The Effects of Plant Phytochemistry on Parasitoid (Hymenoptera: Braconidae) Niche Breadth

The definition of a species, a fundamental unit of biology, has been debated since its inception. This level of classification is vital to our ability to make meaningful comparisons across all subdisciplines of biology. Cryptic species, those which are indistinguishable from another species using morphology alone, pose a unique problem. This is especially true for biological control programs, where the control of an invasive pest is achieved through the importation of a natural enemy or parasitoid from the pest\u27s native range. The accidental importation of a cryptic species could have long lasting negative environmental effects. Molecular taxonomy provides a solution. A recent large-scale phylogenetic study of Eadya paropsidis, a potential biological control agent for the invasive New Zealand pest Paropsis charybdis, also known as the Eucalyptus tortoise beetle, is a perfect model for the integration of molecular taxonomy into biological control research. This study not only uncovered a cryptic species, but three additional non-cryptic species as well, each of which exhibit varying degrees of host flexibility. Here I formally describe three new species of Eadya (E. daenerys, E. spitzer, E. annleckieae) using an integrative taxonomic approach, and redescribe the two previously known species of Eadya (E. paropsidis and E. falcata). An additional species (E. duncan) from the Australian National Insect Collection is described using morphology. The formal description of these host flexible species enables investigation on the influence of plant phytochemistry on parasitoid niche breadth. Using 112 compounds extracted from Eucalyptus leaves, I conclude that host selection is heavily influenced by infochemicals from the 1st trophic level. With this evidence, I amend the reliability- detectability hypothesis of Vet and Dick (1992) on infochemical use by natural enemies of herbivores, to include the scenario in which an oligophagous parasitoid utilizes oligophagous hosts