Thisresearch concerns the relationship between oviposition preference and larval performance in closely-related butterfly species of Papilio (Lepidoptera) that differ in the plant families on which they feed. The study will take advantage of the recent finding that oviposition preference in P. oregonius is controlled partly by loci on the X chromosome. This finding provides for the first time the opportunity to ask some fundamental questions on how oviposition preference and larval performance are genetically related in the evolution of host associations in insect/plant interactions. Section I of the study tests whether larval performance on different plant species is controlled, partly or solely, by loci on the X chromosome as is oviposition preference in these species. Section II then analyzes whether there is variation among isofemale lines within population in larval performance on different plant species as there is for host selection in ovipositing females in these species. Finally, section III considers how variation in larval performance correlates with variation in oviposition preference with respect to inheritance through the X chromosome. Together, the results from these three sections will aid in the development of the theory of insect/plant interactions and the evolutionary ecology of host association by addressing the fundamental problem of the relationship between oviposition preference and larval performance on different hosts.
