Utetheisa ornatrix pyrrolizidine alkaloids

We knew Utetheisa to feed on poisonous plants as a larva (Figure 1B). The plants, of the genus Crotalaria (family Leguminosae), were known to contain pyrrolizidine alkaloids (henceforth abbreviated as PAs), intensely bitter compounds potently hepatotoxic to mammals (7). Other species of Utetheisa were known to sequester PAs (8). We found this to be true for U. ornatrix as well. Adult Utetheisa raised on Crotalaria spectabilis, one of the principal foodplants available to the moth in the United States, contain on average about 700 p,g of monocrotaline (1), the principal PA in that plant (9, 10). 

Eisner, T. and Eisner, M. (1991). Unpalatability of the pyrrolizidine alkaloid-containing moth Utetheisa ornatrix, and its larva, to wolf spiders. Psyche 98 111-118. 

Hare, J. F. and Eisner, T. (1993). Pyrrolizidine alkaloid deters ant predators of Utetheisa ornatrix eggs effects of alkaloid concentration, oxidation state, and prior exposure of ants to alkaloid-laden prey. Oecologia 96 9-18. 

Figure 12.3 Utetheisa ornatrix that were offered to the orb-weaving spider Nephila clavipes. The specimen on the right, rejected intact, was raised on one of its normal, pyrrolizidine alkaloid-containing food plants (Crotalaria mucronata). The one on the left, raised on an artificial diet devoid of alkaloid, was eaten. See also Figure 12.4. (From Eisner, 1982. American Institute of Biological Science.)...

Figure 12.5 Utetheisa ornatrix. A Male (above) stroking its everted coremata against female during courtship. B Larva feeding on seed pod of its natural, pyrrolizidine alkaloid-containing food plants (Crotalaria spectabilis). C Scanning electronmicrograph of abdominal tip of male, showing coremata in everted (left) and retracted condition. [Bar = 1 mm A and C from Eisner, 1980].

Pyrrolizidine alkaloids parental transmission to egg ( Utetheisa ornatrix and Danaus gilippus)... 

Host plants play a key role in the production and use of sex pheromones by herbivorous insects through larval or adult sequestration of chemically active compounds and pheromone precursors [210]. One of the best examples of sequestration of plant chemicals by larvae and their subsequent use by adult males in sex attraction or courtship interactions is shown in Utetheisa ornatrix (Arctiidae), whose courtship pheromone derives from pyrrolizidine alkaloids (PAs) ingested at the larval stage from the host plant Crotalaria spectabilis [211]. U. omatrix larvae sequester PAs (e.g. monocrotaline) and retain the alkaloids through metamorphosis into the adult stage to provide egg protection for the next generation. 

The moth Utetheisa ornatrix consumes plants of the genus Crotalaria that contain pyrrolizidine alkaloids. Although adults normally are not eaten by the spider Nephila clavipes, moths raised in the laboratory were consumed. Males of this species also produce two pyrrolizidines that are closely related to danaidal (10) and three hydrocarbon pheromones. The pyrrolizidines are passed from the male to the female and deposited in the eggs (Eisner and Meinwald, 1987). 

---