Oviposition preference of Megathymus yuccae (Lepidoptera: Hesperiidae): Effects of host plant and microhabitat variables

The reproductive success of vagile phytophagous insects is dependent upon locating and assessing the quality of host plants and then allocating eggs accordingly. We evaluated how plant and microhabitat variables affect the presence and abundance of Megathymus yuccae (Boisduval and Leconte) eggs and larvae on one of its larval host plants, Yucca filamentosa L. (Agavaceae) in north-central Florida. We measured plant height, conspecific density, the number of surrounding herbaceous and woody stems, and the burn status for 642 individually marked Y. filamentosa plants and surveyed these plants over the 2008 flight period of M. yuccae for evidence of oviposition. We then tested the importance these variables in explaining patterns of occupancy and abundance of M. yuccae. Probability of oviposition increased with plant height and decreased with density of herbaceous stems and with fire damage. For occupied plants, the number of eggs present also increased with height and decreased with fire damage but was unaffected by herbaceous stem density. These results suggest that plant apparency, as indicated by the density of surrounding vegetation, was important only for host location whereas plant height was important for both host location and perceived host plant quality by the ovipositing female. The results also suggest that recent fire can deter oviposition by M. yuccae directly through damaging crowns but may also increase plant apparency by thinning the surrounding vegetation; however, the long-term effects of fire in this system cannot be inferred from our study.