The Effects of Host Alternation on the Development of Spongy Moth (Lymantria dispar L.)

The spongy moth is a significant Lepidopteran species across Europe, where it occurs in oak stands. Tree species composition has a crucial effect on larval development, population density, and outbreaks. Host switching is more likely to occur in a mixed forest than in a monospecific forest. We aimed to better understand the effect of host alternation on the development of the spongy moth. In a laboratory, we reared spongy moth larvae on either (a) Turkey oak (Quercus cerris L.) or (b) European hornbeam (Carpinus betulus L.) only or on host plants that were changed from Turkey oak to European hornbeam (c) in the early (L3) or (d) late (L5) larval instar. Both Q. cerris and C. betulus proved suitable hosts for the spongy moth larvae. However, the larvae fed exclusively on Turkey oak leaves had better developmental indicators than the others. The groups that switched hosts had weaker developmental indicators than the larvae fed only on Turkey oak but showed better development than the group reared only on Hornbeam leaves. The results of our laboratory research on host switching may offer valuable insights into the developmental dynamics of spongy moths in monospecific forests versus those with higher biodiversity.