 0.86 m x 0.86 m ) and constru cted of 1 rrm mesh plastic screen. The bottom was provided with a fl ap of plastic which had a brass. grommet at each corner. Pegs were inserted through the grommets to secure the fl ap in the soil. Two 76 em zipper openings permitted access to the cage.

Placement. In Ju ly of both 1983. and 1984 seasons, pheromone traps ( Guss et. al ., 1983) were used to determine the time of beetle emergence. When beetle emergence was first detecte d by the sticky traps , emergence cages were placed randoml y over the three different · species of grasses. Four cages were pl aced on each grass species. To place the emergence cages a trench was dug in the soil to a depth of

12.7 em and the flap of the cage buried therein. The tallest blades of grass were cut shorter to pennit a ready capture of the emerged adults through the use of an aspirator. The cage s were examined daily from July to Septembe r and all emerged beetles were removed sexed and counted.

De scri ption and Placement of Sticky Traps

The sti cky traps were ma de from modi fied hal f gal lon mi lk cartons ( Guss et. al ., 1983). The top and bottom ends of the cartons we re removed and the box cut a 1 ong one edge ( Figure 2). Ho 1 es we re punched on the upper and lowe r edges. The sides which had been cut 20

Fi gure 1. Eme.rgence cage. 21

fi gure 2. Half gal lon mi lk carton trap design. 22

were ove rl apped and bound together with wire ties to produce a three­ sided structure , · open at the top and bottom. The outer faces of the trap were coated with Tangle-Tra� in the laboratory and the cardboard block was taken to the field and unfolded exposing the sticky surface. Tangle Trap® is a commercial ly available sticky material that retains beetles or any other insects or small animals which contact it. Traps were placed on vertical wooden stakes that consisted of a hori zontal cross piece na iled 20 em down from the top.

Trap Height During July of 1983 _one could see that the plot wh ich contained big bluestem grass had many adult D. cri stata . As a result of these observations , the height of the big bluestem grass was measured weekly, from July to September 1983 , and three different experiments were conducted to dete rmine whi ch trap height had the greatest beetle count.

In a prel iminary experiment , July 20-August 3, the fol lowing trap heights were tested in four blocks. Traps at heights of 0.45 m,

0.60 m and 0.91 m were placed on a line transect 2.5 m from the edge of a big bluestem plot. Traps were spaced 5 m apart and a 7 m space existed between bl ocks. During the fi rs t experiment the height of the grass was 0.71 m-0.95 m. The second experiment conducted from August

5-August 17 was conducted by using the same design as above. Trap hei ghts were 0.60 m, 0.91 m and 1.06 m. At that time the grass height ranged from 0.96 m-1. 21 m. In the final experiment conducted from 23

August 19-September 27 when grass height ranged from 1.27-1. 57 m the

0.60 m trap was re placed by one at 1.52 m. Sti cky traps were used in all experiments. The beetl es were counted daily. Beetles were removed from the traps with a spatula and insects immersed in hexane to remove the Tangle Trap® adhesive befo re sex determination . and counting.

Habitat of Adult D. cristata

Data for trap heights in 1983 and in 1984 indicated that most of the beetles were captured at the height of the grass canopy. Nine sticky traps placed in 1983 and nine sticky traps in 1984 at 0.45 m height in a brome grass plot and at 0.91 m height in a big bl ues tem and swi tch grass plot we re placed randomly 7 m apart and at 2.5 m from the edge . Trap heights were adj usted according to the growth of the grass species. The big bluestem plot used fo r this study was not the same as the plot used for comparison of catch versus trap height. The traps in the experiment were checked twi ce per week and the numbers of beetles per trap count�d and recorded. The Tangle Trap® adhesive was repl aced weekly or as needed.

Egg Layi ng Site

In September 1983 after beetle activity had ended according to detecti on by sti cky traps , three soil samples were taken from each of ten randomly sel ected plants in the plots of both big bluestem and swi tch grass . The absence of rows among the brome grass required that 24

the thi rty soil samples be taken randomly. Ten soil samples were randomly taken from the plots of the three grass species in May 1984 before the eggs had hatched. The bul b setter method used in Illinois

(Howe and Shaw, 1972) was empl oyed to take samples in this study and included all soil from the surface down to a depth of 15.24 em . Each sample was placed into a plastic bag, labeled and tied with a twi st.

These samples were taken to the laboratory where each sample was . washed by a mechanical apparatus (Shaw et. al ., 1976 ) to extract the eggs . The extracted eggs per soi 1 samp 1 e were counted and then identified to species based on the structure of the chorion (Rowley and Peters , 1972).

Detenni nation of Ovipositional Preference and Collection of Eggs in the Laboratory

Adults of Q. cristata were col l ected from the grass fields in

August 1983 (when the numbers of females caught on the sti cky traps was greatest) to obtain a large number of eggs. The beetles were co 11 ected by brushing. them into a funne1 fastened to a one ga 11on plastic container which had small ventil ation hol es and a lid at the top.

On August 2, 1983 , fi fty field-col l ected beetles we re placed in each of three cages , each cage being a cube 30. 48 em on one side.

Three di fferent ovipositional me dia were al so placed in each cage as fol l ows : (a) pink gauze crumpl ed to provide artificial crevices; (b) soil sifted through an 80 me sh scree n, and (c) lumpy soil , i.e. , soil 25

that passed through a 1.27 em mesh screen but was retained by a 0.63 em mesh screen . Al l media were water dampened and placed in 15 x 100 mm petri dishes ( Branson et. al., 1975). The cages were maintained in a chambe r at 20-2 1° C, and 70 percent relative humidi ty. Beetles were fed fresh lettuce and zucchini squash daily as wel l as a mi xture of artifi cial diet ( Guss · et. al ., 1976) . Once weekly the ovipositional media we re changed, the eggs washed therefrom and the numbers of eggs per di sh recorded.

Longevity of D. cristata in the Laboratory

Ten fiel d col l ected female beetles of unknown age were caged on Jul y 25, 1983 with 10 rna1 e D. crista ta in 5 x 10 em diameter plastic cage s and hel d at 20-21° C and a photopha se of 12 hours light,

12 hours dark. Beetles we re fed as previously described. Six cages we re used for the experiment and cages were checked da i 1 y and the numbers of dead beetles recorded for each sex. 26

RESULTS

Emergence Cages

Adult D. cristata were found only in cage s placed over big bluestem grasses during the two years of observation in this study .

Table 2 summarizes the emergence pattern. No D. cri stata we re captured in the cages placed over switch grass or brome grass.

In both 1983 and 1984 the emergence of adult D. cristata in early July, was earl ier than either the NCR or the WCR that emerged in late July.

Trap Heights

Fi rst Experiment . Thi s experiment took place from July 20-

August 1, when grass hei ght was 0.71-0. 96 m. The analysis of variance revealed that the dates of counti ng were highly significant (P �

0.01). The overal l mean beetle coun ts on sticky traps were 7.5, 15.3, - 18.7 , 21�6, 31.0, 66.0 and 77.0 for the 7 days - July 20, 22, 24, 26,

28, 30 and August 1, re spectively. The average individual col l ection dates di ffered ( Wal ler-Duncan , P � 0.05) as indicated in Table 3.

The mean counts of adult .Q_. cri stata captured at different trap hei ghts from a big bluestem grass plot ( i.e. , among height ) we re

2.8, 47.0 and 52.0 for 0.45 m, 0.60 m and 0.91 m, hei ghts re spectively. These val ues were highly significant (P � 0.0 1). The trap height by date interaction was al so highly signifi cant (P � 0.01)

( Table 4). 27

TABLE 2

Period of · Ernergence of Adult Di abrotica cristata from Bi g Bl uestem Grass Plots near Brook1ngs , South Dakota

Total Number Number Beetl es Mean Year Date of Cages of Days Emerged Beetles/day Range

1983 7/18-7/23 1 6 5 0.83 0-3

7/18-7/23 2 6 52 8.66 6-21

7/18-7/23 3 6 9 1.50 0-9

7/18-7/30 4 13 0 0 0-0

1984 7/12-7/ 18 1 7 _ 18 2.57 0-5

7/12-7/30 2 19 25 1.3 1 0-6

7/23-7/29 3 7 26 3.71 0-17

7/28-7/30 4 3 9 3.00 0-7 28

TABLE 3

Mean Catches of Adult Diabrotica cristata on Sticky Traps at Various Dates from Ju ly 20 to August 1, 1983 in a Bi g Bluestem Grass Plot near Brooki ngs

Dates of Wa ller- Duncan Collection Counts p � 0.05

Ju ly 20 15.3 be

22 17.9 a

24 66.0 a

26 31.0 b

28 18. 0 be

30 21.0 be August 1 7.5 c

Means followed by the same le tter were not significantly different at the 0.05 level of probabili ty (Walle r-Duncan). 29

TABLE 4

Mean Catches of Adul t Di abrotica cri stata on Sticky Traps at Differe nt Heights on Date by Height Interact 1on during July 20 - August 1, 1983 , in a Big Bluestem Grass Plot ne ar Brookings , South Dakota

Dates of Height in m Col lection 0.45 0.60 0.91

July 20 1.5 21. 0 23.5

22 4.7 129.0 100.0

24 0.7 88. 0 109.0

26 1.2 37.0 54.0

28 1.2 21.0 34.0

30 0 31.0 34.0

August 1 10.5 2.0 10.0

b a a Means 2.8 47.0 52.0

Means fol l owed by the same letter were not significantly different (Wall er-Du ncan 0.05 probabi 1 i ty) . Mi nimum signifi can t difference ( MS D) = 2 8. 7 6 . 30

Significantly greater beetle counts we re found on traps placed at 0.60 m and 0.91 m above the ground than on traps placed at 0.45 m above the ground. Although there was no signifi cant difference between the numbers of beetles captured on sticky traps at 0.60 m and

0.9 1 m above the ground the numbers captured at 0.91 m was slightly greater (47.07 and 52.17 respectively) . The trap heights of 0.60 m and 0.91 m were used fo r the second experiment conducted between

August 5-August 17 , and the trap hei ghts of 0.45 m were rep laced by a trap height of 1.06 m.

Second Experiment. The analysis of variance revealed that the dates of counting were highly ·significant (P � 0.01). The overal l mean adul t D. cri stata count on sticky traps were 10.5, 6.0, 4. 1, 4.0,

3.5, and 2.6 on August 10, 8, 5, 15 , 12 , and 17th , re spectively. The bi g bl uestem grass height was 0.96 m- 1. 21 m. Mean catches on August

10 were significantly different from the mean catches on any of the othe r days (Tabl e 5a).

The mean counts of adult Q. cri stata captured at different trap hei ghts from a big bluestem grass plot were 1.0, 6.3 and 8. 0 for

0. 60 m, 0. 91 m and 1. 06 m hei ghts re spectively. The mean counts on the sticky traps at 0. 91 m and 1. 06 m above the ground we re not significantly different from each other (Waller-Duncan , P � 0. 05)

(Table 5b) . They we re different from the mean count on the sticky traps at 0.60 m above the ground. The trap height by date interaction wa s not significant. 31

TABLE Sa

Mean Catches of Adult Diabrotica cristata on Sticky Traps at Various Dates from August 5 - 17, 1983 , in Big Blue�tem Grass Plot near Brookings, South Dakota

Dates of Waller-Duncan Collection Counts p � 0.05

August 5 4. 1 b 8 6.0 b 10 10.5 a 12 3.5 b 15 4.0 b 17 2.6 b

Means fol l owed by the same letter were not signifi cantly di fferent at the 0.05 level of probability {Wal l er-Duncan).

TABLE Sb Mean Catches of Adult D. cristata on Sticky Traps at Di fferent Heights from August 5 - August 17, 1983 , in a Big Bluestem Grass Plot at Brookings, South Dakota Mean are Based on 3 Replicati ons.

Trap Hei ght D. cri stata

b 0.60 m 1.o8 a 0.91 m 6.37 1.06 m 8. 04a

Means fo llowed by the same letter were not significantly di fferent at the 0.05 level of probability (Wall er- Duncan) . Mi nimum significance (MSD) = 4.99. 32

Al though there were no significant difference between the numbers of beetles captured on sticky traps at 0.91 m and 1.06 m, the

highest numbers of captured beetles were observed on sti cky traps at

1.06 m above the ground. Traps at heights of 0.60 m were replaced by

1.52 m trap hei ghts for the thi rd test carried out between August 19-

Septembe r 27.

Third Experiment. The analysis of vari ance of adult D.

cristata count during the test from August 19-Se ptember 27 when grass

hei ght was 1.27-1.57 m indicated that there was no significant diffe r­ ence between trap hei ghts at 0. 91 m, 1. 06 m and 1. 52 m above the ground (P � 0.05). The means count of beetles at 0.91 m, 1.06 m and

1.52 m trap heights were 0.3, 0.8 and 0.6, re spectively.

In summary , traps p 1 aced at the 1 eve 1 of the canopy captured more beetles than traps placed at the lo wer level s.

Habi tat . of Adult D. cristata

Since prel imi nary trap hei ght data of 1983 revealed that mo re

beetles we re capture_d at the canopy hei ght, nine sticky traps were

placed in 1983 and nine in 1984 among three grass species at approxi­ mately the grass hei g�t and adjusted with the growth of the plant. In 1983 the analysis of variance revealed significant dif­

ferences (P � 0.01) between grass species in the adult D. cri stata

counts. The mean beetle counts were 0.1, 0.6 and 6.6 in the brome

grass , swi tch grass and big bluestem grass plots, respectively. The means in the brome and switch grass plots were not significantly 33

significantly different from each other, but they were different from the mean in the big bluestem (Waller-Duncan, P � 0.05). The analysis of variance also revealed that the dates of counting were highly significant (P � 0.01). The overall mean beetle counts on different grass species were : 0, 0.03, 0. 03, 0.07, 0. 1, 0. 1, 0. 1, 0. 14, 0.14,

0.14, 0. 18, 0.2, 0.33, 0.37, 0.37, 2.0, 2.7, 8. 5, 16. 8 and 17. 0 for September 13, 5, 1, Augu st 22, 12, 24, 30, 26, 15, 19 , 17, 8, 3, 5,

10, 1, Ju ly 29, 27, and 22nd respectively. The individual col lection of adults at vari ous dates differed (Wall er-Duncan , P � 0.05) as indi cated in Table 6. The grass species plot by date interaction was also highly significant (P � 0�01) (Table 7). In 1984 the analysis of variance revealed significant dif­ ferences (P � 0.01) between grass species in the adult Q. cri stata counts . The mean beetle counts were 0. 1, 1.4 and 18. 9 for the brome grass, switch grass and big bluestem, respectively. The fi rst two means were not different from each other, but they were different from the last (Wall er-Duncan, P � 0. 05). The analysis of variance al so revealed that the .dates of counting were highly significant (P �

0. 01). The overall mean beetle counts on sti cky traps were 0.03, 0.2,

1.2, 1.4, 3.0, 3.8, 5.2 , 6.8, 6.9, 11. 0, 11. 1, 13. 3, 13.4 and 18.0 for August 30, 27, 10 , 20 , 13, 15 , 17, 8, 1, Ju ly 28, August 5, July 26, 30 and August 3 respe�tively. The average individual collection dates differed (Wall er-Duncan , P � 0 .05) as indicated in Table 8. The grass species plot by date interaction was also highly significant (P

� 0. 01) (Table 9). 34

TABLE 6

Mean Catches of Adult Diabrotica .cristata at Various Dates , July 22 - September 13, 1983 , in Three Grass Species Plots near Brookings, South Dakota

Dates of Waller-Duncan Col l ection Counts p < 0.05

July 22 16.8 a 25 17.0 a 27 8. 5 b 29 2.7 c

August 1 2.0 cd 3 0.3 d 5 0.3 d 8 0.2 d 10 0.3 d 12 0.1 d 15 0.1 d 17 0.1 d 19 0. 1 d 22 0.07 d 24 0.1 d 26 0. 14 d 30 0. 11 d

September 1 0.03 d 5 0.03 d 13 0 d

Means followed by the same letter were not significantly different at the 0.05 level of probability ( Wa ller-Duncan) . Means are based on 9 repl ications. 35

TABLE 7

Mean Catches of Adult Diabrotica cri stata on Sticky Traps Among Three Grass Species by Date Interaction July 22 - September 13, 1983 , at Brookings, South Dakota

Dates of Grass SEecies Collection Switch Grass Bi g Bl uestem Grass Brame Grass

July 22 6.0 45.0 0. 1 25 2.0 47. 5 1.4 27 1.3 24.0 0.3 29 0.8 6.8 0.4

August 1 0.4 5.1 0.4 3 0.4 0.5 0 5 0.2 0.7 0. 1 8 0.1 0. 7 0 10 0.1 0. 7 0.2 12 0 0.3 0 15 0. 1 0.2 0. 1 17 0 0.3 0.2 19 0.3 0 0. 1 22 0.1 0.1 0 24 0.2 0.1 0 26 0. 1 0.3 0 30 0.1 0.2 0 September 1 0 0 0. 1 5 0 0.1 0 13 0 0 0

b Mean 0.6 6 .6a 0. 1b

Means fol l owed by the same letter were not significantly different at the 0.05 level of probability (Wall er-Duncan). Mi nimum signifi cant difference (MSD = 1.62). 36

TABLE 8

Mean Catches of Adult Diabrotica cristata on Sticky Traps at Various Dates from July 26 - August 30, 1984 , in Di fferent Grass Speci es Plots near Brookings, South Dakota

Dates of Wa11 er-Duncan Col lection Counts p � 0.05

July 26 13.3 ab 28 11.0 be 30 13.4 ab

August 1 6.9 cd 3 18. 0 a 5 11. 1 be 8 6.8 cd 10 1.2 ef 13 3.0 def 15 3.8 def 17 5.2 ed 20 1.4 ef 27 0. 2 f 30 0.3 f

Means fol fowed by the same letter were not significantl y different at the 0.05 level of probability (Waller-Duncan ). 37

TABLE 9

Mean Catches of Adu lt Di abrotica cristata on Sticky Traps Among Three Grass Species on Date by Grass Species Interaction from July 26-August 30, 1984, at Brookings, South Dakota

Dates of Grass S�eci es Collecti on Switcn Grass BigB1u estem Grass Brame Grass

July 26 5.5 34 .3 0.2 28 1.7 40 .0 0.3 30 0.2 50.3 0. 1

August 1 3.3 30. 7 0.3 3 3.7 31.0 0.3 5 2.2 17. 1 0. 1 8 1.7 18.4 0. 1 10 0.4 3.4 0 13 0.1 9.1 0 15 0.6 10.7 0 17 0.2 15.4 0 20 0 4. 2 0 27 0 0.4 0.2 30 0 0. 1 0

b a Mean 1.4 18. 9 0.1b

Mean s fol l owed by the same letter were not significantly different at the 0.05 level of probabili ty (Wall er-Duncan ). MSD = 2.82. 38

In summary in both years 1983 and 1984 significantl y higher catches of adult Q. cri stata were made in big bluestem grass than in either swi tch grass or . brome grass. Thus big bl ues tem grass could be consi dered as resting , feeding and mating sites of adult D. cristata in a habitat of three mixed grasses.

Egg Oviposition Sites in the Fi eld

Tabl e 10 summari zes the occurrence of D. cri stata eggs from different grass species sampled. It appears from the table that egg occurrence was more frequent in big bluestem grass than in brome grass or swi tch grass. Switch grass mixed in Sorghastrum nutan (Indian grass) had the highest egg coun ts in 1983 and none in 1984 . In 1 ate

Ma y ( 1984) eggs of Q. vi rgi fe ra , Q. barberi and Q. cri stata co11 ected from the field before adul ts were observed, began to hatch within two days in the laboratory at 75° F. Eggs conti nued to hatch until June

15th, but no hatching occurred after the 15th of June. In two to three · wee ks , thi rd instar larvae pupated and adults that emerged consisted of the three species.

Laboratory Tests

Adul ts of D. cristata we re successfully sustained by feeding them with a diet composed of fresh zucchini squash, lettuce and an arti ficial diet described by Guss et. al . ( 1976). Some eggs from a field soil sampl e al so developed to adults when fe d upon corn roots. 39

TABLE 10

Egg Occurrence of Q. cri stata from Different Grass Species nea r Brookings , South Dakota in 1983 and 1984

No. of Soi 1 Total Mean Eggs Per Years Grass Species Samples Eggs Soil Sample Range

September Big Bluestem 30 20 0.66 0-19 1983 Swi tch Grass 30 12 0.40 0-6

Swi tch Grass + Indian Grass 30 91 3.03 0-22

Brame Grass 30 6 0.20 0-4

May 1984 Big Bluestem 10 59 5.90 0-27

Swi tch Grass 10 10 1.00 0-4 40

These results agree with the findings of Branson and Krysan ( 1981) working with the WCR and D. cri stata.

Determination of Ovipositi onal Preference

The percentage of eggs laid during the first three weeks after the col l ection of D. cri stata adults from the fi eld ranged from 15.41 percent to 17. 36 percent, 22.24 percent to 25.83 percent and 58. 20 percent to 60.45 percent in a dish with pink gauze, 80 me sh soil, and lumpy soil, respectively (Table 11a).

The ANOVA revealed that lumpy soil contained a higher per­ centage of eggs than soil sifted through an 80 mesh screen ; however, the latter had a significantly higher percentage of eggs than pink gauze (Table 11b).

Longevity of Adult D. cri stata Ta ble 12 summari zes the longevity of male and female D. cristata . The range was 11-43 days for the 120 fi eld co llected adults according to the date of col lection. The means longevity for both maleand female was 22.5. 41

TABLE 11a

The Percentage of Ovi position of D. cri stata in Three Ovi positional Media from �ugust 18-September-1 , Unde r Laboratory Condi tions

Cage Eggs Laid (Percent) Numbe r Pi nk Ga uze 80 Me sh Soil Lumpy So 1l

1 17.37 22.24 60. 38

2 15.41 24. 12 60.45

3 15.95 25.83 58.20

(20-21° C and 70% Rh )

TABLE 11b

Me an Occurrence of Eggs Laid in Three Ovi positiDnal Media in the Labo ratory from August 18-Se ptember 1. Means are Based on Three Replicates.

Ovipositional Media Me an eggs Laid (Percent)

Pink Gauz-e 16. 24**

80 Mesh Soi 1 24. 06**

Lumpy Soi 1 59.67**

**Means significantly di fferent from each other at 5 percent level (Analys is of Variance LSD) LSD = 2.79 0 _ 05 42

TABLE 12

Longevity of Adult D. cristata Collected from the . Fiel d from July 15 - September 9, 1983

Dates of Cage No. of Range Observation Number Sex Beetles Mean s (Days )

7/25-9/8 1 male 10 26.2 16-43

7/25-9/8 1 female 10 25.0 16-43

7/25-8/26 2 male 10 17.0 9-29

7/25-8/22 2 female 10 19.0 12-25

7/25-8/22 3 male 10 20.3 14-25

7/25-8/28 3 female 10 20. 5 12-32

7/25-8/28 4 male- 10 27.4 22-33

7/25-9/2 4 female . 10 25.8 19-36

7/25-8/30 5 male 10 25.0 13-34

7/25-9/9 5 female 10 21.2 11-43

7/25-9/6 6 male 10 19.9 11-40

7/25-8/30 6 female 10 17.5 11-34 · 43

DISCUSSION

Thi s study consisting of observations completed in 1983 and

1984 revealed a signifi cantly higher catch of adul t D cri stata in big bluestem grasses than in either swi tch grass or brome grass. Adul ts were captured only in emergence cages placed over big bluestem grass.

Q_. cri stata eggs we re found in the soil of all grass species. The largest numbers of Q. cri stata eggs were found in a mi xed plot of switch grass and Indian grass. Wiesenborn and Krysan (1980 ) had collected adult D. cristata from Indian grass during their survey in

Brookings County , SO. Indian grass may be a host for the larvae but thi s grass species was scarce in the study area so that emergence cages could not be placed over it alone. No adults we re caught, however, from emergence cages p 1 aced over switch grass in the p 1 ot whe re Indian and switch grass were mi xed. These data indicated that larvae of D. cristata most likely feed on the roots of big bluestem grasses. Adul ts after emergence can disperse to other grass species.

Even though big bluestem grass has been considered as an indicator fo r the presence of D. cri stata in the state of Illinois ( Ruesink in

Wi esenbo rn and Krysan , 1980), Wiesenbor n and Krysan ( 1980 ) indicated that in South Dakota Q. cri stata was frequently found where there was little big bl uestem present and the reverse was true. The relation ­ ship between Q. cristata and big bl ues tem grass species is not abso 1 ute. Duri ng this study Q. cri sta ta has been co11 ected from alfalfa Medicago sati va , di fferent grass species and from weeds . The 44

pl ant species fl owers on which the adult beetles were col l ected were as follows : grasses - Polygonum .erectum , Setaria lutescens ; weeds -

Asclepi as syriaca mi lk weed , Convolvulus arven sis bind weed, Ambrosia artemisiaefol ia hog weed , Sonchus arvensis, Tarascacum offici nale and

Amaranthus retroflescus, pig weed.

There are some 1 imitati-ons to the use of sticky traps to detennine the distri bution of adult insects. The sti cky trap is a

re lative sampling method. Southwood ( 1978) reported that the effi­ ciency of sticky traps varies with wind speed and the size of the insect . Variation in efficiency provides a very real 1 imi tation on the val ue of relative estimates. During the trapping period appreci­ able variability was · noti ced wi th the numbe rs of beetles captured within the p 1 at of the same grass species . Southwood ( 1978) stated that trapping may give widely different counts for the same aerial population if the wind speeds on the sampl ing occasions differ.

Taylor on page 243 in Southwood ( 1978) , however, has shown that it was possible to correct the catches from traps if the wind speed was known . The wind speed was not taken into account in this study, howeve r, trap hefght played an important role in the numbers of beetles captured.

In a pre 1 iminary experiment conducted from July 20-August 1, in 1983 the mean catches of D. cristata on sticky traps at heights of

0.45 m, 0.60 m and 0.91 m · above the ground were 2.85, 47. 07 and 52. 07 45

respecti vely when the height of the big bluestem grass ranged from

0.71-0.96 m. In a second series of experiments conducted from August 5-

August 17, 1983 the mean catches of D. cristata on the sticky traps at hei ghts of 0.60 m, 0.91 m and 1.06 m above the ground were 1.08, 6 .37

and 8.04 respectively, when the height of the b;-g bluestem grass

· ranged from 0.96 m- 1.21 m. In a third seri es of experiments whi ch involved peak grass height carried out duri ng the period from August 19-September 27 the mean catches of D. cri stata on the sti cky traps at 0 .91 m, 1.06 m and

1.52 m were 0.33, 0.88 and 0.63 respectively.

Thus, trap hei ght at the 1 eve1 of the canopy captured more beetles than traps placed at lowe r level s. These fi ndings agree wi th studies by Guss ( 1976} which revealed more WCR beetles on traps at the

hei ght of the tassel in cornfiel ds. Bartelt and Chiang ( 1977) also indicated that traps placed at 0.3 m and 0.9 m height above the ground

we re· most effective for corn rootworm capture .

Insect death , mi gration ; di spersa1 or changes in fl i ght be­ havior may affect the numbers of counts on the sticky traps. Beetles must fly or walk in order to be trapped. Despite these limitations , sticky traps placed in adjacent monocul tures of diffe rent grasses should provide an indication of · relative abundance of beetles in the i 1111'1edi ate area. The occurrence of males and females on the sticky traps among different grass species was simila r. Thus it appears that male and female D. cri stata were acti ve at the same time at the grass 46

canopy. Similar re sults we re found by Witkowski et. al . (1975) wi th their studies on the fl ight and distribution of the WCR.

An experiment on the ovipositional preference of D. cristata indicated that females laid mo re eggs in lumpy soil than among soil seived through an 80 mesh screen and soil in general contained mo re eggs than pink gauze. This result is similar to the findings of Ki rk et. al . (1968) with the WCR. They found that as the soil aggregate size increased, ovipositional preference al so increa.sed.

Female Q cri stata laid very few eggs in this study compared wi th WCR in the studies by Branson and Johnson (1973). Perhaps female

D. cri stata had laid some eggs pri or to col lection .

·- The longevity of Q. cristata ranged from 11-43 days according to the data of col lection . This range was diffe rent from the range of

19-126 days obtai ned by Branson and Johnson for WCR ( 1973). Hooten

(1979) reported a mean longevity of 60 and 67 days· re spectively fo r female WCR col l ected from El kton and Beresford sites. The mean number of da.ys obtained duri ng this study was 22.5. Hooten (1979) studi.ed the WCR that emerged from field col l ected eggs maintai ned in the laboratory , whi le in the study carried out with Q. cristata , adults of unknown age were investigated. Guss et. al . (1976 ) found that diet played a major role in the longevity of we stern corn rootworms . Singh and Howe ( 1971) al so reported that diet was very important in the longevity and fecundity of western com rootwonns. Different diets , however, we re used in the studies by Hooten (op. cit. ) and SiAgh and

Howe (op. cit. ) and there are also diffe rences between species. 47

CHAPTER 4

THE RESPONSE OF D. CRISTATA ( HARRIS) TO INDOLE, EUGENOL

AND TWO EUGENOL DERIVATIVES

Eugenol (4 al lyl 2 rnethoxy phenol ) obtained commercially by the fractionation of clove Tri folium sp or cinnamon Cinnamomum sp oil has b�en found attractive to the NCR but has not been found attractive to the WCR ( Ladd et. al ., 1983). Eugenol analogs have also been found to be attractive to NCR ( Ladd , 1984). Indole, a volatile attractant for Di abroti ca in cucu rbits , has been reported to attract the WCR but not the NCR in the state of Illinois (J.F. Ande rson , personal conmun i cation) . Isozyme data ( J. L. Krysan , persona1 conmuni cation ) indicated that D. cristata and the NCR are very closely re lated , howeve r, the WCR is not as closely related to the other two. Tollef­ son et. al . (1975) reported that the adult corn rootwonn Di abrotica spp , were most frequently attracted to yel low traps. The purposes of the studies to be descri bed we re : ( a ) to test the effect of the yel low color on trapping Q. cri stata, ( b ) to test the response of Q. cristata to indol e, eugenol and eugenol derivatives in orde r to determi ne if the response pattern of Q. cri stata will be more like the

NCR or the WCR, and ( c ) to test the above attractants wi th the NCR and the WCR in a corn field where both species were present. The behavioral response to these attractants may have important impli­ cations for understanding the mechani sms underlying host relationships in Diabrotica. 48

MATERIALS AND METHODS

These studies we re conducted in 1984 on two sites owned by the

South Dakota State Uni ve rsity Experiment Station. An experiment using

Q. cristata was designed in big bluestem grass (Andropogon ge rardi ) as previously descri bed (Chapter 1) from July through August. An additional experiment invol ving the WCR and the NCR was designed in a corn field near Aurora (16 km east of Brookings County ) in August.

The first experiment completed with D. cri stata consisted of severa 1 parts.

Co lor Comparison

A prel imi nary exper1ment conducted from July 16-July 23 eval uated the number of D. cristata captured on traps of three dif­ fe re nt colors ; unpainted {a cream color) , white and yel low. Yel low traps we re painted by sprayi ng a glossy John Deere yel loW® paint and whi te traps were treated with glossy whi te enamel. Traps were then coated with Tangle Trap® and placed on a wooden stake approximately at the highest 1 eve1 of the grass canopy. Traps were p1 aced within the bi g bl uestem plot in a ran domized complete block design and re pl i cated

4 times. The traps we re placed 2.5 m in from the field border and 7 m apart. Nine meters separated the blocks . The traps we re checked daily, the numbe r of D. cri stata counted and the sex of the beetles was determi ned. The most attractive color in this prel imi nary test was combi ned with diffe rent chemi cal attractants for subsequent experiments . 49

Comparison of Two Methods of Dispensing Attractants

In the second part from July 25-August 2, indole and eugenol were compared as attractants for Q. cri stata in big b 1 uestem grass plots. Two methods of dispensing the chemi cals were used. In the first method, attractants we re mi xed with the Tangle Trap® at the rate of 10 percent by weight ( Ladd , 1984). In the second method the attractants were dispensed from a cotton- wi ck and affixed above the trap with a pin. Indole (1 gram of 99+ percent purity) was wrapped with cheese cloth. Eugenol (1 ml of 99 percent commerci al grade ) was p 1 aced in a cotton wick , 38 l11T1 1 ong and 15 mm in diameter. The unbaited trap bore an empty cotton wick. A randomized complete block design was used with three repl ications for both dispensing methods.

The attractants dispensed from cotton were renewed twice per week.

When mi xed with Tangle Trap® they were re placed daily. The sticky traps were checked dai ly, the beetles removed by a spatula, then immersed in hexane to remove the Tangle Trap®, then counted and sexed.

The third part tested eugenol and two of its analogs : sol id i soeugeno1 acetate , and 1 i quid 2 methoxy 4 propyl pheno1 , (Fi gure 3) , in a big bluestem grass plot different from the grass plot that which was used to determi ne the distri bution of adult D. cristata . Three attractant materials and an unba ited trap were placed in a randomized complete block des ign and re pl i cated four times. Chemical attra·ctants were wrapped in cheese cloth as previously descri bed. Traps we re placed at 2.5 m from the edge of the plot , 7 m apart and a distance of

9 m separated the blocks. Unpainted sticky traps were placed 50

0 CH 3

HO

Eugenol

HO

2-methoxy-4-propyl phenol

CH = CHCH3

Isoeugenol Acetate

Fi gure 3. Structure of eugenol and rel ated compounds (from Ladd , 1984). 51

approximately at the level of the grass canopy . Beetles adhering to the sticky traps were counted and the sex determi ned on a daily basis.

Attractant Experiments with NCR and WCR

This experiment invol ved the use of a corn field and consisted of 5 treatments : ( a ) indo 1 e, ( b ) eugeno1 , ( c ) i soeugeno 1 acetate , ( d )

2 methoxy 4 propylphenol and ( e ) use of unbai ted sticky traps as a control . The five treatments we re placed in a randomized complete block des ign in the field wi th 4 repl ications. Unpainted sticky traps were exposed at a distan ce of 2. 5 m from the border of the fi e 1 d.

They were separated by 6 m and the repl ications were separated 8 m apart. Traps were placed 0. 91 m above the ground and attractant materi als we re dispensed as described above. Beetles of both species

(NCR and WCR) adheri ng to the sticky traps were counted daily and the sex determi ned. Data were analyzed by the analysis of variance and means were separated by the Wal ler-Duncan K rat io t test. 52

RESULTS

Co 1 or Campa rison

Data sui11Tlarizing the response of Q. cristata to traps of three colors appears in Table 13. An analysis of variance of these data revealed no significant differences between catches on yel low, whi te or unpainted traps. Unpainted traps , therefore , were used for the succeeding experiments.

Compari son of Two Methods of Di spensing the Attractants

.... . Method of Mixing Attractant with Tangle Trap®. Th� analyses of variance fo r mal e and female Q. cri stata captured on sti cky traps when attractants · were mixed with Tangle Trap® revealed no signifi cant differences between attractants (Appendix 3). Tangle Trap® and the attractants when mi xed oxi dized to fo rm a reddish material . This result, in addition to the lack of significance , pursuaded me to abandon the method and use cheese cloth in succeeding experiments. Method of Cheese Cloth Wrappi ng. An analysis of variance revealed that there were highly significant differences (at the 0.01 level of probabi lity ) between eugenol and indol e as to the numbe r of males attracted to the sticky traps. The mean male counts were 3.3, 14. 2, and 28.8 fo r the control (or unbaited sticky trap), the ·indole and eugenol bai ted traps respectively. The mean of beetles attracted to eugenol ba i ted traps was different from the two me.ans on indole and the control which were similar (Wall er- Duncan , 5% probability ). The 53

TABLE 13

Mean Catches of D. cri stata by Date and Color Interaction in a Big Bl uestem Grass Plot near Brookings , SD. Means are Based on 4 Replications.

Dates of ResEonse Freguenci es Col l ection Yellow Wh1te On pa1nted

July 17 4.0 3.6 1.0

18 5.0 4.8 1.0

19 8.0 8.6 8.0 20 17.0 21.2 16. 1

21 23.0 13.6 12. 5 22 6.0 5.5 4. 7

23 6.0 5.7 4.8

Means 9.8a 9.0a 6.8a

Means fol l owed by the same letter were not signifi cantly di fferent · Waller-Duncan at the 0.05 level of probability. 54

analysis of variance revea led that the dates of counting mal e .Q_. cri stata were highly significant (5% probability). The overall mean beetle counts on the sticky traps were 20.6, 23.0, 16. 3, 27. 1, 9.5,

6.6, and 5.0 fo r the dates July 26, 27 , 28, 30, 31, August 1, and 2nd respectively. The ave rage individual date diffe red (Wal ler-Duncan , at the 0. 05 proba bility) as indicated in Table 14. The attractan t by date interaction was highly signifi cant at the 0.01 level of prob­ abil ity (Table 15). The analysis of variance revealed signifi cant differences at the 0.01 level of probability between attractants as to the number of females captured on the sticky traps. The mean female counts were

2.6, 8.0 and 32.2 for the unbaited sticky traps , indole and eugenol baited traps respectively. The mean of adult females attracted to eugeno l bai ted traps was signifi cantly different from the mean of females attracted to indole baited or unbai ted sticky traps. The last two means were not signifi cantly different (Wal ler-Duncan at the 0.05 level of probability) (Table 16a). An analysis of variance al so revealed that the dates of counting female Q. cri s tata were not significantly different. No significant differences were fo und wi th the attractant interaction by dates.

Overa 11 both rna1 e and fema 1 e Q. cri stata were attracted to eugenol but the re were no significant diffe rences between the mean counts of beetles on indole and unbai ted sticky traps. Eugenol and two of its analogs , therefore , were tested for their attractancy to D. cristata from August 4-11, 1984 . 55

TABLE 14

Mean Count of Ma le D. cri stata at Various Dates to 2 Attractants and Control Wrapped with Cheese Cl oth in a Big Bluestem Grass Plot near Brookings , SO, in 1984. Means are Based on 3 Replications.

Dates of Waller-Duncan Collection Counts (P � 0.05)

July 26 20.6 ab

27 23.0 ab 28 16.3 be

30 27. 1 a

31 9.5 be

August 1 6.6 cd

2 5.0 d

Means fol l owed by the same 1 etter were not significantly different (Wall er-Duncan P � 0.05). 56

TABLE 15

Mean Catches of Ma le D. cri stata on Date by Attractant Interaction for-3 Lures Exposed by Wrappi ng wi th Cheese Cloth in a Big Bluestem Grass Plot near Brookings, SO, in 1984 . ·Means are Based on 3 Replications.

Dates of Res�onse Freguencies Col l ection Eugenol Indole Onba1 ted Trap

July 26 42.6 15. 0 4.3

27 41.6 21• . 3 6.0 28 30.6 13. 0 5.3 30 39.0 36.0 6. 3

31 20.6 - 7.6 0.3 August 1 15.3 4. 3 0.3 2 12.0 2.3 0.6

a b b Mean 28.8 14.2 3.3

Means fol l owed by the same letter were not significantl y di ffe rent {Waller-Duncan at the 0.05 level of probability). Minimum significant difference (MSD) = 13. 6. 57

TABLE 16a

Mean Catches of Female D. cri stata on Sticky Traps Using 3 Lures Exposed by Wrapping with Cheese Cloth in a Big Bluestem Grass Plot near Broo ki ngs, SO, in 1984 Means are Based on 3 Repl ications.

Lure D. cristata

Eugenol 32.2a Indole 8.ob Unbai ted Trap 2.6b

Means fol l owed by the same letter were not significantly di fferent at the 0.05 level of probability (Wall er-Duncan). MSD = 6.62.

TABLE 16b

Mean Counts of Male D. cri stata at Various Dates Using Eugenol and Its Ana logs Incorporatea in Ba 1 ted Sti cky Traps in a Big Bluestem Grass Plot near Brooki ngs August 5-11, 1984 . Means are Based on 4 Replications.

Dates of Wal l er-Duncan Col l ection Counts (P � 0�05)

August 5 30.0 a 6 22.0 b 7 2.3 c 8 3 .8 c 9 17.3 b 10 5.1 c 11 3.5 c

Means fol lowed by the same letter were not significantly di fferent (Wall er-Duncan, P � 0.05). 58

When the compounds were mi xed with Tangle Trap®, the mi xture rapidly turned reddi sh in the field. This procedure exposed the materi al directly to sunl ight , a condition that leads to very rapid oxidation (J.F . Anderson , personal communication ). The other dispensing method, (the cheese cloth wrapping) presumably protected the indole from oxi dation , but evaporation was. permi tted.

Experiment Testing the Attractiveness of Eugenol and Two of Its

An alogs for D. cri stata Attractiveness of the Attractant for Male D. cri stata

_ An analysis of vari _ance revealed signifi cant dt ffe rences (at the 0. 01 1 eve 1 of probabi 1 i ty ) among attractants to the numbers of male ·Q. cri stata captured on the sticky traps. The mean male counts were 1.0 , 2.2, 19 .6, and 25.2 for the unbai ted sticky traps , iso­ eugeno 1 acetate , 2 methoxy 4 propyl pheno 1 and eugeno 1 bai ted traps respectively. Eugenol baited sticky traps were more attractive for male beetles than the other attractants . Two methoxy 4 propylphenol was a ·lso attractive to males as shown by the mean which was signifi ­ cantly different from the other means (Waller-Duncan , at the 0.05 level of probabi lity). The analysis of variance also revealed that the dates of counting males on the sticky traps were highly signifi­ cant (at the 0.01 level of probabi lity). The overal l mean male D. cristata counts on th e sticky traps were 30. 0, 22.0, 2.3, 3.8, 17.3, 5. 1 and 3.5 for August 5 , 6, 7, 8, 9, 10 and 11 respecti vely. The average individual dates diffe red (Wall er-Duncan , 0.05 level of 59

probability) as indi cated in Ta ble 16b. The attractant by date inter­ action was highly significant at the 0.01 level of probability (Table

17).

Attractiveness of the Attractants for Female D. cristata

The analysis of variance revealed signifi cant diffe re nces at the 0.01 level of probability among attractants to the numbers of female D. cri stata captured on · the sticky traps. The mean female counts were 0.9, 1.1, 17. 1 and 28.4 fo r unbaited sti cky traps , iso­ eugenol acetate , 2 methoxy 4 propyl phenol , and eugenol , re specti vely

(Table 18) . Eugenol bai ted traps attracted more female beetles than 2 methoxy 4 propyl phenol which in turn attracted more fema 1 es than the last two materi als.ut ilizing the isoeugenol acetate and un bai ted traps. These last two were not significant ly di fferent from each other (Wal l er-Duncan , at the 0.05 level of probability). An analysis of vari ance a 1 so revea 1 ed that the dates of counti ng fema 1 es on the sticky traps were highly signifi cant at the 0.01 level of probability.

The overal l mean female D. cristata co unts on the sticky traps we re

2 . 6 , 4 . 6 , 5 . 8 , 5 . 8 , 19 . 7 , 21. 5 , and 2 3. 1 for August 7 , 1 0 , 11 , 8 , 9 ,

6 , and 5 respectively. The fi rst four were not significantly dif­ fe rent from each other. They were , however, signifi cantly diffe rent from the last three whi ch were simi lar (Wal ler-Duncan , at the prob­ ability of 0.05). The attractant by date interaction was highly signtficant at the 0.01 level of probabi lity (Table 18). 60

TABLE 17

Mean Catches of- Male D. cri stata on Date by Attractant Interaction in a Big Bluestem Grass Plot near Brookings, SO, 1984. Means are Based on 4 Repl ications.

Dates of ResEonse Freguencies Collecti on Eugenol Isoeugenol Methoxy Unbai ted Traps Acetate

August 5 66.7 7.5 43. 5 2.2

6 45 .2 5.0 35 .5 2.2

7 6.2 0.5 2.2 0.2

8 8.2 0 6. 7 0.2

9 36.5 0.2 32.0 0.7

10 9.2 0.5 10.5 0.5

11 4.5 1.7 7.0 1. 0

a c b c Means 25.2 2.2 19.6 1.0

Means fo llowed by the same letter were not significantly different at the the 0.05 level of probability (Wal ler-Duncan). Minimum signifi ­ cant difference (MSD) = 4. 8. 61

TABLE 18

Mean Catches of Female D. cr i stata on Date by Attractant Interaction in a Big Bluestem Grass Plot near Brookings , SO, August 1984 . Means are Based on 4 Replications.

Dates of ResEonse Fr�uencies Col lection Eugenol Is oeugenol thoxy Onba1ted Traps Acetate

August 5 59.2 2.7 30.2 0.2

6 46.0 2.7 35.0 2.5

7 7.0 0.2 3.0 0.2 8 16.7 0.2 6. 2 0.2 9 50. 0 1.0 26. 2 1.7 10 9.7 0 8. 2 0.5

11 10.2 1.2 11.0 1.0

a c b Means 28.4 1. 1 17. l 0.9c

Means fol l owed by the same letter were not significantly different (Wall er-Duncan at the 0.05 level of probability). Minimum significant difference (MSD) = 5.1. 62

These data have revea led that eugenol was far mo re attractive to both rna1 es and fema 1 es of D. cri stata than any of the other compounds tested. Two methoxy 4 propylphenol also was more attractive to both · rna1 es and fema 1 es than i soeugenol acetate which was not significantly diffe rent from the unbaited traps.

Experiment with NCR and WCR: Attractancy to Indol e, Eugenol and Two

Anal ogs of Eugenol

Male NCR . The analysis of variance re vealed signifi cant differences at the 0.01 level of probabi lity among attractants. The mean male counts were 14.6, 21.2, 22.7, 86 .5 and 112.8 for indole, isoeugenol acetate , unbai ted sticky trap , 2 methoxy 4 propyl phenol and eugenol , re spectively. Eugenol and 2 methoxy 4 propylphenol were signifi cantly attractive for the male NCR. Isoeugenol acetate and indole, however, were not significantly different from the unbai ted sticky trap

( Wal ler-Duncan at 5% probability ) . The analysis of variance revealed that there was no significant difference between the dates of counting males and the attractant by date interaction.

Female NCR. The analysis of variance re vealed signifi cant differences at the 0.01 level of probability among attractants. The mean female coun ts were 2.2, 4.9, 7.6, 110.0 and 115.2 for indole, unbai ted sticky trap , isoeugenol acetate , 2 methoxy 4 propylphenol and eugenol respecti vely. The eugenol and 2 methoxy 4 propyl phenol bai ted traps were more attract ive to female NCR than to isoeugenol acetate and indole whi ch were not signifi cantly di fferent from the unbaited sticky trap {Wall er-Duncan , at 0.05 probabil ity ) . The analysis of variance 63

also reveal ed that the dates of counti ng females NCR on the sticky traps were highly significant at the 0.01 level of probability. The ove ral l mean female NCR counts on the sticky traps were 18. 3, 28. 6,

41.0, 57.1 and 72.0 for the date of August 22, 23, 25, 24, 26 and

27th respect ively. The average individual date for female NCR counts di ffered ( Waller-Duncan at the 0.05 leve l of probability ) as indicated in Tabl e 19. The attractant by date interaction was highly signifi­ cant at the 0.01 level of probabi lity ( Table 20) .

Male WCR . Table 21 surrunarizes the catch of mal e WCR on the sticky traps bai ted with different lures. An analysis of variance re veal ed no significant differences at the 0.05 leve l of probability among attractants .

Female WCR. The analysis of variance revealed that there were . signi­ fi cant differences among attractants at the 0.01 level of probabi lity.

The mean female counts we re 0.3, 0.3, 0.4, 0.5 and 1. 7 for unba i ted sticky traps , indol e, eugenol , isoeugenol acetate and 2 me thoxy 4 propylphenol respectively. Two me thoxy 4 propylphenol was signifi­ cantly attracti ve fo r female WCR. Eugenol , isoeugenol acetate and indol e attracti veness were not significantly different from that of the unbaited sti cky traps. Table 22 has summa ri zed the mean catches of NCR and WCR on un ­ painted sti cky traps bai ted wi th di ffe rent attractant materials.

Eugenol and 2 methoxy 4 propylphenol we re attractive to both sexes of

NCR, however, 2 methoxy 4 propyl phenol was att�active to only female

WCR. Isoeugenol ·acetate and indol e were not attractive to either NCR or WCR. 64

TABLE 19

Mean Counts of Female NCR at Various Dates on Different Attractants from a Corn Field near Auro ra (Brookings County , SO) August 1984 . Means are Based on 4 Replications.

Dates of Waller-Duncan Collection Counts (P � 0.05)

August 22 18.0 d

23 28. 6 cd

24 57. 15 b 25 41.0 c

26 71.0 a

27 72.0 a

Means fal l owed by the same 1 etter were not s i gni fi cantly di fferent (Wall er-Duncan at the 0.05 -level of probability) . 65

TABLE 20

Mean Catches of Female NCR on Date by Attractant Interaction in a Corn Fi el d near Aurora , 1984. Means are Based on 4 Repl ications.

Response Frequencies Dates of Onba 1ted Collection Eugenol Methoxy Isoeugenol Indole Sti cky Trap Acetate

August 22 38.0 51.2 1.0 0. 2 1.2

23 77.0 63.7 0.5 0.7 1.0 24 146.5 127.2 7.5 2.2 2.2

25 89.2 91.5 13. 5 4.0 6.7 26 163.7 163.7 . 15.2 3.7 9.2

27 177.2 162.7 8.0 2.7 9.2

a a b b Mean 115 .2 1lO.O 7. 6 2.2 4.9b

Means fol l owed by the same letter were not signifi cantly di fferent at · the 0.05 level of probability (Wall er-Duncan). MSD = 34. 73. 66

TABLE 21

Mean Catches of Mal e WCR by Date and Lure Interaction in a Corn Field near Aurora , SO, in August 1984 Means are Based on 4 Repl ications.

Reseonse Freguencies Dates of 2 Methoxy Isoeugenol Unba i ted Col l ection Eugenol 4 Propyl phenol Acetate Indole Trap

August 22 11.0 1.0 4. 7 2.5 4.5

23 6.0 1.0 1.5 2.2 4.2

24 4.0 1.5 1.2 0.7 2.2

25 6.5 0.5 3.0 2.0 3. 5

26 11.7 1..2 5.0 2.7 5.2

27 17.0 3.0 7.0 3.0 7.7

a a a a a Mean 9.3 - 1.3 3. 7 2. 1 4. 5

�\'leans fol l owed by the same letter were not significantly diffe rent (Wa 11er- Dunca·n) at the 0.05 level of probability. 67

TABLE 22

Mean Catche s of NCR and WCR on Unpainted Sticky Traps Baited with Di fferent Attractant Materi als in a Corn Field at Aurora near Brookings, SD (August 22-27, 1984). Means are Based on 4 Replications.

Mean Catches Bait Northern Co rn Ro otwo rm Western Co rn Ro otwonn Materials Male Female Male Female

a a a Eugenol 112.8 115.2 9.3 0.4b a a a Methoxy 86 .5 110.0 1 . 3 1. 7a

Isoeugenol b b a b Acetate 21. 1 7.6 3.7 o . s b b a Indo 1 e 14.6 2.2 2 . 2 0.3b b b a Unbait 22.7 4.9 4.5 0.3b

MSD=48. 42-- MSD=34 . 7 MSD=O. 63

Means fol l owed by the same lette r in the same col umn were not signifi­ cantly diffe rent at the 0.05 level of probability (Waller-Duncan ). 68

DISCUSSION

Color Preference for D. cristata

This study indicated that Q. cri stata did not show any prefer­ ence for yel low col ored sti cky traps. Al though there were no signi­

ficant differences in numbers of adults captured, the total beetle

counts were higher on yel low sti cky traps than on white traps, 690 and

630 beetles , re spectivel y. The total number of beetles counted on the unpainted sticky traps was only 481. The yellow color has been known to be attractive for other species of insects. Broadbent et. al . in

Southwood (1978) found a yel low trap more attractive to aphids than a whi te colored model . To llefson et. al . (1975) reported that yellow was attractive to Di abroti ca spp , and Ladd et. al . (1984 ) found ye llow attractive ·to the NCR. Surpri singly, in this study Q.. cri stata showed no preference for ye llow colored obj ects. Wiesen born and Krysan

(1980} al so found Q. cristata on flowers that were not yel low. In ·

1983 and 1984 , adult Q. cristata were collected in thi s study not only from yel low fl owers but also from weeds such as bindweed and . Pigweed that have non-yellow colored blooms . These observations re veal that

Q. cri stata is not especial ly associated with yel low flowers but this behavior of D. cristata is diffi cult to explain real izing that ye llow is attractive for other species of Diabrotica. The specifi c yel low color or texture of the paint used in this study may not be attractive to Q. cri stata , otherwi se the response of many insects to the yel low color is rather general . 69

Compa ri son of Two Methods of Di spen sing Attractant Lure

The me thod deve 1 oped by Ladd et. a 1. ( 1983) for the NCR, in which the lure was mixed- wi th the Tangle Trap®, captured large numbers of insects in their study so I compared their method of adding lure to the Tangle Trap® with ours in which the lure was applied using a wick.

Sticky traps in this study were renewed daily throughout the period of sampling from July 27 to August 2. Ladd's method was not as desirable in thi s study since the mi xture of lure and Tangle Trap® turned red in color with the oxi dati on of the substrate when exposed to sunlight.

Even though the method of dispensing eugeno 1 from a cotton wi ck attracted fewer D. cristata than exposure by mi xing attractant wi th the Tangle Trap®, the new method was preferab 1 e as preva 1 ent signifi cant differences were observed between treatments. . . The wi ck method also demonstrated an attractiveness of eugenol for D. cristata and required fewer trap re placements.

Attractiveness of the Te sted Compounds to D. cristata, NCR and WCR

Thi s study indicated that the response of Q. cristata to eugenol and to 2 methoxy 4 propyl phenol was similar · to the response of

NCR to the same compounds. Both sexes of the two species, Q. cristata and NCR, were similarly attracted to eugenol and to 2 methoxy 4 propyl phenol . These lures we re extracted from clove or cinnamon , thus confirming early reports regarding the similari ty of adult feeding habits of the two species. Krysan and Branson (1982 ) indicated that 70

NCR and �- cri stata have simi lar adult host plants and that adults of both species feed on the pol len of a great variety of prai rie fo rbs .

Ladd {1984 ) found eugenol , 2 methoxy 4 propyl phenol attracti ve to the

NCR but i soeugenol acetate was not attractive for NCR. . In thi s study simi lar re sults we re obtained wi th eugenol , 2 methoxy 4 propyl phenol and isoeugenol acetate .

There appeared to be · a sex diffe rence with the WCR in the re sponse to 2 methoxy 4 propyl phenol . Only female beetles we re attracted to 2 methoxy 4 propylphenol . Nei ther sex of WCR was attracted to eugenol . Ladd et. al . (1983 ) al so found that the WCR was not attracted to eugenol . Al l three species , Q. cri stata , NCR , and

WCR we re not attracted to isoeugenol acetate or to indole in this study. John An derson ( personal commun ication ) found indole attrac­ tive, howe ver, to WCR in the State of Illinois. His study site, however, had cucurbits planted there in addition to corn . He stated that indole was found to be a vol ati le component of cucurbit fl owers , thus res pons i b 1 e at 1 east in part , for the attractiveness of those flowers to the WCR. It is possible that genetic differences in the pre-adaptation of WCR to indol e may be invol ved within the species and could explain the differences observed in the two states . 71

CHAPTER 5

CONCLUSION

Th is study was undertaken to detennine: (a) the distribution of D. cristata among three grass species : big bluestem, switch grass and brome grass , (b) the types of grasses consumed by both larvae and adults , (c) the egg layi ng preferences of .Q.. cristata fo r the dif­ ferent grass species , and (d) the response of adult beetles to colors and to attractants. The data were statistically analyzed with the analysis of variance and Wal l er-Duncan K ratio t tests. The big bluestem grass p·l ot contained more .Q.. cristata than any of the other examined grasses during both years of 1983 and of 1984 . Very few beetles were col l ected from sticky traps that were placed in switch or brome grass plots. The distributional pattern of D. cristata regard­ ing the emergence of adults from cages placed over big bluestem grass and the col l ection of eggs among grass plots indicates that the big bl uestem grass is a host for the larval stages of this insect. Females must lay eggs in or near the s1tes that provide food fo r larvae after the eggs have hatched. The height of the trap ,plays an important rol e in the numbers of beetles captured. Severa l other factors should also be taken into account such as the wind speed during the sampling time and the color of the traps . Since sensori al and biological di fferences occur among insects , one needs to determi ne the response of the speci fi-e insect to different co lors. 72

In the laboratory tests , thi s study showed that lumpy soil was a preferable ovipositional medium fo r females of D. cristata. The mean longevity of both male and female D. cristata according to the col l ection date was 22.5 days.

This study al so revealed differences among the three species in their re spon se to the materials tested. Eugenol and 2 methoxy 4 propyl phenol were cl earl y attractive fo r both sexes of NCR and of D. cristata. Female WCR were attracted to 2 methoxy 4 propylphenol .

Indole and isoeugenol acetate, however, attracted none of the 3 above species . The findings in this study empha size the simi lar adult feeding behavior of the NCR with Q. cristata . Further study, however, needs to be done in order to draw some defi nitive concl usions regard­ ing the host plants of D. cri stata , and thei r relationshi.P wi th the

NCR corn pests. 73

LITERATURE CITED

Apple, J.W. 1971. Ga ins from the use of Carbofuran fo r Northern corn rootworm control . Proc. N. Cent. Br. En tomol . Soc. Am. ' 26 :26-27.

Atyeo , W.T. , Weekman , G. T. , and D. E. Lawson . 1964. The identifi cation of Diabrotica species by Chorion sculpturing. J. Kansas Entomol . Soc. 37 :9-11.

Ball, H.J. and G.T. Weekman . 1962. Insecticide resis tance in the adult western corn rootworm in Nebraska. J. Econ . Entomol . 55 :439-41.

Ball, H.J. 1973. Western corn rootworm: A ten year study of potenti al res istance to diazinon and phorate in Nebraska . J. Econ � Entomol . 66: 1015-1018.

Bartelt, R.J. and H.C. Chiang. 1977. Field studies invol ving the sex attractant pheromones of the western and northern corn rootworm beetles . Environ . Entomol . 6:853-861.

Bergman , M.K. , Tol l efson , J.J. , and P.N. Hinz. 1981. Sampling scheme fo r estimating populations of corn rootworm larvae. Envi ron . Entomol . 10: 986-990.

Bi gger, J.H. 1932 . Short rotation fai ls to prevent attack of Di abrotica longi cornis Say . J. Econ. Entomol . 25 : 196-99.

Branson , T.F. and E.E. Ortman . 1967. Host range of larvae of the we stern corn rootworm. J. Econ . Entomol . 60: 201-203 .

Branson , T. F. and E.E. Ortman. 1970 . The host range of larvae of the we stern corn rootworm: further studies. J. Econ . Entomol . 63: 800-803. Branson , T. F. and E.E. Ortman . 1971. Host range of larvae of the northern corn rootworm: further studies. J. Kan sas Entomol . Soc. 44:50-52. Branson , T. F. and R.D. John son . 1973. Adult western corn rootworms : ovi position , fecundity and longevity in the laboratory. J. Econ . Entomol . 66:417-418.

Branson, T. F. , Guss , P. L. , Krysan , J.L. , and G.R. Sutter . . 1975 . Corn rootworms : laboratory rea ring and manipulation . Agricul . Res. Results. N.C. U.S. Dept . Agric. , p. 1-17. 74

Branson , T. F. , Sutter, G. R. , and J.R. Fi sher. 1980 . Plant response to stress induced by arti ficial infes tations of western corn rootworm. Envi ron . Entomol . 9:253-257.

Branson , T.F. and J.L. Krysan. 1981. Feeding and oviposition behavior and life cycle strategies of Diabrotica : an evoluti onary view with impl ications for pest management. Envi ron . · Entomol . 10 :826-831.

Burkhardt , C.C. 1972. Insect pests of corn . In Pfadt (ed) Fundamenta ls of applied entomology . MacMi llan Publ ishing Co . , Inc. , New York. p. 798 .

Chiang, H. C. 1973. Bionomics of the northern and western corn rootworms . Ann . Rev. Entomol . 18:47-72.

Chiang , H�C. , French , L.K. , and D.E. Rasmussen. 1980 . Quantitati ve rel ationship between western corn rootworm population and corn yield. J. Econ . Entomol. 73: 665-666 .

Chi ttenden , F.H. 1902. Some. insects injurious to vegetabl e crops. U.S. Dept. AGri c. Di v. Entomol . Bull. No . 33, New Ser. 117 p.

Do uglas , J.R. 1929. Chrysomelidae of Kansas. J. Kansas Entomol . Soc. 2:2-14.

Foster, R. E. , Ruesink, W.G. , and W.H. Luckmann. 1979 . Northern corn rootworm egg sampling. J. Econ . Entomol . 72 � 659-663.

Fo ste r, R.E. , Tollefson , J.J. and K. L. Steffey. 1982. Sequential sampl ing plans for adul t corn rootworm (Coleoptera : Chrysomel idea). Econ . Entomol . 72 : 659-663.

Goul d, G.E. 1971. The corn rootworm problem in Indiana. Proc. Ind. Acad. Sci . 80: 267-27 3.

Green , G.L. 1970. Seasonal occurrence of chrysomelidae in a native prairie near Manhattan, Kansas . J. Kans. Entomol . Soc. 43:95-101. Guss, P.L. and J.L. Krysan . 1972. Esterases and the identiffcation of lipases from eggs of Diabrotica undecimpunctata howardi and virgi fe ra . J. Insect . Phys1ol . 18:1181-1195.

Guss, P. L. , Branson , T.F. , and J.L . Krysan . 1976 . Adaptation of a dry diet for adults of the western corn rootworm. J. Econ . Entomol . 69: 503-505. 75

Guss, P.L. , Carney, R. L. , Sonnet , P.E. , and J.H. Tuml inson. 1983. Stereospecific sex attractant for Diabrotica cristata ( Harri s ) ( Co 1 eoptera : Ch ry some1 i dae ) . En vi ron . Entomo 1. 12:1296-1297. Hami lton, E.W. 1972 . _ Pol len substitute a.nd honey in diet fo r Diabrotica. J. Econ. Entomol . 52(2):473-474.

Harris, T. 1837. North American coleoptera . Trans. Hartford Nat. Hist. Soc. 1:65-91.

Hein, G. L. and J.J. To llefson . 1984. Compari son of adult corn rootworm ( Col eoptera : Chrysomelidae) trapping techniques as populations esti mators. Environ. Entomol . 13: 266-271.

Hill, R. E. , Hixon , E. E. , and M.H. Muma. 1948. Corn rootworm control tests with benzene hexachloride, DDT, nitrogen fe rti lizers and crop rotations. J. Econ . Entomol . 41:392-401.

Hi ll, R.E. 1975. Mating, ovi position patterns, fecundity and longevity of the western corn rootwonm. J. Econ. Entomol . . 68:31 1-315.

Hills, T.M. and D. C. Peters . 1971. A method of evaluating post planting insecticide treatments for control of western corn rootworm larvae. J. Econ . Entomol . 64 : 764-765.

Hooten , R.S. 1979. Egg hatching patterns for individual western corn rootworm females. M.S. Thesis. South Dakota State Un iv. 58 pp ..

Howe , w·.L. , Ortman , E. E. , and B.W. George. 1963. Observations of the northern and western corn rootworms in South Dakota. Proc. N. C. Branch Entomol . Soc. Am. 18:83. Howe , W.L. and J.T. Shaw. 1972. Soil sampling techniques for esti mating rootwonn egg populations. Proc. N. C. Branch. Entomol . Soc. Am. 27: 123-127.

Kantack, B. H. , Wal genbach, D. , and W.L. Berndt . 1977. Corn rootworm control in South Dakota. Cooperati ve Extension Servi ce . USDA F.S. 491 (Revised). Ki rk, V.M. , Cal kins, C.O. , and F.J. Post. 1968. Oviposition preferences of western corn rootwonns for various sci 1 surface conditions. ·J. Econ. Entomol . 61(5): 1322-4.

Ki rk, V.M. and E.U. Bal sbaugh , Jr. 1975. A list of beetles of South Dakota . SDSU Agri . Exp. Stn. Tech. Bul l. 42 , 139 pp. _ 76

Krysan , J.L. , Smith, R. F. , Branson , T. F. , and P.L. Guss. 1980. Anew subspecies of Dia brotica virgi fe ra (Coleoptera : Chrysomel idae): description , spec1es d1stribution ; and sexual compatibility. Ann . Entomol . Soc. Am. 73: 123- 130.

Krysan , J.L. 1982 . Di apause in the Nearctic species of the virgifera group of Diabrotica : evidence fo r tropical ori gin and temperate adaptations. Ann . Entornol . Soc. Am. 75 : 136- 142 .

Krysan , J.L. and T. F. Branson. 1982 . Biology, ecol ogy and di stri bution of Diabrotica. Proceedings international maize vi rus disease colloqui um and wo rkshop. Wooste r, Ohio. (In press. )

Krysan , J.L. , Smi th , R. F. , and P.L. Guss . 1983. Diabrotica barberi (Coleoptera : · Chrysomel idae ) elevated to species rank based on behavi or, habitat choice, morphometries , and geographical variation of color. Ann. Entomol . Soc. Am. 76 : 197-204.

Ladd, T. L. , Stinner, B. R. , and H.R. Krueger. 1983. Eugenol , a new attractant for the northern corn rootwo nn (Coleoptera : Chrys­ omelidae). J. Econ . Entomol . 76 : 1049-1051.

, Sti nner, B. R. , and H. R. Krueger. 1984. Infl uence of color and ---:height of eugenol baited sticky traps on attractiveness to northern corn rootwonn beetles (Coleoptera : Chrysomelidae). J. Econ. Entomol . 77:652-654.

. 1984. Eugenol -related attractants for the northern corn --rootwonn (Co 1 eoptera : Chrysome1 i dae). J. Econ. Entomo 1. 77 : 339-341.

Le Conte , J. L. 1859. A de scri ption of the insects of North Ameri ca . American Entomol . Vol . II, Henry Sotheran Co . , P. 224.

Lovett , O.L. 1975 . Wisconsin corn rootwo rm survey. Proc. N. Cent. Branch. Entomol . Soc. Am. 30 :30-36 .

Ludwig, K. A� and R. E. Hi ll. 1975 . Comparison of gut contents of adult western and northern corn rootworms in Northeast Nebraska . Environ . Entomol . 4 ( 3 ) :435-438. Mendoza , C.E. and D. C. Peters . 1964. Species differen tiation among mature larvae of Di abrotica undecimpunctata howa rdi , D. virgi fera and· Q. longi cornis. J. Kansas Entomol . Soc. 37: 123-25.

Mi hm , J.A. and H.C. Chiang. 1974. Temperature effects on corn rootworm oviposition . Proc. North. Ce nt. Branch� Entomol . Soc. Am. 29 : 135-7. 77

Rowl ey , W.A. and D.C. Peters . 1972 . Scanning electron mi croscopy of the eggshel l of 4 species of Diabrotica (Coleoptera: Chrysomel idae). An . Entomol . Soc. Aill. 65: 1188-1191.

Shaw, J.T. , Ellis, R.O. , and W.H. Luckmann. 1976 . Apparatus and procedure for extracting corn rootworm eggs from soil. Ill inois Nat. Hi st. Surv. Biol . Notes 96 Sta. Dept RAE .

Singh, Z. and W.L. Howe . 1971. Feeding, longevity and fecundity of the adult western corn rootwo rm fed artificial diets. J. Econ . Entomol . 64 : 1136-1137.

Smi th, R. F. 1966. Di stributional pattern of selected western North Ame rican insects: the di stri bution of Di abrotici tes in western North America. Bull. Entomol . Soc. Ame r. 12 : 108-110.

Smi th, R. F. and J.F. Lawrence . 1967. Cl arifi cation of the status of the type specimens of Dia brotici tes (Coleopte ra , chrysomelidae , Galerucinae ). Un iv. Cal if. Publ . Entomol . 45 , 174 pp.

Steffey, K. L. , Tollefson , J.J. , and P.N. Hinz. 1982 . Sampling plan fo r popul ation esti mation of northern and western corn rootworm adults in Iowa corn fields. Envi ron . Entomol . 11:287-291.

Southwood, T. R. E. 1978. Ecological methods with particular re fe rence to the study of insect .populations. 2nd Ed. Hal sted Press. New York. pp. 524.

Tate , H. D. and O.S. Bare. 1946 . Co rn rootworms. Nebraska Ag . Exp .. Station Bull. 381 :1-12.

To llefson , J.J. , Owens, J.C. , and J.F. Witkowski . 1975 . Infl uence of sti cky trap color and size on catch of corn rootwo rm adults. Proc. N.C . Branch. Entomol . Soc. Am. 30 :83.

Webster, F.M. 1895. On the probable origin, deve lopment and diffusion of North American species of the genus Diabrot ica. J. New York Entomol . Soc. 3:158-166.

Wiesenborn, W. O. and J.L . Krysan. 1980 . A survey for Diabrotica cri stata (Coleoptera : Chrysomelidae ) on re lict pra1ries of Eastern South Dakota and Southwestern Mi nnesota . Proc. S.D. Acad. Sci . 59: 130-137. Wi lcox , J.A. 1972 . Col eopterorum catalogus suppl ementa , Pars . 78. fasc. 2. (Editi seconda ) (Galerucinae , Luperini : Aul acophori na). p. 296-431. 78

Wi tkowski , J.F . , Owens , J.C. , and J.J. Tol l efson. 1975. Di el activi ty and vertical fl ight distribution of adul t western corn rootworms in Iowa corn fields. J . Econ. Entomol . 68:351-2. 79

APPENDIX 80

APPENDIX 1

Weekly Egg Counts of D. cri stata in Three Ovipositional Media, Northern Grain Inse ct Laboratory , Brookings , SD - 1983

Dates of Numbe rs of ETgs Collection Cages Ga uze 80 Mesh So l Lumpy Soil Total

August 18 1 30 30 98 158 2 35 35 100 170 3 28 47 115 190

1 64 90 144 298 August 25 - 2 50 110 130 290 3 57 100 120 277

September 1 1 13 17 130 160 2 16 13 166 195 3 20 23 148 191

Total 313 465 1151 1929 81

APPENDIX 2

Frequencies of Adul t D. cristata on Th ree Different Colors of Sticky Traps in the B1 g Bl uestem Grass Plot in 1984

Dates of ResEonse Freguencies Collection Yellow Wh1te On pa1nted Tota l

July 17 22 51 26 99

July 18 59 48 19 126

July 19 86 86 88 260

July 20 176 212 161 549

July 21 230 136 124 490

July 22 61 55 47 163

July 23 65 57 48 · 170

Total 699 645 513 1857 82

APPENDIX 3

Total Adu lt D. cristata from 9 Sticky Traps Mixed with Attractant in a-Big Bluestem Grass Plot near Brookings , SO. (July 27-August 2, 1984)

Adult Counts Dates of �ugenol Inool e (JnEai teo T·ra2. Total Col l ection �ale �emale Male F'e male �ale F'ema1e Male �ema1e

July 27 498 130 11 3 10 7 519 140

July 28 101 63 2 1 4 0 107 64

July 30 501 309 5 2 12 7 518 318

July 31 672 367 3 4 20 12 695 383 August 1 301 155 2 0 30 15 333 170

August 2 206 124 0 0 3 1 7 237 131

Total 2279 1148 23 10 107 48 2409 1206 83

APPENDIX 4

Total Adult D. cri stata Counts from 9 Sticky Traps Where Attractants Were Wrapped-i n Clieese Cl oth in a Big Bluestem Grass Plot (July 1984 )

Adult Counts Dates of E:ugeno1 Inaole On6a1tea Trap Total Col l ection �ale Female �a le Fe male �a le Female �a le Female

July 26 128 216 45 26 13 5 186 247

July 27 125 135 84 30 18 16 227 181

July 28 92 71 39 19 16 2 147 92

July 30 111 185 108 36 19 13 238 234

July 31 62 211 23 41 1 3 86 255

August 1 46 123 13 11 1 11 60 145

August 2 36 45 7 7 2 5 45 57

Total 600 986 319 170 70 55 989 1211 84

APPENDIX 5

Total Adult D. cristata Counts from 16 Sticky Traps Bai ted with Different Attractants in a Big Bluestem Grass Plot near Brooki ngs , SD, August 1984

Aoult l;ounts Dates of £ugeno1 Isoeugeno1 �etnoxy Cnecl< Total Collection � F R F � F � F � F

August 4 267 237 30 11 174 121 9 1 480 370

August 6 181 184 20 11 142 140 9 10 352 345

August 7 25 128 2 1 9 12 1 1 37 42

August 8 33 67 0 1 27 25 1 1 61 94

August 9 146 200 1 4 128 105 3 7 278 316

August 10 37 39 2 0 42 33 2 2 83 74

August 11 18 41 7 5 28 44 4 4 57 94

Total 707 796 62 33 550 480 29 26 1348 1335 85

APPENDIX 6

Frequencies of the Northern Corn Rootworm Captured on 20 Bai ted Sticky Traps in a Corn Field near Aurora in August of 1984 .

Adult Counts !so- Onba1ted Date of Eugenol Methox Eugenol Indole Trap Total Collection R F � t R F � F' � F � t

August 22 320 152 223 205 51 4 52 1 66 5 712 367

August 23 421 308 332 255 30 2 15 3 30 4 828 572

August 24 458 586 341 509 46 30 22 9 31 9 898 1143

August 25 470 357 364 366 121 54 104 16 144 27 1203 820

August 26 426 655 435 655 153 61 83 15 92 37 1189 1423

August 27 613 709 383 651 110 32 76 11 184 37 1366 1440

Total 2708 2767 2078 2641 511 183 352 55 547 119 6196 5765 86

APPENDIX 7

Frequencies of the Western Corn Rootworm Captured on 20 Baited Sticky Traps in a Corn Field near Aurora in August , 1984

Adult Counts I so- Onba 1ted Date of Eugenol Methoxy Eugenol Indole Trae Total Col l ection � F' R F' � t � F' � t M �

August 22 44 4 4 1 19 0 10 0 18 0 95 5

August 23 24 1 4 - 9 6 2 9 0 17 0 60 12

August 24 16 0 6 9 5 3 3 0 9 1 39 13

August 25 26 0 2 6 12 2 8 1 14 2 62 11

August 26 47 2 5 11 20 4 11 3 . 21 3 104 23

August 27 68 4 12 7 28 2 12 4 31 3 151 20

Total 225 11 33 43 90 13 53 8 110 9 511 84