Successful overwintering of Lepidoptera larvae and eggs on spruce trees uprooted by the wind

Abstract

Windstorm on November 19, 2004 seriously affected Norway spruce (Picea abies) forests in Tatra Mountains, Northern Slovakia. We studied as to whether moth larvae and eggs overwintered successfully on branches of uprooted spruce trees. Also, we evaluated differences in assemblage structure of overwintering developmental stages of moths between the upper and middle crown area of wind-felled spruce trees. In May 2005, we sampled branches from a total of 12 wind-felled trees in Tichá dolina valley in the altitudes between 1,020 and 1,050 m. From each tree, a total of 30 branches were collected from both its upper and middle crown area. In addition, a total of 400 cones were sampled from the wind-felled trees. Moth larvae or hatched adults were obtained from branches or cones through photoeclectors in the laboratory. Larvae of one species developing in cones (Cydia strobilella), 3 species of bud-borers (Argyresthia glabratella, A. amiantella, A. bergiella), 7 needle spinning species (Batrachedra pinicolella, Chionodes electella, Syndemis musculana, Dichelia histrionana, Pseudohermenias abietana, Epinotia tedella, E. nanana), one free living species (Thera variata) and one species feeding on lichens or algae (fam. Psychidae – Naryciinae, not identified) were recorded. The moth Zeiraphera griseana was the only species overwintering in the egg stage. Branches of uprooted spruce trees hosted all moth species common on living standing spruce trees in other mountain valleys of Tatra Mountains. Specimens of needle-spinning species overwintering in the larval stage were collected in significantly greater numbers on the upper crown than on the middle crown branches of the individual wind-felled trees (p < 0.05, Wilcoxon matched pairs test). In bud-borers, such significant differences were not found. The numbers of moth specimens belonging to the rest feeding groups were low. Successful development of all moth species overwintering on uprooted trees in the larval stage (13 species) was highly likely. Most larvae of Z. griseana emerging from eggs in spring, possibly, died because of the lack of opening buds and young needles on most fallen trees which were drying out gradually.