A REPLY TO DR. FARRIS' COMMENT ON EVOLUTION IN THE DROSOPHILA OBSCURA SPECIES GROUP

Host plant selection, larval survival, and reproductive phenology in Megathymus yuccae (Lepidoptera: Hesperiidae)

Our primary objective in this study was to determine the plant level and environmental factors that affect oviposition choice and subsequent offspring survival in Megathymus yuccae (Boisduval and Leconte) on its host plant, Yucca filamentosa L. A preliminary survey suggested that the frequency of pupal eclosion tent presence increased only with host plant height. In an expanded survey conducted during the adult flight period the following spring, we found that plant height increased the probability of oviposition, whereas the density of herbaceous stems and fire damage decreased the probability of egg presence. Similarly, the number of eggs on occupied plants increased with plant height and decreased with fire damage. When we surveyed the plants from the spring 2008 sampling the following winter to determine presence of late-instar larvae or pupae, we found that the probability that at least one larva survived on previously occupied plants decreased with the density of herbaceous stems. These results collectively suggest that larger, unburned Y. filamentosa individuals and those in relatively open areas are more attractive as host plants for oviposition and that larval performance is generally, but not exclusively, consistent with female preference in this system.