The noctuid sibling taxa Diachrysia chrysitis s. str. and D. tutti, of yet uncertain taxonomic status, have previously been shown to possess differences in morphology and to be attracted to different mixtures of the two presumed pheromone components (Z)-5-decenyl acetate and (Z)-7-decenyl acetate. Typical D. tutti males (clearly broken forewing marking) are known to respond to a 2: 100 mixture of the two isomers, whereas D. chrysitis males (unbroken marking) are attracted to a 100: 10 mixture. We investigated female pheromone production and male electroantennographic (EAG) response in Diachrysia families raised in the laboratory from field-collected gravid females. Extracts of individual females from typical D. tutti and D. chrysitis families were subjected to gas chromatography with simultaneous flame ionization and electroantennographic detection. All females produced mixtures of Z5- and Z7-10:OAc, but female D. chrysitis produced predominantly Z5-10:OAc and the antennae of their brothers responded more strongly to the Z5 peak than to the Z7-10:OAc peak, whereas the opposite was true for D. tutti families. The pheromone components were shown to be biosynthesized from hexadecanoic and tetradecanoic acid, respectively by Z11-desaturation followed by chain shortening, reduction, and acetylation. The EAG responses of males trapped with the typical D. tutti and D. chrysitis blends, as well as with an intermediate blend, were investigated. Males trapped with the D. tutti mixture almost exclusively had a clearly broken wing marking and showed strongest EAG response to Z7-10:OAc. The intermediate blend and the D. chrysitis mixture gave more mixed catches, but with a prevalence of males with an unbroken (or almost unbroken) wing marking and with a higher mean response to Z5-10:OAc. Some males with typical D. tutti EAG responses were attracted in the field to the D. chrysitis pheromone. In the flight tunnel some D. chrysitis males were attracted also to the D. tutti mixture. This indicates that cross attraction may take place between the two taxa under natural conditions.
- Diachrysia chrysitis
- Diachrysia tutti
- electroantennographic responses
- sibling taxa
ASJC Scopus subject areas
- Ecology, Evolution, Behavior and Systematics