The spicebush swallowtail, Papilio troilus (L.), lays its eggs on plants in
the family Lauraceae. Sassafras [Sassafras albidum (Nutt.) Nees], spicebus
h [Lindera benzoin (L.) Spreng.], redbay (Persea borbonia (L.)] and camphor
tree [Cinnamomum camphora (Nees) Eberm.] are four of its known host plants.
in one-choice tests, free-flying spicebush swallowtail females laid eggs o
n chemical extracts of the leaves of each of these four hosts. In two-choic
e experiments, females always preferred to oviposit on an extract of sassaf
ras compared to extracts of the other three hosts. It was shown for spicebu
sh extract that this response was not due to oviposition experience. Previo
usly we had identified one of the host plant chemicals acting as an oviposi
tion stimulant in sassafras extract as 3-caffeoyl-muco-quinic acid (3-CmQA)
. Extracts of the other three hosts did nor contain this compound. The addi
tion of 3-CmQA alone to spicebush extract did not increase oviposition acti
vity. It did, however, increase discrimination between hosts and nonhosts.
When a fraction of sassafras extract containing 3-CmQA and other synergisti
c stimulants was added to spicebush extract, preference for sassafras extra
ct was no longer recorded. These results show existing differences in ovipo
sition chemistry among host plants of the spicebush swallowtail and how the
se differences can influence oviposition choice in bioassay experiments.