| The insect family Cerambycidae, the longhorned beetles, includes more than 35,000 species in about 4,000 genera. The larvae are phytophagous and bore into woody plants that may be alive, moribund, dead, and decomposing. It is commonly assumed that cerambycids use pheromones to locate mates; however, convincing evidence of long-range pheromones has been limited to very few species attacking living or dead hosts. Studies of several species that utilize moribund hosts have revealed no evidence of long-range sex pheromones, instead the sexes are united by their mutual attraction to the larval host.; Larvae of many cerambycid species require woody host plants that are stressed or weakened in some way. Such hosts represent an ephemeral and unpredictable resource, with prime subcortical tissues being rapidly degraded by a variety of wood-feeding insects. Thus, the first larvae to colonize a host will have access to the best nutrition, selecting for rapid host location and mate recognition strategies by the adults. In this study, I test the hypothesis that adult longhorned beetles are attracted to volatile compounds emanating from larval host plants. Once on the larval host, the mating strategy is scramble and interference competition among males for females. I also find that large body size confers a mating advantage in aggressive competition among male cerambycid beetles. I test the hypothesis that contact pheromones mediate mate recognition in four species of longhorned beetles, Neoclytus mucronatus mucronatus (F.), Megacyllene caryae (Gahan), Megacyllene robiniae (Förster), and Plectrodera scalator (F.). In addition, I identify the female-produced contact pheromone of Xylotrechus colonus F, M. robiniae, and M. caryae. I then explore the use of synthetic hydrocarbons in mark-recapture studies. In the final chapter, I study the genetic structure of the Asian longhorned beetle, Anoplophora glabripennis Motschulsky, an invasive cerambycid native to China and Korea. |
