Fate of an alkaloidal nuptial gift in the moth Utetheisa ornatrix: systemic allocation for defense of self by the receiving female.

In the moth Utetheisa ornatrix defensive pyrrolizidine alkaloids are sequestered by both sexes as larvae from their foodplants. The adult male transmits some of this alkaloid to the female at mating for eventual incorporation into the eggs. We now show by chemical analyses that the female herself is the first beneficiary of the alkaloid she receives from the male. By the end of mating the male's alkaloid is found already to be generally distributed throughout the female's body (including even the wings), while it is still largely absent from the ovaries. This result is in line with our earlier finding that the male's alkaloidal gift can itself suffice to render a female fully protected against spiders from the moment she uncouples from the male.