I NF OR MAT I ON T O USERS

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I
I
73-5478
ROMERO S . , J o s e I s r a e l , 1 9 3 4 RELATIONSHIPS BETWEEN TARNISHED PLANT BUG
AND ALFALFA PLANT BUG (HEMIPTERA: MIRIDAE)
ON ALFALFA IN MICHIGAN.
M i c h ig a n S t a t e U n i v e r s i t y , P h . D . ,
E n t o m o lo g y

1972

U n iv e rsity M icro film s. A XEROX C o m p a n y , A n n A rb o r, M ic h ig a n

RELATIONSHIPS BETWEEN TARNISHED PLANT BUG
AND ALFALFA PLANT BUG {HEMI PTERA :

Ml Rl DAE)

ON ALFALFA IN MICHIGAN
By
J o s e I . Romero S .

A THESIS

Subm? t t e d t o
Michigan S t a t e U n iv e r s ity
in p a r t i a l f u l f i l l m e n t of th e r e q u ire m e n ts
fo r the degree of
DOCTOR OF PHI LOSOPHY
D e p a r t m e n t o f Entomology
1972

PLEASE NOTE:
Some p a g e s may h a v e
indistinct
Filmed a s

U niversity M icrofilm s,

print.
received.

A X e r o x E d u c a t i o n Company

ABSTRACT
RELATIONSHIPS BETWEEN TARNISHED PLANT BUG
AND ALFALFA PLANT BUG (HEMIPTERA: Ml Rl DAE)
ON ALFALFA I N Ml CHI GAN
By
J o s e I * Romero S.

The p r e s e n t s t u d i e s w e r e c a r r i e d o u t b o t h a t
fie ld conditions,

l a b o r a t o r y and

and were d i r e c t e d a t d e t e r m i n i n g i n t e r s p e c i f i c

c o m p e t i t i o n b e t w e e n t h e mi r i d s t a r n i s h e d p l a n t b u g , Lygus
(Pali sot de B e a u v o is ) , and th e a l f a l f a
11n e o l a t u s

bug, A d e l p h o c o r i s

(Goeze).

The d e v e l o p m e n t a l
for

plant

p e r i o d o f t h e t a r n i s h e d p l a n t b u g was f o l l o w e d

five successive generations

beans as th e h o s t .

in t h e

l a b o r a t o r y u s i n g pods o f green

In tr a s p e c ific competition

in t h e t a r n i s h e d p l a n t

b u g was o b s e r v e d t o b e a c c e n t u a t e d by l a c k o f f o o d ,
h a b i t , a n d i n t e r f e r e n c e by a c c i d e n t a l
alfalfa
in the

cannibalistic

p l a n t bug c o u l d be r e a r e d o n l y d u r i n g t h e p a r e n t a l
laboratory.

subject.

velopmental

generation

there is a diapause

b u t mor e i n v e s t i g a t i o n

in

i s n e e d e d on

I n t e r s p e c i f i c c o m p e t i t i o n between t h e t a r n i s h e d

p l a n t bug a n d a l f a l f a
period,

The

The p r e l i m i n a r y o b s e r v a t i o n s on t h e a l f a l f a

t h e egg s t a g e of t h i s s p e c i e s ,

mental

its

c o n t a c t between them.

p l a n t bug i n t h e l a b o r a t o r y i n d i c a t e s t h a t

this

1i n e o l a r i s

shorter

plant

bug i s shown by t h e l o n g e r d e v e l o p ­

l o n g e v i t y , and h i g h e r v a r i a b i l i t y

of de­

t i m e o f t h e t a r n i s h e d p l a n t b u g when r e a r e d t o g e t h e r

with the a l f a l f a
r e a r e d by i t s e l f .

p l a n t bug t h a n when t h e t a r n i s h e d p l a n t b u g was

Jose I . Romero S.

A w e e k l y s u r v e y by n e t
ferent a lf a lfa

s weep s a m p l i n g was made i n f i v e d i f ­

f i e l d s a n d o b s e r v a t i o n s w e r e made on t h e v a r i o u s

aspects of biology, h a b its ,
plant

behavior, n atu ral

enem ies, and h o s t

r e l a t i o n s h i p s o f b o t h s p e c i e s o f mi r i d s .

o th er than those p re v io u sly

Natural

enemies,

r e p o rte d , were found, but t h e i r presence

h a d n o s i g n i f i c a n t e f f e c t on t h e p o p u l a t i o n d e n s i t i e s o f t h e mi r i d s .
These n a t u r a l

enemies were t h e s p o t t e d

lady-btrd b eetle,

C o l e o m e g i 11 a

m a c u 1a t a D e G e e r , t h e common t o a d , Bu f o a m e r i c a n u s H o l b r o o k ,
fungus

i d e n t i f i e d as

be a p p r o x i m a t e l y

a

Hyphomi c e t e .

and a

The s e x r a t i o was f o u n d t o

1:1 i n t h e t a r n i s h e d p l a n t bug w h i l e t h e f e m a l e s

o u t n u m b e r e d t h e m a l e s o f t h e a l f a l f a p l a n t b u g.
p l a n t bug has a b r o a d e r range of h o s ts

The t a r n i s h e d

than the a l f a l f a

p l a n t bug.

T h e s e t wo mi r i d s a r e f o u n d i n t h e same a l f a l f a p r o d u c i n g a r e a s
o f t h e U n i t e d S t a t e s and occupy s i m i l a r e c o l o g i c a l
alfalfa

fields.

19^0

to

1959

b s

we l l a s i n t h e p r e s e n t

s t u d y show t h a t t h e t a r n i s h e d p l a n t b u g p o p u l a t i o n
t h e numbers o f th e a l f a l f a
m a i n t a i n e d by d i f f e r e n t

tition

in th e

The r e c o r d s o f d i s t r i b u t i o n and a b u n d a n c e o f t h e

two s p e c i e s d u r i n g t h e y e a r s

enemies,

niches

p l a n t bug.

is dominant over

This equilibrium

p a r a m e t e r s f o r t h e two s p e c i e s :

p e r i o d ic c u t t i n g of the a l f a l f a

is probably
the natural

a n d i n t r a s p e c i f i c compe­

p robably being of major importance t o the t a r n i s h e d p l a n t
*

bug; t h e h i g h female t o male sex r a t i o and t h e r e s i s t a n t
o f t h e eg g (Knight

chorion

19*+0 t h a t p e r m i t s o v e r w i n t e r i n g a s e g g s a r e

p r o b a b l y t h e dominant f a c t o r s

in flu en cin g the a l f a l f a p lan t

bug.

Jose I . Rom ero

A c o m p l i c a t i n g f a c t o r i s t h a t t h e a l f a l f a p l a n t bug i s an i n t r o ­
d u c e d s p e c i e s t h a t may n o t h a v e f u l l y a d a p t e d t o i t s
ment.

The t wo s p e c i e s a r e c l o s e l y

niches

in the a l f a l f a

fields.

new e n v i r o n ­

r e l a t e d and do occupy s i m i l a r

They a r e , h o w e v e r ,

differentially

a f f e c t e d by t h e s e d i f f e r e n t p a r a m e t e r s and no d i r e c t

evidence of

i n t e r s p e c i f i c c o m p e t i t i o n b e t w e e n t he m was m e a s u r e d i n t h e f i e l d .

ACKNOWLEDGEMENTS

My s i n c e r e a p p r e c i a t i o n and m o s t g r a t e f u l
t o D r . R o b e r t F. Ruppel

f o r h i s h e l p in s e l e c t i n g t h i s

h i s c o n s t a n t e n c o u r a g e m e n t , and h i s
at all

suggestions,

i n s p i r i n g and f r i e n d l y

guidance

t o Dr . F r e d e r i c k W. S t e h r f o r h i s h e l p f u l

c r i t i c i s m and r e v i e w i n g o f t h e m a n u s c r i p t a n d s e r v i n g

i n my g u i d a n c e c o m m i t t e e .

I w i s h a l s o t o e x p r e s s my t h a n k s t o

E t h e l b e r t C. M a r t i n , a n d J a me s A. W e b s t e r

E n t o m o l o g y ) , a n d Dr .
Science),

F r e d e r i c k W. E l l i o t t

(Department of

( D e p a r t m e n t o f Crop

f o r s e r v i n g a s members o f my g u i d a n c e c o m m i t t e e .

To Dr ,
I

project,

t i m e s a s my m a j o r p r o f e s s o r .

1 am v e r y g r a t e f u l

Drs.

thanks a r e extended

Gordon E.

Guyer, Chairman o f t h e De pa rt m en t o f Entomology,

e x p r e s s my s i n c e r e a p p r e c i a t i o n

for h is personal

encouragement

d u r i n g my s t u d i e s on t h i s Campus.
Thanks a r e a l s o
Michael

e x t e n d e d t o M i s s Anne H a t h e wa y and M e s s r s .

G e k e l e r and Dennis K a i s e r f o r t h e i r h e l p and t e c h n i c a l

assistance,

and t o M i s s D i a n e Ra d e ma c h e r f o r h e r t y p i n g and p r o o f ­

reading of the manuscript.

TABLE OF CONTENTS

Page

1NTRODUCTI O N .............................................................................................

1

OBJECT! V E S ...............................................................................................................

3

REVIEW OF LI T ERA TURE.....................................................................................

3

METHODS........................................................................................................................

10

BIOLOGY OF THE TARNISHED PLANT BUG
AND ALFALFA PLANT BUG...............................................................................

12

LABORATORY REAR! N G .........................................................................................

28

FI ELD STUD I E S .........................................................................................................

33

Dl SCUSSI O N ..............................................................................................................

52

CONCLUSIONS..............................................................................................................

61

REFERENCES CITED ..............................................................................................

6 b

iii

L IS T

OF TABLES

T a b le

1

2

3

4

5

6

7

8

Page

R a te o f development in days of t h e t a r n i s h e d
p l a n t bug a t l a b o r a t o r y c o n d i t i o n s ( 78 -8 0°F )
i n f i v e d i f f e r e n t r e p l i c a t i o n s r e a r e d f r o m 29
M a r c h t o 1 D e c e mb e r 1971* E a s t L a n s i n g , M i c h .
1 9 7 1 ......................................................................................................................
Summary o f p o p u l a t i o n n u m b e r s i n f i v e g e n e r a ­
t i o n s o f t a r n i s h e d p l a n t b u g e g g s * nymphs a n d
a d u lts , reared at laboratory conditions
( 7 8 - 8 0 ° F a n d 65 + 5% RH) w i t h f i v e r e p l i c a t i o n s
f r o m Ma r c h 29 t h r o u g h D e c e m b e r 1, 1971* E a s t
L a n s i n g , M i c h i g a n ..............................................................................
Organisms found in t h e gut o f f o u r to a d s ,
B u f o a m e r i c a n u s , pi e k e d up f r o m a l f a l f a f i e l d s .
E a s t L a n s i n g , M i c h i g a n . 1 9 7 0 ........................................................

19

20

22

C o m p a r i s o n o f t h e n u m b e r o f e g g s l a i d i n common
b e a n s by t h e p a r e n t a l g e n e r a t i o n s o f t h e t a r n i s h e d
and a l f a l f a p l a n t b u g s , r e a r e d mixed and s i n g l y
i n g r o u p s o f f i v e p a i r s , a t 7 8 - 8 0 ° F a n d 65 + 5%
RH. E a s t L a n s i n g , M i c h i g a n , 1 9 7 1 ........................................

31

Comparison of t h e p o p u l a t i o n d e n s i t i e s of
t h r e e p l a n t bugs as c o l l e c t e d by s w eeping in
f i v e f i e l d s at th e Michigan S t a t e U n iv e r s ity
farm, East Lansing, Michigan.
1 9 7 0 .......................................

34

Comparison o f t h e p o p u l a t i o n d e n s i t i e s of
t h r e e p l a n t b u g s a s c o l l e c t e d by s w e e p i n g i n
f i v e f i e l d s a t th e M ichigan S t a t e U n i v e r s i t y
f a r m , E a s t L a n s i n g , M i c h i g a n . 1 9 7 1 .......................................

35

T o t a l number o f m a l e s and f e m a l e s o f t h e
t a r n i s h e d and a l f a l f a p l a n t b u g s f r o m w e e k l y
s w e e p s a m p l i n g i n 1970 a n d 1971- E a s t L a n s i n g ,
Mi ch i g a n .......................................................................................................
A b u n d a n c e o f _L, I i n e o l a r i s a n d A. I i n e o l a t u s i n
d i f f e r e n t reg io n s in a l f a l f a f i e l d s in the U.S.
a n d d i f f e r e n t y e a r s , a d j u s t e d t o a common b a s e
o f 100 n e t s w e e p s .....................................................................

iv

48

54

T a b le

9

10

Page

Biological c h a r a c t e r i s t i c s of the tarnished
p l a n t bug r e a r e d a t 7 8 - 8 0 ° F , 65 + 5 % RH, a nd
16 h o u r s o f l i g h t , E a s t L a n s i n g , M i c h i g a n .
1 9 7 1 ..................................................................................................................
D u r a tio n in days o f th e development of
t a r n i s h e d p l a n t b u g when r e a r e d mi x e d w i t h
a l f a l f a p l a n t bug a t 7 8 - 8 0 ° F , 65 + 5% RH, a nd
16 h o u r s o f l i g h t , f r o m S e p t e m b e r
18 t o
December 2 2 , E a s t L a n s i n g , M i c h i g a n . 1971 . . . .

v

57

60

LI ST OF FI GURES

Fi gure

1
2

3

k

5

6

7

8

9

10

11

Page

T a r n i s h e d p l a n t bug o v i p o s i t i n g i n t h e p e e l e d
a r e a o f a b e a n pod a t l a b o r a t o r y c o n d i t i o n s . . . .

17

Common bean pod a t t a c k e d by a f u n g u s i n f e c t i o n
h o w e v e r , t h e e g g s l a i d by t h e t a r n i s h e d p l a n t
bug were s t i l l v i a b l e . . . .
..................................................

17

T a r n i s h e d p l a n t bug e m e r g i n g f r om t h e f i f t h
nymphal i n s t a r .........................................................................................

26

A l f a l f a p l a n t bug e g g s l a i d i n a common b e a n
pod a t l a b o r a t o r y c o n d i t i o n s ......................................................

26

R e g r e s s i o n l i n e o f numb e r o f t a r n i s h e d p l a n t
b u g r e a r e d u n d e r l a b o r a t o r y c o n d i t i o n s on
g e n e r a t i o n ...................................................................................................

29

P op ulatio n d e n s i t i e s of the ta rn ish ed p lan t
b u g , t h e a l f a l f a p l a n t b u g, and T r i q o n o t y l u s
r u f i c o r n i s d u r i n g t h e 1970 s e a s o n ............................................

36

Population d e n s i t i e s of the ta rn ish ed p lant
b u g , t h e a l f a l f a p l a n t b u g , and T. r u f i c o r n i s
d u r i n g t h e 1971 s e a s o n .................................................................

37

Nymphal p o p u l a t i o n d e n s i t i e s o f t h e t a r n i s h e d
p l a n t bug and t h e a l f a l f a p l a n t bug d u r i n g t h e
1970 s e a s o n . ..........................................................................................

1+0

Nymphal p o p u l a t i o n d e n s i t i e s o f t h e t a r n i s h e d
p l a n t bug and t h e a l f a l f a p l a n t bug d u r i n g t h e
1971 s e a s o n ...............................................................................................

1+1

R e l a t i o n s h i p s b e t w e e n a d u l t and nymphal p o p u l a ­
t i o n d e n s i t i e s o f t h e t a r n i s h e d p l a n t bug d u r i n g
t h e 1970 s e a s o n .....................................................................

*+3

R e l a t i o n s h i p s b e t w e e n a d u l t and nymphal p o p u l a ­
t i o n d e n s i t i e s of t h e a l f a l f a p l a n t bug d u r i n g t h e
1970 s e a s o n .............................

*+5

vi

Page

FI g u r e
12

R e l a t i o n s h i p s b e t w e e n a d u l t a n d nymphal
population d e n s itie s of the tarnished plant
b u g d u r i n g t h e 1971 s e a s o n ................................................................. ^ 6

13

R e l a t i o n s h i p s b e t w e e n a d u l t a n d nymphal
population d e n sitie s of the a l f a l f a plant
b u g d u r i n g t h e 1971s e a s o n ................................................................. h

1*+

Maximum a n d minimum t e m p e r a t u r e s ( ° F ) a n d
p r e c i p i t a t i o n (in c h e s ), fo r the East Lansing
S . E. S t a t i o n d u r i n g t h e 1970 a n d 1971
s e a s o n ............................................................................

vi i

i

50

INTRODUCTI ON

A lfalfa

(Hedicaqo s a t i v a L.)

c a u s e i m p o r t a n t problems in i t s

h a s a wi d e r a n g e o f i n s e c t s t h a t

production.

mi r i d s h a v e b e e n c o n s i d e r e d p e s t s
of the United S ta te s .

Various species of

in t h e a l f a l f a p r o d u c i n g a r e a s

T h r e e s p e c i e s o f Lygus h a v e b e e n p r e s e n t

the Western United S t a t e s ;

Lygus h e s p e r u s K n i g h t ,

Lygus e l i s u s

Van D u z e e , a n d Lygus 1i n e o l a ri s ( P a l i s o t de B e a u v o i s ) .
11neolaris occurs
according to the

in almost a l l

and i t

i s t h e common e a s t e r n

species

(S titt

19*+0).

alfalfa

fields

in Michigan i n c l u d e t h e a l f a l f a

O t h e r mi r i d s u s u a l l y f o u n d i n number s i n

(Uhler).

Losses in a l f a l f a p r o d u c t i o n

c a u s e d by t h e s e Lygus s p e c i e s a r e w e l l
damage i s o f t e n n o t s p e c t a c u l a r ,
t h a n t h a t o f many o t h e r i n s e c t s .
the population

found in M ic h i g a n ;

in which n e i t h e r p o p u l a t i o n

needs;

and i s t h u s

less

readily noticed

T h i s r e s e a r c h was d e s i g n e d t o

t h e t a r n i s h e d p l a n t bug a n d t h e a l f a l f a p l a n t

o r mor e s p e c i e s may i n t e r a c t

2) c o m p e t i t i o n ,

the other

known, a l t h o u g h t h e p l a n t

i n t e r a c t i o n s b e t w e e n t wo mi r i d s commonly

As s t a t e d by Odum ( 1 9 6 6 ) ,

other;

p l a n t b ug ,

( G o e z e ) , Tr i g o n o t y l u s r u f i c o r n i s ( G e o f f r o y ) ,

and P l a q i o q n a t u s p ol 1 i t u s

investigate

Lygus

a l f a l f a a r e a s of th e United S t a t e s ,

records to d a te ,

A d e l p h o c o r i s Ii n e o l a t u s

in

theoretically,

p o p u l a t i o n s o f two

i n e i g h t d i f f e r e n t ways;

1) n e u t r a l i s m

i s a f f e c t e d by a s s o c i a t i o n w i t h t h e

in which ea c h p o p u l a t i o n a d v e r s e l y a f f e c t s

in t h e s t r u g g l e f o r f o o d ,

3) m u t u a l i s m o r s y m b i o s i s ,

bug

l i v i n g s p a c e , o r o t h e r common

i n whi c h g r o w t h and s u r v i v a l

2

o f b o t h p o p u l a t i o n s a r e b e n e f i t e d and n e i t h e r can s u r v i v e u n d e r
natural

conditions without

both p o p u latio n s b e n e f i t
not o b lig a to ry ;
but

the other

5)

the other;

*0 p r o t o c o o p e r a t i o n ,

from th e a s s o c i a t i o n but r e l a t i o n s a r e

commensa1ism,

is not a ffe c te d ;

in which one p o p u l a t i o n

6) a m e n s a l i s m ,

i s i n h i b i t e d and t h e o t h e r n o t a f f e c t e d ;

7)

in which one p o p u l a t i o n a d v e r s e l y a f f e c t s
but

in w h ich

is benefited

i n w h ic h one p o p u l a t i o n

p a r a s i t i s m a n d 8)

predation,

t h e o t h e r by d i r e c t

attack

are

in

i s d e p e n d e n t on t h e o t h e r .
All

of th e se p o p u latio n

t h e av e ra g e community.

Furtherm ore,

may i n v o l v e common f o o d ,
conditions,

interactions

space, natural

le a s t under h y p o th e tic a l

e q u i l i b r i u m a d j u s t m e n t s by two s p e c i e s ,
species population

enemies,

these asp ects

interaction

severe clim atic
interactions.

conditions,
or

can r e s u l t

i t may r e s u l t

replacing another or forcing i t

a n o t h e r space o r t o use a n o t h e r food

to occur

the com petitive

d i s e a s e s a n d many o t h e r t y p e s o f m u t u a l

Competition, a t

clarify

likely

(Odum 1 9 6 6 ) .

t o occupy
Attempts

i n t h e mi r i d c o m p l e x on a l f a l f a

o f th e purpose of t h i s work.

in one

to

are part

in

OBJECTIVES
Th e p u r p o s e o f t h i s

study i s

to determine th e

interspecific

r e l a t i o n s h i p s b e t w e e n t h e t a r n i s h e d p l a n t bu g a n d t h e a 1f a 1f a p l a n t
b u g on a l f a l f a

f o r hay p r o d u c t i o n

in M ichigan,

t o u n d e r s t a n d i n g c o m p e t i t i o n and fa u n a l
tivated

as a c o n t r i b u t i o n

relatio n sh ip s within c u l­

fields.

REVIEW OF LI TERATURE
T h e r e h a s b e e n a good d e a l
years as

to the

relative

animals of d i f f e r e n t
competition

broad
et a[.

particularly,

tn i n s e c t p o p u l a t i o n s .

of com petition

in te r s p e c if ic com petition

follow ing sin g le d e f in itio n

"Competition

1 957) *

fo r use

Milne

s ame p a r t i c u l a r

(Pearce

(1961)

in e c o lo g y ,

i n t r a s p e c i f i c and i n t e r s p e c i f i c
is

or to gain

Nicholson

(1933)

states

1 9 3 9 , At l e e

t o gain the

in co m petition

from t h e

fo r both or

between s e a r c h i n g

a n i m a l s , w h e t h e r t h e s e a n i m a l s a r e c o n t r o l l e d by c o m p e t i t i o n
food,

or fo r s u i t a b l e places

of th e ir

natural

enemies,

in which t o l i v e ,

there

3

is

the

relationship:

th e measure each wants

that

In i t s

g e n e t i c s and e v o l u t i o n ,

t h e e n d e a v o r o f t w o o r mo r e a n i m a l s
thing,

inter­

proposes

s u p p l y o f a t h i n g when t h a t s u p p l y i s n o t s u f f i c i e n t
all".

interspecific

d e f i n i t i o n and meaning o f t y p e s of

1 9 ^ 9 , Odum 1967* B i r c h

t o cover both

as t o th e

Many t e x t b o o k s a n d i n v e s t i g a t o r s

t h a t can o c c u r bet we en two s p e c i e s ,
s e n s e , and o f

f o r many

im po rtance of t h e r e l a t i o n s h i p s between

species,

give the d e s c r ip tio n ,
action

o f w r i t i n g and d i s c u s s i o n

for

o r by c o m p e t i t i o n

f o r each s p e c i e s a p a r t i c u l a r

1*

density,

r e f e r r e d t o as th e “ s t e a d y d e n s i t y " a t which b a l a n c e e x i s t s

and he adds:

"Com petition always tends to cause animals t o reach ,

and t o m a i n t a i n ,

their

steady d e n s i t i e s .

Factors,

a n d m o s t k i n d s o f a n i m a l b e h a v i o r , may h a v e a n
on t h e v a l u e s a t w h i c h c o m p e t i t i o n m a i n t a i n s
DeBach
as

rare,

density

(1966) d e s c r i b e s

they e x h ib it

th e absence of a s p e c ie s

this

and between

respect,

gical

important

influence

these d e n sitie s".

p o p u l a t i o n s and a l l

organisms

common o r a b u n d a n t , a c c o r d i n g t o t h e t y p i c a l a v e r a g e
that

factors,

insect

such a s c l i m a t e

in t h e i r h a b ita b le zones.
from a h a b i t a t ,

these,

he r e f e r s

He a t t r i b u t e s

to physical,

to in te rs p e c if ic

or biolo g ical

interactions.

In

t o c o m p e t i t i v e d is p l a c e m e n t between e c o l o ­

homologues where one s p e c i e s b r i n g s a b o u t

the e x tin c tio n

or

d i s p l a c e m e n t o f a n o t h e r e c o l o g i c a l l y homologous s p e c i e s o r p r e v e n t s
su ch s p e c i e s fro m i n v a d i n g and c o l o n i z i n g a l l
DeBach
principle"

(op ci t . )

prefers

exclusion p r in c ip le ,

o f t h e phenomenon,

the Volterra-Gause p r in c ip le ,

a u t h o r d i s c u s s e s w ith examples t h e

as having a p p l ic a tio n
and p a r t i c u a r l y

such a s

Cause's

The s ame

importance of the c o m p e titiv e

converse,

i n many f i e l d s

in b i o l o g i c a l

habitat.

the com petition

or the L o tk a -V o lte rra p r i n c i p l e .

displacem ent p r i n c i p l e or i t s

its

th e term " c o m p e titiv e d isplacem ent

to oth er designations

law, G r i n n e l ' s axiom,

or part of

the co ex iste n ce p r i n c i p l e ,

such a s e v o l u t i o n ,

control,

ecology,

e r a d i c a t i o n and o t h e r

control

programs o f a p p l i e d entomology.
On i n t e r s p e c i f i c c o m p e t i t i o n
field,

little

has been s t u d i e d

in

the

b u t on t h e c o n t r a r y , many l a b o r a t o r y e x p e r i m e n t s h a v e b e e n

p e r f o r m e d on c o m p e t i t i o n b e t w e e n d i f f e r e n t

species,

mainly

5

granivorous

i n s e c t s and D r o s o p h i l a

A complete a n a ly s is
are present
sorts

A c c o r d i n g t o them,

sist

complex s i t u a t i o n s

is

ecology,

together.

as a p p lie d

Th e s t u d y o f

f l u e n c e d by m a t h e m a t i c a l

identical
to

t h a t " wh e n a p o p u l a t i o n o f a n i m a l s ,

and V o l t e r r a

(1926,

obey two s i m p l e

laws:

decreases

f r o m a maximum t o z e r o a s

increases

from very

range".

unlim ited

Crombi

increase,

and p h y s i c a l
conditions

all

E ssentially
of

but

th ey meet

t o which i t

b)

the

that all

linear

throughout

organisms tend

the organism i t s e l f

reproduction);

(environmental

b)

and c)

is usually referred
Th e p h y s i c a l

such as

the physical

Th e b i o l o g i c a l

factors".

toward

r e s i s t a n c e from t h e i r b i o l o g i c a l

which can occur d i r e c t l y

ferred

rate of increase

r e l a t i o n s h i p between

o f o r g a n i s m upon o r g a n i s m ,

dependent" or " b i o t i c

they

the d e n s ity of the p o p u latio n

(such as c l i m a t e and s o i l ) ;

environment

to

f i n i t e and c o n ­

i s a d a p t e d and c h a r a c t e r i s t i c s

i t s method of

a b i o t i c environment

a)

in­

t h e same k i n d ,

the r e la tiv e

i s assumed t o be

(19**7) h a s s a i d

environment:

life history,

a)

f ew t o s a t u r a t i o n ;

r a t e o f i n c r e a s e and d e n s i t y
this

1931).

i n a p l a c e w h e r e f o o d and s p a c e a r e

i t will

can not p e r ­

th e o r y which i s u s u a l l y a t t r i b u t e d

state

stant,

in n a t u r e ,

i n t e r s p e c i f i c c o m p e t i t i o n has been

(1925,

increasing

(195**).

r e q u i r e m e n t s and i d e n t i c a l

insects

Lotka

is

1932)

k in d s and o t h e r

g i v e n by A n d r e w a r t h a a n d B i r c h

species with

1957) *

in which t h e r e

in th e environm ent an im a ls o f d i f f e r e n t

of organisms

or s im ila r

of c e rta in

( P a r k 195**, Sol omon

its

and

the e f f e c t s

or in d ir e c tly .

to as " d e n s ity
environment

is

re­

t o as "independent of p o p u latio n d e n s it y " or " a b i o t i c

factors"

( Thompson

1 9 39) *

The b i o l o g i c a l

facto rs are also called

6

" I n d i v i d u a l i z e d " o r " f a c u l t a t i v e " and t h e p h y s ic a l
or "catastrophic"

(A ndrew artha and B i r c h

Among i n s e c t s ,
some a t t e n t i o n .

(1963)

(Hymenoptera;

ectoparasites attacking
aurantii

(Haskell),

to occur.

the C a lif o r n ia

s p e c i e s always e l i m i n a t e d
Flanders

(1966)

experimental

parasitic

discusses

there

that

to recip ro cal

is a host

reciprocal

the

regulative effect

that

it

i s no h o s t

consists

that

it

replacement

i s m o s t commonly

and i n t r i n s i c c o m p e t i t i o n .
i n t e r a c t i o n s , when

by t h e p a r a s i t e ;

and n o n - r e c i p r o c a 1

r e g u l a t i v e e f f e c t by t h e p a r a s i t e .
t h e same a u t h o r

of i n t e r f e r e n c e between

starvation,

(op c i t .)

individuals of
as c a n n i­

s u f f o c a t i o n and p r o d u c t i o n o f

r e p e l l e n t e x c r e t i o n s and s e c r e t i o n s .

he r e f e r s

control.

a n d n o n - r e c i p r o c a 1 b a l a n c e among

i n t e r a c t i n g p o p u l a t i o n s , m a n i f e s t e d by s u c h f a c t o r s

b alism , mutualism,
or

s howed t h a t o n e

b ala n c e in h o s t - p a r a s i t e

regard to i n t r i n s i c com petition,

explains

studies

groups a r e c o r r e l a t e d w ith th e two t y p e s of s p e c i e s

b a l a n c e , when t h e r e
In

for com petitive d is p la c e ­

the cases of species

r e p l a c e m e n t a s d e t e r m i n e d by e x t r i n s i c
He r e f e r s

T h i s s t u d y s howed t h a t

in them b e c a u s e of t h e i r d o m i na nc e in b i o l o g i c a l

His c o n c l u s io n s a r e
this

species of

the o th e r .

a mo ng p a r a s i t i c H y m e n o p t e r a and s t a t e s
observed

related

t h e com­

r e d s c a l e , Aon i d i e 11 a

in Southern C a l i f o r n i a .

Likew ise,

have r e c e iv e d

A p h e li n id a e ) which a r e m inute

an a b s o l u t e food s h o r t a g e i s not n e c e s s a r y
ment

studies

have r e p o r t e d

p e t i t i v e d i s p l a c e m e n t between t h r e e c l o s e l y
th e genus A p h y tis

"general"

195M-

in te rs p e c if ic com petition

De Ba c h a n d Su n d b y

factors,

On e x t r i n s i c

toxic

competition

t o i n t e r a c t i o n o f p o p u l a t i o n s a s gr o u p s and m a n i f e s t e d

m a i n l y by h o s t - h a b i t a t

f i n d i n g , h o s t - f i n d i n g and h o s t - a c c e p t a n c e .

7

I n t h e same way I s t o c k

( 1967) o b s e r v e d a t r a n s i e n t c o m p e t i t i v e

d i s p l a c e m e n t o f Pi n e u t e s ni g r i or by 0 .

horn i in a n o r t h e r n Michigan

pond and t h e u n i f o r m r a t e o f d i s p l a c e m e n t d u r i n g o n e l a r v a l
t i o n was e s t i m a t e d .

He c o n c l u d e d t h a t c o m p e t i t i v e d i s p l a c e m e n t and

com petitive co ex iste n ce are the r e s u lts
displacement!

the f i r s t

o f h i g h a nd low r a t e s o f

lead in g to s p e c i e s s o r t i n g in t h e communities,

w h e r e a s t h e s e c o n d may c o n t r i b u t e t o c o mmu n i t y s t a b i l i t y
prolonged,

genera­

and,

if

to d iv e rsify in g evolution.

On t h e o t h e r h a n d , R o s s

(1957)

s p e c i e s o f sycamore l e a f h o p p e r s ,

in I l l i n o i s ,

showed t h a t s e v e r a l

c o m p r i s i n g a c o mp l e x o f t h e gen us

E r y t h r o n e u r a , may o c c u p y t h e same e c o l o g i c a l

niche at

t h e same t i m e .

During the period o f h i s study i n t e r s p e c i f i c c o m p e titio n did not
o c c u r and h i s o b s e r v a t i o n s
Erythroneura, if

indicate that

in the e n t i r e

in te rs p e c if ic competition occurs,

it

genus
is

sporadic

a n d 1o c a 1.
Evidence fo r i n t e r s p e c i f i c c o m p e titio n
o f t h e Monar ch a nd Queen B u t t e r f l i e s ,
q i l i ppus ber en i ce in South C e n t r a l
fact

that

in n a t u r a l

populations

D a n a u s pi exi p p u s a n d _D.

F l o r i d a was s u g g e s t e d by

1) t h e

t h e r e i s a p e r i o d i c c h a n g e b e t w e e n e x t e n s i v e s y m p a t r y and

n e a r l y complete a l l o p a t r y as the annual m i g r a t i o n c y c l e o f the
Monarch o c c u r s ;

2)

the fact

that

th e r e d u c t i o n in numbers of t h e

Monarch c o i n c i d e d w i t h t h e b u i l d - u p o f t h e Queen p o p u l a t i o n and
t h a t d u r i n g t h e h e a v y s p r i n g b r e e d i n g o f t h e Mo n a r c h ,

t h e Queen

f e m a l e s a v o i d e d t h e m o s t common s p e c i e s o f A s c l e p i a s f o o d p l a n t
but
left

later

r e a d i l y o v i p o s i t e d on i t a f t e r m o s t o f t h e Mo n a r c h had

( Br ower 1 9 6 2 ) .

8

C o m p e t i t i o n among t h r e e
T herioaphis maculata

of th e

( B u c k t o n ) was f o u n d i n

due t o such f a c t o r s as

the a b i l i t y

r a p i d l y and f r e q u e n t l y ,
become a t t r a c t i v e

parasites

to find

spotted a l f a l f a aphid,

the
host

laboratory stu d ies
rapidly,

to oviposit

and t o p a r a s i t i z e young a p h i d s b e f o r e

to other p a r a s ite

species

they

( F o rc e and M e s s e n g e r

1965) .
The p h e n o m e n o n o f i n t e r s p e c i f i c c o m p e t i t i o n among i n s e c t
sites

h a s b ee n a n a l y z e d by S m i t h

such co m p e titio n

(intrinsic

between p a r a s i t i c

com petition);

to physical

this

t h e body o f

refers

outside

s u c h a s f i g h t i n g among a d u l t s

the

to environmental

the host

(extrinsic

or d iff e r e n tia l

survival

factors.

Wi t h mi r i d p o p u l a t i o n s ,
of

type

in

one t y p e r e f e r s

larvae w ithin

the other

re la tio n sh ip s of the adult p a ra s ite s
com petition),

who c o n c l u d e d t h a t

t wo t y p e s c a n be d i s t i n g u i s h e d ;

to the competition
host

(1929),

para­

type.

fiv e species

A fter trying
o f mi r i d

he concluded t h a t

only Richards

insects

such as

l i v i n g in S c o t c h broom in E n g l a n d ,
of these species

t o d i s c o u r a g e one from a t t e m p t i n g t o

c o n s t r u c t any s i m p l e m a t h e m a t i c a l model.

In r e l a t i o n

i n v e s t i g a t i o n s w e r e made on t h e

u l a t i o n s o f L y g u s h e s p e r u s Kni g h t , i n a I f a I f a
and Wardecker

h a s made a s t u d y

t o d e t e r m i n e s ome f a c t o r s c o n t r o l l i n g

the com plexity of the r e l a t i o n s

w i t h one a n o t h e r i s

populations,

(1963)

f l u c t u a t i o n s of pop­
i n Ar i z o n a

1 9 7 0 ) . They e m p h a s i z e d t h e e f f e c t s o f

a p a rtic u la r crop,
of the p o p u la tio n .

the

t o Ly qu s

( But 1e r

l y g u s b u g s on

i n t e r c r o p m i g r a t i o n and t h e s e a s o n a l

L i n d q u i s t and Sorensen

(1970)

show t h a t

trend
the

9

t a rn i s h e d p l a n t b u g i n c r e a s e on a p h i d - s u s c e p t i b 1e v a r i e t i e s
a l f a l f a was 1 2 3 . 2 % c o m p a r e d w i t h

1 7 . 6% on a p h i d - r e s i s t a n t

of

varieties.

They o b s e r v e d t a r n i s h e d p l a n t b u g s f e e d i n g on p e a a p h i d s , A c y r t h o s i phon
pi sum ( H a r r i s ) ,

a n d on s p o t t e d a l f a l f a

aphids,

Theri oaphi s m a c u l a t a

(Buckton) ,
I t c a n b e s e e n by r e v i e w i n g t h e mo r e r e c e n t
studies

on c o m p e t i t i v e

entomology.

interactions

The p r e s e n t

are of importance

s tu d ie s having th is

toward exam ining t h e p o s s i b i l i t i e s

i n hi c h i gan .

in mind,

that

in a p p l i e d
were aimed

o f any i n t e r s p e c i f i c c o m p e t i t i o n

between t h e t a r n i s h e d p l a n t and t h e a l f a l f a
have a p p l i c a t i o n s

literature,

p l a n t b u g t h a t may

i n f u t u r e s t u d i e s o f ma n a g e m e n t o f

these pests

METHODS

The p r e s e n t wo r k was c a r r i e d o u t b o t h
laboratory conditions.
'V ernal*

variety,

F i e l d s t u d i e s w e r e made on a l f a l f a

at Michigan S t a t e U n i v e r s i t y ,

unsprayed a l f a l f a
mi r i d

in t h e f i e l d and u n d e r
fields,

East Lansing.

Five

f i e l d s w e r e ch o se n and a w e e k ly s u r v e y o f a l l

s p e c i e s was d o n e i n t h e m .

In each o f t h e s e f i e l d s ,

five

d i f f e r e n t p l a c e s w e r e c h o s e n a s a good r e p r e s e n t a t i v e s a m p l e ,
i n t h e c o r n e r a r e a s and o n e i n t h e c e n t r a l

area of each f i e l d .

i n s e c t s w e r e c o l l e c t e d by s w e e p i n g 20 t i m e s w i t h a s t a n d a r d
d i a m e t e r n e t on e a c h a r e a o f t h e f i e l d .
i n g l a s s j a r s w i t h 70% a l c o h o l
wa s d o n e i n t h e

laboratory.

AM

s ta g e s of a l l

o f t h e mi r i d s

f o r t h e mi r i d c o m p l e x was

f o u n d by s w e e p i n g .

plastic

funnel,

with

1f h

the top,

With R u p p e i ' s p r o ­

c o n t a i n i n g 70% a l c o h o l
t h u s t h e d e b r i s was h e l d

s i e v e o r f l o a t e d on t h e s u r f a c e o f t h e a l c o h o l

at

and immature

in each g l a s s j a r were poured

11 i n c h e s w i d e ,

i n c h mesh a t

(unpublished)

and i n c l u d e d t h e a d u l t

th e samples c o l l e c t e d

15 i n c h

and t h e s o r t i n g and c o u n t i n g p r o c e s s

The s o r t i n g

cedure,

The

i n s e c t s were placed

made u s i n g t h e m e t h o d d e v e l o p e d by D r . R u p p e l
Michigan S t a t e U n i v e r s i t y ,

four

and th e

in a

and a s i e v e
in th e
insects

s a n k t o t h e b o t t o m w h e r e t h e y w e r e t a k e n o u t by m e a n s o f a r u b b e r
t u b e and a c l i p

f o r c o u n t i n g and p r e s e r v i n g them.

The d a i l y a c t i v i t y o f t h e mi r i d s
b y s a m p l i n g on t h r e e d i f f e r e n t
7 : 0 0 and
as

11:00 p.m .;

the f i e l d

days a t

collecting,

in a l f a l f a
5 : 0 0 and

11:00 a . m . ,

and

s o r t i n g and c o u n t i n g t h e i n s e c t s

s t u d i e s mentioned b e f o r e were done.

10

f i e l d s was r e c o r d e d

The f o l l o w i n g

o b s e r v a t i o n s w e r e a l s o made on f i e l d

conditions:

hosts other

alfalfa,

habits of

enemies,

and d a t e and f r e q u e n c y o f c u t t i n g o f t h e h o s t p l a n t .

The

f e e d i n g , mo ve me nt and o v i p o s i t i o n ,

incubators

in t h e

plant

l a b o r a t o r y and t h e

Research C enter.

1968),

natural

l a b o r a t o r y s t u d i e s w e r e u n d e r t a k e n by c o l l e c t i n g a d u l t

t a r n i s h e d p l a n t bugs and a l f a l f a

rearing

than

As t h e a l f a l f a

lygus bugs

in th e

r e a rin g chambers at

plant

laboratory

g r e e n p o d s o f t h e common b e a n

bugs and r e a r i n g them i n

is not

the P e s ti c i d e

satisfactory

(Beards and Leigh
(Phasedus

for

I960,

v u 1q a r i s L . )

B utler
were

used a s a food

s o u r c e and f o r o v i p o s i t i o n .

were bought

t h e m a r k e t a n d o t h e r s w e r e grown i n t h e g r e e n h o u s e s .

This

in

r e a r i n g procedure followed

t h a t o u t l i n e d by R i d g wa y a n d G y r i s c o

( I 9 6 0 ) , w i t h some m o d i f i c a t i o n s .
c o n t a i n e r s and p l a c e d
v i d e d by a f l o u r e s c e n t
The r e a r i n g

in t h e

Th e p o d s w e r e h e l d

16 h o u r s a d a y ,

mi r i d ,

reared together

i n t h e same c a g e ,

observations

interspecific

petitive

a n d 65 + 5 % R . H .

the a l f a l f a

plant

bug.

Both s p e c i e s w e re

and each s p e c i e s

relationships,

separated

for

e s p e c i a l l y a n y com­

interaction.

The e x p e r i m e n t a l

plastic

t h e t a r n i s h e d p l a n t b u g , and t h e most

abundant o th e r

of

in sm all

incub ator at 78-80°F, with a lig h t

lamp f o r

included both

Some o f t h e b e a n p o d s

d e s ig n can be s p e c i f i e d as

follows:

pro­

12

Treatment

Repli c a t i o n s

1

Code

6

E

P o p u l a t i o n C a t e g o r y ______________
Mi x e d s p e c i e s ,
5 pairs

TPB a n d

APB,

(5 m a l e s and 5 f e m a l e s )

of each species.
2

6

C

Single species,

TPB,

5 pairs

( 5 m a l e s and 5 f e m a l e s )
3

6

C

Single

s p e c i e s , APB,

5 pairs

(5 m a l e s and 5 f e m a l e s )
O b s e r v a t i o n s w e r e made o f b o t h a d u l t a n d i m m a t u r e s t a g e s o f n a t u r a l
enemies

that

parasites.

t h e y may h a v e h a d by d i s s e c t i n g a n d e x a m i n i n g t h e m f o r
R e c o r d s w e r e made o f t h e s t a g e a t t a c k e d ,

and t h e s p e c i e s o f some p a r a s i t e s a n d p r e d a t o r s

found

t h e numbers
in t h e f i e l d .

BIOLOGY OF THE TARN!SHEP PLANT BUG
AND THE ALFALFA PLANT BUG

TARN I SHEO PLANT BUG
H o s t s The l i t e r a t u r e

about

records of s e r io u s
country

(Crosby and L e o n a rd

and M e d l e r

!9*+7» T a k s d a l

injury

t o many c u l t i v a t e d

191*+, P o r t e r

19 26,

S titt

1 9 63 , N t e m c z y k a n d Guyer

a n d Luckman 1 9 7 0 ) .

It

mo r e t h a n

species

120 p l a n t

t h e t a r n i s h e d p l a n t bug shows e x t e n s i v e
plants

in t h i s

19*+5, S c h o l l

19 6 3 ,

Broersma

shows t h e wide h o s t r a n g e whi ch i n c l u d e s
v a r y in g from e c o n o m ically

important

13
plants

such as a p p le ,

potato,

beans,

economically
L.),

beets,

(Echinochloa c r u s q a lli

a n a t t e m p t wa s made t o
observed fe e d in g .

foot clover

less

(Solanum c a r o l i n e n s e
daisy

fleabane

In t h e p r e s e n t

studies

i d e n t i f y o t h e r weeds where t h e bugs were
o f t h e s e weeds f o ll o w s :

( T r i f o l i u m a r v e n s e L.)

(Ambrosi a e 1a t i o r L . )
(Amaranthus

k na pwe e d

r e t r o f 1e x u s L . )

( C e n t a u r e a m a c u l o s a Lam. )

M ouse-ear chickweed

( C e r o s t i u m v u l g a t u m L.)

Dandelion

( T a r a x a c u m o f f i c i n a I e We b e r )

Old-witch

grass

Common mu 11e n
thistle

Yellow nut
Sow t h i s t l e
Quackgrass

(Panicum c a p i l l a r e L.)

(Verbascum t h a p s u s L .)
(Ci r s i um v u 1g a r e L . )

grass

(Cyperus e x c u l e n t u s L.)

(Sonchus a r v e n s i s

L.)

(Aqropyron repeus L.)

Foxtai 1 g r a s s
It

t o w i l d and

(C h e n o p o d i um a 1bum L - )

Rough p i g weed

Bull

L.)»

grape,

t humb (P o l y g o n u m p e r s i c a r i a L . )

Rag we e d

Spotted

straw berry,

a n d many o t h e r s .

A list

Lambs q u a r t e r
Rabbit

peach,

c o r n , w h e a t, and a l f a l f a ,

ramosus W a lt.) *

Lady's

apricot,

im p o rta n t ones such a s h o r s e n e t t l e

barnyard grass

(Erigeron

pear,

(Setari a spp.)

is d i f f i c u l t

to c la s s if y

t h e most and l e a s t p r e f e r r e d h o s t

weeds b e c a u s e o f t h e m i g r a t o r y h a b i t o f t h e t a r n i s h e d
When d i s t u r b e d

p l a n t bug.

t h e y move s l o w l y a r o u n d t h e s t e m o r f l o w e r w h e r e

t h e y a r e o r move f r o m o n e f l o w e r r a c e m e t o a n o t h e r o n t h e same

14

or a d ifferen t
f o o d i s made,
mirids

plant.
as

When t h e d e s t r u c t i o n

in a l f a l f a

to adjacent

cutting,

in the a d ja c e n t a l f a l f a

F e e d ! n g habi t

s

tissues.

Conversely,

is cleaned up,

the c o lle c tio n

flow ers,

tip

l e a v e s and o t h e r

in a c h a r a c t e r i s t i c

( C e n t a u r e a m a c u l o s a Lam. )
Bel ow t h e p e t i o l e ,

made

to
tender

g r o u p s o f 2 t o 8 bugs wer e f r e q u e n t l y
radial

in a l f a l f a

they remain

found

way on t h e s t e m i m m e d i ­

a t e l y b e l o w t h e p e t i o l e s o f s ome l e a v e s o f s p o t t e d

observed

i t was

A p p a r e n t l y t h e t a r n i s h e d p l a n t bug p r e f e r s

Ho we v e r ,

feeding to g eth er

of insect

f i e l d was h i g h e r t h a n n o r m a l .

f e e d on b u d s ,
plant

removal

subsequent m igration of these

f o o d p l a n t s may r e s u l t .

o b s e r v e d t h a t when a weed f i e l d

or

kn apweed

fields.

immobile f o r a

long t i m e ,

being

f o r a b o u t o n e h o u r on d i f f e r e n t d a y s ; o n e by o n e t h e y w e r e

moving s h o r t d i s t a n c e s ,
down on a l f a l f a

t a k i n g d i f f e r e n t d i r e c t i o n s and s e t t i n g

or other p la n ts .

Some s m a l l

g a l l s probably produced

b y t h e s e i n s e c t s w e r e o b s e r v e d on t h e s t e m b e l o w t h e p e t i o l e w h e r e
t h e bugs w er e f e e d i n g .

Also,

t h e i r e x c r e m e n t was f o u n d t o p r o d u c e

a k i n d o f d a m a g e 1i k e a b u r n e d s p o t o f a c i g a r e t t e ,

the size of

a pin head.

Overwi n t e r i n g . -

I t has been s t a t e d
overw inter in

under f a l l e n

l e a v e s and t r a s h

that the tarnished plant

the ad u lt

stage.

of a l f a l f a ,

bugs

The y h i b e r n a t e

clover,

and o r c h a r d s

and a l o n g s i d e h e d g e s , u n d e r s t o n e s ,

loose b a r k o f dead t r e e s

c r e v i c e s and o t h e r p r o t e c t e d p l a c e s

in t h e ground.

and

Some b u g s d o

n o t go i n t o h i b e r n a t i o n u n t i l

the advent of the a c tu a l

1 have s w e p t them from a l f a l f a
the Michigan S t a te U n i v e r s i t y
(1950)

observed that

fie ld s as
farms.

cold weather.

l a t e a s No v e mb e r

On t h e o t h e r h a n d ,

17th a t
Zia-ud~Din

t h e c o l d w i n t e r o f M ichigan c a u s e s a heavy

m o r t a l i t y of the o v erw in terin g a d u l t s .

Spring a p p e a ra n c e .- A dults of ta rn is h e d p la n t
to pass
from a l f a l f a
third,

fields at

1971-

the w in te r

bug w h i c h w e r e a b l e

in th i s

s t a g e w e r e swept

th e Michigan S t a t e U n i v e r s i t y

f a r m s on May

They w e r e f e e d i n g on t h e t e n d e r s h o o t s a n d

of a l f a l f a .

The l i t e r a t u r e

reports

that

the in se c t a t

this

d o e s n o t b r e e d t o any e x t e n t on o p e n i n g b u d s o f a p p l e ,
or plum t h a t
or grassy

they a t t a c k ,

but

in such p l a n t s

f i e l d s a n d l ow w e e d s

Ovi p o s i t i on . - A c c o r d i n g t o C r o s b y a n d L e o n a r d
p l a n t bug
petiole

those plants

usually

fe e d s on.

s c a t t e r e d and in i r r e g u l a r

rows o r

groups,

stem s,

and l e a v e s o f t h e p l a n t s ,

are deposited
plants

days.

In

( op c i t . )

the present

conditions,

quince

alfalfa,

(1914),

th e t a r n i shed

l e a v e s and l e a f

Eggs a r e a l s o i n s e r t e d ,

into tender tip s ,

a n d i n some c a s e s ,

blossom

th e eggs

in t h e f l o w e r he a d s o f v a r i o u s s p e c i e s o f c o m p o s i t e

such as d a i s i e s ,

and L e o n a r d

time

1914).

lays eggs in t h e m id rib s o f
it

buds,

of

pear,

like clover,

(Crosby and Leonard

leaves

asters,

h o r s e n e t t l e a nd o t h e r s .

observed th at

Crosby

t h e eggs s t a g e was a bout

s t u d y by r e a r i n g t h i s

insect at

t h e e g g s t a g e was a b o u t 6 . 6 8 d a y s ,

b e i n g 5 d a y s and t h e maximum 13 d a y s , a t

laboratory

t h e mi ni mi mum

78-80°f,

10

a n d 65 + 5X

16

R.H.

(Table

in the

!)•

The n u m b e r o f e g g s

l a b o r a t o r y t o be a b o u t

2 k t

l a i d by a f e m a l e was o b s e r v e d

w i t h a mi ni mum o f 5 e g g s a n d a

maximum o f 6 0 , w i t h common b e a n p o d s a s o v i p o s i t i o n
numbers o f eggs
Th e e g g s a r e

laid

varied w ith the in d iv id u a l

l a i d o n e by o n e a n d i n s e r t e d

almost com pletely

(Fig.

1).

by f u n g u s b u t t h e e g g s s t i l l
eggs

laid,

third,

fourth,

Nymphal

th e beans were invaded

hatched

2).

(Fig.

From t h e n u m b e r o f
stage

generations,

respectively

s t a g e s . " The mean d e v e l o p m e n t a l

in S t.

being almost
Paul,

t h e s ame a s

M innesota.

(first

generation),

a n d 7- 6 7 %, 6. 7 5 %* and 9.*i8% o f t h e

period

(Table 2 ) .

of the f iv e

o f t h e t a r n i s h e d p l a n t b u g wa s
results

tissue

I n some c a s e s

generation,

and f i f t h

but the

from day t o d a y .

in to the plant

a mean o f 23.1**% r e a c h e d t h e a d u l t

9.55% o f th e second

sites,

16.9 d a y s ;

t h o s e o b t a i n e d by Hughes

The v a r i a t i o n

factor

instars
these
(19^3)

in t h i s nymphal

d e v e l o p m e n t a p p a r e n t l y was d u e t o t h e a m o u n t o f f o o d a v a i l a b l e a nd
the population d e n s ity

inside the rearing cages.

velopment has been d e s c r i b e d
A f t e r t h e t h i r d nymphal
observed.
while

instar

In th e f o u r t h

in t h e f i f t h

in d e t a i l

instar

instar

The n y m p h a l

de­

by d i f f e r e n t a u t h o r s .

t h e d e v e l o p m e n t o f w i n g p a d s may b e
th e wing pads a r e c l e a r l y e v i d e n t

t h e wing pads u s u a l l y extend b ack t o th e

m i d d l e o f t h e abdomen

(Fig.

3).

th e bugs m ig ra te very

little.

Apparently,

in

t h e n y mp h a l

stage

Figure

1.

T a r n i s h e d p l a n t bug o v i p o s i t i n g in t h e p e e l e d
a r e a o f a b e a n pod a t

Figure 2.

laboratory conditions.

Common b e a n pod a t t a c k e d b y a f u n g u s
however,

t h e eggs were s t i l l

viable.

infection,

18
A d u I t s . - As a r u l e t h e m a l e s a r e
the fem ales.
However,

the

they reached

s omewh at d a r k e r a n d s m a l l e r

D u r i n g t h i s s t u d y m a t i n g was n e v e r o b s e r v e d .

females did s t a r t

laying eggs about 9-35 days a f t e r

the ad u lt s ta g e .

A d u l t s a n d nymphs a r e v e r y a c t i v e d u r i n g t h e s ummer .
t o f i e l d s a m p l e s t h e r e was n o s i g n i f i c a n t d i f f e r e n c e
vities

than

of th is

bug a t d i f f e r e n t

weather co n d itio n s

T h e y r e a c h maximum d e n s i t i e s a b o u t e a r l y

t o t h e same p e a k a t

in t h e a c t i ­

t i m e s o f d a y and even w i t h d i f f e r e n t

s u c h a s s u n n y and c l o u d y ,

cu ttin g of the fie ld s

According

windy o r c a l m d a y s .

s umme r , a n d b e c a u s e o f t h e

t h e i r n u m b e r s go d o wn , b u t

th e end o f the s e a s o n ,

in crease again

d e c r e a s in g again with

t h e comi n g f a 1 1 .

Mi g r a t i o n . - T h e r e
plant
o f food

is evidence of

the m ig ra to ry h a b it of th e

bug e s p e c i a l l y a s c a u s e d b y c u t t i n g o r

( S c h o l l and H e d l e r

19*f7).

The m o s t

m i g r a t i o n w o u l d p r o b a b l y be t h e w i d e h o s t
of this
clover

insect.
fields,

If

the a l f a l f a

cereal

field

important

range

is c u t,

adjacent

removal

factor

for

(polyphagous h a b i t )

t h e y may m i g r a t e

to

p l a n t i n g s o r g r a s s y o r we e dy f i e l d s w h e r e

t h e y c a n a l s o b r e e d and b u i l d up p o p u l a t i o n s .
study,a

tarnished

During the p r e s e n t

f ew c a s e s w e r e o b s e r v e d w h e r e t h e c u t t i n g o f we e d y f i e l d s
to the sampling a rea brought about

a considerable

increase

in the s i z e of th e sample.

Natural

enem ies.- Studies

to determine the s ta tu s of the ta rn is h e d

p l a n t bug p a r a s i t e s and p r e d a t o r s w er e p r e v i o u s l y

19

T a b l e 1. R a t e o f d e v e l o p m e n t i n d a y s o f t h e t a r n i s h e d p l a n t bug a t l a b o r a t o r y
c o n d i t i o n s (78-80 °F) in f i v e d i f f e r e n t r e p l i c a t i o n s r e a r e d from
29 Mar ch t o 1 December 1971East Lansing, Michigan.
1971*

Group
Number

1

S t a t i s t i cs

H a t c h i ng

Se c on d
1n s t a r

T o t a 1*

166

105

1 10

237

809

97 0

7.72

4.4

9.48

32.36

38.80

S t d . Dev.

1.04

• 91

1 .21

1.0

2.35

2.56

8.89

101

161

187

1 14

224

786

964

Mean

6.44

4.04

7.48

4.56

8.96

31.44

38,56

S t d . Dev.

1 . 23

1 .06

1-39

1 . 73

1.81

2.72

9-45

137

81

157

197

97

669

845

Mean

6.85

4.05

7.85

4.85

9.85

33-45

42.25

Std.Dev.

1 . 34

. 99

1.23

1.59

2.68

3.78

15.65

84

138

161

88

179

648

743

Mean

6.90

4.29

8.05

4.4

8.95

32.40

37.15

Std.Dev.

1 .02

1.24

1.60

1.6

1.96

2.28

8.82

Tota 1
5

193

4.20

Tota 1
4

E9 9 5

Adult
Longe vi t y

6.64

Tota 1
3

Adu I t s

Total
D u r a t i on

Mean

Tota i
2

Fi f t h
t nstar

Mean

145
7.25

. 83

.97

1 .25

* The c o u n t s w e r e b a s e d on 25 r e a r e d

4.1
•

4.10

210

00

6.55

82

-3-

S t d . Dev.

82

131

652

8 04

10.50

32.60

40.20

2.95

3.25

8.26

i n d i v i d u a l s on e a c h r e p l i c a t i o n .

Table 2.

Summary o f p o p u l a t i o n numbers in f i v e g e n e r a t i o n s o f t a r n i s h e d p l a n t bug e g g s , nymphs,
and a d u l t s , r e a r e d a t l a b o r a t o r y c o n d i t i o n s ( 7 8 - 8 0 ° F , and 65 + 5% RH) w i t h f i v e r e p l i ­
c a t i o n s , from March 29 t h r o u g h December 1, 1971. E a s t L a n s i n g , M i c h i g a n .

Generation

Aepli c .
1

Parents
Eggs
A d u l t s Fj
Eggs
Nymph 2nd
Nymph 5 t h
A d u l t s F2
Eggs
Nymph 2nd
Nymph 5 t h
A d u l t s F3
E99S
Nymph 2nd
Nymph 5 t h
A d u l t s Ft*
Eggs
Nymph 2nd
Nymph 5 t h
A d u l t s F5

10
298
70
2018
253
144
101
1854
238
180
160
3460
333
273
212
2869
638
518
435

1.
I.

1.
1.

1.
1.

1.
I.

‘I

23.49

5.00

8.63

6.13

1 5. 16

Repli c ,
2

10
110
32
1081
263
97
75
2033
278
200
157
3224
228
180
155
4798
433
300
233

%;

29.09

6.94

7.72

4.81

4.86

R ep li c .
3

10
117
14
900
175
141
135
2069
149
125
112
2509
275
205
176
2862
245
209
187

*1

11.97

15.00

5.41

7.01

6.53

Replic.
4

10
149
45
912
310
135
81
2638
336
245
223
2794
308
256
213
2682
400
272
260

;1

3 0 .2 0

8.88

8.45

7.62

9.69

Rep l i e .
5

10
86
18
1063
343
180
127
3701
285
196
250
2723
382
266
223
3561
530
423
399

%

20.93

11.95

8.14

8.19

11 .20

21

s umma r i z e d a n d r e c o r d e d
we r e found i n
Tachinidae,

( C l a n c y and P i e r c e

1966).

t h e f a m i l i e s Mymaridae, B r a c o n i d a e ,

Tn Ca na d a and t h e U n i t e d S t a t e s .

Several

parasites

I c h n e u m o n i d a e and

Among t h e p r e d a t o r s ,

m o s t l y p o l y p h a g o u s s p e c i e s o f He mE p t e r a , C o l e o p t e r a a n d N e u r o p t e r a
were r e c o r d e d

( C l a n c y and P i e r c e

Geocoris spp.

a n d Nabi s s p p .

Painter

(1929)

I9 6 6 ) .

Th e more common s p e c i e s w e r e

r e p o r t e d p a r a s i t i z a t i o n of about

tarnished p la n t adults c o lle c te d

11% o f t h e

i n swampy a r e a s by t h e n e m a t o d e

Hexamermi s s p p .
By o b s e r v a t i o n
l a r v a of t h e

spotted

in the f i e l d during th e years
lady-bird beetle,

1970 a n d

C o i e o m e g i l l a m a c u l a t a DeGeer ,

was f ound a t d i f f e r e n t t i m e s f e e d i n g on f o u r t h and f i f t h
o f the t a r n i s h e d p lant bug.

1971* t h e

i n s t a r nymphs

F u r t h e r m o r e , a few t o a d s , B u f o a m e r i c a n u s

H o l b r o o k , w e r e f o u n d and c o l l e c t e d when s a m p l i n g t h e a l f a l f a
in 1 9 7 0 .

fields

I n t h e d i s s e c t i o n o f f o u r , t wo o f t hem had s e v e n t a r n i s h e d

p l a n t bug a d u l t s

in t h e i r

gut.

A small

had f i v e t a r n i s h e d p l a n t b u g s in i t s

t o a d about

gut,

1 ^ inches

long

o n e o f t hem a l m o s t e n t i r e l y

w h o l e ; t h e o t h e r s we r e i d e n t i f i e d by t h e i r h e a d s .

Organisms o t h e r

t h a n mi r i d s w e r e n o t c o u n t e d i n t h e s e t w o t o a d s .

The m o r e a b u n d a n t

organisms found
weevils

in the o t h e r to ad s were a n t s , m i l l i p e d e s ,

( l a r v a e and a d u l t s ) ,

(la rv ae) and c o c c l n e i i i d s

elaterids

lygaeids,

( l a r v a e and a d u l t s ) ,

( l a r v a e and a d u l t s )

noctui ds

( T a b l e 3)■

I n 1 9 7 0 , a r e c e n t l y k i l l e d t a r n i s h e d p l a n t bug was f o u n d i n f e c t e d
with a fungous d is e a s e .

T h i s s p e c i me n was s e n t t o t h e U n i v e r s i t y o f

C alifo rn ia a t Berkeley fo r
identified

the

identification,

f u n g u s a s a n Hy p h o my c e t e .

and Dr . G e r a r d M. Thomas
T h i s f u n g u s may h a v e c a u s e d

22

T a b le 3.

Organisms found in t h e gut o f f o u r t o a d s , Bufo
a m e r l c a n u s , p i c k e d up f r o m a l f a l f a f i e l d s ,
East Lansing, Michigan,
1970.

T o a d Humber
O r g a n i sms

2a

3

k

12

0

0

0

hi 1 1 i p e d e s

8

0

0

0

Lygaei d s - a d u l t s

6

0

0

0

E l a t e r i d s - a d u 1t s

5

2

0

0

W e e v i 1s - a d u l t s

k

0

0

0

W e e v i 1s - 1a r v a e

1

0

0

0

Cent ip ed es

h

0

0

0

S t a p h y 1 i ni d s - a d u 1 t s

h

2

0

0

FI i e s

1

0

0

0

Cocci n e 11i ds

0

3

0

0

N o c t u i d s - 1a r v a e

0

5

0

0

Co r i z i d s - a d u 1 t s

0

2

0

0

T a r n i s h e d p l a n t bugs

0

0

5

2

Uni d e n t i f i e d - l a r v a e

2

0

0

0

Nabi d s - a d u 1t s

0

2

0

0

A n t s - a d u 1t s

1

A i l k i n d s o f body p a r t s o f i n s e c t s and m i l l i p e d e s w e r e found
in t h i s t o a d and w e r e d i f f i c u l t t o i d e n t i f y .

23

a number o f o t h e r u n e x p l a i n e d a d u l t
was p e r h a p s n o t a l w a y s d e t e c t e d
may h a v e d e v e l o p e d

later

d e a th s found

in th e e a r ly

in t h e s eason a f t e r

in th e f i e l d

and

stages of infection

or

sam p lin g had c e a s e d .

ALFALFA PLANT BUG
By r e v i e w i n g t h e p e r t i n e n t
studies

l i t e r a t u r e a n d by m e a n s o f t h e p r e s e n t

on t h e b i o l o g y o f t h e a l f a l f a

p la n t bug,

the

follow ing fe a tu re s

may b e o b s e r v e d .

H o s t s . - The a l f a l f a

p l a n t bug h a s been

a l f a l f a and c l o v e r s a n d ,
golden

ro d , and b e a n s .

i n some c a s e s ,

When d i s t u r b e d

moves a g r e a t e r d i s t a n c e

than the

reported

t o f e e d e s p e c i a l l y on
on p o t a t o e s ,

in a l f a l f a

tarnished plant

fields,
bug,

buckwheat,

this

but

bug

generally

n o mo r e t h a n t w e n t y f e e t .

Feed i n q habi t s . - The a l f a l f a
stems,
downwards p o s i t i o n .

p l a n t b u g was a l w a y s

or buds,

fe e d in g or

f o u n d a l o n e on l e a v e s ,

resting

Th e y a r e mo r e r e a d i l y d i s t u r b e d

in an upwards or
than the ta rn is h e d

p l a n t bu g, and even t h e g r a v i d f e m a l e s , w hich w e r e h e a v i e r
o t h e r bugs, were a b l e t o f l y

O v e r w i n t e r f n q . - The a l f a l f a

s h o r t d i s t a n c e s when d i s t u r b e d .

p l a n t bug o v e r w i n t e r s

in M ichigan,
The e g g s i n t h e s e s t e m s h a t c h
h a s a b e a r i n g on t h e

than th e

especially

in t h e egg s t a g e

in t h e s t u b b l e o f a l f a l f a .

i n e a r l y May.

Temperature probably

length of th e h a tc h in g time

(Hughes

(9^3)»

2k

a lt h o u g h Knight

(19^1)

states

that

t h e s e mi r i d e g g s h a v e a r e l a t i v e l y

impermeable c h o r i o n which p e r m its

them t o remain v i a b l e f o r s e v e r a l

months,

even embedded in m a t e r i a l

which is alm o st c o m p le te ly d e s i c ­

cated.

I n th e p r e s e n t work,

several

alfalfa

stems w ith a l f a l f a

b u g e g g s embedded i n t h e m w e r e b r o u g h t t o t h e
19 71 -

These eggs were c a r e f u l l y

c o n t a i n e r s w i t h humid f i l t e r
kept

in in cu b ato rs a t

laboratory

taken out and p la c e d

p a p e r in t h e botto m .

l a mp.

The f i l t e r

The f i r s t

nymphs a p p e a r e d a t

and o t h e r emerged a t
the

incubators.

after

of

others

o f nymphal
spent

emer­

55 d a y s

th e eggs were p la c e d

in
alive

thi s tim e .

to the fact that
As t h i s

in time f o r

the a lf a lfa

could h appen,

in t h e p l a s t i c

t h e s e eggs t o h a t c h

p l a n t bug d i a p a u s e s

i s p r o b a b l y due

in th e egg s t a g e .

t h e egg d e v e l o p m e n t would n o t be resumed u n t i I
container

is a v a ila b le ,

but only a f t e r

the period

o f d ia p a u s e developm ent in t h e egg i t s e l f has been c o m p leted .
is

light

p a p e r was m o i s t e n e d e v e r y

17 d a y s ;

and 81 d a y s a f t e r

plastic

O t h e r u n h a t c h e d e g g s were o b s e r v e d t o be s t i l l

The d i f f e r e n c e

water

72

in small

16 h o u r s

day and o b s e r v a t i o n s were c o n d u c t e d as t o t h e d a t e s
gence.

in m i d - O c t o b e r ,

These cages were

7 8 - 8 0 ° F , a n d 6 5 + 5 % RH, a n d

p r o v i d e d by a f l o u r e s c e n t

plant

the p o s s ib ility

season,

that

th e s e eggs were l a i d a t

s o t h o s e w h ich were

laid e a r lie r

p e r i o d o f d i a p a u s e and h a t c h e d e a r l i e r
l a t e r on.

different

There

times of

probably completed t h e i r

than the o th e r s

t h a t were

O b v i o u s l y , much mo r e r e s e a r c h w o u l d b e n e e d e d t o s t a t e

a n y c o n c l u s i o n s on t h e a l f a l f a

plant

the

bug e g g d i a p a u s e .

laid

25

S p r i n g a p p e a r a n c e . - The f i r s t

nymphs o f a l f a l f a

p l a n t bugs w ere c o l ­

l e c t e d on t h e M i c h i g a n S t a t e U n i v e r s i t y ,
L a n s i n g f a r m s on J u n e U,
on t h e new t e n d e r a l f a l f a
host

range

1970 a n d J u n e 5*
stems.

rod and b ea n s

( Hu g h e s

Ovi p o s i t i o n . - The a l f a l f a

plants

species e x h ib its a r e s tr ic te d

The a l f a l f a

including potatoes,

p l a n t bug i s p r o b a b l y more s p e c i f i c
bug in i t s

plants

in t h e

choose the tender succulent

laboratory,

growth,

tarnished
done under

p l a n t bug

(Figure 4 ) .

the

stems.

By

in cages

i n s e c t s seemed t o

p o s s i b l y b e c a u s e t h e s te m s were

to puncture with t h e i r o v ip o s ito r s .
in g ro up s o r rows, b e i n g a

than

oviposition h abits.

i n t h e f i e l d a n d when a d u l t s w e r e c o n f i n e d

containing a lf a lf a

together

buckwheat,

p l a n t bug c o n f i n e s most egg l a y i n g t o a l f a l f a

observations

sweet

19*0)-

the tarnished plant

easy

1971 * when t h e y w e r e f e e d i n g

( o l i g o p h a g o u s ) , by f e e d i n g e s p e c i a l l y on a l f a l f a ,

c l o v e r a n d a f ew a d d i t i o n a l
golden

This

East

The e g g s a r e

little

laid closely

b ig g e r than those o f the

I n b o t h o f t h e m , when r e a r i n g was

laboratory co n d itions,

t h e egg c a p s p r o t r u d e d

slightly

above t h e e p i d e r m is of th e bean pod.

Nymphal s t a g e s . -

The mean d e v e l o p m e n t a l
of the a l f a l f a

plant

period of

the fiv e

bug h a s b e e n s t a t e s

2 8 . 3 0 d a y s a f t e r mean t e m p e r a t u r e s o f 7 9 - 2 8 a n d 6 2 . 7 ^ ° F ,
t h e t e m p e r a t u r e b e i n g t h e most
required for successive in s ta rs
t h e mean t e m p e r a t u r e ,

important f a c to r
t o emberge

in the

instars
as

period.

, a nd

respectively,

le n g th of time

( H u g h e s o p . ci t ) .

t h e s h o r t e r t h e n ymp hal

18.^7

The h i g h e r

Fi gure 3

Tarnished
nymphal

Fi g u r e

k

p l a n t bu g e m e rg in g from t h e f i f t h

instar.

A l f a l f a p l a n t bug e g g s
at

laid

laboratory co n d itio n s.

i n a common b e a n pod

27

A duIts.-

The f i r s t

alfalfa

p l a n t bugs c o l l e c t e d

f i e l d were taken a t
June 2nd,

1970.

r e a d i l y when

the Michigan S t a t e U n i v e r s i t y

The a d u l t s a r e

disturbed,

active

in a l f a l f a

m i g r a t i o n and o c c a s i o n a l l y ,

so spread

f i e l d s and

fly

is probably due to gradual

t h e y may b e t r a n s p o r t e d

long d i s t a n c e s

in t h e egg s t a g e .

N a tu r a 1 enem ies.- During the p resen t

study perio d ,

were ob serv ed f o r th e a l f a l f a
o f them h a v e

b e e n r e p o r t e d by t h e

that

not have them.

it

f a r m s on

u s u a l l y only to a d ja c e n t p l a n t s , but they

are not considered strong f l i e r s ,

in hay

by s w e e p i n g i n t h e

does

literature.

no n a t u r a l

p l a n t bug,

enemies

and none

T h i s d o e s n o t mean

LABORATORY REARlNG

The r e a r i n g p r o c e s s
with

relative

success

f o r t h e t a r n i s h e d p l a n t b u g wa s c a r r i e d o u t

in t h e

of 78- 8 0 ° F , with a r e l a t i v e
v i d e d by a f l o u r e s c e n t

laboratory under a c o n tro lle d
h u m i d i t y o f 65 +

lamp f o r

the techniques of

or at

, and w ith

16 h o u r s a d a y .

was p e r f o r m e d w i t h some d i f f i c u l t i e s ,
reproduction at all

S%

temperature
light

Initially,

pro­

the process

a s many s p e c i m e n s d i e d w i t h o u t

le a s t without

laying eggs.

However,

gradually

r e a r i n g them in t h e i n c u b a t o r s w ere im proved,

so

d a t a c o u l d be r e c o r d e d .
Five s u c c e s s iv e

g e n e r a t i o n s were r e a r e d w ith f i v e

tarn ish ed plant bugs,
tions.

The a d u l t s

s t a r t i n g with fiv e

for the

five

p a i r s as p a r e n ta l

at

stages

Table 2,

especially

i n j u r e d by h a n d l i n g .
usually attacked

in th e

t h e whole

stages,

a n d some s p e c i m e n s w e r e

first

especially

laboratory

r e a r i n g of the

th e a l f a l f a p l a n t bug d id not

This kind of

intraspecific

t h e s e t wo mi r i d

i n t e r f e r e n c e w ith each o t h e r .

n ymph al

of ta r n is h e d

a d u l t s and nymphs, a c a n n i b a l i s t i c h a b i t

In c o n t r a s t ,

the s ta tu s of

some s p e c i m e n s t h a t

M ortality

T h o s e i n j u r e d a n d some d e a d i n d i v i d u a l s w e r e

show a n y c a n n i b a l i s m a t a l l .
might a f f e c t

197'•

immature s t a g e s ,

throughout

t a r n i s h e d p l a n t bug.

I and 2.

r e a r i n g p r o c e s s was h i g h , a s can be se en in

by n o r m a l

t h a t was o b s e r v e d

in T a b le s

o f th e t a r n i s h e d p l a n t bugs were taken

2 day i n t e r v a l s d u r i n g t h e y e a r o f

p l a n t bugs d u r i n g t h e

genera­

generations are presented graphically

in F i g u r e 5, and t h e c o m p l e t e d a t a a r e p r e s e n t e d
Counts o f d i f f e r e n t

groups of

species

in t h e i r c o m p e t i t i v e

I t was o b s e r v e d t h a t

reached the a d u lt
on t h o s e a f t e r
28

stage

competition

i n some c a s e s ,

f e d on t h e o t h e r

th e second i n s t a r .

It

Fi g u r e 5

Regression

l i n e o f number o f t a r n i s h e d

bug r e a r e d u n d e r
generat i on.

laboratory conditions*

plant
on

400-

300

11 i c u i n

200

6 3 . 9 3 x (37.7 4X )

100 .

March

Apri 1

May

June

July
GENERAT1ONS

August

S e pt e m be r

October

November

30

seemed t h a t
after

this

c o n d i t i o n wa s o n e o f t h e h i g h e s t m o r t a l i t y

lack o f food,

for the

last

t h r e e nymphal

counts of the a d u lts are p resen ted because
stage

i s mo r e r e l i a b l e

ticular

generation

it

instars.

from t h e

stages of the tarn ish ed p lant

were t h e

required

for

most p a r t ,

with

f o r nymphal

in t h i s

study.

variable

(1943)

Th e h a t c h i n g p e r i o d

sects

(Table

1).

d a y s , and t h e a d u l t
The a l f a l f a

and f i f t h

p l a n t b u g was o n l y

instars

in the fiv e d i f f e r e n t
The f i r s t

and th e f i f t h

instar

re p li c a tio n s of
to

in­
10.50

to 42.25 days.

reared d u rin g the p aren tal
in t h e b e a n p o d s ,

h a t c h and t h e bean pods got d r y .

tarnished plant

length

for the

r a n g in g from 8 . 9 5

l o n g e v i t y a mean o f 3 7 * 1 5

Th e y w e r e f e e d i n g a n d o v i p o s i t i n g

eggs d i d not

in th e

on t h e t i m e r e q u i r e d

The f i v e

s h o we d a mean p r e o v i p o s i t i on p e r i o d

ation.

in a p a r ­

s howed a mean r a n g i n g f r om 6 . 4 4 t o 6 - 9 0 d a y s .

to 4.85 days

this

the d i f f e r e n t

These d a t a a g r e e ,

i n s t a r h a d a mean p e r i o d o f 4 . 0 4 t o 4 . 2 0 d a y s ,
a mean o f 4 . 1

that

The f i r s t

t h a t p r e s e n t e d by Hughes

development.

replications

bug a r e q u i t e

t h e i r development.

longer stages

that

reproductive stan d p o in t.

I t wa s o b s e r v e d d u r i n g t h e p r e s e n t s t u d i e s

of time

On l y t h e

is believed

in d e m o n s t r a t i n g p o p u l a t i o n p e a k s

factors,

b u g was r e a r e d up t o t h e f i f t h

Therefore,

but

only

g e n e r a t i o n , when

gener­
the
the
it

was s t o p p e d a r b i t r a r i l y .
The n u m b e r o f e g g s
o f t a r n i s h e d and a l f a l f a
is presented

in Table 4.

laid

i n b e a n pods by t h e

plant

b u g s , when c a g e d

parental

generations

t o g e t h e r and s e p a r a t e l y

31

Table 4.

C o m p a r i s o n o f t h e n u m b e r o f e g g s l a i d i n common b e a n s by t h e
p a r e n t a l g e n e r a t i o n s o f t h e t a r n i s h e d and a l f a l f a p l a n t bugs,
r e a r e d mixed and s i n g l y in groups o f f i v e p a i r s , a t 78-80°F
a n d 6 5 + 5 % RH, E a s t L a n s i n g , M i c h i g a n .
1971-

_________ Number o f e g g s
Replic.
Number

l a i d ___________

Mi xed
Date

Singly

TPB

APB

TPB

APB

777

230

1

7/29/71

to 8/14/71

142

119a

2

7/29/71

to 8/20/71

181

210

1919

236

3

7/29/71

t o 8/12/71

98

189

1019

178

4

7/29/71

t o 8/12/71

171

17

1340

28 4

5

7/29/71

to 8/12/71

54

122

91 1

248

6

7/29/71

to 8/12/71

48

74

b

317

115.67

120.17

Means

1193-2

248.83

The a l f a l f a p l a n t b u g e g g s d i e d a n d t h e p r o c e s s c o u l d n o t b e
f o l l o w e d f o r more th an one g e n e r a t i o n .
Data no t

registered.

32

The t a r n i s h e d p l a n t

b u g e g g s , when t h e

in se c ts were

s i g n i f i c a n t l y outnumbered e i t h e r the a l f a l f a
tarnished
that

p l a n t bug m i x e d w i t h t h e a l f a l f a

the tarnished p lan t

weeks a f t e r

accomplished without c o n ta c t
mate o n c e and o v i g e n e s i s
O viposition
a small

p l a n t bug.

continues a f t e r

in t h e t a r n i s h e d p l a n t

laying eggs several

probably because the females

o v i p o s i t i o n h a s begun.
b u g was f a v o r e d by p e e l i n g

l o n g i t u d i n a l l y o r c u t t i n g an end.

t h i s way o v i p o s i t i o n wa s c o n c e n t r a t e d
eggs were e a s i l y c o u n te d .

I t was o b s e r v e d

i n s u c h a way t h a t o v i p o s i t i o n was

between s e x e s ,

s t r i p o f t h e b e a n pods

observed

p l a n t bug a l o n e , or th e

bug fe m a le s w e r e even

t h e males had d i e d ,

reared alone,

in

t h o s e a r e a s o f t h e bean and

Most o f t h e a l f a l f a p l a n t

bug eggs were

la id c lo se to th e ju n c tio n o f the p e t i o l e of th e bean,

though th e y

laid

In

some e g g s on t h e p e e l e d a r e a o f t h e b e a n s .

even

On s e v e r a l

occasions,

t h e b e a n s w e r e a t t a c k e d by f u n g u s where p e e l i n g o r c u t t i n g

was m a d e .

Ho we v e r , m o s t o f t h e nymphs h a t c h e d .

e g g s , when t h e
the t a r n is h e d
se c ts were
In s i x
alfalfa

in s e c ts were reared a lo n e s i g n i f i c a n t l y
p l a n t b u g e g g s and a l f a l f a

bug e g g s

bug

outnumbered

generation

(Table 4 ) .

r e p l i c a t i o n s o f ea c h s p e c ie s d u r i n g th e p r e s e n t work,
plant

plant

p l a n t b u g e g g s when t h e i n ­

reared to g e th e r during th e p aren tal

when r e a r e d t o g e t h e r .
hatch,

The a l f a l f a

the

s l i g h t l y outnum bered th e t a r n i s h e d p l a n t bug,
But,

as th ese a l f a l f a

plant

bug e g g s d i d n o t

t h e o b s e r v a tio n s could not be follow ed fo r subsequent

generations.

FI ELD STUDI ES

The s a m p l e s o f t h e mi r i d c o m p l e x t a k e n
Michigan S t a t e U n i v e r s i t y ,
of

East Lansing,

1971, a r e p r e s e n t e d

i n T a b l e s 5 a n d 6 , a n d s howed g r a p h i c a l l y
im p ortance in t h i s

alfalfa

plant

bug.

study a re

fields

at

f r o m May 19 t o No v e mb e r 17

1 9 7 0 , a n d f r o m May 3 t o November 3 o f

most

in a l f a l f a

in F i g u r e s 6 - 1 3 .

in d e t a i l
Of f o r e ­

t h e t a r n i s h e d p l a n t bug and t h e

T h e s e t wo p e s t s o c c u r t h r o u g h o u t much o f t h e

Eastern United S ta te s .

T a r n i s h e d p l a n t b u g . - The f i r s t

m i r i d b u g s o f t h e c o m p l e x t o s how up

were th e t a r n i s h e d p l a n t bugs,
of t h e i r h a b it

of o v erw in terin g

t a k e n on May 3 ,
a total

in t h e a d u l t

probably because

stage.

With t h e samp le

1971 t h e p o p u l a t i o n d e n s i t y was 2 i n f i v e

o f 500 s w e e p s .

Th e p o p u l a t i o n d e n s i t i e s

up t o t h e t i m e o f t h e f i r s t

cutting

in e a r l y

p o s sib ly died or m igrated to the c l o s e s t

fields

gradually

a nd

increased

J u n e , when some o f t he m

fields,

a n d some o f t he m

r e m a i n e d on t h e g r o u n d a n d f e d on t h e y o u n g s t e m s a n d b u d s a f t e r c u t ­
ting,

Some o t h e r s may a p p e a r a f t e r

leaves,

straw ,

the overw intering stage under

c r e v i c e s and v e g e t a b l e m a t e r i a l

when s w e e p i n g a f t e r c u t t i n g ,

in

1970, and i n m i d - J u l y ,

b o t h y e a r s w e r e f l o w e r i n g t h e mo s t

the f i r s t

so

( F i g u r e s 6 and 7 ) .

the previous peak.

33

c u t t i n g was r e a c h e d

1 9 7 1, when t h e a l f a l f a

t h e s e c o n d c u t t i n g wa s d o n e a n d t h e p o p u l a t i o n
t o ab o u t one f o u r t h

in t h e f i e l d ;

some a d u l t b u g s a r e c o l l e c t e d .

The a d u l t p o p u l a t i o n p e a k a f t e r
e a rly July

left

A fter

fields

By t h i s

time

d e n s i t i e s w e n t down
this cutting,

the

in
in

34

Table 5.

Comparison
o f t h e p o p u l a t i o n d e n s i t i e s o f t h r e e p l a n t bugs
a s c o l l e c t e d by s w e e p i n g i n f i v e f i e l d s a t t h e M i c h i g a n S t a t e
U n iv e r s ity farm, E ast Lansing, Michigan.
1970.

Accumulated
Da ys

Date

T a rn i shed
P l a n t Bug

A d u 11 s
May
June

19
29
5
12

19
23
July

1

1I
15
21

August

31
4
10

17
24
September

October

November

2
8
16
21
28

139
149
156

I63a
170
174
182
192
196
202a
212
216
222
229

236a
245
251
259
264
271

5

278

12
21

2 83

27
3
11

17

292
298

305
313
319

Nymphs

A d u 1t s

59
84
103
14
83
43
140
605
434
319

29
90

4
23
4
27
37
36

121

16

108

124

0
0

70
95
23
1
1

0
0
2

195

326

90
127

282

486

162

448
4 27

166

163
184
146
214

368

351
827
581
616
41 7
719
300

117
183
4 72
905
399
231
164
117
42

188
185
151

11
8

10

0

4

a Cutting
b Nymphs f o r t h i s

A l f a 1f a
P l a n t Bug

s p e c i e s were not c o u n te d .

216

177
125
81
105
44
15
20
8
1

Nymphs
0
0
22
1

7
9
24
69
1 18

145
245
510
75 3
7 29
575
396
446
231
118

97
52
41
21
0
0
0
0

T r i q o n o t v 1u s
ruf i corni s

A dultsb
0
0
2

4
1
0
0

46
77
139
121

164
118

30
193
2 07
2 45
135
56
16

4
29
5
2
0
0
0

35

Table 6.

C o m p a r i s o n o f t h e p o p u l a t i o n d e n s i t i e s o f t h r e e p l a n t b u gs
a s c o l l e c t e d by s w e e p i n g i n f i v e f i e l d s a t t h e M i c h i g a n S t a t e
U n iv e r s i ty farm, East Lansing, Michigan.
1971

Date

Accumulated
Days

Tarni shed
P l a n t Bug

AduIts
May

3
12
18
29
June
4
11
18
29
July
8
13
20
26
Au g u s t
3
10
16
24
30
September 8
13
22
29
October
5
12
18
25
November
3

123
132
138
149
155a
162
169
180
189
19**
201 a
207
215
222
228
236
242
251
256
265
272
278
285a
291
298
307

2
4
27
67
51
13
17
482
590
853
256
312
201
386
568
414
382
478
625
800
706
561
276
151
332
8

Nymphs
0
0
0
0
0
69
35
8
32
182
137
309
377
4 29
372
255
361
1103
1191
49 0
208
59
13
5
3
0

A lfalfa
P l a n t Bug

Adul15
0
0
0
0
0
6
22
355
277
269

11
133
138
271
307
395
4 74
205
196
81
62
24
7
2
2
0

Nymphs
0
0
0
1
13

214
100
67
164
21 1
180
370
554
541
491

131
81
32
45
25
15
2
0
0
0
0

Tr i q o n o t y l u s
rufi corni s
A d u 1t s

Nymphs

0
0
0
0
0
1 16
10
42
65
59
40
39
245
157
370
315
152
39
22
8
9
6
2
8
2
0

0
0
0
0
33
371
7
2
3
5
4
7
61
34
25
22
14
19
3

a Dates of c u t t i n g .
The d r y s e a s o n p r o b a b l y c a u s e d t h e d e l a y i n t h e
cutting.
T h i s happened in onl y one f i e l d .

0

0
0
1
0
0
0

last

Fi g u r e 6

Population d e n s itie s
the a l f a l f a

of the tarnished p lant

p l a n t b u g , a n d T r i g o n o t y 1u s

rufi corn!s d u rin g the

1970 s e a s o n .

bug,

240.

APB and
T.R. s c a l e

1200
ADULTS 1970

O--- o
X— *If—
..

200

f

TPB
T. r u f i c o r n i s

—

APB
C utting

.1000

—

160-

DENSI TY

t

X

-800

120

h 600

80

40

•200

— *■'

30
Hay

19
June

29

4

Ju ly

August

September

October

November

ADULTS 1971
T. rufi corn i s
APB
Cutting

i* r
August

)

i)

September

\i

October

&

November

38

t a r n i s h e d p l a n t bug p o p u l a t i o n i n c r e a s e d a s t h e a l f a l f a
r e a c h in g t h e h i g h e s t d e n s i t y in m id-S eptem ber fo r
l a t e r in
this

1971*

in

th is event,

such a s t h e

them t o t h e o v e r w i n t e r i n g s t a g e ;
and a l s o ,

1970 a n d a week

T h e t a r n i s h e d p l a n t b u g p o p u l a t i o n s w e n t down a f t e r

t i m e mo r e r a p i d l y t h a n t h e y h a d b u i l t

took part

grew up,

a third

a n d Ge o c o r i s

spp.

(which were o b s e r v e d

an im portant

role

(C lancy and P e a r c e
noted

Many f a c t o r s

probably

decreasing temperature that

t h e e f f e c t o f some b i o l o g i c a l

t h i s was c l e a r l y

up.

alfalfa cutting
agents,

in the p r e s e n t

i n some c a s e s ,

s u c h a s Nabi s s p p .

in th e f i e l d ) ,

1966),

lead

p o ssib ly played

alth o u g h no e v id e n c e o f

study.

A l f a l f a p l a n t b u g . - The a l f a l f a p l a n t b u g p o p u l a t i o n s a p p e a r e d i n
lower d e n s i t i e s
nished plant
swept a bout
b u g s , and in

bug ( T a b l e s 5 and 6 ) .
15 d a y s a f t e r
1971,

and
In

the i n i t i a l

later
1970,

than th o s e of the t a r ­
the f i r s t

collection

of ta r n is h e d

th e y were c o l l e c t e d more than one month

( F ig u r e s 6 and 7 ) .

These f a c t s

g i v e more s t r e n g t h

winters

in c o n t r a s t w ith th e t a r n i s h e d

in th e a d u l t

the a l f a l f a

plant

s t a r t i n g to hatch out
alfalfa

stubble.

relativ ely at

later

plant

bug in

p l a n t bug w h i c h o v e r ­

stage.

Apparently the f i r s t
of

plant

to the generally

accepted concensus of the o v erw in terin g of the a l f a l f a
t h e egg s t a g e ,

a d u l t bugs were

c u t t i n g does not a f f e c t

bug p o p u l a t i o n ,

the

because at th is

initial

increase

time they are

from t h e o v e r w i n t e r i n g egg s t a g e i n

the old

T h e ir p o p u l a t i o n d e n s i t i e s were i n c r e a s i n g a lth o u g h

low l e v e l s ,

and d e c re a s in g a f t e r

r e a c h i n g t h e h i g h e s t peak a b o u t m id - S e p te m b e r ,

th at as

rapidly as the

tarnished p lan t

bug i n

1 9 70 .

39

The c u r v e f o r

1971

( F i g u r e 7) shows t h e e f f e c t o f c u t t i n g ,

i f t h e s a m p l e i s t a k e n t h e same we e k t h e c u t i s ma d e .
week i a t e r ,
density

in

th e numbers a r e ab out t e n t i m e s more,
late August,

Trigonotylus

and d e c r e a s i n g

l a t e r on t o z e r o in m i d - O c t o b e r .

r u f i c o r n i s This s p e c i e s s l i g h t l y outnumbered t h e a d u l t

1970, b u t w e r e s i g n i f i c a n t l y

another,

inferior

r e a c h e d t wo p e a k s d u r i n g

the highest one,

i n t h e mi r i d c o mpl e x t h a t

I97i-

The

1970; o n e i n e a r l y A u g u s t a nd
D u r i n g 1971,

t h e pop­

peak in a b o u t m id-A ugust, b e i n g t h e

showed up a n d t h e f i r s t

last

to disappear.

s t a g e s . - The nymphal p o p u l a t i o n s a r e a l s o shown i n T a b l e s
5 and 6 , and p r e s e n t e d g r a p h i c a l l y

13*

p l a n t bug d u r i n g

i n n u mb e r s d u r i n g

in e a r l y S ep t em be r .

u l a t i o n o n l y showed a s m a l l

Nymphal

Ho we ve r , a

reaching the highest

populations of the a l f a l f a

population

especially

I n 1 9 7 0, t h i s

in F ig u re s 8 -

s t a g e showed up e a r l y i n t h e s e a s o n f o r b o t h t h e

t a r n i s h e d and a l f a l f a

p l a n t bugs.

In

1971 a l f a l f a

p l a n t bug nymphs

a p p e a r e d f i r s t and i n h i g h e r nu mbe r s t h a n t h e t a r n i s h e d p l a n t b u g .
T h i s may be e x p l a i n e d by t h e o v e r w i n t e r i n g o f t h e f o r m e r i n e g g
s t a g e and t h e l a t t e r
not

in ad u lt

stage.

The f i r s t a l f a l f a

seem t o a f f e c t e i t h e r o n e o f t h e p o p u l a t i o n s ,

their

low d e n s i t i e s ,

c u ttin g did

po ssib ly because of

a n d b o t h in 1970 a n d 1971 t h e nymphal a l f a l f a

p l a n t bug d e n s i t i e s w er e h i g h e r t h a n t h o s e of t h e t a r n i s h e d p l a n t
bug a t
first

t h e same t i m e .
but

The nymphal a l f a l f a p l a n t bug p e a k s w e r e r e a c h e d

t h e i r d e n s i t i e s a t t h i s p o i n t were a b o u t h a l f t h o s e r e a c h e d

Fi g u r e 8

Nymphal
plant

population d e n s itie s

bug and t h e a l f a l f a

1970 s e a s o n *

of the tarnished

p l a n t bug d u r i n g t h e

NYMPHS 1970

• — *—

TPB
APB

J

30
May

19
J une

Cutting

19

9

July

18
A ugust
OATE

)

¥7
Se p te m b e r

1
October

5

5
November

Fi g u r e 9

Nymphal

population d e n s itie s of the tarnished

p l a n t bug a n d t h e a l f a l f a
1971 s e a s o n .

p l a n t bug d u r i n g t h e

NYMPHS 1971

12001

•—

1000-

•—

TPB

„__x—

f

APB

..

Cutting

800

-6001
V)
UJ
o

/
40 0

/
t

*

/

It

200

9

\

f \

/
1

/

\

/

x

,

\

’ 1

/

f
x~

j

&
June

19
J u ly

S
August
DATE

28

^
September

—

7

___

27
October

W2

by t h e t a r n i s h e d p l a n t b u g n y m p h s .
A fter

this

t i m e t h e nymphal d e c r e a s i n g was e v i d e n t ,

stage of the a l f a l f a

p l a n t b u g wa s s t i l l

t h a t by O c t o b e r 2 7 ,
c o lle c te d with
found in

T h i s h a p p e n e d by m i d - A u g u s t .

1970, a l f a l f a

t h e s we e p n e t .

1971 was O c t o b e r 5 .

as the a d u lt

increasing,

to the point

p l a n t b u g nymphs w e r e n o l o n g e r

Th e

last

time a l f a l f a

p l a n t bugs were

T h e h i g h e s t p e a k o f n y mp ha l

populations

i n t a r n i s h e d p l a n t b u g was r e a c h e d by a b o u t m i d - S e p t e m b e r i n
and a l s o

in

197 1, a f t e r w h i c h t h e y d e c r e a s e d a n d ,

1 9 7 0 , a n d November 3 ,

Nymphs-adults

1 971, n o n y m p h a l

r e la tio n s h ip s .-

by November

1970
17,

s ta g e s were found.

The r e l a t i o n s h i p s b e t w e e n nymphs a n d
a d u l t s o f t h e t a r n i s h e d and a l f a l f a

p l a n t bugs d u r i n g t h e y e a r s
in F ig u re s

10 -

13.

and

1970

D u rin g 1970,

1971 a r e p r e s e n t e d

t h e nymphal

o f t h e t a r n i s h e d p l a n t bug w e r e r e l a t i v e l y
the adult populations early
a lfa lfa cutting,

in th e s e a so n ,

h ig h e r than th e
rapidly

latter.

The l a s t

f i e l d was Nov e mbe r 11, when
(Figure

During the year
alfalfa

however,

after

peak,

the th ird

i n s u c h a way

t h e f o r m e r was

t i m e t h e ny mp h s d e c r e a s e d m o r e
d a t e t h a t ny mp h s w e r e f o u n d i n t h e

were c o l l e c t e d .

T he re were

151 a d u l t s

10) .

197 0 ,

t h e n ymp h a l

population

d e n s i t i e s of the

p l a n t bug r e a c h e d a p e a k more t h a n t w i c e a s h i g h a s t h a t

r e a c h e d by t h e a d u l t
first

low i n c o m p a r i s o n w i t h

reached t h e i r

A fter th is

than the a d u l t s .

i n 500 s w e e p s

population d e n s itie s

t h e nymphal d e n s i t i e s w e r e i n c r e a s i n g

t h a t when t h e nymphs a n d a d u l t s

graphically

populations.

Th e nymphs s t a r t e d

a n d t h e d e c r e a s e was a l s o i n t h e same w a y ,

to increase

showing o n ly one

Figure

10.

R e l a t i o n s h i p s b e t w e e n a d u l t a n d nymphal
ulation densities
during the

pop­

o f t h e t a r n i s h e d p l a n t bug

1970 s e a s o n .

TPB 1970
*— • -----

Adults
Nymphs
C utting

/

50

f9

Hay

J une

9

^9
July

18
Aug ust
DATE

)

27
S e p te m b e r

1^

§

October

November

44

peak through the season.

Th e

t a s t nymphs c o l l e c t e d w e r e on O c t o b e r

21 w h i l e t h e a d u l t s w e r e s t i l l
D u r i n g t h e s a m p l i n g made i n
a n d nymph p o p u l a t i o n d e n s i t i e s
identical

to that

of adult density,
the

l a t e r one

f o u n d on No v e mb e r
1971,

o f t h e t a r n i s h e d p l a n t bug w e re a lm o st
However,

th e e a r l y one b e in g a l i t t l e

(Figure

the a l f a l f a

n ymph s ) w e r e q u i t e d i f f e r e n t
(in

higher

(mid-July)

than

r e a c h e d by t h e a d u l t

12).

On t h e o t h e r h a n d ,

two p e a k s

t h e r e w er e two peaks

t h e nymphs s h o w e d o n l y a c o n s p i c u o u s

peak ab o u t one f o u r t h h i g h e r th a n t h e h i g h e s t
populations

11).

the r e l a t i o n s h i p s between a d u lt

of the previous year.

(mid-September);

17 ( F i g u r e

l a t e June and

p l a n t bug p o p u l a t i o n s

d u r i n g t h e same y e a r :

( a d u l t s and

the a d u lts

l a t e August) w ith d e n s i t i e s

almost

showed
twice

a s h i g h a s t h e p r e v i o u s y e a r a n d nymphs w i t h o n l y o n e c o n s p i c u o u s
p e a k in e a r l y A u g u s t ,
adult

peak (F ig .

Summarizing,
1970 a n d
bug

197 1,

its

density

s l i g h t l y outnumbering the h ig h est

13).
the tarnished

significantly

( T a b l e s 5 and 6;

Figs.

p l a n t bug p o p u l a t i o n d e n s i t i e s ,
outnumbered t h o s e o f th e a l f a l f a

6 and 7 ) ,

72% o f t h e t wo ml r i d p o p u l a t i o n s a t
However,

t h e n y mp h a l

again,

th e end o f each y e a r ,

o f t h e t wo mi r i d n ymp h s a t

Fi g s . 8 a n d 9 ) •

respectively.

p l a n t bug c o m p r i s e d

p o p u l a t i o n s of t h e t a r n i s h e d p l a n t bug in

t h e t a r n i s h e d p l a n t b u g nymphal

the to ta l

plant

t h e f o r m e r m a k i n g up 80% a n d

p o p u latio n of the a l f a l f a

54% o f t h e t wo ny mph al

both in

1970;

p o p u l a t i o n s c o m p r i s e d 64% o f

t h e end o f

1971

( T a b l e s 5 and 6;

Figure

11.

R e l a t i o n s h i p s b e t w e e n a d u l t a n d n ymp h a l
ulation d en sities of
the

1970

season.

pop­

th e a l f a l f a p l a n t bug d u r in g

Adult Scale
200*

APB 1970
•------ • —

A dults

*

Nymphs

p-—

|

..

Nymph S c a l e
‘1000

C utting

160,

-800

120'

-600

\ji

80-

JlOO

\

*♦0-

■200

f
*

\

X - —

0.

t~ t
^0
Hay

-0

19
June

9

29
July

— IT "
A ug ust
DATE

Se pte mb er

19
October

8
November

Figure

12. R e l a t i o n s h i p s b e t w e e n a d u l t and nymphal
population d e n sitie s of the tarnished plant
bug d u r i n g th e

1971 s e a s o n .

1200
Adults
Nymphs
C u t t i ng

100Q

DENS1 TY

800

600

200

May

June

July

Aug ust
DATE

September

October

November

Figure

13-

R elationships

between a d u l t

a n d n ymp h a l

population d e n s it i e s of the a l f a l f a
bug d u r i n g t h e

1971

season.

plant

APB 1971

/

t*— - • ■

A dults

X-----

Nymphs
C u t t i ng

?

■p-

*
f\

\

\

»

\

1
/

Jo
May

20
June

8

Z9

re

July

August
DATE

7

27
Se pt e m be r

l'7
October

us

T a b l e 7-

T o t a l nu mb e r o f m a l e s a n d f e m a l e s o f t h e t a r n i s h e d a n d a l f a l f a
p i a n t b u g s f r o m w e e k l y s w e e p s a m p l i n g i n 1970 a n d 1971"
East Lansing, Michigan.

C a t e g o r y a n d Sp p.

Year

Ma 1e s

Feme 1e s

J u n e t o November
T a r n i s h e d P l a n t Bug

1970

3697

4216

34.04**

J u n e t o No vember
A l f a l f a P l a n t Bug

1970

969

1058

3.90*

J u n e t o November
T a r n i s h e d P l a n t Bug

1971

4185

4189

.002

J u n e t o November
A l f a l f a P l a n t Bug

1971

1469

1726

** D iffe re n c e highly s i g n i f i c a n t
*

Difference

significant

at

5%

level.

Chi

Square

20.67**

49

Sex r a t i o . - P r e 11 fi>1 n a r y i n v e s t i g a t i o n s o f t h e s e x r a t i o i n b o t h
t a r n i s h e d a n d a l f a l f a p l a n t b u g s a r e r e c o r d e d i n T a b l e 7The t a r n i s h e d p l a n t b u g f e m a l e s s i g n i f i c a n t l y o u t n u m b e r e d t h e m a l e s
i n t h e s a m p l i n g made w i t h a s t a n d a r d sweep n e t

i n 1970; w h e r e a s ,

a l f a l f a p l a n t bug f e m a l e s s l i g h t l y ou tnumbered t h e m a l e s ,
square being s ig n i f i c a n t at the
determined throughout the
17th)
this

for both s p e c ie s .
instance that

5%

level.

t h e Chi

I n s e c t s e x r a t i o was a l s o

1971 s a m p l i n g ( f r o m J u n e 5 t h u n t i l
The Chi

the

November

s q u a r e v a l u e c o mp u t e d i n d i c a t e d

t h e t a r n i s h e d p l a n t b u g s e x r a t i o was a l m o s t

in
1 t o 1.

The a l f a l f a p l a n t bug f e m a l e s s i g n i f i c a n t l y o u t n u m b e r e d t h e m a l e s .
Therefore,

these

r e s u l t s a r e n o t c o n c l u s i v e and more c o l l e c t i o n s a r e

needed to a u t h e n t i c a t e

i n f o r m a t i o n a b o u t t h e s e x r a t i o i n b o t h mi r i d s .

Envi r o n m e n t a l Condi t i o n s :

Weather,-

It

is well

known t h a t

t e m p e r a t u r e and p r e c i p i t a t i o n

o ne o f t h e mo s t i m p o r t a n t
a n d minimum t e m p e r a t u r e s ,
period of the
rainfall

roles

in In se c t b e h a v io r .

as well as th e r a i n f a l l

Maximum

d uring th e sampling

1970 and 1971 s e a s o n s , a r e p r e s e n t e d i n F i g u r e

is what f e l l

play

14.

The

d u r i n g t h e tim e p e r i o d between each sa mp le .

The t e m p e r a t u r e was r e l a t i v e l y mor e s t a b l e and c o n s i s t e n t d u r i n g
t h e 1970 and 1971 s e a s o n s t h a n t h e r a i n f a l l .

The r a i n f a l l

1970 was m o d e r a t e f o r t h e E a s t L a n s i n g a r e a w h i l e t h e
c h a r a c t e r i z e d by a l a c k o f p r e c i p i t a t i o n .

during

1971 s e a s o n was

How t h i s c a n b e c o r r e l a t e d

w i t h p o p u l a t i o n d e n s i t i e s o f t a r n i s h e d a n d a l f a l f a p l a n t b u g s c a n be

Ft g u r e

1A

Maximum a n d minimum t e m p e r a t u r e s
precipitation

(inches),

S* £ . S t a t i o n d u r i n g t h e

(°F) and

fo r the East Lansing
1970 a n d

1971 s e a s o n .

o
Inc. Prec.

1970

Max. Temp.

Min. Temp.

Max. Temp.

Min. Temp.

May

June

July

August

S e p te m b e r

October

51

e x p l a i n e d by t h e d i r e c t a n d i n d i r e c t e f f e c t s ,
a n d minimum t e m p e r a t u r e a n d p r e c i p i t a t i o n
and

since

fluctuations

p r e s e n t g r a p h i c a l l y a complex

i r r e g u l a r mosaic o f h it-a n d - m is s v a r i a t i o n .
B e f o r e e a r l y May t h e r e

due t o t h e f a c t
so p r e c i p i t a t i o n
populations,

that

i s a l m o s t no a c t i v i t y

tarnished

plant

and r a i n f a l l

not only a f f e c t

t h e p l a n t bugs f e e d ,

but

whereas p l a n t a t i o n s

in t h e c a s e o f a l f a l f a .

also

i n hu mi d a r e a s a l m o s t

reported that

th e dry season

In c o n t r a s t ,

1971 d i d n o t a f f e c t
the a l f a l f a

d e n s i t y peak in t h e " d ry s e a s o n " o f

increase.

Consequently,

reaching

A lfalfa

populations,

i n v a r i a b l y have l a r g e p l a n t bug

From t h e d a t a c o l l e c t e d by s w e e p i n g a t

bug p o p u l a t i o n s .

mini mum

l e a v e s on w h i c h

insect

populations.

in

On t h e

Temperature

insect populations.

s u p p o sed ly have small

bug

w ith the high

increasing,

the succulence of a l f a l f a

indirectly,

in drought a r e a s

Furthermore,

food s u p p l i e s a r e

p e a k s when c u t t i n g s a r e ma d e ,

1970.

tarnished plant

p l a n t bug e g g s p r o b a b l y do n o t h a t c h u n t i l

t e m p e r a t u r e and p r e c i p i t a t i o n ,

plantations

affect

hibernating,

d e s t r o y i n g some a d u l t s a n d p o s s i b l y nymphs a s w e l l .

t e m p e r a t u r e s go u p t o a b o u t 5 0 ° F ( I O ° C ) .

their

of e i t h e r bug, p r o b a b l y

bug a d u l t s a r e s t i l l

and c o l d t e m p e r a t u r e d i r e c t l y

o th e r hand, a l f a l f a

in

i n maximum

East Lansing,

it

may be

the tarnished plant

p l a n t bug had a p o p u l a t i o n

1971 o f mo r e t h a n t w i c e t h a t

the dry season favored the a l f a l f a

reached

p l a n t bu g

D1 SCUSSI ON

By r e v i e w i n g t h e b i o l o g y o f t h e t a r n i s h e d a n d a l f a l f a
bug,

it

c a n be r e p o r t e d

that

t o occupy s i m i l a r e c o l o g i c a l
sim ultaneously

throughout

they r e p r e s e n t
niches,

p h y s i o l o g i c a l l y and g e n e t i c a l l y .

different
niche

they d i f f e r

genera.

(1966):

b a s e d u po n i t s

its

"Ecological
precise

for survival

ecological

from each o t h e r ,

nich r e fe r s

food,

spatial,

What a n a n i m a l
and r e p r o d u c t i o n

feeding

i n t h e same a l f a l f a
as

they

represent

to the

fields,
t wo

of ecological

r o l e p l a y e d b y an a n i m a l

or h a b itu d in a l

requirements

does and what i t

needs as

in a given h a b i t a t

in

re­

determines

niche."

Eve n t h o u g h t h e a l f a l f a
habitat

but d iff e r in g m orphologically,

This a g r e e s w ith DeBach's d e f i n i t i o n

a particular habitat.
quisites

food is c o n c e r n e d ,

He r e t h e t wo mi r i d s a r e

On t h e same p a r t s o f o n e s p e c i e s o f p l a n t
but obviously

two gr o u p s w h ich a p p e a r

as f a r as

t h e same a r e a s ,

plant

p l a n t bug i s

duplicated

by t h e t a r n i s h e d p l a n t b u g i n a l f a l f a a r e a s ,

p l a n t bug d i f f e r s

a little

in i t s

a lte r n a te hosts.

The t e r m h a b i t a t

the tarnished

food r e q u i r e m e n t s and a l s o has o t h e r

and b i o t i c e n v i r o n m e n t o f a n a t u r a l
where i n d i v i d u a l s

i n t h e same

is used h ere to denote th e physical
population

of th a t p o p ulation normally

in a l o c a l i t y

or a r e a ,

l i v e and r e p r o d u c e

( U d v a r d y 1959) ■
Ho we v e r ,

the s im ila r ity

d o e s n o t make i t

niches of these

impossible fo r com petitive In te ra c tio n s

among t h e m i n n a t u r a l
plant

in e c o l o g i c a l

e n v ir o n m e n ts where t h e y a t t a c k

and where t h e y o v e r l a p

in t h e i r d i s t r i b u t i o n s .

52

t w o mi r i d s

to occur

t h e s a me h o s t
These com peti-

53

tive

in tera ctio n s are a biological

i n t e r a c t i o n s and o t h e r d i f f e r e n t
One f a c t o r

to c o n s id e r

is

p h e n o me n a

involving

characteristic

that

intraspecific

f a c t o r s and mechanisms.

i n some c a s e s an a p p a r e n t a b u n ­

dance of food or o th e r

r e s o u r c e s does no t p r e c l u d e o c c u r r e n c e of

com petition.

DeBach

actual

( o p . ci t . )

states:

involves

com petition,

(in th e sense of b o th er)

com petitive

and o t h e r

in a l f a l f a ,

plants)

both sp e c ie s.

the other

in t h e p r o c e s s " .
plant

are abundant

in r e l a t i o n

This can p r o b a b ly e x p l a i n

in d i f f e r e n t

in T a b le 8 .

the

f o r e v e r y y e a r and e v e r y

fact

states

table,

1930),

plant

bug o c c u r r e d

the tarnished
p l a n t bug

p e r h a p s b e w o r t h y t o men­
s p e c ie s , while the

in th e

late

The e s t a b ­

1920's

i n Iowa

from w he re t h e s p e c i e s has s p r e a d t o t h e n e i g h b o r i n g

and C a na da .

But

its

colonization,

in r e l a t i o n

to

the tarnished

p l a n t bug, has not been acco m p lish e d in numerous p o p u l a t i o n s ,
because of

summary

in d i f f e r e n t

1959

outnumbered the a l f a l f a
It will

t wo mi r i d s

A brief

p l a n t b u g i s a n i n t r o d u c e d o n e f r o m t h e Old W o r l d .

lishment o f the a l f a l f a
(Knight

the

f r o m 19^0 t o

According t o t h i s

location.

(alfalfa

l e v e l s o n c e t h e y b e c o me

t i o n h e r e t h a t t h e t a r n i s h e d p l a n t bug i s a n a t i v e
alfalfa

that

in the U n ite d S t a t e s .

p l a n t bug has al w a y s s i g n i f i c a n t l y

plant

t o the immediate needs of

o f t h e a b u n d a n c e shown by t h e s e t wo mi r i d s
is presented

bug a n d t a r n i s h e d

t h e same p o p u l a t i o n

regions

inter­

Therefore

e v e n when t h e s u p p l i e s o f f o o d

have been re c o rd e d a t about
established

even i f one does n o t harm or

i n t e r a c t i o n s a mon g a l f a l f a

bug can o c c u r

states

"The a t t e m p t o r

u t i l i z a t i o n by t wo o r m o r e o r g a n i s m s o f common r e s o u r c e s o r

requisites
fere

In f a c t ,

interspecific

interactions.

apparently

54

T a b l e 8.

Ab u n d a n c e o f L_. I i n e o l a r I s a n d A. 1 1 n e o l a t u s i n d i f f e r e n t r e g i o n s
i n a l f a l f a f i e l d s i n t h e U. S . a n d d i f f e r e n t y e a r s , a d j u s t e d t o
a common b a s e o f 100 n e t s w e e p s .

P lace

Species

Year

Number

Reference

S. P a u l , Mi n n e s o t a

L.

H neolarls

1940

1308

Hughes,

1943

S. P a u l , Mi n n e s o t a

A.

1i n e o l a t u s

1940

392

Hughes,

1943

S . P a u I , Mi n n e s o t a

L. 1i n e o l a r i s

1942

4608

Hughes,

1943

S. P a u l , Mi n n e s o t a

A.

lineolatus

1942

1532

Hughes,

1943

Mad i s o n , Wi s c o n s i n

L.

lineolaris

1945

371

Scholl &
M e d l e r , 1947

Mad i s o n , Wi s c o n s i n

A.

1i n e o la t u s

1945

133

Schol1 6
M e d l e r , 1947

1959

200

Ni emczyk £
G u y e r , 1963
Ni emczyk &
G u y e r , 1963

Lower P e n i n s u l a ,
Mi c h i g a n

L.

lineolaris

Lower P e n i n s u l a ,
Mi c h i g a n

A.

lineolatus

1959

20

A u r o r a , New York

L.

lineolaris

1959

1246

Ridgway &
G y r i s c o , I960

A u r o r a , New York

A.

1i n e o l a t u s

1959

------- A

R1dgway &
G y r i s c o , I960

*Data n o t found in t h e

literature.

55

There a r e ,

however, d i f f e r e n t

p l a n t bug t o c o m p e t e w i t h t h e
plant

factors that

closely

favor the a l f a l f a

related species,

bug, w i t h o u t b e i n g d i s p l a c e d a t a l l .

the tarn ish ed

The o v e r w i n t e r i n g i n t h e

e g g s t a g e p r o b a b l y p r o v i d e s t h e ma i n way t o s p r e a d and p o s s i b l y t o
c o l o n i z e new a r e a s ;

the morphological

c h a r a c t e r i s t i c s o f th e egg

such a s t h e c h o r i o n

im permeability being adapted to r e s i s t

long p e r i o d s

of d e s ic c a te d environment.

A n o th e r p o i n t i s t h e p r e s e n c e of n a t u r a l

enemies:

r e v i e w a n d by o b s e r v a t i o n s d u r i n g t h e

by t h e

present

studies,

natural

enemies

literature

the tarnished plant

( p a r a s i t e s and p r e d a t o r s ) , w h i l e t h e r e c o r d s t o d a t e

d o n o t show n a t u r a l

INTERSPECI

FI

bug h a s b e e n r e p o r t e d w i t h s e v e r a l

enemies f o r t h e a l f a l f a p l a n t

C COHPETITI ON J_N THE LABORATORY

The r e s u l t s

obtained

to the conclusion

that

in th e

p l a n t bug.

ditions

are q u ite d iffe re n t

and b e c a u s e o f t h e

l a b o r a t o r y would l e a d u n d o u b t e d l y

t h e t a r n i s h e d p l a n t bug would d i s p l a c e t h e

alfalfa

However , a s

it

i s well

known,

b u t t h i s d o e s n o t mean i t
p l a n t bug.

p l a n t b u g was n o t
beans.

Therefore,

environments,

l a c k o f e n o u g h d a t a on t h e a l f a l f a p l a n t b ug ,

As i t

is said

these

The p o l y p h a g o u s c o n d i t i o n

o f t h e t a r n i s h e d p l a n t bug p r o b a b l y f a v o r s i t

alfalfa

la b o r a to ry con­

from t h o s e found in n a t u r a l

r e s u l t s can not be taken as c o n c l u s iv e .

ments,

bug.

in

laboratory environ­

has a b s o l u t e dominance over th e
in a n o t h e r s e c t i o n ,

reared s u c c e ss fu lly

in t h e

the a l f a l f a

l a b o r a t o r y on common

by c o m p a r i n g t h e o v i p o s i t i o n o f b o t h s p e c i e s when

r e a r i n g s i n g l y a n d t o g e t h e r o n l y d u r i n g t h e a l f a l f a p l a n t bug p a r e n t a l
generation,

p r e l i m i n a r y r e s u l t s c a n be dr awn f r o m t h e i r c o m p e t i t i v e

interactions

(Table 4 ) .

bug s l i g h t l y o u t n u m b e r e d
plant

The number o f e g g s

( on an a v e r a g e o f s i x

b u g e g g s when r e a r e d

singly,

together.

t h e number o f e g g s

outnumbered

those

species

or the o th er,

groups)

plant

the tarn ish ed

H o w e v e r , when b o t h w e r e r e a r e d

l a i d by t h e t a r n i s h e d p l a n t b u g s i g n i f i c a n t l y

l a i d by t h e a l f a l f a

f a c t o r s may b e i n v o l v e d ,

l a i d by t h e a l f a l f a

p la n t bug.

Here,

again,

different

s u c h a s m o d i f i c a t i o n o f t h e medi um by o n e

and a c t i v e

i n te r f e r e n c e with each o th e r.

Factors

c o r r e l a t e d w i t h i n t r a s p e c i f i c c o m p e t i t i o n such a s c a n n i b a l i s m , which
is

known t o o c c u r i n t a r n i s h e d p l a n t b u g s , may a l s o come t o d e t e r m i n e ,

not the s t a t u s

of the w inner,

on t h e o t h e r .

No e v i d e n c e o f a g g r e s s i v e a c t i o n b e t w e e n a d u l t s o r nymphs

in th e se

but

the depressing e ffe c t

t wo mi r i d s wa s o b s e r v e d d u r i n g t h e p r e s e n t

it occurs

it

may b e a c c i d e n t a l

The r e s u l t s

show t h a t

up r a t h e r c o n s t a n t l y ,

o f one s p e c i e s

studies,

and i f

when t h e y c o n t a c t o n e a n o t h e r .

t h e t a r n i s h e d p l a n t bug p o p u l a t i o n s b u i l d

reaching the f i f t h

The r e a r i n g was s t o p p e d h e r e a r b i t r a r i l y .

g e n e r a t i o n when r e a r e d a l o n e .
U nfortunately,

the a l f a l f a

p l a n t b u g was n o t

reared su ccessfu lly during th is

of the b io lo g ic a l

c h a r a c t e r ! s t i c s when b o t h mi r i d s a r e c a g e d t o g e t h e r ,

such a s
mental

their

sex r a t i o ,

the adult

p e r i o d and t h e a v e r a g e t o t a l

f e c u n d i t y , which a r e h e l p f u l
in tra s p e c ific com petition.
acteristics
The s e x

are presented

longevity,

time fo r comparison

their

average develop­

progeny per fem ale o r a c t u a l

to evaluate

the r e s u lts

of

For t h e t a r n i s h e d p l a n t b u g ,

i n t e r - and
these char­

i n T a b l e 9*

r a t i o f o u n d f o r t h e t a r n i s h e d p l a n t b u g wa s a p p r o x i m a t e l y

50 m a l e s a n d 50 f e m a l e s , when common b e a n s w e r e u s e d a s h o s t m a t e r i a l .
Th e d e v e l o p m e n t a l

p e r i o d from o v i p o s i t ion t o a d u l t

stage

(startin g to

57

T a b l e 9*

B i o l o g i c a l c h a r a c t e r i s t i c s o f t h e t a r n i s h e d p l a n t bug
r e a r e d a t 7 8 - 8 0 ° F , 65 + 5% RH, and 16 h o u r s o f l i g h t ,
East L ansing, Michigan.
1971*

females)
.........................
(%

Sex r a t i o
Adult

longevity.

50.02

.

39-39

A v e r a g e d e v e l o p m e n t a l p e r i o d . , (^*a Ys )
Average t o t a l
actual

progeny p e r female,

fecundity

Theoretical

number

(reachingadult

................................................

32.**5

or
s t a g e ) ..........................................

o f f e m a l e s a t t h i r d g e n e r a t i o n .........................

7.1
220.00

58

l a y e g g s a g a i n ) was a b o u t
groups

32.**5 d a y s a t 7 8 - 8 0 ° F ,

f r o m 31-**** t o 33.*+5 d a y s ,

ranging

in

five

i n t h e s a me way , t h e a d u l t

longe­

v i t y was 3 9 * 3 9 d a y s , a n d t h e a v e r a g e p r o g e n y p e r f e m a l e w a s 7 * 1 ;

this

was i n d i c a t e d by t h e n u m b e r o f p r o g e n y p e r f e m a l e w h i c h r e a c h e d t h e
adult

stage.

90 d a y s

Therefore,

(third

generation)

5 p a irs of bugs,
the to ta l
parental

w o u l d b e 220

5 males and 5 females,

p ro g e n y p e r f e m a l e b e i n g 7*1,
g e n e r a t i o n would b e

of females

for

the next

and t h e t h e o r e t i c a l
be

the th eo retic al

(62 x 7 - 0 / 2

F i g u r e 5*

number of f e m a l e s a f t e r about
(Table 9).
the

sex r a t i o b e in g

(5 x 7 - U / 2 = 1 7 - 7 ;

g e n e r a t i o n would b e

This

In these t e s t s

relationship

( 1 7>7 * 7 * 1 ) / 2

the third
is

period,

t h e r e was

but d ire c t

shown g r a p h i c a l l y

in

conducted under co n d itio n s mentioned before,

less

The c a u s e may

f o o d p e r nymph d u r i n g t h e d e v e l o p m e n t a l

plant

bugs t o g e t h e r under t h e

previously discussed.

in t h i s

case,

from r e a r i n g
laboratory

They a r e s u m m a r i z e d i n T a b l e

By c o m p a r i s o n o f t h e a v e r a g e d e v e l o p m e n t a l
is observed that

= 62;

e v i d e n c e was n o t f o u n d .

t h e t a r n i s h e d and a l f a l f a

it

number

g e n e r a t i o n wou l d

A f e w d a t a on t h e r a t e o f d e v e l o p m e n t w e r e r e c o r d e d

conditions

fo r the

the t h e o r e t i c a l

a h ig h m o r t a l i t y o c c u r s d u r i n g t h e immature s t a g e s .
have been t h a t

1 : 1 , and

t h e number o f f e m a l e s

n u mb e r o f f e m a l e s f o r

= 220.

S t a r t i n g with

p erio d a t such c o n d i t i o n s ,

the average developmental
longer

(1*0 d a y s )

p e r i o d of

the t a r n is h e d

p l a n t bug was s i g n i f i c a n t l y

the tarnished

p l a n t bug wa s

the tarnished

p l a n t b u g , on t h e o t h e r h a n d , w a s s i g n i f i c a n t l y

reared alone.

10.

Th e a d u l t

t h a n when

l o n g e v i t y of

( a n a v e r a g e o f 2 7 * 8 8 d a y s w h i c h r e p r e s e n t s a b o u t 30% l o n g e v i t y

reduced
reduction)

59

Table

10.

The c o m p e t i t i v e

interaction

c a n be s e e n e v e n

small

test

b u t c o n c l u s i o n s ca n n o t be drawn from i t

in t h i s

a n d mo r e d a t a

would b e n e e d e d .

FI ELD I NTERACTI ONS
As f a r a s
t w o mi r i d s ,
alfalfa

is

known ,

fields

in t h e U n i t e d S t a t e s .
immigrant

time.

Its

concensus th a t
the com petition

small

This fa c t

the c lo s e r
is.

the re la tio n

is

subject

(lady-bird b e e tle s ,

in the

literature),

clim ate

c u ttin g of the host p la n t,
acting as control
On t h e o t h e r h a n d ,

bug was p e r h a p s

in the v a r io u s

toads,

in T a b le 8,

s t a t e s where

c o r r e l a t e d with the general

among s p e c i e s ,

the stronger

t e s t s on b i o l o g i c a l

and p h y s i o ­

p l a n t bugs

indi­

some a d v a n t a g e s o v e r t h e

in n a t u r a l

environments.

fungus d i s e a s e s ,

Biological

and o th e r s

reported

( d r o u g h t p e r i o d s and w i n t e r t e m p e r a t u r e s ) ,
and i n t r a s p e c i f i c

f a c t o r s on t h e t a r n i s h e d

com petition are probably

plant

bug.

t h e h i g h fe m a le t o m ale sex r a t i o and o v e r ­

in th e egg s t a g e a r e p ro b a b ly t h e major

the a l f a l f a

found in

presented

o f t h e t a r n i s h e d and a l f a l f a

agents

w intering

is clo se ly

each of th e s e m irid s p o s se s se s

o t h e r one t o which i t

plant

1959 i s

densities

These p r e lim in a r y

characteristics

that

The a l f a l f a

a b u n d a n c e f r o m 19^0 t o

i t became c o l o n i z e d .

cate

193 0, o f t h e s e

f r o m t h e Ol d W o r l d , w h i c h b e c a m e e s t a b l i s h e d

w h i c h g i v e n an i d e a o f i t s

logical

f o r a long time p rev io u s t o

t h e t a r n i s h e d p l a n t b u g wa s t h e o n l y s p e c i e s

an a c c i d e n t a l
by t h i s

it

p l a n t bug t o

remain a t even

o f t h e t a r n i s h e d p l a n t bug.

fa c to rs causing

lower d e n s i t i e s

than tho se

T a b l e 10.

Repli c .
No.

D u r a t i o n in d a y s o f t h e d e v e l o p m e n t o f t a r n i s h e d p l a n t bug when r e a r e d
mixed w i t h a l f a l f a p l a n t bug, a t 7 8 - 8 0 ° F , 65 + 5% RH, and 16 h o u r s o f
l i g h t , from S e p te m b e r 18, t o December 2 2 , E a s t L a n s i n g , M i c h i g a n .
1971 *

Hatching

1
2
3
4
5
6
7
8
9
10
11

8
11
7
13
11
11
10
10
9
10

Total

too

Mean
S.O.

2n d.) n s .

6
8
4
4
2
6
it
5
U
4
4

5 t h . 1n s .

A dults

6
9
10
6
lit
5
5
9
10
7
11

6
it
3
5
5
6
4
3
3
3
4

51

92

10 .0

it. 64

1.7

1.57

P r e o v i p o s i t i on
P e r i od

8
-

12
-

14
24
11
-

12

34
35a
36
28a
46
52
34
27a
38

Longevi t y
of Adults

27
-

24
22
38
18
27
35
-

10

K
29

46

91

38 3C

223

8.36

4.18

13.0

40.0

27.88

2.84

1.17

5.2

7.4

6.7

Development p e r i o d w i t h o u t p r e o v i p o s i t i o n t i m e .
^ - Development p e r i o d w i t h o u t h a t c h i n g t i m e .
c - Summation o f t h e c om p le te development p e r i o d s .

•

Total
Dev.
P e r i od

32

CONCLUSIONS

The p r e s e n t s t u d i e s were c a r r i e d o u t

under both

f i e l d co n d itio n s with the o b je c tiv e of fin d in g

if

c o m p e titio n e x is t e d between th e t a r n i s h e d p l a n t
bug.

Th e s t u d i e s

set at

78-80°F,

a flourescent

in the

65 +

5%

l amp.

State U niversity

interspecific

bug a n d a l f a l f a p l a n t

la b o ra to ry were performed u s in g

incubators

RH, a n d a 16 h o u r p h o t o p e r i o d p r o v i d e d by

Th e f i e l d

farms,

l a b o r a t o r y and

s t u d i e s w e r e made a t

East Lansing,

the Michigan

during the years of

1970 a n d

1 9 7 1.
The d e v e l o p m e n t a l
for five

period of the ta rn ish e d

successive generations

beans a s t h e h o s t .

in t h e

p l a n t b u g was f o l l o w e d

l a b o r a t o r y u s i n g pods o f green

In tra s p e c ific com petition

in th e t a r n i s h e d p l a n t

b u g was o b s e r v e d t o b e a c c e n t u a t e d b y l a c k o f f o o d ,
habit,
alfalfa

a n d i n t e r f e r e n c e by a c c i d e n t a l

its

cannibalistic

c o n t a c t between them.

p l a n t bug c o u l d be r e a r e d o n l y d u r i n g t h e p a r e n t a l

in t h e l a b o r a t o r y .
bug in t h e

generation

The p r e l i m i n a r y o b s e r v a t i o n s on t h e a l f a l f a p l a n t

laboratory

stage o f th i s

The

species,

indicates

that

there

is a diapause

b u t more i n v e s t i g a t i o n

in t h e egg

i s n e e d e d on t h i s

subject.

I n t e r s p e c i f i c c o m p e t i t i o n between t h e t a r n i s h e d p l a n t bug and a l f a l f a
p l a n t b u g i s shown b y t h e
gevity,

longer developmental

and h i g h e r v a r i a b i l i t y o f d ev elo p m en tal

p l a n t b u g when r e a r e d

to g e th e r with

the a l f a l f a

period,

shorter

time of
plant

the

lon­

tarnished

b u g t h a n when

t h e t a r n i s h e d p l a n t b u g was r e a r e d b y i t s e l f .
A w e e k l y s u r v e y by n e t
alfalfa

s we e p s a m p l i n g was made i n

five different

f i e l d s a n d o b s e r v a t i o n s w e r e made on t h e v a r i o u s
61

aspects of

62

biology,

habits,

behavior,

natural

s h i p s o f b o t h s p e c i e s o f mi r i d s .
previously

r e p o r t e d were fo u n d ,

enemies,
Natural

and h o s t p l a n t

enemies,

but t h e i r

lady-bird b e e tle ,

These n a t u r a l

C o l e o m e g i l l a m a c u l a t a DeGeer,

common t o a d , B u f o a m e r i c a n u s H o l b r o o k , a n d a f u n g u s
Hyphomycete.

than those

p r e s e n c e had no s i g n i f i c a n t

e f f e c t on t h e p o p u l a t i o n d e n s i t i e s o f t h e mi r i d s .
were th e s p o tte d

other

relation­

identified

The s e x r a t i o was f o u n d t o b e a p p r o x i m a t e l y

1: 1

enemies
the

as a
in th e

t a r n i s h e d p l a n t bug w h i l e t h e f e m a l e s o u t n u m b e re d t h e m a l e s o f t h e
alfalfa
hosts

p l a n t bug.

The t a r n i s h e d p l a n t b u g h a s a b r o a d e r r a n g e o f

than th e a l f a l f a

plant

bug.

T h e s e t wo mi r i d s w e r e f o u n d i n t h e s ame a l f a l f a
of

t h e U n i t e d S t a t e s and o c c u p y s i m i l a r e c o l o g i c a l

fields.

The r e c o r d s o f d i s t r i b u t i o n

during the years
the ta rn is h e d
alfalfa

19^*0 t o

p l a n t bug.

parameters

of the a l f a l f a ,

as

i n t h e p r e s e n t s t u d y show t h a t

i s p r o b a b l y m a i n t a i n e d by d i f f e r e n t

the natural

enemies,

periodic cu ttin g

an i n t r a s p e c i f i c c o m p e t i t i o n p r o b a b l y b e i n g o f m a j o r

im portance to t h e t a r n i s h e d p l a n t bug;
r a t i o and the

t h e h i g h fem ale t o male sex

r e s i s t a n t ch orion of the egg

(Knight

19*+1) t h a t

o v e r w in te r in g as eggs a re prob ab ly th e dominant f a c t o r s
t h e a l f a l f a p l a n t bug.

A com plicating facto r

p l a n t b u g i s an i n t r o d u c e d
to

its

in th e a l f a l f a

i s dominant o v e r t h e numbers o f th e

This e q u ilib riu m

f o r t h e t wo s p e c i e s :

niches

and. a b u n d a n c e o f t h e t wo s p e c i e s

1959 a s w e l l

p l a n t bug p o p u l a t i o n

producing areas

new e n v i r o n m e n t .

occupy s i m i t a r n ic h e s

species

is

that

permits

influencing

the a lf a l f a

t h a t may n o t h a v e f u l l y a d a p t e d

The two s p e c i e s a r e c l o s e l y

in t h e a l f a l f a

fields.

r e l a t e d and do

They a r e ,

however,

63

d iffe re n tia lly affected

by t h e s e d i f f e r e n t

p a r a m e t e r s and no d i r e c t

e v i d e n c e o f i n t e r s p e c i f i c c o m p e t i t i o n b e t w e e n t h e m wa s m e a s u r e d
the fie ld .

in

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A l l e e , W. C . , A. E. E m e r s o n , 0 . P a r k , T. P a r k , a n d K. P . S c h m i d t
P r i n c i p l e s o f a n i m a l e c o l o g y . P h i l a d e l p h i a . W. B. S a u n d e r s
Co.
A n d r e w a r t h a , H. G. a n d L. C. B i r c h .
1953* The L o t k a - V o l t e r r a t h e o r y
o f i n t e r s p e c i f i c c o m p e t i t i o n . A u s t r a l i a n J . Z o o l . 1; 1 7 4 - 7 1954. The d i s t r i b u t i o n and a b u n d a n c e o f a n i m a l s . U n i v e r s i t y
o f Ch ic a g o P r e s s . C h i c a g o , 111.
Beards,

Birch,

G. W. a n d T . F . L e i g h . I 9 6 0 . A l a b o r a t o r y r e a r i n g m e t h o d f o r
Ly q u s h e s p e r u s K n i g h t . J . E c o n . E n t o m o l . 5 3 :
327-8.
L. C. 1957- The m e a n i n g s o f c o m p e t i t i o n . Am. N a t u r a l i s t
5-18.

Broersma,

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