Conduritols as oviposition stimulants for the danaid butterfly, Parantica sita, identified from a host plant, Marsdenia tomentosa.
Host-plant chemicals responsible for egg-laying by the chestnut tiger butterfly, Parantica sita, were identified from one of its hosts, Marsdenia tomentosa. Ovipositing females responded positively to a methanolic extract of the plant. Solvent partitioning of the extract and oviposition bioassays indicated that the active principle resided in the aqueous fraction. Further activity-directed fractionation of the water-soluble constituents by various forms of column chromatography led to the isolation of several saturated and unsaturated cyclitols together with their glycosides. Of these, conduritol A, a predominant cyclitol present in the plant, moderately stimulated oviposition, while conduritol F 2-O-glucoside, although present in a very small amount, evoked a stronger response from females than conduritol A when tested at the same dose. In contrast, its aglycone, conduritol F, which was also a trace component, was almost inactive by itself. However, the oviposition-stimulatory activity of conduritol A was significantly enhanced when tested in combination with a small quantity of conduritol F. Addition of a small quantity of conduritol F 2-O-glucoside to conduritol A resulted in a substantial elevation in female responses. Consequently, the synergistic action of a large amount of conduritol A and small amounts of co-occurring conduritol F and its glucoside can account for the stimulation of egg-laying by P. sita on M. tomentosa.
Honda
Keiichi
K
Division of Environmental Sciences, Faculty of Integrated Arts and Sciences Hiroshima University, Higashihiroshima 739-8521, Japan. honce@hiroshima-u.ac.jp
Omura
Hisashi
H
Hayashi
Nanao
N
Abe
Fumiko
F
Yamauchi
Tatsuo
T
D000818:Animals; D002080:Butterflies / Q000502:physiology*; D003511:Cyclohexanols / Q000737:chemistry / Q000494:pharmacology*; D004357:Drug Synergism; D005260:Female; D005960:Glucosides / Q000737:chemistry / Q000494:pharmacology; D006790:Host-Parasite Interactions; D010058:Oviposition / Q000187:drug effects*; D010944:Plants / Q000737:chemistry* / Q000469:parasitology; D012995:Solubility
D003511:Cyclohexanols; D005960:Glucosides