Major Sex Pheromone Component of Female Herald Moth Scoliopteryx libatrix is the Novel Branched Alkene (6Z,13)-Methylheneicosene

The major component of the female-produced sex pheromone of Scoliopteryx libatrix has been characterized by chemical analysis, synthesis, electrophysiological studies and field tests as (6Z,13)-methylheneicosene, probably the 13S-isomer. This is the first example of a branched chain alkene as a sex pheromone in the Noctuidae and is markedly different from the pheromones of other members of the family. The systematic position of S. libatrix, belonging to a monotypic genus of a one-member subfamily within the Noctuidae, may reflect the unusual structure of the sex pheromone.     

Characteristic odor of Osmoderma eremita identified as a male-released pheromone

Osmoderma eremita (Scopoli) is an endangered scarab beetle living in hollow trees. It has mainly been known for its characteristic odor, typically described as a fruity, peachlike or plumlike aroma. The odor emanating from a single beetle can sometimes be perceived from a distance of several meters. In this paper, we show that the characteristic odor from O. eremita is caused by the compound (R)-(+)--decalactone, released in large quantities mainly or exclusively by male beetles. Antennae from male and female beetles responded in a similar way to (R)-(+)--decalactone in electroantennographic recordings. Field trapping experiments showed that (R)-(+)--decalactone is a pheromone attracting female beetles. Lactones similar to (R)-(+)--decalactone are frequently used as female-released sex pheromones by phytophagous scarabs. This is, however, the first evidence of a lactone used as a male-produced pheromone in scarab beetles. We propose that the strong signal from males is a sexually selected trait used to compete for females and matings. The signal could work within trees but also act as a guide to tree hollows, which are an essential resource for O. eremita. Males may, thus, attract females dispersing from their natal tree by advertising a suitable habitat. This signal could also be exploited by other males searching for tree hollows or for females, which would explain the catch of several males in our traps.     

Identification of the Sex Pheromone of Idolus picipennis (Bach, 1852) Revealed the Presence of a Cryptic Sibling Species

The click beetle Idolus picipennis represents the only species of its genus in Europe, where it is widely distributed but is rare and only occurs locally. In order to identify its sex pheromone we investigated gland extracts of females from populations in southern Germany. GC/MS analyses revealed two distinct types of gland compositions that correspond to slight but consistent morphological differences in the respective beetles. Extracts of one type contain four compounds, geranyl hexanoate (~ 40 %), (Z,E)-farnesyl hexanoate (~ 10 %), (E,E)-farnesyl hexanoate (~ 40 %), and (E,E)-farnesyl octanoate (~ 10 %), and this type belongs to the authentic I. picipennis (Bach 1852). Extracts of a second type contain neryl hexanoate (~10 %) and neryl octanoate (~ 90 %), and this type belongs to an Idolus species that apparently has been overlooked to date, presumably due to similarity with the authentic I. picipennis and insufficient material in collections. Synthetic blends of the identified compounds in their naturally-occurring ratios, as well as the main compounds alone, proved to be highly attractive to swarming males of the respective species in the field. A strong species-specific attraction also was observed in a locality where both species co-occur, thus confirming effective reproductive isolation. This study shows the potential of sex pheromones for monitoring rare and threatened insects as well as for detecting hitherto unknown cryptic species.     

Sex Pheromone of the Rare Click Beetle <Emphasis Type="Italic">Betarmon bisbimaculatus</Emphasis>

The click beetle Betarmon bisbimaculatus (Fabricius, 1803) (Coleoptera: Elateridae) has a scattered distribution throughout a large area in Europe and the near East. Due to its scarcity, little is known about the ecology, biology, and development of this peculiar species. Here, we studied the composition of the female-released sex pheromone of B. bisbimaculatus. Neryl hexanoate, neryl octanoate, and neryl decanoate, in a ratio of approximately 3:1:6, were the only volatile compounds present in the extracts of pheromone glands. A synthetic mixture of all three compounds in the natural ratio was highly attractive to males in field traps. When the compounds were tested individually, only traps baited with neryl hexanoate were attractive, but they caught only a sixth of the males compared to the mixture. Based on the similarity of their sex pheromones, we propose that the tribe Pomachiliini with B. bisbimaculatus is closely related to the tribe Agriotini. This study shows the potential of sex pheromone studies for monitoring of rare and threatened insects as well as for elucidating phylogenetic relationships.