248
Stefan Schulz
41
(S)-40
(R)-40
Fig.12. Chemical structures and biosynthetic origin ofmonoterpenes (37, 38, 42, 40) used as
pheromone components by arthropods
pheromones. Several modes of enantiomer usage in chemical communication systems can be found in nature and have been discussed in depth by Mori (1996).
Different compositions of the two enantiomers (R)-40 and (S)-40 are used by different races of I. pini. The California race is attracted by (R)-40; as little as 5% of
the (S)-enantiomer, which is the aggregation pheromone of I. paraconfusus, inhibits
attraction, because both species use the same host tree. The New York race, facing
no competition from another species, is attracted by (R)/(S)-mixtures ranging from
60: 40 to 30: 70 (Miller et al. 1996). This case exemplifies not only the ecological
impact on the composition of a pheromone, but also the flexibility of mixtures.
The males of the giant danaine butterfly, Idea leuconoe, use a complex blend of
chemicals for pheromonal communication (see Fig. 13). One of the three principal components of its sex pheromone is geranyl methylsulfide ( 42) (Nishida et al.
1996). This terpenoid compound carries the same carbon skeleton as 37, but also
a thiomethyl functional group. It is the only sulfur compound so far known as an
arthropod pheromone. The other two components are the alkaloid 5 and the 13lactone 43. They are derived from host pyrrolizidine alkaloids that are transformed
into the pheromone by the butterflies (Nishida et al. 1991 ). In the moth Utetheisa
ornatrix, the amount of the related pheromone hydroxydanaidal (44) advertises the
amount of protective alkaloid that the females can obtain, as a nuptial gift during
copulation, with the sperm to protect their eggs (Dussourd et al. 1991 ). A large
number of male Lepidoptera of different families obtain pyrrolizidine alkaloids and
derive a closely related family of pheromones therefrom, including 5 and 44 (Schulz
1998). The exact function of the dihydropyrrolizine in most species is unknown, but
their use during courtship points to similar functions as that in U ornatrix. Nevertheless, long-range attraction of females to 44 seems to operate in I. leuconoe (Nishida
et al. 1996) and in the arctiid moth Creatonotos transiens (Boppre and Schneider
1989). In the latter case, the uptake of the pheromone precursor even has a morphological effect, regulating the size of the coremata and the amount of 44 they contain
(Boppre and Schneider 1985).
Stefan Schulz
41
(S)-40
(R)-40
Fig.12. Chemical structures and biosynthetic origin ofmonoterpenes (37, 38, 42, 40) used as
pheromone components by arthropods
pheromones. Several modes of enantiomer usage in chemical communication systems can be found in nature and have been discussed in depth by Mori (1996).
Different compositions of the two enantiomers (R)-40 and (S)-40 are used by different races of I. pini. The California race is attracted by (R)-40; as little as 5% of
the (S)-enantiomer, which is the aggregation pheromone of I. paraconfusus, inhibits
attraction, because both species use the same host tree. The New York race, facing
no competition from another species, is attracted by (R)/(S)-mixtures ranging from
60: 40 to 30: 70 (Miller et al. 1996). This case exemplifies not only the ecological
impact on the composition of a pheromone, but also the flexibility of mixtures.
The males of the giant danaine butterfly, Idea leuconoe, use a complex blend of
chemicals for pheromonal communication (see Fig. 13). One of the three principal components of its sex pheromone is geranyl methylsulfide ( 42) (Nishida et al.
1996). This terpenoid compound carries the same carbon skeleton as 37, but also
a thiomethyl functional group. It is the only sulfur compound so far known as an
arthropod pheromone. The other two components are the alkaloid 5 and the 13lactone 43. They are derived from host pyrrolizidine alkaloids that are transformed
into the pheromone by the butterflies (Nishida et al. 1991 ). In the moth Utetheisa
ornatrix, the amount of the related pheromone hydroxydanaidal (44) advertises the
amount of protective alkaloid that the females can obtain, as a nuptial gift during
copulation, with the sperm to protect their eggs (Dussourd et al. 1991 ). A large
number of male Lepidoptera of different families obtain pyrrolizidine alkaloids and
derive a closely related family of pheromones therefrom, including 5 and 44 (Schulz
1998). The exact function of the dihydropyrrolizine in most species is unknown, but
their use during courtship points to similar functions as that in U ornatrix. Nevertheless, long-range attraction of females to 44 seems to operate in I. leuconoe (Nishida
et al. 1996) and in the arctiid moth Creatonotos transiens (Boppre and Schneider
1989). In the latter case, the uptake of the pheromone precursor even has a morphological effect, regulating the size of the coremata and the amount of 44 they contain
(Boppre and Schneider 1985).