|Dötterl, S; Jürgens, A; Seifert, K; Laube, T; Weißbecker, B; Schütz, S: The role of flower volatiles for the interaction between the seed predating pollinator Hadena bicruris and its main host plant, Silene latifolia, 12th International Symposium on Insect-Plant Relationships (SIP) (2004)|
Thirteen nursery pollination systems are worldwide known, where pollinators reproduce within the flowers they pollinate. One of these systems is the noctuid moth Hadena bicruris and the dioecious Caryophyllaceae species Silene latifolia. Male and female moths use this plant to drink nectar, and the females additionally lay their eggs in female flowers. Flowers are thereby pollinated and the larvae develop on the growing seeds. Since the 70ies it is known that the moths are attracted to the flowers by their scent. However, it was not known which compounds are important for the attraction. A floral scent analysis of plant specimens originating from seeds of different populations indicated that the scent is generally very variable. We found that different compounds abundant in a particular chemotype were only minor compounds or even absent in other chemotypes (e.g. lilacaldehyde isomers, (E)-ocimene, benzaldehyde, phenylacetaldehyde, veratrole). Wind tunnel biotests with flowers releasing different scents have shown that the moths are attracted to different chemotypes. Especially the variable compounds were electrophysiologically very active in GC-EAD and GC/MS-EAD studies respectively. Strong EAD signals were elicited e.g. by lilacaldehydes, phenylacetaldehyde, and (E)-ocimene. To evaluate the importance of single EAD-positive substances for the attraction of H. bicruris, we offered standard compounds in a wind tunnel. Some compounds attracted moths (e.g. lilacaldehydes, phenylacetaldehyde, veratrole), other compounds did not attract any specimen (e.g. benzaldehyde). The most attractive compounds were lilacaldehyde isomers. Natural doses of these particular compounds were as attractive as the scent of single flowers.