We studied the effect of previous defoliations of Pinus sylvestris on the performance of two geometrid moths, Bupalus piniarius and Macaria liturata, using a field experi-ment. Prior to the experiment, we found defoliation to increase the concentrations of certain secondary chemicals and reduce the N (nitrogen) concentration of needles. Hence, it was predicted that defoliation-induced changes should decrease the perform-ance of geometrids feeding on P. sylvestris. As B. piniarius is a monophagous species on P. sylvestris, and M. liturata is oligophagous feeding also on Larix and Juniperus species, we predicted that M. liturata should suffer more than B. piniarius from defo-liation-induced changes in needle chemistry. As predicted, defoliation had a negative effect on the performance, the oligophagous M. liturata being more vulnerable. Defo-liation resulted in decreased sex-specific survival of M. liturata, but did not affect the survival of B. piniarius. In M. liturata, no males survived to the pupal stage in previ-ously defoliated trees. Defoliation also resulted in lower pupal weights in both species. We conclude that defoliation-induced changes on the performance of insects with dif-ferent host ranges merit more attention.
|Journal||Annales Zoologici Fennici|
|Number of pages||7|
|Publication status||Published - 2005|
|MoE publication type||A1 Journal article-refereed|