Journal of Chemical Ecology, Vol. 10, No. 10, 1984
ANTIFEEDANT ACTIVITY OF QUASSINOIDS
VIOLA LESKINEN, j JUDITH POLONSKY, 2 and S U B O D H B H A T N A G A R 2 IDepartment of Chemistry, Columbia University New York, New York 2Institut de Chimie des Substances Naturelles C.N.R.S., 91190 Gif-sur- Yvette, France
(Received December 2, 1983; revised March 5, 1984) Abstract--The antifeedant activity of 13 quassinoids of different structural types has been studied against the Mexican bean beetle (Epilachna varivestis Mulsant) 4th instar larvae and the southern armyworm (Spodoptera eridania Crawer) 5th instar larvae. All quassinoids tested displayed significant activity against the Mexican bean beetle and, thus, do not reveal a simple structure-activity relationship. Five quassinoids were active against the southern armyworm. Interestingly, four of these-bruceantin (I), glaucarubinone (VI), isobruceine A (VIII), and simalikalactone D (XI)--possess the required structural features for antineoplastic activity. The noncytotoxic quassin (X) is an exception; it is active against both pests. Key Words--Antifeedant, Mexican bean beetle, Epilachna varivestis, Coleoptera, Coccinetlidae, southern armyworm, Spodoptera eridania, Lipidoptera, Noctuidae, quassinoids, Simaroubaceae.
INTRODUCTION Q u a s s i n o i d s are the c h a r a c t e r i s t i c b i t t e r principles o f the p l a n t f a m i l y S i m a r o u b a c e a e ( P o l o n s k y , 1973) which is o f m o s t l y p a n t r o p i c a l d i s t r i b u tion. T h e y are d e g r a d e d t r i t e r p e n e s , and m a n y o f t h e m possess diverse and p o t e n t i a l l y useful b i o l o g i c a l p r o p e r t i e s . Thus, m u c h a t t e n t i o n c o n t i n u e s to be focused on q u a s s i n o i d s b e c a u s e o f their p o t e n t in vivo a n t i n e o p l a s t i c activity ( C a s s a d y et al., 1980), their a b i l i t y to i n h i b i t cell t r a n s f o r m a t i o n i n d u c e d b y the R o u s s a r c o m a virus ( P i e r r 6 et al., 1980), a n d the a n t i a m e b i c (Gillin a n d R e i n e r , 1982; Gillin et al., 1982) a n d the recently o b s e r v e d a n t i m a l a r i a l p r o p e r t i e s (Trager et al., 1981). T h e q u a s s i n o i d c o n s t i t u e n t s 1497 0098-0331/ 84/i000-1497503.50/09 1984PlenumPublishingCorporation
1498
LESKINEN ET AL.
such as bruceantin (I), now undergoing clinical trial by the U.S. National Cancer Institute (Kupchan et al., 1975), have been of special interest. Since it is highly desirable to develop new methods of pest control (Meinwald, 1978), it seemed interesting to investigate the possible antifeedant effects of the quassinoids. Preliminary antifeedant test (Odjo et al., 1981) were carried out on third stage larvae of Locusta migratoria migratorioides R and F (Orthoptera, Acrididae). The quassinoids bruceine A (II), bruceine B (III), chaparrinone (V), glaucarubinone (VI), and simalikalactone D (XI) were found to be insect antifeedants, whereas soulameanone (XIII) (Polonsky et al., 1980), soulameolide (Polonsky et al., 1979), and simarolide (XII) were inactive. We now report on the antifeedant activity of 13 quassinoids against two pests, Epilachna varivestis Mulsant (Mexican bean beetle) and Spodoptera eridania Crawer (southern armyworm). The former is monophagous and highly selective, whereas the latter is polyphagous and is a voracious eater.
METHODS AND MATERIALS The quassinoids tested were isolated in the pure state from natural sources. Only those which did not appear in the review (Polonsky, 1973) have been referenced. Quassin is commercially available, and its total synthesis has been accomplished recently (Grieco et al., 1980). Each compound was dissolved in acetone at the concentrations (in ppm) indicated in Tables 1 and 2. The feeding bioassays were carried out as follows: A mature bush bean plant, with two leaves approximately the same size, was chosen for each replicate (Figure 1). One leaf top was coated with compound, and one leaf top with solvent alone as a control. These were allowed to dry. In the initial southern armyworm tests, and in all Mexican bean beetle tests, the cut stem was placed in a vial with water and a tissue plug to support the stem. The base of the stem was coated with vaseline to prevent the insects from crawling off. If any compound merited further testing against the southern armyworms, the plant was left rooted in its pot, the leaves coated as before, and the stem covered with vaseline as before. This change in procedure was initiated because the cut stems did not survive the 24-hr test period too well; they tended to wilt and also suffered from the heavier weight of the worms. All plants were then placed inside a cage for the test period to prevent the insects from escaping. Care was taken that no plants or leaves touched, so that the original test subjects stayed on their original plants. Five replicates were run for each test. For the Mexican bean beetles, two fourth instar larvae were placed on each leaf. For the southern
ANTIFEEDANTACTIVITYOF QUASSINOIDS
1499
TABLE 1. ANTIFEEDANT ACTIVITY OF QUASSlNOIDS AGAINST MEXICAN BEAN BEETLE
Eaten (%) Compound Bruceantin (I)
Conc. (ppm) 500 250
100
R 1-5 1 2 3 4 5 1 2
Bruceine A (II)
500
Bruceine B (III)
500
Bruceine C (IV)
500
Chaparrinone (V)
200 100 50 25 10
Glaucarubinone (VI)
500 250 100 50
3 4 5 I 2 3 4 5 1 2 3 4 5 1 2 3 4 5 1-5 1-5 1-5 1-5 1
2 3 4 5 1 2-4 1-5 1 2-4
1 2 3 4 5
C 50-80 90 80 100 50 20 2
10 80 80 33 100 100 90 100 100 95 80 90 95 95 90 90 95 75 70 66-100 50--80 50-100 75-100 66 90 90 75 80 15 10-33 33-90 10 33-75 33 33 25 50 50
X
Result
2-5 15 10 15 10 5
+ + + + + +
20
-
10 20 20 50 15 20 2 50 20 5 10 10 10 30 10 15 5 25 30 5-10 5-10 5-20 5-15 25 20 20 10 10 15 0-5 5 10 2-5 20 5 5 5 5
+ + + + + + + + + + + + + + + + + + + + + +
+ + + + + + -
+ + + + + +
1500
LESK1NEN ET AL TABLE 1. C o n t i n u e d
Eaten (%) Compound
Conc. (ppm) 25
Glaucarubolone (VII)
500
Isobruceine A (VIII)
500
200 100
50 25 10
Picrasin B (IX)
500
Quassin (X)
500 250 100 50 10
Simalikalactone D (XI)
200
Simarolide (XII)
500
R 1 2 3 4 5 1 2 3 4 5 1 2 3-5 1-5 1 2 3-5 1-5 1-5 1 2 3 4 5 1 2 3 4 5 1-5 1-5 1-5 1-5 1 2 3 4 5 1 2 3 4 5 1 2
33 20 50 66 75 10 25 I0 80 33 15 20 15-50 15-100 15 5 10-90 50-80 10-75 33 25 33 66 50 80 80 50 95 90 10-66 50-66 50-100 33-90 50 75 50 40 90 80 25 90 75 50 20 50
X
Result
5 5 5 5 15 5 2 5 5 5 I0 50 5 3-5 10 10 5 3-15 5-10 5 5 5 5 5 5 5 2 10 5 1-3 1-5 5 2-5 5 5 10 5 15 5 5 5 5 5 5 2
+ + + + + + + + + § _ + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + +
ANTIFEEDANT ACTIVITYOF QUASS1NOIDS
1501
TABLE I. C o n t i n u e d
Eaten (%) Compound
Soulameanone (XllI)
Conc. (ppm)
500
R
C
X
Result
3 4 5
50 50 50 25 90 66 90 33
5 5 5 25 66 66 80 25
+ + +
1 2
3 4 5
-
+ __+ _
TABLE 2. ACTIVITY OF QUASSINOIDS AGAINST SOUTHERN ARMYWORM E a t e n (%) Compound B r u c e a n t i n (I)
Conc. (ppm) 500
250
Bruceine A (II)
500
Bruceine B (III)
500
Bruceine C (IV)
500
C h a p a r r i n o n e (V)
500
R
C
X
Result
1 2 3 4 5 1 2 3 4 5 1 2 3 4 5 1 2 3 4 5 1 2 3 4 5 1 2 3
20 25 33 25 33 25 50 20 20 66 65 45 10 50 45 30 65 30 35 15 50 45 20 25 95 25 25 15
15 15 15 15 15 75 15 33 20 50 20 30 15 25 30 50 45 75 45 40 50 70 10 45 99 15 10 15
_+ + + _ + + + + + + + + + + + -
I
I
I ~- §
-I- ~r
I I§ I~ -I- I§ ~- ~- -b- -I- -~ ~
I§ ~-
I §
o
I
I
I
I
I I§
I 4-
1 14- 4-
I 4- -I- 4-
o
4-
I -i- I 4- 4-
I e-,
C~
Z
1503
ANTIFEEDANT ACTIVITY OF QUASSINOIDS
TABLE 2. C o n t i n u e d
Eaten (%) Conc. (ppm)
Compound
Picrasin B (IX)
500
Quassin (x)
500
R 4 5 1 2 3 4 5 1 2 3 4 5 1 2 3 4 5
250
100
1 2
Simalikalactone D (XI)
200
Simarolide (XII)
500
Soulameanone (XIII)
armyworms, The worms
3 4 5 1 2 3 4 5 1 2 3 4 5 1 2 3 4 5
500
two newly emerged
X
-
• + + + + + ? + -
on the leaves, since
like the beetles. After 24 hr, the percentages
eaten from
each leaf were estimated had
had
+ • + ? + + + + + + +
fifth instar larvae were placed on each leaf.
the
eaten
Result
10 10 10 5 66 50 50 20 10 20 66 ? 10 10 10 5 15 2 5 I0 15 5 15 5 15 5 20 10 15 15 50 20 10 20 15 15 33 50 10 20 25 15 15 20 25 0 66 2 25 2 33 2 25 2 All stems chewed throughout but leaves evenly eaten ? ? 20 10 evenly eaten 10 10 25 25
were starved for 1-2 hr prior to placements
they do not eat continuously worms
C
visually. Occassionally
to be taped
to graph
paper
the leaves that and
the
outline
1504
LESKIr~ENEXAL,
LEAF- CHOICE TEST C
X
Control
Compound
~
Vaseline
"
]
I'(