30 Insect Antifeedant Terpenoids in Wild Sunflower A Possible Source of Resistance to the Sunflower Moth 1,4
51,
1
JONATHAN GERSHENZON , MARYCAROL ROSSITER, TOM J. MABRY, CHARLIE E. ROGERS , MICHAEL H. BLUST, and THEODORE L. HOPKINS 2,6
3
3
1
Departments of Botany and Zoology, University of Texas, Austin, TX 78713
2
Conservation and Production Research Laboratory, Agricultural Research Service, U . S .
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Department of Agriculture, Bushland, TX 79012 3
Department of Entomology, Kansas State University, Manhattan, KS 66506
Sunflower (Helianthus annuus) cultivation in the United States is frequently limited by the severity of insect damage. However, many wild Helianthus species are resistant to the major insect pests of cultivated sunflower. This resistance has been suggested to have a chemical basis. We found high concentrations of sesquiterpene lactones and diterpenes in glandular hairs on several resistant wild species of Helianthus and demonstrated that these compounds were toxins and antifeedants towards some major sunflower insect pests. Experiments were conducted on the southern armyworm (Spodoptera eridania), the migratory grasshopper (Melanoplus sanguinipes) and the sunflower moth (Homoeosoma electellum). Of particular interest was the presence of terpenoids on the portions of the flower immediately adjacent to the pollen. The early larval stages of the sunflower moth, the most destructive insect pest of cultivated sunflower in the United States, feed principally on pollen. Examination of several cultivated lines of sunflower showed that these had lower densities of glandular hairs than the wild species. Thus, increased resistance to sunflower moth predation might be achieved simply by breeding for an increased density of glandular hairs on floral parts surrounding the pollen.
4
Current address: Institute of Biological Chemistry, Washington State University, Pullman, W A 99164.
5
Current address: Department of Entomology, Pennsylvania State University, University Park, P A 16802.
6
C u r r e n t address: Insect Biology and Population Management Research Laboratory, Agricultural Research Service, U . S . Department of Agriculture, Tifton, G A 31793.
0097-6156/85/0276-0433$06.00/0 © 1985 American Chemical Society Hedin et al.; Bioregulators for Pest Control ACS Symposium Series; American Chemical Society: Washington, DC, 1985.
BIOREGULATORS FOR PEST CONTROL
434
The
environmental
synthetic natural
products
best-studied levels
of
subject
and
economic
i n s e c t i c i d e s have to
toxic
to
control
approach of or
insect
insect
this
pests
type
antifeedant attack
to
damage
(1).
Our
suggest
that
plant-produced
contribution
drawbacks
is
the
of
increasing
to
scale
of
sunflower
resistance
may
to
of
plant
Perhaps for
in
the
greater
plant
resistance
products
use
using
breed
products
their
with
ways
crop plants.
natural
natural
large
on
simply
increase
investigations
towards
to
focused attention
parts
to
insect
(Helianthus
annuus)
make
insect
a
significant
damage
in
this
crop. Sunflower crops
in
s o i l ,
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in
tion
of
their
has
further
new
problems
over of
are
insect
feed
on
in
of
major is
no
obvious
might
account
this
isolated results
of
discuss
the
insect
pest
describe damage
to
resistance greenhouse chemically were
and
to
f i e l d to
be
terpenoid
diterpenes.
diterpenes diterpenes
and in
We
have
most
have
fifty
terpenoid
of
Because plants
prédation,
in
the
the
constituents
and
present
compounds. the
Then
we to
destructive
States
in
the
resistance
most
United
exploited
species
t r i a l s a
(4), a n d
reducing
Helianthus
of
small
group
now high
the two
(13-25). from
began
insect
17
of
Both
our
parts
species of
by
which
The
major
these
plants
sesquiterpene species
in
studies
resistant.
aerial
shown some
sunflower
Helianthus
types:
studied levels
isolated
of
insect
of
have
cultivated We
(6-12).
compound o f have
of
pests
especially
these
been
of
moiety
the in
12 a n d
6 or
lactones
are
Asteraceae, these
methylene-γ-lactone atoms
in
some
of
lactones
Helianthus
sesquiterpene
lactones
and
sesquiterpene
lactones
and
species
of
Helianthus
by
other
(26-44).
members
lactone
insect
Helianthus these
be
to
Helianthus
insect
found
of
Sesquiterpene many
the
major
of
secondary metabolites be
chemically
workers
might
to
resistant
to
terpenoids
sunflower
adapt
sunflowers
(6-12).
these
(4).
because
c h e m i c a l b a s i s (12).
the
of
implicates
species
investigating
lipophilic
a
oil
therefore to
be r e s i s t a n t
in
(3).
sunflower.
of
the
reported
proved and
half
to
review
of
States
wild
of
limiting
(5) a n d
of
immunity
the
years
20
yield
varieties
feature
of
of
c u l t i v a -
factors
opportunity
(Homoeosoma e l e c t e l l u m ) ,
from w i l d
Approximately
shown to
species
information
last
United
number
bioassays with
which
cultivated
Terpenoids
a
relative
wild
the
o i l
range
concentrations
America
cultivated
f i r s t
the
had the
r e s i s t a n c e has
we
cultivated
this
in
wide
sunflower
depressing the
However,
this
in
vegetable
a
because
high
principal
North
been
to and
(2)
very
serious have
their
insect
moth
of
how
and to
the
major
States,
the
morphological for
evidence
sunflower
of
native
have
resistant
some
one
country
of
chapter,
from
with
United
hundred-fold
is
(4).
suggested that In
the
is
pests
which was
the
sunflower
Helianthus)
insect
there it
a
this
sunflowers
(species the
taxa
In
world's
adaptability
conditions
particularly
genus Helianthus
many
the
varieties
(3).
damage
cultivation
Insect
of its
water
hybrid
achenes
insect
one
because of
and
increased
Extensive
the
become
years
temperature
development oil
has
recent
8 on
with the
secondary metabolites
composite
compounds
function
12 a n d
typical
the
the
is
family
usually
lactone
present
bridge
sesquiterpene
(45,
46). as
joining
skeleton
(see
Hedin et al.; Bioregulators for Pest Control ACS Symposium Series; American Chemical Society: Washington, DC, 1985.
an
of The α
-
carbon Figure
30.
GERSHENZON ET AL.
Insect Antifeedant Terpenoids
435
1 f o r numbering scheme). Most H e l i a n t h u s s e s q u i t e r p e n e l a c t o n e s a r e c h a r a c t e r i z e d by t h e f u s i o n o f t h e l a c t o n e r i n g t o c a r b o n 6 and t h e presence of a f i v e carbon a n g e l a t e or a n g e l a t e - d e r i v e d a c i d s i d e c h a i n e s t e r i f i e d t o p o s i t i o n 8. Four s t r u c t u r a l t y p e s o f s e s q u i t e r pene l a c t o n e s have been i s o l a t e d f r o m H e l i a n t h u s : germacrolides h e l i a n g o l i d e s , e u d e s m a n o l i d e s and g u a i a n o l i d e s ( F i g u r e 1). The b i o s y n t h e t i c a l l y - s i m p l e r g e r m a c r o l i d e and h e l i a n g o l i d e t y p e s a r e t h e most common i n t h e genus. Four s t r u c t u r a l t y p e s o f d i t e r p e n e s a r e known from H e l i a n t h u s ; l a b d a n e s , k a u r a n e s , a t i s i r a n e s and t r a c h y l o b a n e s ( F i g u r e 2), w i t h t h e t e t r a c y c l i c kaurane t y p e b e i n g t h e most w i d e s p r e a d i n t h e genus. The m a j o r i t y o f H e l i a n t h u s d i t e r p e n e s have an α-oriented c a r b o x y l i c a c i d f u n c t i o n a t t a c h e d t o c a r b o n 4.
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f
T o x i c i t y and a n t i f e e d a n t a c t i v i t y l a c t o n e s t o sunflower i n s e c t s
of
Helianthus
sesquiterpene
T e r p e n o i d s i s o l a t e d i n l a r g e q u a n t i t i e s f r o m r e s i s t a n t s p e c i e s were tested with several sunflower insect pests. Since sesquiterpene l a c t o n e s were p r e s e n t i n much h i g h e r c o n c e n t r a t i o n s t h a n d i t e r p e n e s i n t h e most r e s i s t a n t s p e c i e s s t u d i e d , our i n v e s t i g a t i o n s emphasized s e s q u i t e r - p e n e l a c t o n e s . Three s p e c i e s o f i n s e c t s were used i n t h e s e s t u d i e s : Spodoptera e r i d a n i a , M e l a n o p l u s s a n g u i n i p e s and Homoeosoma electellum. S p o d o p t e r a e r i d a n i a ( L e p i d o p t e r a : N o c t u i d a e ) - t h e s o u t h e r n armyworm. T h i s s p e c i e s was chosen f o r s t u d y because i t i s c l o s e l y r e l a t e d t o S. e x i g u a , t h e b e e t armyworm, an i n s e c t w h i c h has p e r i o d i c a l l y damaged f i e l d s o f c u l t i v a t e d s u n f l o w e r i n t h e s o u t h e r n G r e a t P l a i n s (47). A l a b o r a t o r y c o l o n y o f S^ e x i g u a c o u l d n o t be s u c c e s s f u l l y m a i n t a i n e d . Both S^ e r i d a n i a and S^ e x i g u a a r e t e r m e d g e n e r a l i s t f e e d e r s because t h e y c a n f e e d on v a r i o u s o r g a n s o f a v a r i e t y o f t a x o n o m i c a l l y u n r e l a t e d p l a n t s (48, 49). E x p e r i m e n t s on £L e r i d a n i a were p e r f o r m e d i n c o l l a b o r a t i o n w i t h Dr. K. N a k a n i s h i ' s l a b o r a t o r y a t C o l u m b i a University. The g r o w t h o f S^ e r i d a n i a l a r v a e was s i g n i f i c a n t l y r e d u c e d by s e s q u i t e r p e n e l a c t o n e s added t o t h e i r d i e t . Two sesquiterpene l a c t o n e s were used i n t h e s e t e s t s : 8 3 -sarracinoyloxycumambranolide (8 3 SC) f r o m H e l i a n t h u s m a x i m i l i a n i (18) and d e s a c e t y l e u p a s s e r i n f r o m H. m o l l i s (13) ( F i g u r e 3 ) . T h e s e c o m p o u n d s w e r e a d d e d t o an a r t i f i c i a l d i e t a t c o n c e n t r a t i o n s o f 0.1% a n d 1.0% a n d f e d t o f i f t h i n s t a r l a r v a e o f S^ e r i d a n i a . A t a c o n c e n t r a t i o n o f 1.0%, both compounds c a u s e d s i g n i f i c a n t g r o w t h i n h i b i t i o n ( T a b l e 1). Both compounds a r e p r e s e n t i n H e l i a n t h u s l e a v e s a t l e v e l s o f 1-5%. L a r v a e o f S^ e r i d a n i a were a l s o s u b j e c t e d t o p r e f e r e n c e t e s t s t o see i f t h e y would a v o i d i n g e s t i n g s e s q u i t e r p e n e l a c t o n e s i f g i v e n t h e c h o i c e o f f e e d i n g on t r e a t e d o r u n t r e a t e d f o o d . Starved f i f t h i n s t a r l a r v a e were s i m u l t a n e o u s l y p r e s e n t e d w i t h bean l e a v e s ( P h a s e o l u s v u l g a r i s ) c o a t e d w i t h a 1% a c e t o n e s o l u t i o n i n w h i c h a s e s q u i t e r p e n e l a c t o n e had been d i s s o l v e d and bean l e a v e s c o a t e d w i t h solvent only. A f t e r 24 h o u r s , l e a v e s c o a t e d w i t h 8 3 SC s h o w e d s i g n i f i c a n t l y l e s s f e e d i n g than the s o l v e n t - c o a t e d c o n t r o l s , but l a r v a e showed no p r e f e r e n c e between c o n t r o l s and l e a v e s c o a t e d w i t h desacetyleupasserin (Table 2).
Hedin et al.; Bioregulators for Pest Control ACS Symposium Series; American Chemical Society: Washington, DC, 1985.
BIOREGULATORS FOR PEST CONTROL
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Germacrolides
Heliangolides
Guaianolides
F i g u r e 1. S t r u c t u r a l Helianthus.
types o f sesquiterpene
labdane
kaurane
F i g u r e 2.
lactones i n
atisirane
trachylobane
S t r u c t u r a l types o f diterpenes i n Helianthus.
Hedin et al.; Bioregulators for Pest Control ACS Symposium Series; American Chemical Society: Washington, DC, 1985.
30.
GERSHENZON ET AL.
437
Insect Antifeedant Terpenoids
ο
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80-Sarracinoyloxycumambranolide (8pSC )
Ο Desacetyleupasserin Figure 3. Sesquiterpene
lactones used i n the insect bioassays.
Table 1. E f f e c t of two Helianthus sesquiterpene the growth of S^ eridania larvae.*
compound and concentration 8 3 SC control 0.1% 1.0% desacetyleupasserin control 0.1% 1.0%
1st
lactones on
average d a i l y weight gain, mg 4th day dav 2nd day 3rd day
122 128 -28** 97 76 44**
97 102 -14** 83 67 56**
143 118 _g** 76 64 45**
82 71 -11** 45 40 50
•Sesquiterpene lactones were added t o a r t i f i c i a l d i e t s at concentra tions indicated. Ten early f i f t h instar larvae were raised on each concentration. Gain i n weight was measured d a i l y f o r each individual. Negative numbers indicate average weight loss f o r larvae i n that group. • • S i g n i f i c a n t l y d i f f e r e n t from control at 1% l e v e l ( t - t e s t ) .
Hedin et al.; Bioregulators for Pest Control ACS Symposium Series; American Chemical Society: Washington, DC, 1985.
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438
BIOREGULATORS FOR PEST CONTROL
Melanoplus sanguinipes (Orthoptera: Acrididae) - the migratory grasshopper. G r a s s h o p p e r s o c c a s i o n a l l y damage c u l t i v a t e d s u n f l o w e r i n t h e U n i t e d S t a t e s (4). M e l a n o p l u s s a n g u i n i p e s i s a g e n e r a l i s t f e e d e r and a major c r o p p e s t s p e c i e s w i d e l y d i s t r i b u t e d i n N o r t h A m e r i c a (50). 8 3 SC a d d e d t o t h e d i e t o f M^_ s a n g u i n i p e s a t a c o n c e n t r a t i o n o f 1% h a d no e f f e c t on t h e g r o w t h o r s u r v i v o r s h i p o f t h i s i n s e c t o r i t s r a t e o f development t o t h e a d u l t s t a g e ( T a b l e 3). However, 8 3 SC was shown t o be a s i g n i f i c a n t f e e d i n g d e t e r r e n t i n p r e f e r e n c e t e s t s w i t h M. s a n g u i n i p e s . G r a s s h o p p e r s t h a t had been s t a r v e d f o r 48 h o u r s were g i v e n t h e c h o i c e o f f e e d i n g on s u c r o s e - t r e a t e d nitrocellulose membrane f i l t e r d i s k s w i t h and w i t h o u t added 83 SC. 8 3 SC was d r i e d o n t o t h e d i s k s i n c h l o r o f o r m s o l u t i o n s a t l e v e l s o f 0.25%, 2.5% a n d 25% o f t h e d r y w e i g h t o f t h e d i s k s . C o n t r o l d i s k s were t r e a t e d w i t h chloroform only. A t a l l l e v e l s o f 8 3SC t e s t e d , sanguinipes consumed more o f t h e c o n t r o l d i s k s t h a n t h e t e s t d i s k s (Table 4). Homoeosoma e l e c t e l l u m ( L e p i d o p t e r a ; P y r a l i d a e ) - t h e s u n f l o w e r moth. I n c o n t r a s t t o S^ e r i d a n i a a n d M^ s a n g u i n i p e s , H. e l e c t e l l u m i s a s p e c i a l i s t w h i c h f e e d s on t h e i n f l o r e s c e n c e s o f a few s p e c i e s o f t h e Asteraceae (4, 5 1 ) . Since s e s q u i t e r p e n e l a c t o n e s a r e found i n s e v e r a l p a r t s o f t h e i n f l o r e s e n c e s o f Helianthus species which are c o n s i d e r e d t o be r e s i s t a n t t o t h e s u n f l o w e r moth (52), i t was t h o u g h t t h a t t h e s e compounds m i g h t s e r v e t o l i m i t t h e damage caused by t h i s insect. L a r v a e o f IL e l e c t e l l u m were r a i s e d on a r t i f i c i a l wheat germbased d i e t s t o w h i c h v a r y i n g c o n c e n t r a t i o n s o f 8 3 SC had been added. T h i s compound was d i s s o l v e d i n acetone, c o a t e d on c e l l u l o s e powder under vacuum and t h e n mixed i n t o t h e d i e t a t c o n c e n t r a t i o n s o f 0.01%, 0.1% and 1%. The c o n t r o l d i e t c o n t a i n e d c e l l u l o s e powder w h i c h had been soaked i n a c e t o n e and d r i e d under vacuum. A t l e v e l s o f 0.1% and 1%, 8 3 SC s i g n i f i c a n t l y r e d u c e d p u p a l w e i g h t ( T a b l e 5 ) . H o w e v e r , l a r v a l s u r v i v a l and development t i m e were n o t a f f e c t e d . F o r f e e d i n g p r e f e r e n c e t e s t s , 8 3 SC was a d d e d t o s q u a r e s o f a r t i f i c i a l d i e t a t a c o n c e n t r a t i o n o f 5%. S t a r v e d H^_ e l e c t e l l u m l a r v a e were p l a c e d i n t h e c e n t e r o f a d i s h c o n t a i n i n g both t r e a t e d and c o n t r o l d i e t s q u a r e s a n d a l l o w e d t o f e e d . A f t e r two h o u r s , s i g n i f i c a n t l y more f i r s t and second i n s t a r l a r v a e were found f e e d i n g on t h e c o n t r o l d i e t (73%) t h a n on t h e t r e a t e d d i e t (12%) ( T a b l e 6 ) . However, t h e t h i r d , f o u r t h a n d f i f t h i n s t a r s d i d n o t show a s i g n i f i c a n t preference i n t h i s experiment. The r e s u l t s o f t h e s e b i o a s s a y s i n d i c a t e t h a t s e s q u i t e r p e n e lactones i s o l a t e d from species of Helianthus r e s i s t a n t t o major insect pests of c u l t i v a t e d sunflower a r e t o x i n s and f e e d i n g d e t e r r e n t s t o some o f t h e s e i n s e c t s . P r e v i o u s i n v e s t i g a t i o n s have shown t h a t s e s q u i t e r p e n e l a c t o n e s have t o x i c and a n t i f e e d a n t a c t i v i t i e s t o w a r d s a v a r i e t y o f phytophagous i n s e c t s (53-62). E v o l u t i o n a r i l y , s e s q u i t e r p e n e l a c t o n e s may have come t o f u n c t i o n as f e e d i n g d e t e r r e n t s because i n s e c t s have been s e l e c t e d f o r t h e i r a b i l i t y t o r e c o g n i z e t h e p r e s e n c e o f t h e s e t o x i c compounds i n p o t e n t i a l f o o d s t u f f s and a v o i d i n g e s t i n g them. Sesquiterpene l a c t o n e s e x h i b i t a number o f t o x i c e f f e c t s a t t h e c e l l u l a r l e v e l , i n c l u d i n g t h e i n h i b i t i o n o f p r o t e i n s y n t h e s i s (63, 64), n u c l e i c a c i d s y n t h e s i s (63-66) and r e s p i r a t o r y enzyme a c t i v i t y (67). The t o x i c i t y of t h e s e compounds i s t h o u g h t t o be due t o t h e i r a b i l i t y t o a l k y l a t e n u c l e o p h i l i c s i t e s on p r o t e i n s (63, 68-70) o r DNA (64, 6 6 ) .
Hedin et al.; Bioregulators for Pest Control ACS Symposium Series; American Chemical Society: Washington, DC, 1985.
30.
GERSHENZON ET AL.
T a b l e 2.
F e e d i n g d e t e r r e n c e o f two H e l i a n t h u s l a c t o n e s t o S. e r i d a n i a l a r v a e . *
compound
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439
Insect Antifeedant Terpenoids
8 3 SC desacetyleupasserin
sesquiterpene
average amount o f l e a v e s e a t e n treated control 21.0%** 54.2% 36.7% 30.0%
*1% Acetone s o l u t i o n s o f each s e s q u i t e r p e n e l a c t o n e were c o a t e d on bean l e a v e s . C o n t r o l l e a v e s were c o a t e d w i t h s o l v e n t o n l y . S t a r v e d f i f t h i n s t a r l a r v a e were g i v e n a c h o i c e o f f e e d i n g on c o n t r o l o r t r e a t e d l e a v e s . T e s t s o f each compound a g a i n s t a c o n t r o l were r e p e a t e d w i t h t e n l a r v a e . • • S i g n i f i c a n t l y d i f f e r e n t from c o n t r o l a t 5% l e v e l ( t - t e s t f o r p a i r e d comparisons).
T a b l e 3.
E f f e c t o f 8 3SC on t h e growth and development o f Melanoplus s a n g u i n i p e s . *
diet control average a d u l t w e i g h t , g ± s . d . female male average t i m e o f development from f i r s t i n s t a r t o a d u l t , days + s.d.
control with added 8 β SC
.021 0.224 0.187 + .033
0.210 t .015 0.198 ± .024
40.3 f 1.9
41.7 -t 3.6
*Diet consisted of finely-ground freeze-dried rye grass. 8 3SC i n d i c h l o r o m e t h a n e s o l u t i o n was c o a t e d on t h e d i e t a t a l e v e l o f 1% o f t h e d r y w e i g h t o f t h e d i e t and t h e s o l v e n t a l l o w e d t o evaporate. C o n t r o l d i e t was t r e a t e d w i t h s o l v e n t o n l y . Twenty i n s e c t s were i n d i v i d u a l l y r e a r e d on each t r e a t m e n t . T h e r e were no s i g n i f i c a n t d i f f e r e n c e s between t h e t r e a t m e n t s .
Hedin et al.; Bioregulators for Pest Control ACS Symposium Series; American Chemical Society: Washington, DC, 1985.
BIOREGULATORS FOR PEST CONTROL
440
Table
4.
E f f e c t o f 8 ÉISC sanguinipes·
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p e r c e n t a g e o f 8 (3SC per d r y wgt. o f d i s k 0.25 2.5 25
on
the
feeding
preference
of
a v e r a g e amount o f c o n t r o l d i s k s5 e a t e n i n e x c e s s o f t e s t d i s k s , cit£ ± s.d. . 0.30 + 0.46** 1.19 + 0.99** 0.97 + 1.25**
•Grasshoppers t h a t had been s t a r v e d f o r 48 h o u r s were p r e s e n t e d w i t h 5 cm n i t r o c e l l u l o s e membrane f i l t e r d i s k s t o w h i c h 5% s u c r o s e s o l u t i o n had been added. T e s t d i s k s were t r e a t e d w i t h 8 3 SC i n chloroform solution while control disks received chloroform only. A l l d i s k s were a i r - d r i e d . A r e a o f d i s k e a t e n was deter mined w i t h an a r e a meter. * * S i g n i f i c a n t p r e f e r e n c e a t t h e 1% l e v e l ( t - t e s t f o r p a i r e d c o m p a r i sons ) ·
T a b l e 5.
E f f e c t o f 8 3 SC on t h e s u r v i v a l , development and weight of electellum larvae.*
survival to adult, % development t i m e (from h a t c h t o a d u l t e c l o s i o n ) , days pupal weight, g
control 82 25.7 34.4
concentration i n d i e t 0.01% 0,1% 89 83 25.6 33.3
25.7 32.4**
pupal
1.0% 77 25.7 31.3**
*8 3 SC was d i s s o l v e d i n a c e t o n e and c o a t e d on c e l l u l o s e powder w h i c h was added t o t h e d i e t t o g i v e t h e c o n c e n t r a t i o n s i n d i c a t e d . C o n t r o l d i e t c o n t a i n e d c e l l u l o s e powder w h i c h had been soaked i n acetone. Each c o n c e n t r a t i o n was t e s t e d on a t l e a s t 100 l a r v a e . * * S i g n i f i c a n t l y d i f f e r e n t f r o m c o n t r o l s a t t h e 5% l e v e l ( a n a l y s i s o f v a r i a n c e ) . Data on development t i m e and s u r v i v a l d i d not show any s i g n i f i c a n t e f f e c t o f 8 3 SC dose. Development t i m e d a t a were s u b j e c t e d t o an a n a l y s i s o f v a r i a n c e and s u r v i v a l d a t a t o a t e s t o f independence u s i n g t h e G - s t a t i s t i c .
Hedin et al.; Bioregulators for Pest Control ACS Symposium Series; American Chemical Society: Washington, DC, 1985.
30. GERSHENZON ET AL.
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Possible role of s u n f l o w e r moth.
Insect Antifeedant Terpenoids sesquiterpene
lactones
i n resistance
441 to the
Homoeosoma e l e c t e l l u m , t h e s u n f l o w e r m o t h , i s c u r r e n t l y t h e m o s t s e r i o u s p e s t o f c u l t i v a t e d s u n f l o w e r i n t h e u n i t e d S t a t e s (4). I n t h e p r e v i o u s s e c t i o n , we s h o w e d t h a t s e s q u i t e r p e n e l a c t o n e s f r o m s p e c i e s o f H e l i a n t h u s r e s i s t a n t t o FL e l e c t e l l u m a r e t o x i c a n d a n t i f e e d a n t t o IL e l e c t e l l u m l a r v a e when added t o a r t i f i c i a l d i e t s . To e v a l u a t e t h e p o s s i b l e i n v o l v e m e n t o f s e s q u i t e r p e n e l a c t o n e s i n r e s i s t a n c e t o H. e l e c t e l l u m i n t h e i n t a c t p l a n t , i t i s n e c e s s a r y t o consider the feeding habits of this insect i n r e l a t i o n to the l o c a t i o n of sesquiterpene lactones i n the i n f l o r e s e n c e s of r e s i s t a n t species of Helianthus. S e s q u i t e r p e n e l a c t o n e s a r e found i n g l a n d u l a r t r i c h o m e s on t h e t e r m i n a l a n t h e r appendages, i m m e d i a t e l y a d j a c e n t t o t h e p o l l e n (52) ( F i g u r e 4 ) . Y o u n g H. e l e c t e l l u m l a r v a e ( f i r s t a n d second i n s t a r s ) e a t p r i n c i p a l l y p o l l e n , w h i l e l a t e r i n s t a r s f e e d on a variety of f l o r a l parts: corollas, styles, ovaries, developing achenes and p a r t s o f t h e r e c e p t a c l e (4, 51, 7 1 ) . How m i g h t young IL e l e c t e l l u m l a r v a e o b t a i n p o l l e n ? Before the f l o r e t s open, t h e p o l l e n i s p r o d u c e d and s t o r e d i n t h e a n t h e r s . To r e a c h t h e p o l l e n i n an unopened f l o r e t , l a r v a e must c r a w l o r e a t t h e i r way i n t o t h e f l o r e t a n d t h e n e a t i n t o t h e a n t h e r s . The s e s q u i t e r p e n e l a c t o n e - c o n t a i n i n g g l a n d u l a r t r i c h o m e s on t h e a n t h e r t i p s seem t o be s i t u a t e d i n j u s t t h e r i g h t l o c a t i o n t o p r e v e n t t h e l a r v a e from r e a c h i n g t h e p o l l e n ( F i g u r e 4 ) . A f t e r a f l o r e t opens, p o l l e n i s shed i n t o t h e c e n t e r o f a c y l i n d e r f o r m e d by t h e f u s e d a n t h e r s and t h e s t y l e b r a n c h pushes up t h r o u g h t h e c y l i n d e r r a i s i n g t h e p o l l e n above t h e a n t h e r s f o r p r e s e n t a t i o n t o p o t e n t i a l p o l l i n a t o r s (72). To r e a c h t h e p o l l e n a t t h i s s t a g e , young l a r v a e would have t o c r a w l up and o v e r t h e a n t h e r s ( F i g u r e 4). The s e s q u i t e r p e n e l a c t o n e - c o n t a i n i n g g l a n d u l a r t r i c h o m e s on t h e a n t h e r appendages c o u l d a l s o d e t e r l a r v a e f r o m t h e a n t h e r s ( o r s t i g m a s ) i n t h i s manner a f t e r t h e f l o r e t s a r e open. However, t h e r e i s as y e t no e v i d e n c e t o s u p p o r t t h i s p o s s i b i l i t y . The p r o x i m i t y o f s e s q u i t e r p e n e lactones to the pollen i n r e s i s t a n t species of Helianthus, i n conjunction with the deleterious e f f e c t s o f t h e s e compounds on IL e l e c t e l l u m when i n c o r p o r a t e d i n t o artificial diets, suggests that the presence of sesquiterpene l a c t o n e s may h a v e b e e n s e l e c t e d f o r b e c a u s e t h e s e c o m p o u n d s c a n r e d u c e s u n f l o w e r moth prédation by p r e v e n t i n g t h e young l a r v a e f r o m r e a c h i n g t h e i r p r i n c i p a l food source. I f young IL e l e c t e l l u m l a r v a e c a n n o t o b t a i n s u f f i c i e n t p o l l e n , t h e y may n o t s u r v i v e t o c a u s e f u r t h e r damage t o t h e i n f l o r e s e n c e . O b s e r v a t i o n s on t h e c u l t i v a t e d l i n e s of sunflower support the r o l e of sesquiterpene lactones i n r e s i s t a n c e t o t h e s u n f l o w e r moth. C u l t i v a r s w h i c h a r e f r e q u e n t l y h e a v i l y damaged by IL e l e c t e l l u m l a r v a e were found t o have much l o w e r d e n s i t i e s o f g l a n d u l a r t r i c h o m e s on t h e i r a n t h e r s t h a n t h e r e s i s t a n t s p e c i e s o f H e l i a n t h u s (52). T h e r e f o r e , i t may be p o s s i b l e t o i n c r e a s e t h e r e s i s t a n c e o f c u l t i v a t e d s u n f l o w e r t o IL e l e c t e l l u m b y b r e e d i n g f o r i n c r e a s e d concentrations of sesquiterpene lactone-containing glandular t r i c h o m e s on t h e a n t h e r t i p s . T h e d e v e l o p m e n t o f new c u l t i v a t e d l i n e s w i t h h i g h d e n s i t i e s o f g l a n d u l a r t r i c h o m e s may p r o v e t o be an
Hedin et al.; Bioregulators for Pest Control ACS Symposium Series; American Chemical Society: Washington, DC, 1985.
BIOREGULATORS FOR PEST CONTROL
442
Table
6.
larval
E f f e c t o f 8 |3SC on t h e f e e d i n g p r e f e r e n c e larvae.*
instar
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1 s t and 2nd 3 r d , 4 t h and 5 t h
feeding on c o n t r o l 73%** 45%
o f IL e l e c t e l l u m
not feeding 15% 23%
f e e d i n g on treated diet 12% 32%
* L a r v a e were a l l o w e d t o choose between f e e d i n g on a d i e t c o n t a i n i n g 5% 8 BSC and a c o n t r o l d i e t . Twenty l a r v a e o f each i n s t a r were tested. R e s u l t s f o r f i r s t and second i n s t a r s , on t h e one hand, and f o r t h i r d , f o u r t h and f i f t h i n s t a r s , on t h e o t h e r , were s i m i l a r and t h e r e f o r e combined. * * S i g n i f i c a n t p r e f e r e n c e a t t h e 5% l e v e l ( c h i - s q u a r e t e s t ) .
Unopened disk floret (cut-away view )
Disk floret (pollen-donor phase)
F i g u r e 4. L o c a t i o n o f s e s q u i t e r p e n e l a c t o n e - c o n t a i n i n g t r i c h o m e s on s u n f l o w e r d i s k f l o r e t s .
glandular
Hedin et al.; Bioregulators for Pest Control ACS Symposium Series; American Chemical Society: Washington, DC, 1985.
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30.
GERSHENZON ET AL.
Insect Antifeedant Terpenoids
443
e f f i c i e n t and p r a c t i c a l way o f c o n t r o l l i n g t h e s u n f l o w e r moth a t an e a r l y s t a g e i n i t s development. Glandular trichomes a c t t o put the d e t e r r e n t c o m p o u n d s when a n d w h e r e t h e y a r e n e e d e d f o r d e f e n s i v e p u r p o s e s w i t h o u t t h e h a z a r d s and expense o f a p p l y i n g s y n t h e t i c insecticides. G l a n d u l a r t r i c h o m e c o n s t i t u e n t s have been a s s o c i a t e d w i t h i n s e c t r e s i s t a n c e i n a number o f o t h e r c r o p s , i n c l u d i n g c o t t o n , tomato, p o t a t o , t o b a c c o and a l f a l f a (73). However, t h i s i s t h e f i r s t t i m e t h a t g l a n d u l a r t r i c h o m e s o r any p l a n t n a t u r a l p r o d u c t has been i m p l i c a t e d i n t h e d e f e n s e o f p o l l e n a g a i n s t prédation. S e s q u i t e r p e n e l a c t o n e - c o n t a i n i n g g l a n d u l a r t r i c h o m e s may n o t s e r v e as e f f e c t i v e d e f e n s e s a g a i n s t o l d e r IL e l e c t e l l u m l a r v a e s i n c e , i n o u r p r e f e r e n c e b i o a s s a y s , l a t e r i n s t a r s ( t h i r d , f o u r t h and f i f t h i n s t a r s ) w e r e n o t s i g n i f i c a n t l y d e t e r r e d b y 8 β SC ( T a b l e 6 ) . I n a d d i t i o n , o l d e r l a r v a e f e e d i n g on c u l t i v a r s h a v e b e e n o b s e r v e d t o chew t h r o u g h t h e b a s e o f t h e c o r o l l a s o f u n o p e n e d f l o r e t s t o r e a c h t h e p o l l e n (71). T h i s b e h a v i o r a l l o w s t h e l a r v a e t o a v o i d any g l a n d u l a r t r i c h o m e s w h i c h m i g h t be p r e s e n t on t h e a n t h e r t i p s . Other c h e m i c a l a n d m o r p h o l o g i c a l f e a t u r e s m i g h t be i m p o r t a n t i n t h e r e s i s t a n c e t o o l d e r H. e l e c t e l l u m l a r v a e , s u c h a s t h e p r e s e n c e o f a s o - c a l l e d "phytomelanin" l a y e r i n t h e w a l l s o f d e v e l o p i n g achenes w h i c h may f o r m a b a r r i e r t o l a r v a l f e e d i n g (74). T h e p r o t e c t i o n o f s u n f l o w e r f r o m damage by a l l s t a g e s o f IL e l e c t e l l u m l a r v a e may t h u s r e q u i r e t h e development o f c u l t i v a r s w i t h a c o m b i n a t i o n o f d e f e n s i v e traits. Acknowledgments We t h a n k V. L e s k i n e n a n d K. N a k a n i s h i f o r t h e S. e r i d a n i a t e s t d a t a , G. G r a d o w i t z f o r t e c h n i c a l a s s i s t a n c e w i t h t h e NL s a n g u i n i p e s s t u d i e s a n d M. C o n o l e y f o r h e l p w i t h t h e H^ e l e c t e l l u m e x p e r i m e n t s . This w o r k was s u p p o r t e d by g r a n t s t o T. J . M a b r y f r o m t h e N a t i o n a l I n s t i t u t e s o f H e a l t h (HDO-4488) a n d t h e R o b e r t A. W e l c h F o u n d a t i o n (F-130) and a g r a n t t o J . Gershenzon f r o m t h e S u n f l o w e r A s s o c i a t i o n of A m e r i c a . T h i s i s c o n t r i b u t i o n No. 84-13-A f r o m t h e Department o f Entomology, Kansas A g r i c u l t u r a l E x p e r i m e n t S t a t i o n . We acknowledge t h e use o f t h e U n i v e r s i t y o f Texas B r a c k e n r i d g e F i e l d L a b o r a t o r y .
Literature Cited 1. 2. 3. 4. 5.
Waiss, A.C.,Jr.; Chan, B. G.; Elliger, C. A. In "Host Plant Resistance to Pests"; Hedin, P. Α., Ed.; ACS SYMPOSIUM SERIES NO. 62, American Chemical Society: Washington, D. C, 1977; pp 115-128. Robinson, R. G. In "Sunflower Science and Technology"; Carter, J. F., Ed.; American Society of Agronomy: Madison, Wisconsin, 1978; pp 89-143. Putt, E. D. In "Sunflower Science and Technology"; Carter, J. F., Ed.; American Society of Agronomy: Madison, Wisconsin, 1978; pp 1-29. Schulz, J. T. In "Sunflower Science and Technology"; Carter, J. F., Ed.; American Society of Agronomy: Madison, Wisconsin, 1978; pp 169-223. Heiser, C. B., Jr.; Smith, D. M.; Clevenger, S. B.; Martin, W. C., Jr. Mem. Torr. Bot. Club 1969, 22, 1-218.
Hedin et al.; Bioregulators for Pest Control ACS Symposium Series; American Chemical Society: Washington, DC, 1985.
444
6.
BIOREGULATORS FOR PEST CONTROL Rogers,
C.
Ε.;
Thompson,
T.
Ε.
J.
Econ.
Entomol.
1978,
71,
221-
C.
E.;
Thompson,
T.
E.
J.
Econ.
Entomol.
1978,
71,
622-
C.
E.;
Thompson,
T.
E.
J.
Econ.
Entomol.
1978,
71,
760-
222. 7.
Rogers,
623. 8.
Rogers,
761. 9.
Rogers,
C. E.;
Thompson,
T.
E.
Southwestern
Entomol.
1979, 4,
321-324. 10.
Rogers,
C.
E.;
Thompson,
T.
E.
J.
Kansas
Entomol.
Soc.
1980,
53, 727-730. 11.
Rogers,
C.
E.;
C.
E.
Thompson,
T.
E.
Environ.
Entomol.
1981,
10,
697-
700. 12.
Rogers,
In
Arthropods
Downloaded by CORNELL UNIV on May 25, 2017 | http://pubs.acs.org Publication Date: April 26, 1985 | doi: 10.1021/bk-1985-0276.ch030
Κ.,
Ed.;
"Biology
and
and
Pathogens
Texas
Breeding
in
Agric.
for
Resistance
Agricultural
Expt.
Sta.
Misc.
to
Plants";
Publ.
Harris,
1451,
M. pp
1980;
359-389. 13.
Ohno,
N.;
14.
Ohno,
N.;
Mabry, Mabry,
T.
J.
T.
J.;
Phytochemistry Zabel,
1979, 18,
V.;
Watson,
1003-1006.
W. H.
Phytochemistry
1979, 18, 1687-1689. 15.
Ohno,
N.;
16.
Ohno,
N.;
Mabry,
T.
Phytochemistry 17.
Watanabe,
J. 18.
J.
Phytochemistry
Gershenzon,
J.;
P.;
Mabry,
T.
J.
1981, 20, 2393-2396.
K.;
Ohno,
N.;
Phytochemistry
Gershenzon,
1980, 19, 609-614.
Neuman,
J.;
Yoshioka,
H.;
Gershenzon,
J.;
Mabry,
23,
1959-
T.
1982, 21, 709-713. Mabry,
T.
J.
Phytochemistry
1984,
1966. 19.
Gershenzon,
J.;
Mabry,
T.
J.
Phytochemistry
1984, 23,
20.
Gershenzon,
J.;
Mabry,
T.
J.
Phytochemistry
1984, 23, 2561-2571.
21.
Lee,
E.;
in 22.
Gershenzon,
Mabry,
T.
J.
J.
Nat.
Prod.
1984,
47,
press.
Melek,
F.;
Ahmed,
Α.
Phytochemistry 23.
J.;
2557-2559.
Melek,
F.;
Α.;
Gershenzon,
J.;
Mabry,
T.
J.
1984, 23, 2573-2575.
Gershenzon,
J.;
Lee,
E.;
Mabry,
T.
J.
Phytochemistry
1984, 23, 2277-2279. 24.
Stewart,
E.
S.;
Gershenzon,
J.;
Mabry,
T.
J.
J.
Nat.
Prod.
1984, 47, 748-750. 25.
Gage, J.;
26.
D.
Beale,
M.
Phinney, 27.
Α.;
Gershenzon,
Whittemore,
Bjeldanes,
H.;
A.
J.;
Bearder,
B.
O.
L.
F.;
Mabry,
unpublished J.
R.;
T.
J.;
Melek,
F.;
Pearce,
results. MacMillan,
Phytochemistry
J.;
Matsuo,
Α.;
1983, 22, 875-881.
Geissman,
T.
A.
Phytochemistry
1972, 11, 327-
332. 28.
Bohlmann,
F.;
Jakupovic,
Phytochemistry 29.
Ferguson,
Res.
G.;
J.;
King,
M.
M.;
Robinson,
H.
1980, 19, 863-868. McCrindle,
R.;
Murphy,
S.
T.;
Parvez,
M.
J.
Chem.
(S) 1982, 200-201.
30.
Herz,
W.;
De
31.
Herz,
W.;
Govindan,
Groote,
R. S.
Phytochemistry V.;
Watanabe,
1977, 16, K.
1307-1308.
Phytochemistry
1982,
21, 946-947. 32.
Herz,
W.;
Kulanthaivel,
P.
33.
Herz,
W.;
Kulanthaivel,
P.;
Phytochemistry Watanabe,
1983, 22, K.
2543-2546.
Phytochemistry
22, 2021-2025. 34.
Herz,
W.;
Kumar,
N.
Phytochemistry
1981, 20, 93-98.
35.
Herz,
W.;
Kumar.
N.
Phytochemistry
1981, 20, 99-104.
36.
Herz,
W.;
Kumar,
N.
Phytochemistry
1981, 20, 1339-1341.
Hedin et al.; Bioregulators for Pest Control ACS Symposium Series; American Chemical Society: Washington, DC, 1985.
1983,
30.
GERSHENZON ET AL.
37. 38. 39. 40. 41. 42. 43. 44.
Downloaded by CORNELL UNIV on May 25, 2017 | http://pubs.acs.org Publication Date: April 26, 1985 | doi: 10.1021/bk-1985-0276.ch030
45. 46. 47. 48. 49. 50. 51. 52. 53. 54. 55. 56. 57. 58. 59. 60. 61. 62. 63. 64. 65. 66.
Insect Antifeedant Terpenoids
445
Martin Panizo, F.; Rodriguez, B. Ann. Quim. 1979, 75, 428-430. Morimoto, H.; Oshio, H. J. Nat. Prod. 1981, 44, 748-749. Ortega, Α.; Ayala, Α.; Guerrero, C.; Romo de Vivar, A. Rev. Soc. Quim. Mex. 1972, 16, 191. Ortega, A.; Romo de Vivar, A.; Diaz, E.; Romo, J. Rev. Latinoamer. Quim. 1970, 1, 81-85. Pyrek, J. S. Tetrahedron 1970, 26, 5029-5032. Spring, O.; Albert, K.; Gradmann, W. Phytochemistry 1981, 20, 1883-1885. Spring, O.; Albert, K.; Hager, A. Phytochemistry 1982, 21, 2551-2553. Stipanovic, R. D.; O'Brien, D. H.; Rogers, C. E.; Thompson, T. E. J. Agric. Food Chem. 1979, 27, 458-459. Seaman, F. C. Bot. Rev. 1982, 48, 121-592. Fischer, Ν. H.; Olivier, E. J.; Fischer, H. D. Prog. Chem. Org. Nat. Prod. 1979, 38, 47-390. Rogers, C. E. unpublished results. Soo Hoo, C. F.; Fraenkel, G. J. Insect Physiol. 1966, 12, 693709. Soo Hoo, C. F.; Fraenkel, G. J. Insect Physiol. 1966, 12, 711730. Mulkern, G. B.; Pruess, K. P.; Knutson, H.; Hagen, A. F.; Campbell, J. B.; Lambley, J. D. North Dakota Agric. Expt. Sta. Bull. 148, 1969; pp 25-26. Teetes, G. L.; Randolph, Ν. M. J. Econ. Entomol. 1969, 62, 264265. Gershenzon, J. Ph.D. Thesis, university of Texas, Austin, 1984. Burnett, W. C., Jr.; Jones, S. B., Jr.; Mabry, T. J.; Padolina, W. G. Biochem. Syst. Ecol. 1974, 2, 25-29. Burnett, W.C.;Jones, S. B.; Mabry, T. J. In "Biochemical Aspects of Plant and Animal Coevolution"; Harborne, J. B., Ed.; Academic Press: London 1978, pp 233-257. Doskotch, R. W.; Fairchild, Ε. H.; Huang, C.; Wilton, J. H.; Beno, Μ. Α.; Christoph, G. G. J. Org. Chem. 1980, 45, 14411446. Ganjian, I.; Kubo, I.; Fludzinski, P. Phytochemistry 1983, 22, 2525-2526. Nawrot, J.; Smitalova, Z.; Holub, M. Biochem. Syst. Ecol. 1983, 11, 243-245. Pettei, M. M.; Miura, I.; Kubo, I.; Nakanishi, K. Heterocycles 1978, 11, 471-480. Picman, A. K.; Elliot, R. H.; Towers, G. H. N. Biochem. Syst. Ecol. 1978, 6, 333-335. Wisdom, C. S.; Smiley, J. T.; Rodriguez, E. J. Econ. Entomol. 1983, 76, 993-998. Jones, S. B.; Burnett, W. C.; Coile, N. C.; Mabry, T. J.; Betkouski, M. F. Oecologia 1979, 39, 71-77. Nakajima, S.; Kawazu, K. Heterocycles 1978, 10, 117-121. Lee, K.-H., et al. Science 1977, 196, 533-536. Hladon, B.; Twardowski, T. Pol. J. Pharmacol. Pharm. 1979, 31, 35-43. Spring, O.; Kupka, J.; Maier, B.; Hager, A. Z. Naturforsch. 1982, 37c, 1087-1091. Woynarowski, J. M.; Konopa, J. Mol. Pharmacol. 1981, 19, 97102.
Hedin et al.; Bioregulators for Pest Control ACS Symposium Series; American Chemical Society: Washington, DC, 1985.
446
67. 68. 69. 70. 71. 72.
Downloaded by CORNELL UNIV on May 25, 2017 | http://pubs.acs.org Publication Date: April 26, 1985 | doi: 10.1021/bk-1985-0276.ch030
73.
74.
BIOREGULATORS FOR PEST CONTROL
Van Aswegen, C. H.; Potgieter, D. J. J.; Vermeulen, N. M. J. S. African J. Sci. 1982, 78, 125-127. Hanson, R. L.; Lardy, H. A.; Kupchan, S. M. Science 1976, 168, 378-380. Kupchan, S. M.; Fessier, D. C.; Eakin, M. A.; Giacobbe, T. J. Science 1976, 168, 376-378. Picman, A. K.; Rodriguez, E.; Towers, G. H. N. Chem.-Biol. Interactions 1979, 28, 83-89. Rogers, C. E. Environ. Entomol. 1978, 7, 763-765. Knowles, P. F. In "Sunflower Science and Technology"; Carter, J. F., Ed.; American Society of Agronomy: Madison, Wisconsin, 1978; pp 55-87. Stipanovic, R. D. In "Plant Resistance to Insects"; Hedin, P. Α., Ed.; ACS SYMPOSIUM SERIES NO. 208, American Chemical Society: Washington, D. C. 1983; pp 69-100. Rogers, C. E.; Kreitner, G. L. Environ. Entomol. 1983, 12, 277285.
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