Use of sensory information by cerambycids and their natural enemies to locate resources and mates

The purpose of this dissertation is to extend knowledge of the cues and signals that cerambycids and their natural enemies use to locate mates and resources. Many species of longhorned beetles (Coleoptera: Cerambycidae) prefer to feed in trees that are stressed, weakened, or in the process of dying. These resources are ephemeral, disappearing rapidly as they are colonized by competitors and the condition or quality of these trees degrades. It is therefore imperative for these cerambycids to locate mates and hosts that are suitable for oviposition, quickly and efficiently. In my first chapter, I evaluated whether the brightly colored patterning on the elytra of the cerambycid Megacyllene caryae Gahan was used in mate-location. I tested this prediction by baiting traps with citral, a known attractant from the pheromone blend of M. caryae, or with citral and a dead adult beetle, which acted as a visual cue. More adults of M. caryae were captured on traps baited with both their pheromone and the visual cue, compared to either alone, or controls. This result supported my hypothesis indicating that visual cues contribute to mate-location in M. caryae. In my second chapter, I hypothesized that parasitic Hymenoptera use the pheromones of cerambycids as kairomones to locate potential hosts. I tested this hypothesis by baiting sticky traps with known pheromones of cerambycids over two field seasons. Ten species of parasitoids significantly responded to pheromones of cerambycids. The result that provides the strongest support for my hypothesis is the response by the larval parasitoid Wroughtonia ligator (Say) (Braconidae), which was attracted to the pheromone of its reported host, Neoclyus acuminatus acuminatus, and no other compounds. My finding suggests that responses can be exploited to characterize and identify parasitoids of cerambycids in some cases. In my third chapter, I evaluated the hypothesis that pheromones of cerambycids influenced the rate of parasitism and/or predation of cerambycid eggs. I tested this with the eggs and pheromones of the rustic borer, Xylotrechus colonus (F.) in two field experiments. The first experiment evaluated the role of location and pheromones on the rate of attack on eggs of X. colonus, whereas the second experiment addressed the role of pheromones in modulating response by natural enemies. Using cameras to allowing identification of the arthropods visiting and eating egg masses, I found that eggs of X. colonus are consumed rapidly, regardless of location, although location may interact with pheromones to interfere with the responses of specific natural enemies. Moreover, pheromones appear to influence the rate of attack on eggs by natural enemies, with some species of natural enemies likely driving this result. Lastly, when the eggs of the rustic borer are presented in a semi-natural context, many species of arthropods including species of Diptera, Hymenoptera (especially ants), and Orthoptera are important predators of cerambycid eggs.U of I OnlyAuthor requested U of Illinois access only (OA after 2yrs) in Vireo ETD syste