Host choice of late instar gypsy moths (Lepidoptera: Lymantriidae) between loblolly pine and sweetgum

Host choice of late instar (L4-L6) gypsy moths, Lymantria dispar (L.), was evaluated using stems and foliage of loblolly pine, Pinus taeda L., and sweetgum, Liquidambar styraciflua L. Upon release as 4th instars, larvae were free to roam within arenas, where their location was recorded several times per day until all had pupated. The number of larvae on a particular host species was highly dependent on larval age. After release into experimental arenas, there was nearly unidirectional movement from loblolly pine to sweetgum, resulting in 75% of larvae being found on this host after 4 d. Sweetgum remained the preferred host for most of the larval stage; however, as larvae neared pupation there was strong movement to loblolly pine, which was preferred over sweetgum approximately 3 to 1 for pupation. The initial host of release had no effect on larval host-choice for pupation. Host sequence, defined by host of release and host of pupation, affected larval duration and pupal weight only in the following cases. Insects that began and pupated on loblolly pine developed at a slower rate and weighed less than those that began and pupated on sweetgum. Individuals that switched hosts for pupation generally were not significantly different (in pupal weight or development time) from either of these. Implications of the observed pattern of host use, especially the overwhelming choice of loblolly pine for pupation, on gypsy moth interactions with natural enemies in the southeastern United States are discussed