Group Title: Relationship of resistance in maize (Zea mays L.) to two related species of Pyralidae: Dia traea saccharalis (F.) and Zeadiatraea lineolata (Wlk.) /
Title: Relationship of resistance in maize (Zea mays L.) to two related species of Pyralidae: Dia traea saccharalis (F.) and Zeadiatraea lineolata (Wlk.)
CITATION PDF VIEWER THUMBNAILS PAGE IMAGE ZOOMABLE
Full Citation
STANDARD VIEW MARC VIEW
Permanent Link: http://ufdc.ufl.edu/UF00097736/00001
 Material Information
Title: Relationship of resistance in maize (Zea mays L.) to two related species of Pyralidae: Dia traea saccharalis (F.) and Zeadiatraea lineolata (Wlk.)
Physical Description: 96 leaves : ill. ; 28 cm.
Language: English
Creator: Overman, James Lynn, 1941-
Publication Date: 1970
Copyright Date: 1970
 Subjects
Subject: Corn -- Disease and pest resistance   ( lcsh )
Entomology and Nematology thesis Ph. D
Dissertations, Academic -- Entomology and Nematology -- UF
Genre: bibliography   ( marcgt )
non-fiction   ( marcgt )
 Notes
Thesis: Thesis--University of Florida, 1970.
Bibliography: Includes bibliographical references (leaves 89-94).
Additional Physical Form: Also available on World Wide Web
General Note: Typescript.
General Note: Vita.
Statement of Responsibility: by James Lynn Overman.
 Record Information
Bibliographic ID: UF00097736
Volume ID: VID00001
Source Institution: University of Florida
Holding Location: University of Florida
Rights Management: All rights reserved by the source institution and holding location.
Resource Identifier: alephbibnum - 000414116
oclc - 37711310
notis - ACG1266

Downloads

This item has the following downloads:

PDF ( 3 MBs ) ( PDF )


Full Text































J PRESENTED TO THE GRADUATE CiOUNCIL OFi
THE UNIVERSITY OF FLORIDA
JLFILLMENT OF THE REQUIREMENTS pJo TIM
U L J. O F T q ..... ib, iii h i ...................................
................................................. ..........
........ ...................................


:m mm m m ":::::::


1'
... ... m m .....

...i.I.' ..iiii
iiii iiii iiiii iiiiiiii ii E:



rr E:i .;














ACKIOIILEDGMENlTS


The author wishes to acknowledge his sincere

appreciation to Dr. D.H. Habcck for his guidance and

patience while serving as chairman of his supervisory

committee.

lHe is also grateful to Dr. T.E. Summers,

Dr. H.L. Cromroyv, Dr. L.C. luitert,and Dr. E.S. Horner

for their critical review of this work.

He wishes to acknowledge Dr. S.C. Schankl and

Dr. J.L. Nation for serving on the supervisory committee.

Appreciation is also expressed to Ing. E. Morales

H. and Ing. C. Salas F. for their assistance in

conducting research in Costa Rica.

Special thanks are e::tended to Eliecer and Cccclia

Campos for their hospitalities extended to the author

and his wife during their stay in Costa Rica.

He vould especially like to thank his 'ijfe for her

patience and encouragement.

This investigation was supported by an assistantship

from the Center for Tropical Agriculture, for which the

author is sincerely appreciative.















TABLE OF CONTENTS

Page

ACKNOWLEDGMENTS . . . . . . . . . i i

LIST OF TABLES . . . . . . . . . . .

ABSTRACT . . . . . . . . . ii


INTRODUCTION . . . . . . . . . . 1

LITERATURE REVIEl . . . . . . . . 8

Taxonomic Relationships of Several Corn Borers . 11

Bionomics of Several Borers of Maize . . . 12

Zeadiatraea lineolata . . . . . . 12
Diatraen saccharalis . . . . . . 14
Ostrinia nubilalis . . . . . . . 16

Maize Resistance to Ostrinia nubilalis . . . 17

Effect of plant height and maturity . . . 1
Effect of soil fertility . . . . . 19
Effect of insect behavior . . . . . . 20
Chemical basis of antibiosis . . . . 21

METHODS AND MATERIALS . . . . . . . . 25

Biological Materials . . . . . . . 25

Insect species ........... . 25
Collecting . . . . . . . . . 25
Mai e varieties, lines, and single crosses . 26

Insect-Pearing Techniques . . . . . . 30

Zeadiatraea lineolata . . . . . . 30
Diatraea saccharalis . . . . . . . 30

Resis;:ance in Maize to Diatraea saccharalis . 34

Ovipositional Studies . . . . . . . 35

Experiment 1 . . . . . . . . 35
Experiment 2 . . . . . . . . . 36


iii







Table of Contents, Continued

Antibiosis Studies . .

Experiment 3 . .

Resistance in Maize to Zeadiatraea

Costa Rican field tests in 1967
Experiment 4 . .
Experiment 5 . . . .

Costa Rican field tests in 1968
Experiment 6 . . .
Experiment 7 . .
Experiment . . .

Analysis for 2,4-Dihhyd roxy-7-metho
3-one . . . . . . .

Synthesis of Benzo:,azolinones .

Technique e 1 . . .
Technique 2 .

Standard Curve for 6:1BOA and BOA

Recovery Standards for 6MBOA .

Analysis of Varieties from Experim

RESULTS . . . . . . .

Ovipositional Studies . . .

Diatraca saccharalis . .
Zeadiatraea lineolata . .

Antibiosis . . .

Diatraea saccharalis . . .
Zeadiatraea lineolata . . .

Effect of larvae on plants
Analysis of 6ilBOA . . . .

DIS USSIO . . . . . . .

SUHtlAfY . . . . . . . .

LITERATURE CITED . . . . .

BIOCRAPHIICAL Si'KETCH . . . . .


lineolat


xy-1


e n t s


Page
. . 37

. . . 37

a . . 37

. . . 37
. . . 37
. . . 38

. . . 38
. . . 38
. . . 39
. . . 39


, -benzo


zin-









. .


6 and



. .

. .


I I














LIST OF TABLES

Table Page

1. Pedigree and source of inbred lines,
varieties, and collections of maize tested
in Costa Rica and Florida . .. . . 27

2. Composition of Shorey and Hale's artificial
media and a modification of the diet . 32

3. Composition of artificial medium used by
Hensley and Hammond for rearing the
sugarcane borer larvae. . . . . . 33

4. Distributions of egg masses of D. saccharalis
per hill in Experiment 1 and their fit to
the expected Poisson and negative binomial
models . . . . . . . . . 50

5. Comparisons between means of ovipositional
sites of maize by 1). saccharalis in
Experiments 1 and 2 . . . . . . 51

6. Analysis for homogeneity of variance of
varieties . . . . . . . 55

7. Analysis of variance for eggs, larvae and
pupae, and tunnels for D. saccharalis and
Z. lineolata per maize variety. . . . 56

8. Comparisons between mean number of D. saccharalis
eggs per mass per maize variety in
Experiment 2 . . . . . . . . 57

9. Analysis for correlation of eggs, larvae and
pupae, and tunnels for D. saccharalis and Z.
lineolata. . . . . . . . . . 58

10. Mean number of D. sacchlaralis eggs per mass
and percent of masses laid on different
leaves in Experiment 1. . ... . . 59

11. Distributions of Z. lineojata egg masses per
hill in Experiment 5 and their fit to the
expected Poisson and negative binomial models 61










List of Tables, Continued


Table Page

12 Distributions of Z. lineolata eggs per hill
in Experiment 5 and their fit to the
poisson and negative binomial models. . .62

13 Comparisons between mean number of Z.
lineolata eggs per maize variety in
Experiment 5 . . . . . . . .64

14 Correlation of Z. lineolata egg masses per
hill :ith eggs per hill and with eggs per
mass in E:xperimcents 4 & 5 . . . .65

15 Correlation of Z. lineolata eggs per hill
with tunnels in Experiment 4.... . . . 67

16 Correlation of Z. lineolata larvae pll.s
pupae with eggs per lill in Experiment 4.. 68

17 Comparisons between mean number of Z.
lineolata tunnels per maize variety in
Experiment 4 . . . . . . . 69

18 Comparisons between mean number of .
lineolata tunnels per maize variety
in Experiment 6.. . . . . . . 70

19 Comparisons between mean number of .
lineolata tunnels per maize variety in
Experiment 7 . . . . . . . 71

20 Comparisons between mean number of Z.
lineolata tunnels of maize varieties
in Experiment 5 . . . . . . 72

21 Correlation of Z. lineolata larvae and pupae
with tunnels per hill in Experiment 4 . 73

22 Comparisons between mean number of Z.
lineolata larvae and pupae per mai;:e
variety in Experiment 6. .. . . 7 4

23 Comparisons between mean number of Z.
lineolata larvae and pupae per maize
variety in Experiment 7 . . .75









List of Tables, Continued


Table Page

24 Correlation of Z. lineolata tunnels in
plants of the same hill for
Experiment 5 . . . . . . . 76

25 Location of Z. lincolata tunnels in maize
stalks in Experiment !- . . . . 77

26 Recovery of 6MBOA from maize sample UF9
fortified and unforrified with 61BOA . 80

27 Results of analyses for 6MBOA in varieties
in Experiments 6 & 8S . . . . . 81


vii







Abstract of Dissertation Presented to the Graduate Council
of the University of Florida in Partial Fulfillment
of the Requirements for the Degree of
Doctor of. Philosophy

RELATIONSHIP OF RESISTANCE IN MAIZE
(Z A MAYS I,.) TO TWO RELATED
SPECIES OF PYRALIDAE:
DIATRAEA SACCHARALIS (F.)
AND
Z EA D IAT RAEA L I N E 0 LA T A (ULK.)

b v

James Lynn Overman

June, 1970

Chairman: D.H. Habeck, Ph.D.
Magor Department: Entomology and Nematology

Tests for resistance in S4 varieties of maize to Diatrnea

saccharalis (F.) and 86 varieties of maize to Zeadiatraea

lineolata (11 ) :were conducted respectively in Gainesvil l ,

Florida and Alajuela, Costa Rica. Data were taken on thc

mean number of eggs, egg masses, tunnels, and larvae plus

pupae per variety for both insect species.

lean number of eggs per variety and mean number of eggs

per mass per variety were both good indicators of attractiveness

to oviposition to the two insect species. The ratio of eggs

per mass was independent of the density of egg masses per

plant. The physiological or morphological basis of maize

attractiveness to oviposition was not determined.

Different ovipositional sites on maize (upper leaf sur-

face, lower leaf surface, etc.), for D). saccharalis dif-

fered in nean number of eggs, egg masses and eggs per mass.


V iii








The upper leaf surface along the midrib was the preferred

site.

Mean tunnel and larval counts per variety were correlated

for both species. Tunnel data were a more efficient index

than larval counts. Variety Poey T-66 consistently w'as

rated as most resistant to Z. lineolata. The physiochcmical

mechanism of this resistance was not determined.

Larval feeding of Z. lineolata resulted in an average of

21 cm of tunnel damage per plant. From 12 to 29% of the

plants had tunnels in their ear shanks.

Varieties differed little in their content of 6i1BOA and

all varieties were quite low in comparison to published

reports of varieties resistant to Ostrinia nubilalis (Hubn.).














INTRODUCTION


Corn or maize (Zea mays L.) is an important crop,

both from an historical and current viewpoint, in the

Western Hemisphere. Unfortunately, consumption of this

crop exceeds production in several countries, e.g., Costa

Rica. This disparity has caused concern and prompted the

initiation of several programs to encourage greater pro-

duction through better cultural practices and allocation of

more land to this crop. The primary consideration for most

farmers involves the economics of the crop. Unless high

maize yields can be produced at a profit, such programs

stand little chance of success.

Edaphic, climatic, and biotic factors are all related

to the potential yield of maize for a given environment.

The objectives of the agricultural investigator are to

determine how these factors are related to eacl other and to

crop yield. his studies are directed toward finding v'ays

to manipulate these factors so higher yields can be obtained.

It is important, however, that changes ini the environment be

biologically :ournd both for the present and the future.

The biotic environment involves the interaLction of the

agronomic crop with other biological organisms. This environ-

ment is more complex in the tropics than in temperate zones,










and cultural methods as practiced in the temperate zones

have often proven unsatisfactory when applied indiscrimi-

nately in the tropics. Pesticides are widely used for the

control of many insects in the tropics, and their continual

use has led to the development of insecticidal resistance

in the pests while diminishing populations of beneficial

insects. Thus, many farmers have arrived at the untenable

position of lacking both effective insecticides and biolo-

gical controls to protect their crops. In addition,

chemical controls, when improperly used, can cause acute

effects in non--target organisms. Better methods of insect

control are essential to obtain higher crop yields and

reduction of the effects of ecologically unsound methods of

insect control.

An integrated system, using a maximum of biotic

controls with a minimum of chemicals, is a more desirable

approach. One aspect of biotic control is breeding for

host resistance. The basic flaw in chemical control stens

fro. the use of a static entity, the insecticide, to

ccntrol a dynamic and mobile group of organisms. When not

all of a population is killed by pesticides, a selection

pressure is applied to the genetically variable insect

population. Selection pressure in this system favors

certain insect genotypes, often resulting in the develop-

mcnt of resistance. Biotic control, either by parasites,

predaors, or resistance in the host plant, differs from










chemical control in that selection operates against both

organisms. This interaction often reaches an evolutionary

equilibrium in which neither the host nor its parasite is

eliminated.

Breeding plants for resistance to insects involves

experimental evolution directed toward an increased

advantage for the host plant. Any plant breeding program

such as this necessitates a thorough understanding of the

two organisms; their physiology, behavior, morphology,

and genetics.

The adaptability of any plant species to any specific

environment is partly a function of the individual plant's

ability to develop and reproduce in spite of adverse

environmental factors such as insect attacks. The inter-

action of phytophagous insects with their host plants often

results in a selection pressure on the host plant for those

physicochemical and morphological factors that will permit

the plant to develop normally. The plant breeder may

accelerate the process of selection by intensifying selection

for those qualities he deems important for resistance.

Within a given randomly mating plant population, it

is expected that variance will exist between plants in

their response to insect attack. Plants may also change

in their expression of resistance as they mature. The

observed variance is composed of genetic and environmental

variance and an interaction of the genetic and cnviron-

mental components. In developing resistant varieties, we










are primarily interested in the inherited factors and the

stage or stages of the plant's growth at which selection

should be made.

Genetic advance for plant resistance to insects through

selection may follow the equation Gs=k cr 12 (Allard, 1960).

This refers to selection for a single trait when Gs repre-

sents gain from selection, k represents selection intensity

in standard units, m represents the phenotypic standard

deviation of the population, and h2 represents heritability.

Heritability, in the narrow sense, is the ratio of additive

genetic variance to total variance. Genetic progress

toward resistance is complicated by the great diversity of

insect species and their various developmental stages that

may interact with the host. In addition, there is the

possibility of races developing that are able to attack

resistant crops (Gallun, Deay, and Cartwright, 1961;

Gallun, 1955).

Resistance in plants to a single species of insect

may arise in any or all of three forms; antibiosis,

tolerance, or non-preference. For phytophagous Lepidoptera,

antibiosis and tolerance affect only the larval stage.

Antibiosis is the characteristic of the plant to adversely

affect the insect. Tolerance is a function of tlhe plant's

ability to survive despite insect damage. It does not

adversely affect the insect. Plants may avoid insect

damage by being unattractive for oviposition by the gravid










female moth. Non-preference may involve physicochemical

or morpological characteristics which cause the normal

sites for oviposition on the plant to be rejected or not

identified by the female insect. Thus, for a particular

species of insect, there are usually several factors

contributing to the total resistance of the plant. Each

factor nay be genetically independent, having its own

k, p, and h12 values.

The selection intensity v for any single factor follows

the formula v= 3C\ hen N equals the number of characters

being selected and V equals tle percent of the population

left after selection (Allard, 1960). Assuming equal

selection for two factors (A and B) with 5, of

the popular ion being saved, the selection intensity for

each trait would be equivalent to saving 22X of the

population. Therefor e, the intensity of selection for any

single genetic factor is reduced in proportion to the

number of independent resistance factors involved.

A more complex situation occurs when a plant popula-

tion is being selected for resistance to two or more insect

species. In this case, we may consider several possible

relationships between the resistance factors and the

parasites. Plant resistance to two or more species may be

positively correlated, negatively correlated, or not

correlated. Lack of correlation occurs when the resistance

is comprised of two distinct mechanisms, each of which










affects physiological systems that are peculiar to one of

the species. Selection for resistance in the host plant

to one of the species will not affect the host's relation-

ship to the other species. Positively correlated resis-

tance occurs when selection for resistance to one species

has a similar effect on the host's relationship to the other

species. Positive correlation may be partial or complete,

depending on the degree that the physiological systems in

the different species are affected the same by the

resistant mechanisms of the plant. Negative correlation

occurs wlhie resistance developed to the selecting species

renders the plant susceptible to other species.

Analysis for correlation of resistance to different

insect pests of agronomic crops needs to be investigated

for several reasons. Many closely related species are of

economic importance in the same crop gro.'n in widely

separated geographical areas. Despite quarantine measures,

new insect species are being introduced into agricultural

areas. Know-ledge of the type of resistance correlation in

agronomic hosts of the-se insects vould be of immense

importance in designing breeding programs for resistance.

The objectives of this investigation were to

dcternine some of the in erct iors between maize, Zen

na s L. and two related species of Pvra.lidae; the sugar-

ca o bore a Dia tr.ea s h ralis (i'.), in Florid a nd the.

n otropicnal cornstall: borer, Ze d i traea lin.?olata (l'1k.),










in Costa Rica, Central America. The study involved analysis

of resistance of the same lines of maize from Colombia,

South America, to both species. In addition, investiga-

tions in Florida were carried out on single crosses from

the Midwest which had previously been analyzed for

resistance to the European corn borer, Ostrinia nubilalis

(Hbn.). Zeadiatraea lineolata was also tested against

local varieties from Costa Rica and a collection of lines

from the Rockefeller Foundation in Mexico.














LITERATURE REVIEW


Cross resistance is the capacity of any single genetic

factor in a plant species to contribute to the plant's

resistance to more than one organism (i.e. different

species of insects, fungi, nematodes, etc.) in the biosphere.'

The importance of cross resistance becomes evident upon

consideration of the number and diversity of phytophagous

organisms associated with a plant species in a specific

locality. Among the more important phytophagous organisms

are the insects. Painter (1955) catalogued over 180

species of insects associated with maize in Guatemala,

Central America. Only about half of the species could be

identified by specialists of the different insect groups.

Although not all of these species were of significant

economic importance, the list did include large popula-

tions of several economic pests; Diatraea saccharalis

(Fabr.), Zeadiatraea lineolata (W1 k.), Euxesta major

V.ulp., S.pondio tera frugiperda (Smith), and over 15 species

of Diahroti.a and related genera. In addition, intra-

specific differences exist in many insect species in the

form of races. Each stage of an insect species may also

react differently to a resistant f-ctor ir. a plant species.

Bigger, Snelling. and Blanchard (1941), studying resistance

in nmize to the southern corn rooct:orm (Diahrotica










undecimpuncrata Fabra.), found no correlation between

resistance to larval feeding on roots and leaf injury

by adults. Painter (1955) stressed that resistance is

not developed to aphids, borers, or thrips as a group,

but to individual species.

It is expected that the maximum resistance developed

by a plant species would be toward the insect species most

closely associated with it. To the degree that other

insect species or biotypes differ in their behavior or

physiology, we can expect a lack of correlation of resis-

tance to these other species. Optimal plant resistance

may result from the combination of several factors; one,

a few, or all of which may be correlated to more than

one species. Only when the factors causing the resis-

tance are isolated can judgements be made concerning

cross resistance. Failure to isolate these factors has

led to contradictory results concerning cross resistance

in insects. Huber and Stringfield (1940) found a

correlation b<'.t.Leeu resistance in maize to the cor:n leaf

aphid and the European corn borer. Franklin (1964)

found that susceptibility to the corn leaf aphid and the

European corn borer is not consistent for all hybrids.

Whc.n an individual factor has been isolated, im re

meaningful data have been obtain.r concerning. cross

resistance. Resistance in maize or stall: rot, )ip]odia

zcae (Schw.), the European corn borer, dnd si':A-iirne may










all be correlated. Anderson (1964) found that five inbred

lines with known resistance to stalk rot, and the European

corn borer were much more resistant to the herbicides

simazine and atrazine than were two susceptible lines.

Resistance in the whorls of maize to the first instar

larvae of the European corn borer has been correlated with

a single factor; the concentration of 6-methoxybenzoxazo--

linone (6MBOA), a degradation product of 2, 4-dihydroxy-

7-methoxy-l, 4-benzoxazin-3-one (DIMBOA) (Klun and

Brindley, 1966; Klun and Robinson, 1969). EeMiller and

Pappelis (1965n,b) found correlation of concentrations of

glycosides, including DIMBOA, in maize, with stalk rot

resistance. The fungistatic effects of 6MBOA and its

analogues have been confirmed by several workers

(Wahlroos and Virtanen, 1958; Honkanen and Virtanen, 1960;

Loomis, Beck, and Stauffer, 1957). The aglucones, DIMBOA

and DIBOA (2, 4-dihydro:xy-l, 4-benzoxazin-3-one), and

their glucosides were isolated from maize sap and found

to deto:ify simazine (Roth and Knusli, 1961; Hamilton and

Moreland, 3962). Thus, a single factor, 6M1;OA, has been

shown to have a multifunctional effect, contributing to

the plant's resistance not only to a species of insect,

but also to a fungus and two herbicides.










Ta'i'onomic I~elationship of Several Corn Borers

The probability of a plant factor giving cross

resistance in insects is related to the similarity of

behavior and physiology of the insects involved. The

species of the closely related phytophagous genera,

Diatraea and Zeadiatraea (Lcpidoptera, Pyralidae,

Crambinae), are associated e::tensively with grasses

(Graminae) in the Ucstern Hemisphere. Their host plants

include all of the major food and forage grasses; maize,

Zea mays L.; sugarcane, Saccharum officinarum L.; rice,

Oryza sativa L.; what, Triticum aestivum L. ; sorghum,

Sorghun bicolor L. ; Johnson grass, Sorghum halepensis

Pers.; Grama grass, Tripsacum latifolium Hitch.;

Guatemala grass, Tripsacum laxum Nash.; bamboo, Bambusa

vulgarus Schrad.; and Digitaria horizontalis Wil-ld. (Box,

1935). Several species of Diatraea: P. saccharalis (F.)

and D. zeacolella Dvar; and Zeadiatraea: 7. lineolata

(013k.) and Z. grandiosella Dyar; are of economic importance

on maize (Kevan 1943, 1944; Painter, 1955; Holloway,

Haley, and Loftin, 1928; Metcalf, Flint, and lictcalf, 1962;

Henderson, Bennett, and MlcQueen, 1966). Box (1955)

Created the genus Zeadiatraea with D. lineolata U11k.

as the type specimen, but the two genera are closely

related with no reliable characters apparent by which

Zeadiatraea species can be separated as a group from those

of Diatraea. More distantly related and separated










morphologically is the European corn borer, Ostrinia

nubilalis (Hubn.) (Lepidoptera, Pyralidae, Pyraustinae).

Like species of Zeadiatraea and Diatraea, the European

corn borer is primarily a borer in graminaceous plants.

It has become well adapted to feeding on maize in the USA

and Europe.


Bionomics of Several Borers of Maize

Zeadiatraea lineolata:--Despite the economic

importance of Z. lineolata, little has been published

concerning its bionomics. The borer is almost completely

restricted to maize; however, it has been reared on wheat,

Guatemala grass, sorghum, and teosinte (Euchlaena

me:icana Schrad.) (l:ox, 1951; Painter, 1955). It has

occurred in sugarcane, but this infestation is thought to

be "accidental"; most published reports of its occurrence

in sugarcane are erroneous (Box, 1951). Kevan (1943)

found that larvae, when introduced on the plants, bored

into maize and teosinte but not adlay (Coi: sp.).

lMyers (1935) concluded that the borer is the only well-

studied borer of Diatraea or Zeadiatraea that is

restricted to a cultivated host plant. The borer is

unknown in the wild state as is its host plant maize.

Gravid females oviposit on the uppermost leaves or

on the husk:s of young ears (Kevan, 1943). Maize plants

are attractive for oviposition when they are between

knee- and shoulder-lieight (Painter, 1955). Adults










appear to be most attracted to maize shortly before

tasseling and scarcely at all after the ears are formed.

Females may lay eggs not only on maize, but also on the

sides of plastic containers (Painter, 1955). The number

of eggs deposired per moth in Trinidad ranged from 187

to 448, with an average of 377.5. The average number

of eggs per mass was 8.96 (Kevan, 1944). When two days

old, the eggs develop bright red transverse bands. The

average time from oviposition to eclosion is five days.

Prior to hatching, the black head capsule is apparent

through the chcrion.

Newly hatched larvae feed externally on the

epidermis of the leaves. Other leaf damage consists of

transverse rows of tiny holes caused by the boring of

the larvae in the uhori before the leaves unfold (Keva;,

1944). The larvae feed on the leaves up to the third

instar, at which time they bore into the stall. They

begin tunneling upward and may bore into the shanks of

ears. Burrows are usually continuous, but frequently the

larvae will leave their tunnels and re-enter the stalk

elsewhere (Kevan, 1944). Presence of tunnels is

indicated exteriorly by frass holes in the stalks.

There are from six to eight larval instars; the larval

stage in the laboratory lasts from 22 to 48 days :.'th an

average of 31.2 days (Kevan, 1944). In dry stalks the

larvae enter a resting stage and remain quiescent until










moisture becomes adequate. The duration of the pupal

stage is from 6 to 13 days; the pupal case may or may

not be left behind in the tunnel.

Adult females live from three to five days; males

live approximately three days (Kevan, 1944). Adults

are occasionally found at lights.

Damage to the host plant consists of disruption

of the vascular system by the tunneling in the stem,

loss of ears caused by tunneling in the pith of the

cob and the shank of the ear, breakage of the Lassel due

to a weakened condition of the stalk, and reduction in

overall yield.

Diatraea saccharalis:--Diatraea saccharalis is the

most ubiquitous species of the genera Diatraea and

Zeadiatraea. Its geographic distribution extends from

Louisiana, Texas, and Florida in the United States to

as far south as Buenos Aires Province in Argentina

(Box, 1935). The species has been found infesting over

56 different species of grasses (Box, 1935). It is of

economic importance on several major agronomic grasses;

sugarcane, maize, rice, and sorghum (Bo:, 1935;

Holloway et al., 1928; Painter, 1955; Kevan, 1943).

Oviposition begins at dusk and continues through-

out the night. The eggs may be deposited on either side

of the maize leaf, but usually are placed along the mid-

rib (Painter, 1955). Holloway et al. (1928) found that










the number of eggs per mass varied from 2 to 50 or more.

Kevan (1944) found the mean number of eggs per cluster

in the laboratory to be 10.0.

The eggs are flattened and oval, about 1.16 mm

long by 0.75 mm wide, and are deposited in clusters,

overlapping one another like fish scales. The egg stage

lasts from four to nine days, depending on temperature

(lolloway et al., 1923). One to two days before eclosion,

the black heads of the larvae are visible through the

chorion. The eggs lack transverse red bands but are

white in color when first laid and later take on an orange

cast (Hollouay et al 1928).

Following eclosion the first instar larvae congre-

gate in the whorl of the plant where they feed on patches

of the leaf epidermis. They may burrow through the leaves

of the whorl before the leaves unroll, leaving transverse

rows of holes in the leaves. After the first molt the

larvae may bore into the midrib of the leaves, feed in

the leaf sheath, or bore into the stalk. Larvae usually

do not bore into the stalk until the third instar. Upon

entering the stalk the larvae generally tunnel upward,

filling the tunnel behind them with frass. The shank of

the ears may also be tunneled (Painter, 1955). The number

of instars varies from 3 to 10, depending on the

temperature. Under favorable conditions the larval period

may be as short as 23 days, while for hibernating larvae










it can last up to 262 days (Holloway et al., 1928). In

the USA, the larvae overwinter in the stalks of sugarcane

and maize. The pupal period varies from 6 to 22 days when

subjected to an average temperature of 82.9F (Holloway

et al., 1928).

Ostrinia nubilalis:--The European corn borer had

its origin in Europe, being introduced in the United

States in 1917. Its original hosts in Europe were probably

graminaceous; but the insect is of economic importance on

hops, Humulus _1_i ulus L., and hemp, Cannabis sativa L.,

as veil as maize. Since its introduction into the United

States, the borer has become well adapted to maize and is

a major pest of the crop.

The gravid female begins oviposition within five

days after emergence, and the eggs are laid within two

weeks. The opaque white eggs are deposited in masses with

their edges overlapping. The number of eggs per mass

ranges from a few to over 100. The mo lh, in selecting

ovipositional sites, sho..s a preference for specific parts

of maize pla Lts of a certain height and stage of growth.

The eggs are usually deposited next to the midrib on the

underside of the leaves. Eggs nay also be placed on the

stem, on thel upper surfaces of leaves, on leaf sheaths,

and on ears (Everly, 1959).

The interval between oviposition and eclosion

varies fro:. 5 to 12 days and is related to temperature










(Hawkins and Devitt, 1953). Prior to eclosion the black

head of the developing embryo is visible through the

chorion of the egg.

The first instar larvae feed on the epidermis of

leaves and bore into the leaf sheaths and the leaf whorl.

Newly hatched larvae boring through the unfurled leaves

cause pin-hole damage in the leaves. Tassel buds and

stems are often bored by early instar larvae when the

plant is more mature. In the second and third instars,

the larvae tunnel in the stalks and may enter the base of

ear shanks. The larvae may pass through as many as seven

instars. They overwinter in stalks.

The pupal stage lasts approximately 14 days, and

the adult stage approximately 6.0 days for males and 8.3

days for females (Hawkins and Devitt, 1953).


Maize Resistance to Ostrinia nubilalis

The economic importance of the European corn borer

has engendered a vast amount of research. As early as

1925, a compilation of all known references pertaining to

this species amounted to approximately 900 titles (Wade,

1925). Since then many workers have investigated dif-

ferent aspects of the insect's relationship to maize. They

have shown that analy..is for resistance is a complex

process requiring the partitioning of the various factors;

edaphic, cliati. c, genetic, and biotic; and determination

of how these factors affect resistance. Many of the










concepts developed from these studies are applicable to

studies of other borers.

Effect of plant height and maturity:--Under natural

infestation, the uniformity of oviposition on the different

varieties determines the type of e:x:perimental design and

statistical analysis that can be used. Uniformity of egg

deposition is in part due to several inherent factors in

maize that affect the attractiveness of the plant to the

female moth. These factors are dependent on plant height

and stage of gro: .th (Everly, 1959).

In a study of hybrids, Patch, Holbert, and Everly

(1942) found that the half of the hybrids silking first

vere an average of 3.4 inches taller at the time of moth

flight than the other half. The early silhing varieties

received more eggs and therefore tended to have more

borers. In the early development of the plant, oviposition

is correlated with plant height. During tasseling, the

stage of the plant's development becomes the primary factor

influencing oviposition (Everly, 1959). Jackson and Peters

(1959), comparing brachytic and normal forms of the same

hybrid, found that the stage of the plant's grot.th was more

important than its height in determining infestation.

Everly (1959) concluded that plant height and maturity

are not in themselves the reason for attractiveness of the

plant, but are related to conditions in the plant that











affect attractiveness. The influence of height and stage

of growth on oviposition was found to be best expressed

by a second-degree parabola (Everly, 1959). The popula-

tion of borers in different strains has been predicted,

and based on the multiple regression of borer population

on strain height and silking date. The strains or

varieties that consistently received fewer eggs or had

fewer borers than predicted were classified as resistant

(Patch ct al., 1942).

Effect of soil fertility:--Various environmental

factors (soil fertility, tilth, rainfall, and temperature)

influence oviposition through their effect on factors

related to the plant's height and stage of development

(Everly, 1959). The effects of various plant nutrients

on borer survival in maize have been investigated by

several workers (Franklin, 1964; Taylor, Apple, and Berger,

1952 ; Cannon and Ortega, 1966). In field tests where

plants cerere manually infested, corn borer survival was

better on vigorous plants than on small, nutrient-

deficient plants of the same age (Taylor et al., 1952;

Frankly in, 1964). Borer survival and crop yield were both

higher under manure management than in the control plors

lacking manure. Survival of the first generation larvae

on the susceptible single-cross hybrid was 10-fold greater

at 200ppm of nitrogen than at lOppm, yet survival in the









resistant hybrid was low and not affected by nitrogen

level (Cannon and Ortega, 1966). Feu larvae survived on

plants of either hybrid when they received 2.5ppm or less

of phosphorous. Survival at 10ppm was triple that at 2.5ppm,

but did not improve at concentrations from 20 to SOppm.

Quantitative measurements of feeding damage and tunnels

were equally as effective in determining the effects of

nitrogen and phosphorous on survival. The factors causing

the differences in survival appeared to be operating whenn

the larvae were in the first and second instars.

Effect of insect behavior:--Spatial distribution of

the European corn borer population is due in part to factors

which are independent of the host plant. The behavior of

the insect in its different stages and the insects's

interaction with parasites, predators, and diseases

result in a heterogeneous distribution of the insecL.

Intraspecific interactions of a given stage of the insect

may be density dependent. These interactions also affect

the distribution of the borer (Beall, 1940; bliss, 1953;

McCuire, 1957; Cohen, 1960; Taylor, 1961; Katti and

Gurland, 1962; Waters, 1959; Fisher, 1953).

Field populations of the European corn borer

larvae are rarely, if ever, distributed at random, but

rather show aggregation or grouping of individuals in a

given spatial unit. Aggregation commonly results from

the behavioral characteristic of the moth laying eggs










in masses. This aggregation parameter can be computed

by either of two distribution formulae:k of the negative

binomial, or b of Taylor's power law (Harcourt, 1965;

Taylor, 1961). Based on the degree of aggregation and

the goodness of fit required, the data may be transformed

to make them amenable to analysis of variance.

Statistical analysis of biological data by analysis

of variance is based on the assumed additivity of the data

and the homogeneity of the variance. In addition, the

variance should be independent of the mean. Frequently

these assumptions are not fulfilled by the European corn

borer data, but in many cases the analysis of variance is

sufficiently robust to permit its use. When there is

doubt concerning the data, the k or b values can be used

in selecting the proper transformation technique for the

data (Southwood, 1966).

Chemical basis of antibiosis:--Antibiosis in maize

to the European corn borer is expressed by increased

larval mortality, the inhibition of larval growth, and

the reduction in larval feeding. Larval feeding by

first instar larvae on resistant maize lines causes smaller

and fewer leaf lesions than on susceptible lines (Becl,

1960)

Resistance to larval establishment is correlated with

the concentration of 6-metho:.:yben : o.:azolinone (6MBOA)

(leck, 1957; Klun and Brindley, 1966). Several techniques

were developed for quantitating 6MBOA in maize tissue (Beck









and Stauffer, 1957; Klun and Brindley, 1966; Beck, Kaske,

and Smissman, 1957; Bowman, Beroza, and Klun, 1968). The

6MEOA and related benzo:.azolinones have been isolated

from several graiinaceous plants and also synthesized by

several workers (Wahlroos and Virtanen, 1959; Honkanen

and Virtanen, 1960; Tipton, Klun, Husted, and Pierson,

1967; Gahagan and Mumma, 1967; Smissman, LaPidus, and

Beck, 1957 a,b; Hietala and Wahlroos, 1956).

Beck (1960) found that 6MBOA, when incorporated

into an artificial diet, caused inhibition of larval

growth and reduced feeding. Klun and Erindley (1966)

found resistance in 11 inbred lines to be correlated with

the concentration of 6MBOA. However, when 6MBOA was

placed in diet media containing a vitamin supplement, it

did not have a significant effect on borer development.

In addition, it is doubtful that 6MBOA occurs free in

plant tissue (Uahlroos and Virtanen, 1964). When the

plant tissue is crushed 6MBOA is rapidly released from

its precursors :2, 4-dihydroxy-7-methoxy-l, 4-benzo:xazin-

3-one (DIMBOA) and its glucoside. DIMBOA is found free

in appreciable concentrations in maize (Wahlroos and

Virtanen, 1964).

The biosynthesis of DIMBOA was studied by applica-

tion of isotopically labeled metabolites to mazic seedlings

(Reimainn and Byerrum, 1964). The aromatic ring is

apparently derived from an intermediate in the shikimic acid









pathway. The 0-methyl group is formed from compounds

contributing to the one-carbon pool; such as methionine,

glycine, and glyceric acid. The tvo heterocvclic ring

carbons are derived from carbons 1 and 2 of ribose. The

compound DIMBOA exists as a monoglucoside in the seedlings

of maize and several other graminaceous plants, but the

aglucone is released en;:ymatically when the tissue is

crushed. Since there is a stoichiometric relation between

6MBOA and its precursors (Klun and Brindley, 1966), analysis

for 6MBOA is an indirect measure of its precursors in

plant tissue.

Klun and Brindlcy (1966) suggested that the active

factor is DIMBOA and not 6MBOA. They subsequently found that

DIMBOA inhibited larval development and caused 25%

mortality when incorporated into a diet. The biological

activity was not attenuated by alteration of the vitamin

constituents.

The concentration of DIMBOA is not static through-

out the development of the plant, nor is the concentration

the same in different parts of the plant (Klun and

Robinson, 1969). The levels of DIIBOA are initially very

high in both resistant and susceptible lines, but

decrease rapidly in susceptible lines and somewhat less

in resistant lines. The average level for five inbred

lines, 15-33 inches tall, was highest in the roots,

followed by the stem, whorl, and leaf tissues. Analysis

of the distribution in maize at pollen shedding










indicated that the concentration was highest in the

developing ear and next highest in the stalk. Concentra-

tions were lower in the leaf, sheath and collar, and

tassel portions. The inbred line B49, which is moderately

resistant to the first instar larvae of the second brood,

had higher concentrations of DIMBOA than the other lines.

The sheath and collar tissues are a primary site for the

first instar larvae on more mature maize.

The two other aglucones 2, 4-dihydroxy-l, 4-2H-

benzoxazin-3-one and 2-hydroxy-7mcthoxy-1, 4-2H-

benzoxazin-3-one, have been identified from maize (Tipton

et al., 1967; Gahagan and Humma, 1967). The relationship

of thesc two compounds and their glucosides to plant

resistance has not been investigated.














METHODS AND MATERIALS


Biological Materials

Insect Species:--Determination of species of collected

male moths was made by examination of genitalia. The abdo-

mens were removed from the specimens and immersed in 10% KOH

overnight or in boiling 10% KOH for 20 minutes. The tissue

containing the genitalia was removed from the solution and

placed in 70, alcohol. The genitalia were cleaned of any

adhering tissue; the male genitalia were separated and

mounted in Hover's Modified Berlese Medium on a slide.

Diatraea snccharalis F. in Florida and Zeadiatraea lineolata

(11k.) in Costa Rica were identified by reference to

illustrations of Diatraca and Zeadiatraea sp. genitalia

(Box 1931; Dyar and Heinrich, 1927).

Co]lecting:--Pupae and late-instar larvae of D.

saccharalis collected from sugarcane fields east and south of

Lake Okeechobee, Florida, served as the parent generation for

a laboratory colony at Gainesville, Florida.

One hundred pupae of Z. lineolata were collected from

a maize field at the Finca La Pacifica in Guanacaste,

Costa Rica. Emerging adults were allowed to mate at










random and their egg masses collected for infesting maize

in field experiments in Alajuela, Costa Rica.

Maise varieties, lines, and single crosses:--Inbred

lines and varieties of maize were obtained from Dr. Dale

Harpstcad of the Rockefeller Foundation in Colombia and

Dr. E.J. Wellhausen of the Rockefeller Foundation in

Mexico. Several local Costa Rican varieties and a col-

lection of Chirripo varieties from the mountainous region

of Costa Rica were supplied by Ing. Carlos Salas F.,

of the University of Costa Rica. Mr. R.T. Everly of

Purdue University, .'est Lafayette, Indiana, supplied

several single-cross hybrids from the Midwest. The pedigree

and source of the maize samples that were tested are

shoi:n in Table 1, together with a reference number for

each entry.










Table 1. Pedigree and source of inbred lines, varieties,
anc collections of maize tested in Costa Rica and Florida.




Pedigree Source Number


Variety Diacol V. 351
Variety Blanco Comun
Variety Diacol V. 153
Variety Am. Theobromina-lO
Variety Am. Monteria-9
Variety Cuba 362
Variety USA 342
Linea 114-9
Linea Ath. 13B-21 -4-1-4#-1-D
Linea Ath.-198c-I
Variety Focy T-66
Variety Eto Blanco
Variety Eto Amarillo
Variety Rocamex V-520-C
Variety Tico H-1
Variety Tico H-2
Variety E1 Covol
Single Cross A x W23
Single Cross A x Os426
Single Cross 0s420 x A
Single Cross A x Oh02
Single Cross Tr x A
Single Cross L317 x A
Single Cross WF9 x A
Single Cross L317 :: Os426
Single Cross L317 x Oh02
Single Cross L337 x: 1123
Single Cross L317 x WJF9
Single Cross 1.317 x Tr
Single Cross L317 x Os420
Single Cross Oh02 x 0s426
Single Cross Oh02 x W23
Single Cross Oh02 x WF9
Single Cross Oh02 x Tr
Single Cross Oh02 x Os420


Colombia
Colombia
Colombia
Colombia
Colombia
Colombia
Colombia
Colombia
Colombia
Colombia
Costa Rica
Costa Rica
Costa Rica
Costa Rica
Costa Rica
Costa Rica
Costa Rica
Midwest
M idwest
Mi duest
Midwest
Hidwest
Midwe st
Mides t
Mi d we s t
Midues t
Mi dwes t
Midwest
Mi west
Midwest
Midwest
Midwest
Midw:est
Midios t
Mid wes t


- ~---- ------










Table 1, continued


Pedigree Source Number


Single Cross
Single Cross
Single Cross
Single Cross
Single Cross
Single Cross
Single Cross
Single Cross
Single Cross
Single Cross
Collection 83
Collection 15
Collection 26
Collection 20
Collection 43
Collection 8P
Collection 13
Collection 50
Collection 62
Collection 65
Collection 46
Collection 11
Collection 15
Collection 52
Colelction 64
Mich. 166
Ver. 181
S.L.P. Cpo. 1
S.L.P. Cpo. 1
Ver. Gpo. 6
Ver. Gpo. 7
Ver. Guo. 8
Oa Gpo. 5
Ver. 133
Ver. r 43
Ver. 141.
Ver. 165
Ver. 179
Ver. 208
Ver. 215
Ver. 223


0s420 x 0s426
0s420 x W23
0s420 x WF9
0s420 x Tr
0s426 x W23
0s426 x WF9
0s426 >: Tr
Tr x W23
Tr x WF9
W23 x WF9


*Nidwest
Mid we s t
Midwest
Mlidwest
Midwest

Midues t
Miduest


s iidwes t
Coidsta Rica
Costa Rica
Costa Rica
Costa Rica
Costa Rica
Costa Rica
Costa Rica
Costa Rica
Costa Rica
Costa Rica
Costa Rica

Costa Rica
Costa Rica
Costa Rica
Costa Rica

Cexa ico
Hexi co
Mexico
Mex i co
Mexi co
Mexico
Me i co
Mex i co
Mexi co
Mexico
Mexico
Mexico



Mex:i co
Mex i c o











Table 1, continued


Pedigree Source Number


Ver. 225
Ver. 43
Ver. 14
Ver. 8
Ver. 39
Ver. 187
Ver. 168
Ver. 213
Cupurico
Cuba Antibarsan
Tuxpant igua
Tuxp.-Sanvi bag
Tuxp. F.P. (Peru Crist.)
Puerto Rico Cpo. 2
Granada Gpo. 2
J.S.Y.
Saint Croix Gpo. 2
A z t e c -Tu x p.
R. Dom. Gpo. 3
R. Dom. Gpo. 8
Pto. Rico Gpo. 6
Trinidad Gpo. 1 & 2
Sanvi b a
Antigua Gpo. 2
Cuba Gpo. 1
Cuba Gpo. 2
Cuba Cpo. 4
Cuba Gpo. 5
Haiti Cpo. 1
Pto. Rico Gpo. 1
Pto. Rico Gpo. 3
Pto. Rico Gpo. 6
Saint Croix Gpo. 3
San Vicente Gpo. 3
Sta. Lucin Cpo. 1
Tobago Gpo. 1
Guad. Gpo. 1A
Antigua Cpo. 1
Barbados Gpo. 1


Mexico
Mexico

Me >: c o
M e x i c o
Nexico
Ml c> ico
1M e x i C o


.ex. ico
flexico

Mexico

Mex ico
e e x i c o
le :; i c o
M e > i c o





Mexico

M1e >: i c o
i e i co

1 e x i c o




Mexico
lHex i co






Hexico
MI exico
l e: i c 0






Mexico
M e x i c o
e x i c o


Mie x: i c o
Se>x i C o


Mex i c o
Mexico
Me x i co

e:.: ico
lex i c o
Me:x i C o


77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115


-- -- --










Insect-Rearing Techniques

Zeadietraea lineolata:--Emerging adults from field-

collected pupae were placed in gallon jars lined with

waxed paper. Crumpled waxed paper was placed in the jars

and the tops were covered with waxed paper. Moistened

cotton balls were placed in the jars to prevent dessica-

tion. The jars were kept at room temperature. Following

oviposition, the areas of paper containing egg masses were

cut out and kept in petri dishes lined with moist paper

toweling until a short time before hatching. The eggs

in each mass were counted and placed in the whorls of

maize plants that were to be tested for resistance.

Diatraea oaccharalis:--Ovipositional chambers were

prepared from gallon pasteboaid jie cream cartons. The

bottom of each container was covered with moist vermiculite

and the inside walls lined with waxed paper or green paper

toweling. Folded waxed paper or toweling was placed in

the chamber to provide additional surface for oviposition.

The container was covered with a single layer of cheese-

cloth secured with rubber bands.

Newly emerged adults were introduced into the

chamber and allowed to mate at random. The paper lining

and the folded paper were removed periodically and replaced

with fresh paper. Areas of paper containing egg masses

were cut out and placed in petri dishes that had been

lined with damp filter paper and their tops covered with










Alcoa Film (No. 5602). Pinholes were made in the covering

to provide aeration and reduce condensation. Various

sterilants were evaluated for surface sterilizing the egg

masses. Immersion for 30 seconds in 70% ethanol proved

the most effective.

Upon eclosion, one to five first instar larvae were

placed on artificial media in one-ounce clear plastic cups.

The cups were capped and the larvae left until pupation.

Pupae were then removed from the cups, separated according

to sex, and kept in half-pint ice cream containers until

they emerged. Cartons for the pupae were prepared by

covering the bottoms with moist vermiculite to prevent

dessication of the pupae.

Several artificial diets were evaluated for rearing

thb sugarcane borer. The composition of three of these

diets is given in Tables 2 and 3. The Shorcy and Hale

(1965) diet was used during the summer of 1967. Three

generations of borers were reared in the laboratory and

some of the progeny were used for field studies in

Gainesville, Florida. The Shorey and Hale diet was

modified by substituting soaked field corn for pinto

beans. Two generations of borers were reared on tils

diet.

During 1967, Hensley and Haimmond's diet (1968),

which had been used extensively in Louisiana, was used to

rear three generations.










Table 2. Composition of Shorey and Hale's artificial
media and a modification of the diet.


Ingredient

Scaked pinto beans

Soaked corn kernels

Brewer's yeast*

Ascorbic acid*

Methyl p-hydrc:.:ybenzoate

Sorbic acid*

Formaldehyde (40%)

Agar*

Water (Distilled)


Original Diet Modified Diet

640 g ---

--- 640 g

100 g 100 g

10 g 10 g

6 g 6.g

3 g 3 g

6 ml 6 ml

40 g 40 g

1920 ml 1920 nil


*Nutritional Biochemicals Corp., Cleveland, Ohio.


~










Table 3. Composition of artificial medium used by Hensley
and Hammond for rearing the sugarcane borer larvae,




Ingredient Amount

Water 3116 ml

Wesson's salt* 36 g

Casein* 108 g

Sucrose 180 g

Wheat germ* 108 g

Choline chloride'* 3.6 g

Vanderzant's vitamin mixture* 36 g

Ascorbic acid* 5 g

Formaldehyde (401) 5 ml

Methyl p-hydro:;ben zoate 5.4 g

Agn r* 70 g



*NuLtr tional Bic.chemical Corp., C]c veland, Ohio.











All diets were prepared in basically the same manner.

For the Shorey and Hale diet, either dry pinto beans or

corn kernels were soaked overnight and blended in a

Waring blender with half of the amount of water required

by the diet. Formaldehyde solution and other dry

ingredients, except agar, were added to the mi:x:ture while

blending. For Hensley and Hammond's diet the formaldehyde

and other dry ingredients, except the agar, were added

to one half of the total amount of water and blended.

In all cases, the rest of the water was brought

to a full boil and the agar added while stirring. The

agar solution was allowed to cool to about 700C before

blending with the other ingredients.

The Timedia were poured while still hot into one-

ounce clear plastic cups (Premium Plastic, Inc., Chicago,

Ill.). The cups were filled appro::inately half full,

allowed to cool, and capped with plastic-lined cardboard

lids (Smith-Lee Co., Inc., Oneida, N.Y.). The media

were then kept refrigerated until needed.


Resistance in Hlaize to Diatraea saccharalis

A cage 40 feet long, 16 feet wide, and 11 feet high, was

constructed of 20-mesh, 100" Saran insect screen

(Chicopce Hills Ind., New York, N.Y.) with aluminum

supports.











Diatraea saccharalis was used to study the relation-

ship of its host plant maize under a restricted biotic

environment. The bottom of the cage was covered with

crushed rock. The screen was found to appreciably

lower the wind velocity and reduce the light intensity

in the cage.


Ovipositional Studies

Experiment l:--Resistance in single-cross I idwestern

varieties of maize to the sugarcane borer was studied

under caged conditions in Gainesville. Seeds from source

numbers 18-45 (Table 1) were planted in green plastic

pots, 11 inches in diameter and 11 inches high. The pots

were filled with a mixture of 2/3 fumigated Arredondo

fine sand and 1/3 peat moss. The pots were placed ]-1/2

feet apart in the cage. A completely randomized design

was used with each variety represented twice in each

pot and each varietal pot replicated three times.

After the plants had reached an average height of

36 inches extended leaf measurement, 50 male and 50

virgin female adult sugarcane borers were placed in the

cage in ten half-pint ice cream containers and allowed to

emerge at dusk. The release stations were evenly dis-

tributed in the cage with the sexes in separate release

cartons.










Data on the number of eggs, egg masses, and their

location on the plants were taken every other day for a

week following the release. Egg masses were circled

with India ink to prevent recounting the same egg masses.

Forty days after the initial infestation, the plants were

dissected and data taken on the number of tunnels and

larvae per plant. The length of each tunnel was also

recorded.

Experiment 2:--Six Colombian varieties, references

nos. 1-3 and 5-7 (Table 1), were analyzed for resistance

to the sugarcane borer under caged conditions at

Cainesville. The same soil mixture and pots as in the

previous experiment tcre used. Two plants %were grown

per pot and each varietal pot was replicated six times.

The pots were situated in the cage in a Latin Square design.

Thirty virgin females vere placed in half-pint

containers which were used as release sites. Six

release sites containing five females per site were

evenly placed throughout the experimental plot. Thirty

males were placed in six separate release containers in the

cage.

Data were taken for the week on the number of eggs

and egg masses and their location on the plants. After

40 days, the plants were dissected and the number of

tunnels, their length, and the number of surviving larvae

for each plant recorded.









Antibiosis Studies

Experiment 3:--Seven Colombia varieties, reference

nos. 1-7 (Table 1) were planted in plastic pots. The

seven varieties,were grown with one plant per pot and

each variety replicated seven times. A completely

randomized design was used. When the plants averaged

approximately 36 inches in height, each plant was infested

with 10 newly hatched sugarcane borer larvae. After 30

days the plants were dissected and the number of tunnels

and surviving larvae recorded.


Resistance in Maize to Zeadiatraca lineolata

Costa Rican Field Tests in 1967:--Two initial experi-

ments were conducted in the summer, May through August,

1967, at the agronomy farm of the University of Costa Rica

at Alajuela, Costa Rica. The purpose of these experiments

was to survey maize sources for resistance to the

neotropical cornborer, Zeadiatraea lineolata. Maize

sources evaluated were reference nos. 1-16 (Table 1) in

Experiment 4 and nos. 61-115 (Table 1) in Experiment 5.

Borer infestation in the plots came from the natural

population.

Experiment 4 :--The 16 entries were planted five seeds

per hill and later thinned to two plants per hill. The

experimental design consisted of 16 blocks, each having

16 varietal hills of two plants. The hills within each









block were one meter apart and the blocks two meters apart.

Cultiiral methods were under the supervision of Ing. Carlos

Salas F.

During the ovipositional period of the borer, the

number of eggs and egg masses on each plant was recorded.

The height of the tallest extended leaf was measured for

those plants receiving egg masses. At harvest, data

were taken on the number of tunnels, larvae, and pupae

per plant.

Experiment 5:--The 56 entries were planted in six.

randomized blocks. Five seeds were planted per hill and

later thinned to two plants. The hills within blocks

were one meter apart and the blocks were two meters apart.

Measuremencs were recorded of the heights of plants

receiving eggs and the number of eggs and egg masses per

plant. At harvest, data were taken on the number of

tunnels and larvae per plant.

Costa Rican field tests in ]968:--Three experin ents

were conducted during June through August, 1968, at the

agronomy farm of the University of Costa Rica. The purpose

of these experiments was to continue screening of maize

varieties and lines from tests in 1967. In addition, a

collection of Chirripo varieties from Costa Pica was

surveyed for resistance under natural infestation.

Experiment 6:--Eight entries (reference nos. 1,3,6,










11, 15, and 61 in Table 1) were planted one hill. per

variety per block in 16 randomized blocks. Five seeds

were planted per hill and thinned to two plants per hill

when the average height of the plants was 36 inches.

Distances between hills and blocks were the same as in

Experiment 5. The plants were infested by placing 20 eggs

in the black-head stage in the whorl of each plant. At

maturity the plants were dissected and the number of

larvae and tunnels per plant recorded.

Experiment 7:--Twelve entries (references nos. 17,

61, 67, 71, 81, 82, 88, 90, 98, and 109 in Table l)were

planted one hill per variety per replicate in eight

randomized blocks. Distances between hills and blocks

were the same as in Experiment 5. The plants were thinned

to two per hill when their average height was 36 inches.

Twenty eggs in the black-head stage were placed in

the whorl of each plant. When the plants had matured,

they were dissected and the number of tunnels and larvae

recorded.

Exoeriiaent 8:--Fifteen Chirripo varieties referencee

nos. 46-60 in Table 1) were planted in rows one meter

apart and hills within rows one meter apart. Hills were

thinned to two plants per hill. Infestation came from

the natural field population. Data were taken on the

first 10 plants in each varietal row. The number of

tunnels and larvae per plant were recorded.










Analysis for 2, 4-Dihydroxy-7-methoxy-l, 4-benzoxazin-3-one

Two cyclic hydroxamic acids; 2, 4-dihydroxy-7-

methoxy-l, 4-benzoxazin-3-one (DIMBOA) and 2, 4-dihydroxy-

1, 4-2H-benzoxazin-3-one (DIBOA), and their glucosides

have been isolated from maize. No technique has been

developed for directly quantitating these compounds, but

several methods have been developed for quantitating the

degradation products, 6-methoxybenzoxazolinone (6MBOA)

and benzoxazolinone (BOA). The concentrations of 6IIBOA

and BOA are stoichiometrically related to the concentra-

tions of their respective precursors in plant tissue,

thus, the two cyclic hydroxanic acids may be indirectly

quantitated.

Synthesis of Benzoxazolinones

Benzoxazolinone was commercially available from

Distillation Products Industries, Rochester 3, N.Y. The

6-methoxy-benzoxazolinone was not available commercially

and was synthesized by two different techniques.

Technique l:--To 6 & of 5-methoxy-2-nitrosophenol

(Distillation Products Ind.) in 150 ml water in a 250-mi

Erlenmeyer flask, 18 g Na2S204 (Fisher Sci. Co., Fiarlawn,

New Jersey) uere added slowly. The solution was then

heated to 60-65cC for 15 minutes. The solution was

subsequently cooled to room temperature and neutralized

with solid Na2CO3. The neutralized solution was then

extracted with three 50-ml aliquots of diethyl ether.










The ether fraction vas extracted with three 15-ml aliquots

of 4NHC1. The acid fractions, which turned a deep purple,

were combined and evaporated under reduced pressure. The

hydrochloride of 2-amino-5-metho::yphenol was added to an

Erlenmeyer flask along with approximately three grams of

urea. The flask was fitted with an air condenser, placed

in an oil bath, and heated at 1800C for two hours. Following

fusion, the residue was washed with dilute HC1 and the

acid fraction was extracted with diethvl ether. The ether

fraction was evaporated and the residue taken up in hot

water. Activated charcoal was added, the solution stirred,

and the ni::Lture filtered while still hot. Upon cooling,

white needle-like crystals appeared. The charcoal was

washed with diethyl ether, the ether evaporated, and the

residue taken up in hot water. This was filtered and

yielded crystals upon cooling. The two batches of needle-

like crystals were combined and stored in a dessicator

until needed.

Technique 2:--To 10 g of 5-methoxy-2-nitrosophenol

in 200 ml water, 30 g Na2S204 were added slowly with

constant stirring. The solution was heated to 60-650C

for 15 minutes, cooled, neutralized with solid Na2C03,

and extracted with three 100-ml aliquots of diethyl ether.

The ether extracts were combined and evaporated to dryness

under reduced pressure. The crude residue (7.3 g) was

taken up in 200-ml anhydrous ether. Dichloroaicetyl










chloride (Distillation Products Ind.) was dissolved in

anhydrous ether (35-mi of a 10% solution by volume) and

added by drops with constant stirring.

The blue-purple precipitate of 2-amino-5-

methloxyphenol hydrochloride (2.15 g) was filtered. The

precipitate was added to an Erlenmeyer flask along which

0.75 g urea. The flask was fitted to an air condenser

and the mixture was heated at 180C'C for 2 hours. The

residue was washed with dilute HC1 and the remainder

taken up in anhydrous ether. The I1C1 wash was extracted

with diethyl ether and the ether fractions combined and

evaporated. The residue was taken up in a small quantity

of acetone, and hexane was added until the solution

became turbid. The red crystals which appeared were

placed in 50-ml boiling water, a small quantity of

activitated charcoal added, and the solution filtered.

Upon cooling, white needle-like crystals appeared.

Ultraviolet spectra were taken using a Beckman DI

spectrophotometer. Excitation and emission maxima for

fluorescence were determined with an Aminco-Bowman

spectrophotofluorometer (American Instrument Co., Silver

Spring, Maryland). Spectra compared favorably with

published spectra of 6MEOA isolated from maize seedings.

Stardard Curves for 6MBOA and BOA

The 95% ethanol was redistilled before using. The

synthesized 6:MiOA and the LOA were weighed and stock










solutions made up in 95% ethanol. The stock solution of

6MBOA was diluted with 95% ethanol to give concentrations

of 0.025, 0.05, 0.08, 0.1, 0.25, 0.50, 0.80, 1.0, 2.5, 5.0,

8.0, 10.0, 25.0, 50.0, 80,0, and 100.0 ig/ml. The stock

solution of BOA was diluted with 95% ethanol to give

concentrations of 0.1, 0.5, 1.0, 5.0, 3.0, 10.0, 50.0,

80.0, and 100 Jg/!ml.

Fluorescence was measured with an Aminco-Bowman

spectrophotofluorometer equipped with a xenon lamp and

1P21 detector tube; a 1-cm2 cell was used with a slit

program of 3-2-3-3-2-3-3 mm. The relative intensity

of 6MBOA was read with the excitation wavelength of 280 muL

and emission wavelength of 335 mL. The relative intensity

of BOA was read with excitation set at 264 mni and emission

at 327 mp The 95% redistilled ethanol w.as used as a

blank.

Recovery Standards for 6MBOA

The efficiency of the extraction procedure was

determined by fortifying plant samples with 6MBOA and

subjecting the samples to the complete extraction process

used for analysis of 6MBOA.

The Midwestern inbred line WF9 was grown in pots.

When the plants had reached an extended leaf height of

36 inches, the plant whorls were dried and ground in a

Wiley mill. One-gram amnples were placed in 250-ml

round-bottom flasks. The 6MBOA in 95% ethanol or only










the ethanol was added to the flasks to give plant samples

at four different levels of fortification (0, 75, 750, and

1500 ppm). Boiling chips and 150-ml distilled water vere

added to each flask and the flasks fitted with water-

cooled condensers. The flasks were placed on a hot plate

and refluxed for two hours. After extraction, the liquor

was cooled and filtered. The filtrate was brought up to

150-ml with distilled water and then kept refrigerated.

Twenty milliliters of the solution were placed in

a 60-ml separator, funnel and partitioned with three 10-ml

portions of diethyl ether. The ether fractions were

combined and filtered through a plug of 1a2S04 and the

ether was evaporated under reduced pressure.

Alumina columns were prepared for cleaning the

samples. A glass columnn (10 mm ID) was fitted with a

scintered glass disc and 5 g alumina (Fisher Scientific

Corp., no. A-540) were added. The column was washed

with 20-ml 95:' ethanol and the washings were discarded.

The residue from the etler extraction was taken

up in 10-ml 95% ethanol and added to the column. The

receptacle that had contained the residue was rinsed

with an additional 10-ml ethanol and the rinse added to

the column. The material on the column was eluted with

enough 952 ethanol to provide 100-ml effluent. The

effluent was collected in 100-ml volumetric fJ.asks.










The relative intensity of the ethanol solutions \as

determined by spectrophotofluorometry. The ppm of

6MBOA were determined by reference to the standard curve

for 611BOA. The calculated ppm of the unfortified

samples were subtracted from the readings for the fortified

samples to arrive at the level of added 611BOA that was

recovered.

Analysis of Varieties from Experiments 6 and 7

Field plots 6 and 7 in Costa Rica in 1968 were

thinned to two plants per hill when the average height

of the plants vas 36 inches. The cut plants were placed

in bundles according to variety and dried at 30-500C for

3 days. The dried plants were individually ground in a

Wiley mill and the plant material derived from each was

weighed and placed in a plastic bag.

One-gram samples were placed in 250-ml round-

bottom flasks. Several boiling chips and 150-ml distilled

water were added. The flasks were fitted with water-

cooled condensers and heated on a hot plate for two hours

while the mixture reflu::ed. The contents were allowed

to cool to room temperature, filtered through Whatman

no. 1 filter paper on a Buchner funnel, and the filtrate

was brought up to 150-ml with distilled water.

Twenty milliliters of the filtrate were added to a

60-ml separatory funnel and shaken with three 10 -ml

portions of diethyl ether. The ether fraction was










filtered through a prewashed plug of Na2SO4 in a glass

column. Two boiling chips were added to the effluent,

which was then evaporated under reduced pressure.

The residue was taken up in 10-ml 95% ethanol

and added to an alumina column. The flask was rinsed

with another 10-ml ethanol, which was added to the column.

The column was eluted with ethanol to give 100-ml of

effluent.

The 6NBOA content of the effluent was determined

by spectrophotof3 urometry, using the excitation and

emission values already mentioned. The relative intensity

(RI) was recorded and the amount of 6MBOA related to this

RI was read from the standard curve for 61IBOA. The

amount of 6HBOA in the original one-gram sample was

determined by the following formula:

ppm for one-gram sample=6MBOA ( g/ml) X dilution factor/ Ef.

Ef refers to the efficiency of the extracting procedure.















RESULTS


The expression of resistance in maize to Diatraea

saccharalis and Zeadiatraea lineolata results from the

interaction of plant factors with the insect's biology

to reduce the adaptation of the insects to their host

plants. Reduction in adaptation can result from antibiosis

or failure of the moth to oviposit on the plant. Conse-

quently, the analysis for resistance must be designed

to represent the effect of both factors on the insect,

unless from some prior knowledge it is known that one of

them is not significant.

Ovipositional Studies:--The distribution of insects

in an area determines the design and the efficiency of field

tests for resistance. Uneven distribution increases

variance within treatments and necessitates more repli-

cation. Unfortunately, for experimental purposes, insect

distributions are rarely, if ever, evenly distributed.

There are three basic distribution patterns;

regular, random, and aggregated. The regular pattern is

an overdispersed distribution in which the individuals

are not independent. Presence of an individual in a

unit area decreases the probability of finding other

individuals in that area. In the random pattern there is

no interaction of individuals. Each unit area has equal










of having other individuals in that area regardless of

how many are already there. The aggregated pattern is

commonly found among insects. There is a positive inter-

action among individuals. The presence of an individual

in a unit area increases the probability of finding other

individuals in that area.

The analysis of variance is the common test used

to determine if there are significant differences between

neans. This test is based on the assumption of normality,

homogeneity of variances for the treatments, additivity

of the data, and independence of the mean from the

variance. Insect counts seldom describe a normal curve.

Iany insect counts are approximated by the Poisson curve.

In this distribution, the mean is proportional to the

variance. Where the insects are aggregated, the binomial

distribution generally gives a better fit.

Diatraea saccharalis:--Replicated field experiments

with maize in south Florida gave non-significant results due

to the low infestations of the borer. To obtain a larger

insect population, further investigations were conducted in

the screen cage at Gainesville. Investigations under

caged conditions have the advantages of reducing the

effects of certain parasites and predators of D.

saccharalis and restricting the moths' choice of host











plants to those being tested. The screen reduced wind

velocity, evapotranspiration, and light intensity. These

factors probably affected plant growth and perhaps the

behavior of the insects. Whether the cage biased the

effects of only certain plant varieties is not known.

The distribution of egg masses per plant site

in Experiment 1 is given in Table 4. The fit of the

observed distribution to the expected Poisson w'as very

poor. The umderestimation of zero values indicated

that aggregation might be producing the poor fit. The

expected negative binomial distribution reduced the chi-

square value, but the fit was still above the rejection

level.

There were several ovipositional sites on the

plant with the possibility of each site e:x:hibiting a

different distribution. A number of egg masses were

found at the bases of several plants in Experiment 1.

By considering only those egg masses placed on the leaves,

the fit of the distribution was improved to both the

Poisson and negative binomial distributions. By excluding

the egg masses found on the stalks, the category of 5 or

more masses per plant was significantly reduced.

The locations of the egg masses on the plants were

observed and compared (Table 5). Using the criterion of

eggs per mass as an indicator of preferred ovipositional























C, 0
*4 "H


cl C

7. r-







0




PI











0
7-


- C l-






r'. '.0


t-



-r-4





0. r

Lfl 0
E
V1I O


0 .0



u .i-
U H


l C



0
U



C]
-0



c a
C/) C
.q 0






I4 O

0 o





0 0
0.




j0







Cu



-4u-
--C






C-i Ct


1f) o 1 o
-4 cl r-4


+
o H- cM cS N L




































* ci
1~^ C


00


-10


cnc'04


0 CM clCO 0 -q
.-4 t-4 i-


Er1









>
U)







m0
WO
U)







cE







S4
00

U)U)





E E
0) U)




CC C4


U)





*- a
I-.




TO

0
*-1 r


(0 c
co









Q0 0
U) U)



I-)



)l U)


0a0
C0 )
u u

S4-1


U) U)

4-1 4-





0 (
H -



cO a
0 0

) lcrU
CU) En
SE






M M

;4


coo
0*
C-n 1~
C1 L-1


I r-
0r i-


co CN

* *
IT


c~r(


r-I0


-q- - r-r-4 r-l ,-I -
0ao CO c0 0m coco cOo


cn
V)












>
r-

4J.



U) ej
0o







o o

-4-4
r-- ,-1


-4-


La.


U) Yi
CID
ct a
CO ir


U



u u



3 3




-4-14-
0 0








0H 4
p p



0 0



m4







CiJ CO

CO CAr
C 0
0 0,
r- -


U)


Ca


0 -

E
C-C
0
CIO 0



-i r-



*. .H







UI) C,
c.l C,5
w w
0) 0


Cr



>


U) -4
U J


4-4




I-)I-I
OX a






C/ U


Scr,
0 0








o



E E


t cM
M~ r


Uc



-3 4



vi




0
U)3



-40)



-4 O
0



0)

l C'



SE
rU)






w2 >
til
6; U)


--4 r- r -4 rI -4


1 3






















r~j
.j















(-I0O


r\.


i-l -4 r-I Cj In LIn LIn
co Co rI M 0C3 CJi r) C-',


VH i
.0 ri


.A -0
*.-4 .0

Cl


0

0

-4H


.- .







Ct C
01 Cl
U)U
ri C



LF- Lr


C) C)










0 0
r ri







ri
0 0





C) C)











cU W
0. 0


















LL to
CUo LUf
I-z-0 Li


- CM CN C4


I
Clr
rj
>-










sites, the leaf midrib was preferred over the leaf blade.

There was no difference between the upper leaf midrib and

the lower leaf rpidrib. In Experiment 2, the lower leaf

blade was preferred over the upper leaf blade.

Site preference may be exhibited as a difference

in egg masses between sites. In Experiment 1, the leaf

was preferred over the stem. The number of eggs per site

is determined by the number of eggs per mass and the

number of masses per site. Comparisons of total eggs per

site indicated that leaves were preferred over stalks,

upper leaf surfaces were preferred over lower, and the

midrib was preferred over the blade.

A comparison of the different varieties in

Experiment 2 was desired. Using the number of egg masses

per variety as an indicator of attractiveness, the

variance for each variety was determined. The variances

were found to be heterogeneous. Transformation of the

data (Table 6) removed the heterogeneity and permitted

analysis of variance (Table 7). No significant differences

were found between varieties.

Although no significant differences were found

between varieties in the number of egg masses, the

number of eggs per mass might have been different between

varieties. No correlation was found between the number

of eggs per mass and the number of egg masses per plant.










Analysis of variance for differences between varieties in

the number of eggs per mass indicated significant

differences between varieties (Table 7). Comparisons

between varieties by Duncan's multiple range test indicated

Diacol V-153 contained significantly more eggs per mass

than USA 342, Blanco Comun, and Cuba 362 (Table 8).

In Experiment 1, the number of egg masses per plant

was correlated with both the total number of eggs per

plant and the number of egg masses on plants in the same

pot (Table 9). The inajor it y of the eggs (68.6:2) were

placed on leaves 5-7 (Table 10). Several egg masses

were found on the pots.

Diatraea saccharalis in South Florida is adapted

to sugarcane, with other hosts being strictly secondary.

The ovipositional characteristics are adapted to the

dense plant population of sugarcane, a characteristic that

may not be adapted to the more open stands of maize.

Dispersion avay from the site of oviposition is thought

to occur for several reasons. No zero values were found

in the tunnel data from E::periments 1 and 2, as compared

to more than 15', zero values in the egg data. There was

no correlation between the numbers of eggs and tunnels

per plant. Distribution of tunnel data in Experiment 1

was found to approximate a binomial distribution; the chi.-

square value was 7.12 with 7 degrees of freedom. More

than half of the pots, each pot containing two plants,




















U i Cu j U) CO 01 01 En ()

c c c i c_ C c
CCC?) CL") C CC


N CO0

0r-
CO,


CO 0


4N ON


CO %0 10


co COO
r-A


rH--i v-- 3 3 -
v-q H i-Iq


41
C-I
*-4





ct






r3
CL



Ci
rt


CJ


r.3
ci
0 0

I vI
-j 4-J
C E

o o







S4-J 4- --i
Su U-l
1 44
L i -i








44 LA
(U ae
441 4w I
c-l 4






Ci 0 0 rc
I *-l *-H *r-l >






3 o C)( o U

(U



1 U-lU I E-


r-t
























C;
0E







ci

Li

nc
u\


Lr-
C CC


CM
r-- -.
"- -


-*


LI) Vf Lfl



fl ci
CC
O O
-de r-











Uj t,



ci r.
EE

O O

0 0









-4u-I .-





i) C)
4-14-4


d i


0 0


ll r-lI
0 0



*I *I
C-)-1 0.)
v-A v-I --I

rjr rt
> >


C) 'a) Ci




CO tt tO
Cci Cci C0


- -.7 -I Ln Lr) '-,0 0 co


0
C.


1-
















.r4 r4




> O
,re
H *r3





LJ *c




-3


*- C








0j
3 1













> O







Li 3




4-j
Sri
CE







44
0 0



ci Cr


CC










Table 7. Analysis of variance
and tunnels for D. saccharalis
v variety.


for eggs, larvae and pupae,
and Z. lineolat3 per maize


Ex:per i- Da tt
ment No. Analyzed


Diatraea saccharalis


Source
of
V variance


Mean F-
df Square test


2 Egg masses per
va r iety

2 Eggs per mass
per variety

3 Tunnels per
va ri e t y

3 Larvae per
va r i e t y

Zeadiatraca lineolata

4 Eggs per
v a r i e t v a

T Tunnels per
var i e y b

5 Eggs per
va r i e t 3

5 Tunnels per
va r i ety

6 Larvae + pu ae
per variety"

6 Tunnels per
vari e ty

7 Tunnels per
variety

7 Larvae + pupae
per variety

8 Tunnels per
va ri e t

S Larvae -I- pupae


Varieties
Error

Varieties
Er r o r

Varieties


Varieties
Error


Varieties

Varieties
Va r Io t Ic s




Varieties



V a r i e t i e s
Error

Varieties
Error
Varieties
Error

V a r i e t i e s
Varieties
Error

Va r I e t i e s
Varieties
Error


V a rieties


variety Error
aData transformed.
bData corrected for missing values.
cDifference significant of 5% level
eDifference significanL at 1% level


0.079
0.065


5 876.0
183 304.0


11
165

11
156

54
270

5.4
598

7
103

7
103

14
135

14
135

11
77


1 .89
1.69

5.80
2.06



0.51
0.69

12.27
6.38

0.66
0.30

3.22
2.66

5.14
2.40

13.71
4.96

5.86
2 41
2.42
2.42
0.76

6.04
7.81


11 4.64
77 4.17


of probability.
of probability .


1.21


2.88c


1.12


2.33


1.92c


2 2 d
2.24d


1.21


2.1;c


2.76c

d
2.43


3.17d


_ __ ~I~_
__











Table 8. Comparisons between mean number of D. saccharalis
eggs per mass per maize variety in Experiment 2.


Mean No. of Eggs
Per Mass


Diacol V-153


Amarillo Theobromina


Diacol V-351


USA 342


Blanco Comun


Cuba 362


Means of varieties having same letter are not significantly
different at 5% level.


Variety


30.4 a

24 .8 ab

22.9 ab

18.4 b

17.5 b

16.5 b


--





58




Table 9. Analysis for correlation of eggs, larvae and
pupae, and tunnels for D. saccharalis and Z. lineolata.




Experiment No. Data Analyzed df Correlation
Coefficient


Diatraea
saccharalis

3 Larvae per plant with 41 .506a
tunnels per plant

1 Tunnels with larvae 81 .814a

1 Egg masses per plant 163 .497a
with total eggs

1 Egg masses on plants 81 .866a
in same pot

ZeadiaLraea
lineolata

4 Tunnels per plant with 35 .846a
sum of tunnel lengths

4 Tunnels per plant with 35 .098
average of tunnel length

6 Larvae with tunnels 251 .764a

6 6MBOA per variety with 7 .2416
tunnels per variety

6 6MBOA per variety with 7 .512
larvae per variety


correlation at 1' level.


aSignificant










Table 10. Mean number of D. saccharalis eggs per mass
and percent of masses laid on different leaves in
Experiment 1





Leaf No.a Mean Eggs Standard % of Total
Per Mass Deviation Leaf Masses


1 0 0 0

2 20.0 3.6 2.8

3 32.4 17.2 13.3

4 35.9 27.0 7.0

5 29.8 13.3 18.9

6 29.8 19.9 23.1

7 35.3 25.4 26.6

8 50.4 27.2 5.6

9 23.3 9.6 2.8


aLeaves verc numbered from base of plant to top.











received more than 50 eggs per pot, yet this apparently

had little effect on the number of tunnels.


Zeadiatraea lineolata

The data concerning eggs and egg masses per plant

in Experiments 4 and 5 were recorded on two dates during

the peak of the ovipositional period. The distribution of

eggs and egg masses from Experiment 5 (Tables 11 and 12)

gave better fit to Lhe expected Poisson and negative

binomial distributions than did the D. saccharalis data

(Table 4). The number of egg masses per hill showed a

better fit to the negative binomial than the Poisson.

The Poisson distribution consistently underestimated the

number of zero values, thereby suggesting a degree of

aggregation. The negative binomial gave excellent fit

in all cases.

Varietal differences were examined in both experi-

ments. Variances associated with varieties were

sufficiently heterogeneous to require transformation

before analysis of variance could be performed (Table 6).

The transformations removed the heterogeneity so analysis

of variance (Table 7) and Duncan's multiple range test

(Table 13) were applied. Significant differences were

found between varieties in Experiment 5, but not in

Experiment 4.






















ri
"-i





cu










-r- )
CJ
L







,I 0
a
















V) 0
r -4


cJ Ol
0. *i^


















0
EU

















0
o *r
0E C





Jr-
0(
















Ci











oj
C)
J u
Hl C












0 Cl
0G.






J0-
J


0 U



rH )-4
H 0


"- c
*r-l
H!-0


clI H
-. H-


0 r-4 CJ fC) -7


C0 CO n r-4
om. cr ml -
Cl. % rc c'


ci


0OZ


0 7-
*11










r-l


;OJ


ci




















>
. )
C o





0)



c0


r-
0

cr1
1-H
0
O^


-4


-1





LI


















X 0
co





tO
























0 0
&I
Se






















-,

0
E
-'-


a.
x



-*r

1-4
4l





a e


M-l
cr,

Oc 0





0 0
a c


-l4



0c C






00

-u )




U)









0
.0 r




0Jr


C,
JJ
U



r-J
0
Nr W



C)
O



U)
0















0~
cii
T\



cii

ci,







o
0
D.








0
ci -o


















Cr




OJ






0


0.
ci4














O
'
QC
r
>
9
0









cii%
^3












0
1J








Oj
0j
p-






01


*
0
z


62













u O 0 CO ".

n 0 00 CM rC <- 'T
Nc C1( ri r-i










S CN 0" Ln '.0 0
-








U .D) 0 0 Ln U n L
Cl (N N- -










SC 0o o 00 o L Ln
o O %D -n J (NJ
-i





Hn Ltn 0% C%











1O0 Ln- I % r4I %.0


,.Cl f 0 N o









r" 4l -
ar CN 1-4




'- i .o -.7 0 n If
%0 N. C (N H-
O-I




O .I CNJ r4 *n L
oo o m o n in
*




co 3 i r O -i i-i .-
c-r lm CM 1(-1


~ Cr-i ^ ^ -


r(o ~r~- f C 1-
1-1 N r


O r M ^ o r


o










ci
w) rE

do








U)
UC
0


fr


M 0-


C-0 PI r
(MO*
ciJ ii -










In both experiments the number of egg masses per hill

was not correlated with the number of eggs per mass (Table

14). In Experiment 5, the seven varieties rated as having

the most eggs were grouped together, as were the eight

varieties having the least number of eggs (Table 13). The

ratio of number of eggs per plant to masses per plant aver-

aged 1.56+.75 in the first group and 1.09+.27 in the

second group. Differences between means were significant

after analysis according to Snedecor (1956).

Assuming that no non-random errors were made in

counting eggs, the number of eggs received by each plant

should be correlated to the number of tunnels, larvae,

and pupae for each plant of a variety. Analysis for

correlation of eggs with tunnels and larvae plus pupae

was found to be nonsignificant (Tables 15 and 16). This

lack of correlation indicates that factors in addition to

oviposition are important in determining infestation per

plant.

Antibiosis

Diatra:.a saccharalis :--The efficiency of testing for

antibiosis in maize is related to the evenness of insect

dispersal at the time of egg eclosion and the degree of

migration to surrounding plants. To insure that each

plant was exposed to the same number of insects, each plant

in Experiment 3 received tile same number of first instar











Table 13. Comparisons between mean number of Z.
lineolata eggs per maize variety in Experiment 5.



Mean No, Mean No.
of of
Variety Transformed Variety Transformed
Data Data


Granada Gpo.2
Tuxpantiqua
Barbados Gpo.l
S.L.P. Gpo.10
Ver. 187
S.L.P. Gpo.12
Sta.Lucin Gpo.l
Azteca-Tuxp.
St.Croix Gpo.l
Ver. 133
Cuba Gpo.5
Cupurico
Sanribag
St. Croix Gpo.3
Cuba Antibarsan
Pto.Rico Gpo.l
Pto.Rico Gpo.6
Cuba Gpo.1
Oax. Gpo.5
Haiti Gpo.l
Ver.Gpo.7
Ver 168
Tuxp.FF(Peri Crista)
Ver.213
Tuxp.-Sanribag
Pto.Rico Gpo.2
Guad.Cpo.lA
Ver. 39
Cuba Gpo.4


2.44a
2.42ab
2.40abc
2.25abcd
2.25abcd
2.24abcde
2.17abcdef
2.17abcdef
2.15abcdef
2.12abcdef
2.12abcdef
2.10abcdef
2.08abcdef
2.08abcdef
2.06abcdef
2.06abcdef
2.04abcdef
2 .04abcdef
2.02abcdef
1 .98abcdef
1.97abcdef
1 .97abcdef
1.97abcdef
1.95abcdef
1 .95abcdef
1 .95abcdef
1 .94abcdef
1.92abcdef


Ver.181
Antiqua Gpo.l
Cuba Gpo.2
Ve r.Gpo.6
St.Vicente Gpo.3
Ver. 179
Trinidad Gpo.l&2
Antigua.2
Ver.228
R.Dom.Gpo.8
Pto.Rico Gpo.3
Ver 225
Ver. 4 3
J. Y.
R.Dom Gpo.3
Ver.215
Tobago Gpo.1
Ver .Gpo.8
V e r 14
Ver .8
Ver.143
Pto.Rico Gpo.6
Ver .165
Ver .208
Mich.166
Ver.141


1.88abcdefg
1.87abcdefg
1 .85abcdefg
1.77abcdefg
1.73abcdefg
1.72abcdefg
1.72abcdefg
1.72abcdefg
1.70abcdefg
1.70abcdefg
1.70abcdefg
I.69abcdefg
1.69abcdefg
1 .67abcdefg
1 .65abcdefg
1.63abcdefg
1.62abcdefg
1.62abcdefg
1.58 bcdcfg
1.57 cdefg
1.56 cdefg
1.55 defg
1.48 defg
1.40 efg
1.30 fg
1.05 g


1.90abcdefg


Means of varieties having same letter are not significantly
different at 5. level.







65









"V. I .,-
Ul




r-- l U Cr i
*H ,- In ..
c L-i C I + I I







03
44-1
. O C- "-


uCi
CL



-r- C

0 0 l












-i aU u-
r-l I U n r r d rj r




























F 0
,-I j L r-0
















1-r, >- 80 *--. H .
0i

c3
E X

4FJ

u a CJ

l J C o in r
Si i) O in z r'i
uJvLi H H '- N i

c'1 C) Q r l
0




P o




11I c L
14: iH a I-
*C-1 C) '-
o ui o






'r-1 VI








-" CO r(H H H H-i C


r- C) r(
H a


.f Li 1- I1









aC










larvae. Analysis of variance and Duncan's multiple range

test indicated no differences between larval and tunnel

data from the different varieties (Table 7). Larval

counts were significantly correlated with tunnel damage

(Table 9).

Zeadiatraea lineolata:--Tunnel and larvae plus pupae

data from all experiments were tested for homogeneity of

variance to determine if transformation of the data was

required (Table 6). All variances were homogeneous.

Analysis of variance (Table 7) and Duncan's multiple range

test (Tables 17, 18, 19, and 20) were applied to tunnel

data. There were significant differences between varieties

in Experiments 4, 5, 6, and 7, but not in Experiment 8.

The number of tunnels per plant was correlated with the

larvae plus pupae data for most varieties at the time of

plant dissection (Tables 9 and 21).

Analysis of variance (Table 7) and Duncan's multiple

range test (Tables 22 and 23) were applied to the larvae

and pupae data. The number of tunnels per plant was

correlated for plants in the same hill (Table 24). The

number of tunnels per plant was correlated to the sum of

tunnel lengths per plant, but not to the mean length of

tunnels per plant (Table 9). Tunnels were located

throughout the upper portion of the stalk, with 85% of

the tunnels occurring in internodes 3 through 9 (Table 25).










Table 15. Correlation of Z. lineolata eggs per hill with
tunnels in Experiment 4.




Degrees of Correlation
Variety Freedom Coefficient


Diacol V-153

Poey T-66

Diacol V-351

Eto Blanco

Tico H-1

Tico H-2

Blanco Comun

Eto Anarillo

USA 342

Cuba 362

Amarillo Theobromina

Rocamex V-520-C


-0.277 a

+0.522

+0.351 a

+0.078 a

+0.358 a

+0.415 a

+0.311 a

-0.012 a

-0.247 a

-0.312 a

-0.364 a

-0.195 a


a = correlation coefficient not significantly different
from zero at 5% level.










Table 16. Correlation of Z. lineolata larvae plus pupae
with eggs per hill in Experiment 4.




Degrees of Correlation
Variety Freedom Coefficient


Diacol V-153

Poey T-66

Diacol V-351

Eto Blanco

Tico H-1

Tico H-2

Blanco Comun

Eto Amarillo

USA 342

Cuba 362

Amarillo Theobromina

Rocamex V-520-C


-0.251 a

+0.013 a

+0.457 a

-0.116 a

+0.268 a

+0.166 a

+0.386 a

+0.405 a

-0.271 a

+0.129 a

+0.036 a

-0.120 a


a = correlation coefficient
from zero at 5% level.


not significantly different





69

Table 17. Comparisons between mean number of Z. lineolata
tunnels per maize variety in Ex:periment 4.



Mean No. of Tunnels
Variety Per Hill*



Rocamex V-520-C 7.13 a

Amarillo Theobromina 6.94 a

Cuba 362 6.88 a

USA 342 6.75 a

Lto Amarillo 6.50 ab

Blanco Comun 6.31 ab

Tico H-2 5.94 abc

Tico 11-1 5.94 abc

Eto Blanco 5.69 abc

Diacol V-351 5.13 abc

Poev T-66 4.50 be

Diacol V-153 19 c


are not significantly


*leans of varieties having same letter
different at 5': level.











Table 18. Comparisons between mean number of Z.lincolata
tunnels per maize variety in Le:perimen t 6.






Variety MIean No. of Tunnels
Per Hill


lich 166 6.38 a

Cuba 362 5.47 ab

Eto Blanco 5.3 ab

Diacol V-153 5.22 abc

Tico 11-1 i .63 abc

Diacol V-351 i.09 abc

Etio Anarillo 3.91 bc

Pocy T-66 3.56 c



leans of varieties having same letter are not significantly
different at 5% level.









Table 19. Comparisons between mean number of Z.
lineolata tunnels per maize variety in Experiment 7.





Mean No. of Tunnels
Variety Per Plant



Collection 50 3.7 a

Collection 52 3.2 ab

Collection 46 2.9 abc

Collection 26 2.9 abc

Collection 15 2.7 abc

Collection 43 2.6 abc

Collection 62 2.2 abc

Collection 88 2.0 abc

Collection 13 2.0 abc

Collection 20 1.9 bc

Collection 151 1.5 bc

Collection 64 1.5 bc

Collection 83 1.3 c

Collection 65 1.3 c

Collection 11 1.3 c



Means of varieties having same letter are not significantly
different at 5% level.











Table 20. Comparisons between mean number of Z. lineolata
tunnels of maize varieties in Experiment 5.




Mean No. Mean No.
Variety of Tunnels Variety of Tunnels
per Plant per Plant


Granada
Trinidad Cpo. 1&2
Ver. 181
Ver. Cpo. 8
Ver. Gpo. 6
Ver. 208
Ver. 8
Ver. Gpo. 7
Ver. 143
Ver. 187
J.S. Y.
Haita Cpo. 1
Ver. 213
R. Dom. Cpo. 8
Pto Rico Gpo. 3
Azteca-Taxp.
Cuba Cpo. 1
Sta.Lacin Gpo. 1
Tobago Cpo. 1
S.L.P. Gpo. 10
Ver. 225
Ver. 133
Pto.Rico Gpo. 6
Oax.. Cpo. 5
Ver. 14
Ver. 165
Ver. 179
Cupurico


4.17a
3.75ab
3.58abc
3.50abcd
3.50abcd
3.50abcd
3.50abcd
3.33abcde
3.33abcde
3.33abcde
3.33abcde
3.33abcde
3.25abcde
3.17abcde
3.17abcde
3.08abcde
3.08abcde
3.00abcde
3.00abcde
3.00abcde
3.00abcde
2.92abcde
2.83abcde
2.83abcde
2.83abcde
2.75abcde
2.75abcde
2.75abcde


Cuba Antibarsan
Taxp. FF(PeruCrist)
Ver. 215
Cuba Cpo. 4
Saint Croix Cpo.3
Saint Vicente Cpo.2
Pto Rico Cpo.l
Ver. 141
Ver. 228
Ver. 39
Ver. 168
Taxpantigua
S.L.P. Gpo.12
St. Croix GPO.1
Barbados Cpo.l
Cuad. Cpo. 1A
Ver. 43
Antigua Gpo.2
Cuba Cpo. 5
Cuba Cpo. 2
R.Dom.Cpo. 3
Taxp.-Sanribag
Antigua Cpo. 1
Pto.Rico Cpo. 1
Sanribag
Mich. 166


2.75abcde
2.67abcde
2.67abcde
2.58abcde
.50 bcde
2.50 bcde
.50 bcde
.50 bcde
.50 bcde
.50 bcde
.42 bcde
.42 bcde
.42 bcde
.42 bcde
.33 bcde
.33 bcde
.33 bede
.33 bcde
.23 bcde
.23 bcde
.17 bcde
2.17 bcde
.08 bcde
.00 cde
.92 de
.83 e


Means of varieties having same letter are not significantly
different at 5% level.


l









Table 21. Correlation of Z. lineolata larvae and pupae
with tunnels per hill in Experiment 4.




Degrees of Correlation
Variety Freedom Coefficient



Diacol V-153 15 0.727 h

Poey T-66 14 0.727 b

Diacol V-351 14 0.732 h

Eto Blanco 15 0.487 c

Tico 11-1 14 0.606 c

Tico 11-2 15 0.400 a

El.anco Conun 15 0.707 b

Eto Amarillo 13 0 434 a

lISA 342 13 0.457 a

Cuba 362 13 0.386 a

Amarillo Theobromina 15 0.600 c

Rocamc:;. V-520-C 15 0.566 c



a = not significant at 5' level.
b = significant at 1, level.
c = correlation significantly different from zero at 5. level.











Table 22. Comparisons bet)-eern mean number of Z
Sineolata larvae and pupae per maize variety in
E:: periment 6.


Mean No. of Larvae and
Pupae per Hill


V a rie L V


licli 166


Diacol V-153

Cuba 362

Tico H-1

EtAo Elanco

Eto Am arillo

Diacol V-351


Poev T-66


3.75 a

3.63 a

3.50 a

3.13 ab

2.89 ab

2.63 ab

2.50 ab

2.19 b


Means of varieties having same letter are not significantly
different at 5,: level.










Table 23. Comparisons between mean number of Z. lineolata
larvae and pupae per maize variety in Ex;perinen t 7.







Variety HicMan No. of Larvae and
Pupae per Plant



Collection 26 1.8 a

Collection 50 1.5 ab

Collection 88 1.0 abc

Collection 20 0.9 abcd

Collection 62 0.9 abcd

Collection 15 0.9 abcd

Collection 13 0.8 bcd

Collection 52 0.7 bed

Collection 43 0.5 cd

Collection 83 0.4 cd

Collection 65 0. cd

Collection 46 0.4 cd

Collection 151 0.3 cd

Collection 11 0.1 cd

Collection 64 0.0 d



Means of varieties having same letter are not significanLly
different at 5% level.










Table 24. Correlation of Z. lineolata tunnels in plants
of the same hill for E.:periment 5.


Block Degrees of Correlation
Freedom Coefficient



A 53 0.333 a

E 52 0.766 b

C 50 0. 27 b

D 53 0.566 b

E 54 0.588 b

F 5 4 0.608 b



a = Significant correlation at 5 level of probability.
b = Significant correlation at 1 1 level of probability.










Table 25. Location of Z. lineolata tunnels in maize
stalks in Experiment 4.





Internodea No. of % of Tunnel
Tunnels Total Length in
Tunnels CM


1 1 0.4 10.0

2 6 2.3 2.0

3 21 8.1 4.8

4 41 15.8 6.0

5 40 15.4 6.6

6 43 16.6 -6.5

7 32 12.4 5.9

8 23 8.9 6.0

9 22 8.5 5.0

10 9 3.5 4.8

11 10 3.9 4.1

12+ 11 4.3 5.0


aThe higher the number, the higher the internode is on the
stalk.










Effect of larvae on plants:--Larval damage to maize

consisted of leaf damage caused by first instar larvae,

rupture of the stems' vascular systems by tunneling larvae,

broken stems caused by tunnel-veakened stalks, and fallen

ears due to larvae tunneling in the shank of the ears.


The sum of all tunnel lengths per plant averaged

21 cm. A significant percentage of the ear slanks contained

tunnels. In Experiment 4, 9.9; of 303 ears contained

tunnels. Experiments 6, 7, and 8 had 19, 29, and 12',

respectively, of their plants with tunneled ears.

Analysis of 6MBCOA:--Plant samples from Ex:periments 6

and 8 were assayed for their content of 61IBOA. Readings

were compared with a standard curve (Fig. 1). A correction

factor of 80% was computed (Table 26) and used for

correcting plant sample readings. Results of the analysis

are reported in Table 27.

The 6MIBOA content was not correlated with either

tunnel or larval data in Experiment 6 (Table 9). The

analysis of (.IBOA was low for all varieties tested. Due

to technical problems, the dried tissue w.as not assayed

until a year after the plants were cut. The drying process

or storage might have resulted in a loss of activity in

the samples. Further testing is necessary to determine

the validity of the procedure used.







79








o




















00
o
c





c





O.
C:C




o


u 0

LO

- L
o



f-.



-o -



U \
C

.. ,


I I

0 o --
o
*\ ~ d .





80



Table 26. Recovery of 61BOA from maize sample WF9
fortified and unfortified with 6MBOA


6MBOA 6MBOA Added % of added
Added Found 6MBOA 6MBOA
(ppm) (ppm) Recovered Recovered


270

270

330

900

825


750

750


630

555


1500 1230


S82


1500










Table 27. Results of analyses for 611BOA in varieties in
Experiments 6 and 8.





Variety No. Sanples Average ppm
Assayed of HILOA



IIich 166 8 430

Cuba 362 7 570

Tico H-1 7 380

Lto Blanco 7 379

Eto Amarillo 7 420

Diacol V153 7 510

Diacol V351 7 420

El Covol 7 330

J S. 7 600

Tuxp. San vibag 1 330

Ver. 8 1 520

Ver. 187 1 3 0

K. Dom. Gpo. 3 1 750

Ver. 39 1 600

Trinidad Gpo 1 & 2 1 1030

Ver. 41 1 520

Pto. Kico Gpo. 2 1 390

St. Croix Gpo. 3 1 490











DISCUSSION


The proper testing procedures and the determination

of indices of resistance are important considerations in

the analysis for resistance. The interaction of maize

with D. saccharalis and Z. lineolata may result in

ovipositional resistance and resistance to larval survival.

The mean number of eggs per variety and the mean

number of eggs per mass per variety were both good indices

for varietal differences caused by ovipositional attraction.

The eggs per mass ratio were not correlated with the number

of masses per plant. The efficiency of the test could

therefore be improved by considering each mass as a

replicate and using the number of eggs per mass as an

indicator of resistance. Dispersal of egg masses gave a

skewed distribution and resulted in data requiring

transformation prior to analysis of variance. By using

the ratio index, non-normality and heterogeneity of

variance associated with egg mass distribution were

removed. Using this index, Diacol V-153 was found to be

significantly more susceptible to oviposition by D.

saccharalis than USA 342, Blanco comun, and Cuba 362

(Table 8).

The ratio index was tested in Costa Rica on varieties

that had shown differences in mean number of Z.lineolata

eggs per variety. The seven most susceptible varieties










composed Group 1, while the 8 most resistant composed

Group 2. The difference between ratios of the two groups

was significantly different.

The psysiological or morphological basis for

attraction resistance to oviposition by the two species

was not determined. Differences in oviposition sites for

D. saccharalis were shown to result in significant dif-

ferences between the mean number of eggs per site.

Varietal differences relating to differences in site

selection by the insect were not determined

The mean number of eggs per mass is a function of

the moths' behavior. The response of the insect to the

plant factors resulting in deposition of eggs probably

results from an interaction of the genotype with the

environment. The mean number of eggs per mass for Z.

lineolata averaged less than two and is comparable to

that of Z. grandiosella, which averages 3 eggs per mass

(Rolston, 1955). The average number of eggs per mass

found here is not consistent with the nine eggs per mass

reported for the same species by Kevan (1944) in Trinidad.

The heritability and environmental significance of this

difference night prove academically interesting and

economically significant.

Sites of oviposition of D.saccharalis were found

to be comparable to published data concerning sites of

oviposition of Z. grandiosella (Rolston, 1955). Both the










sugarcane borer and the southwestern corn borer showed

a preference for the upper surfaces of the leaves along

the midrib. Both species occasionally oviposit on the

stalk. In contrast, Ostrinia nubilalis oviposited more

than 80" of its eggs on the undersides of the leaves

with only about 5% on the upper surfaces. Less than 27

of the eggs were placed on the stem and leaf sheaths

(Everly, 1959). The importance of site differences in

resistance was difficult to evaluate without knowledge

of the mechanism or mechanisms of resistance to ovi-

position.

Larval counts and tunnel damage in the stalks of

maize are common indices of resistance to any of the

stalk borers. Tunnel counts were found to be correlated

with the sum of tunnel lengths and larval counts per

stalk for both D. saccharalis and Z. lineclata. The

average length of each tunnel was not correlated with

the number of tunnels per stalk.

No significant difference was found between mean

number of tunnels per Colombian variety tested against

the sugarcane borer. In Costa Rica, these same varieties

were found to differ significantly between mean number

of tunnels and larvae per variety for Z. lineolata.

Based on larval survival and tunnel data from

e:-periments conducted under natural infestation of Z.

lineolata and natural infestations supplemented with egg









masses, variety Pocy T-66 consistently was found to have

the greatest degree of resistance. Significant differences

were also found between other varieties.

The location of tunnels caused by Z. lineolata

occurred principally in internodes 3 9. Appreciable

numbers of tunnels, more than 10 :cre found in ear

shanks. Unlike Z.grandiosella, Z.lineolata did not

girdle the stalks. Z. grandiosella occurs mainly in

the lower part of the stalk (Rolston, 1955). Ostrinia

nubi]alia is more frequently found in the upper portion

of the stalk and frequently caused breakage of tassels

(Haw-khins and Devitt, 1953). In cage studies, D.

saccharalis occurred throughout the stall, causing both

tassel damage and broken stalks.

Breeding programs for resistance to D. saccharalis

and Z. lineolata v'ill be more efficient when the

physiological or morphological basis for resistance is

recognized. Identification of the physico:hemical

resistant factors and their location in the plants, and

the development of laboratory techniques for their

idenLification and quantitation iill permit more efficient

selection procedures in breeding programs. Biological

variation and the non-uniform nature of D. saccharalis

and Z. lineolata distributions in the field experiments

reduce the efficiency of field testing.









Varieties from Cost Rica were analyzed for their

content of6HBOA to determine if maize resistance to Z.

lineolata was correlated with concentration of 6MBOA

or its precursors. Varieties differed little in their

content of 6NBOA and all were quite low in comparison with

published reports of varieties resistant to the European

corn borer. No correlation was found between field

resistance as measured by tunnel or larval counts and

average ppm of 6IBOA for 5 7 samples of each variety.

Further analysis of these varieties is needed to verify

the observations. The results obtained so far neither

prove nor disprove any relationship between 6EBOA and

resistance to D. saccharalis or Z. lineolata.

Ability to quantitate resistant factors in the

laboratory would be of great use in the study of cross

resistance of a plant variety to different insects in

different environments.














S U MMA RY


Tests for resistance in 48 varieties of maize to

Diatraea saccharalis (F.) and 86 varieties of maize to

Zeadiatraea lineolata (W11k) were conducted respectively in

Cainesville, Florida, and Alajuela, Costa Rica. Data

were taken on the mean number of eggs, egg masses, tunnels,

and larvae plus pupae per variety for both insect species.

Mean number of eggs and mean number of eggs per mass

were both indicators of resistance in varieties to ovi-

position by the two insects. The number of eggs per

mass was independent of density of masses per plant.

Variety Diacol V-153 had significantly more D. saccharalis

eggs per mass than Cuba 362, USA 342, and Blanco comun.

The physiological or morphological basis of resistance

to oviposition was not known.

Different ovipositional sites on maize for D.

saccharalis differed in mean number of eggs, egg masses

and eggs per mass. The upper leaf along the midrib was

the preferred site.

Mean tunnel anrd larval counts per variety were

correlated for both species. Tunnel data \xre a more

efficient index in that dissection of the plant was not

required. Variety Poey T-66 consistently was rated as










most resistant to 7. lineolata. The physicochemical

mechanism of this resistance was not identified.

Larval feeding of Z. lineolata resulted in an average

of 21 cm of tunnel damage per plant. From 12 to 29%

of the plants had tunnels in their ear shanks.

Varieties differed little in their content of 6MBOA

and all varieties were quite low in comparison with

published reports of varieties resistant to Ostrinia

nubilalis (Hubn.). Further analysis of these varieties

is needed to verify the 6MBOA readings.

Ability to quantitate resistance in the laboratory

would be of great use in the study of resistance of a

plant variety to different species in different environ-

ments.














LITERATURE CITED


Allard, R.W. 1960. Principles of plant breeding.
John Wiley ,L Sons, Inc Ne York. p. 485.

Anderson, R.NI. 1964. Differential response of corn
inbreds to simazine and atrazine. Weeds.
12:60-6 .

Arbuthnot, K.D., P.R. Walton, and J.S. Brooks. 1958.
Reduction of corn yield by first generation
southluestcrn corn borers. J. Econ. Entomol
51:747-749.

l;ca11, C. 1940. The fit and significance of contagious
distributions w.'hen applied to observations on
larval insects. Ecology. 21 :4'60-474.

Deck, S.D. 1957. The European corn borer, Pvrausta
nubilalis (IHubn.), and its principal host plant.
VI Host plant resistance to larval establishment.
J. Insect 'h sijol 1:158-177.

Beck, S.D. 1960. The European corn borer, PFyrausta
nubilalis (Hubn.), and its principal host plant.
VII. Larval feeding behavior and host plant
resistance. Ann. Entomol. Soc. Amer. 53:206-212.

Beck, S.D., E.T. Kaske, and E.E. Smissman. 1957.
Quantitative cstiiation of the resistant factor,
6-mcth o x bench o:x azolinone, in corn plant tissue.
J Agr. Food Chemn. 5:933-935.

Beck, S.D., and J.F. Stauffer. 1957. The Furopean
corn borer, Pyrausta nubilalis (Hubn.), and its
principal host plant. 111. Toxic factors
influencing larval establishment. Ann. Entomol.
Soc. Amer. 50:166-170.

BeMiller, J.HI., and A.J. Pappelis. 1965a. 2,4-Dihydroxy-
7-methoxy-l, 4-benzoxazin-3-one glucoside in corn.
I. Relation of '.ater-soluble, 1-butanol-soluble
glycoside fraction content of pith cores and stalk
rot resistance. Phyvt opa t ho lo _. 55:1237-1240.










Belliller, J.I ., and A.J. Pappelis. 1965b. 2,4-Dihydroxy-
7-metho:;y-1, 4-henzoxazin-3-one glucoside in corn.
II. Isolation of 6-mct.ho:y-2(3)-benzoxazolinone
fraction as a measure of glucoside content.
Phytopathology. 55:1241-124 3.

Digger, J.11., k.O. Selling, and R.A. Blanchard. 1941.
Resistance of corn strains to the southern corn
rootuorm, Diabrotica duodecimpunctata F. J. Econ.
Entonol. 34:605-613.

Bliss, C.I. 1953. Fitting the negative binomial
distribution to biological data. Biometrics.
9:176-200.

bowman, I.C., tl. Beroza, and J.A. Klun. 1968. Spectro-
plhotofluorometric determination of 6-methoxy,'-2-
benzo:.:o olinone, an indicator of resistance to
European corn borer in Zea mays. J. Econ.
Entomol. 61:120-123.

Bo:-:, II.E. 1931. The crambine penern Diatraca and
XantL oplerne (Lep., Pyral.). Bull. En t o ol. Res.
22:1-5.

RBo II.E. 1935. The food plants of Am Perican Diatraca
species. Govt. Printer, Port-of-Spain. p. 11.

Box, It.E. 1951 II species of Diatraca Guild. from
norLhern Venezuela (Lepid. Pral.). Bull. Entomol.
Res. 42:379-398.

Box, 1. E. 1955. Ileu crambine genera allied to Diatraea
Cuilding (Lcpidopter : Py r a id e) III. ,ro .
Entomnol. Soc. Lond. Proc. 24:197-200.

Burkhardt, C.C., and R.ll. Painter. 1954. 'e rigl t differences
in southwestern corn borer larvae, Diatraca
grand iosella Dy ar, reared on teosinte in Kansas in
1952. Kans. Entomol. Soc. J. 27:21-23.

Cannon, U.N., Jr., and A. Ortega C. 1966. Studies of
Ostrinia nubilalis (L e jpid o p tera:Pvraustidae) on
corn plants supplied with various amounts of
nitrogen an.d phosphorus. 1. Survival. Entoimol
Soc. Amer. Ann. 59:631-638.

Cohen, A.C., Jr. 1960. An extension of a truncated Poisson
distribution. Biometrics. 16:446-450.




University of Florida Home Page
© 2004 - 2010 University of Florida George A. Smathers Libraries.
All rights reserved.

Acceptable Use, Copyright, and Disclaimer Statement
Last updated October 10, 2010 - - mvs