Winter-moth populations are isolated on co-occurring tree species with contrasting budburst-phenology

Differences between neighbouring tree species in phenology could isolate populations of host-plant generalists that depend on matching the phenology of their host. We studied the relationship between the budburst phenology of two co-occurring tree species with early (hornbeams) and late (oaks) budburst, and the egg-hatching date of associated winter moths (Operophtera brumata) during two seasons (autumns starting in 2020 and 2021). A previous study in spring 2019 had found no winter moth larvae on the focal oaks, while we found them mainly on oaks with hornbeam neighbours in 2022. Congruently, adult winter moths were rarely encountered during the autumns of 2018 and 2019 and sparsely in 2020 and 2021, and then mainly near hornbeams.The vast majority of winter moths had early-hatching eggs when both hornbeams and oaks were present, matching the hornbeams rather than the oaks. Where hornbeam was absent in the neighbourhood, the few winter moths had late-hatching eggs.These results suggest..., Study system: We selected 35 individual mature sessile oaks and recorded the species identity of neighboring trees (trees with which the crown is in touch) in the Puszcza Zielonka forest in Western Poland [52°33′12″N 17°06′48″E; 17]. This forest consists mainly of sessile oaks and pines (Pinus sylvestris L., not suitable for winter-moth larvae), with a sub-canopy of common hornbeam in some areas [18]. The selected oaks were located in two clusters near the villages Kamińsko and Zielonka. The neighbourhoods of focal oak trees near Kamińsko often included hornbeams (4 out of 7 sites), but hornbeams were absent in sites near Zielonka village (6 sites). In this region, hornbeams typically are among the first trees to burst buds, and oaks the last.
Winter-moth larvae are generalist feeders, attacking leaves and flowers of most woody angiosperms in temperate regions, including oaks and hornbeam. They can cause extensive defoliation in forest stands during cyclic outbreaks, leading to reductio..., These are Excel files with raw data, plus the R code for the eg-hatching data., # Data from: Winter-moth populations are isolated on co-occurring tree species with contrasting budburst-phenology

One file shows the data on collection of winter moths at the trunk of trees, and subsequent egg hatching date. There is a separate sheet for each year. The file also gives information about the neighborhood of the focal trees (trees with which the crown is in contact). The other file shows the budburst phenology of the trees. Each file has a sheet with explanations of column names.

Moths were collected into vials in the field and females were then transferred to a vial with tissue paper on which she could lay eggs in autumn. Vials with eggs were stored outdoors. In spring, we daily checked all the vials for hatchling caterpillars. 

Egg hatching data column names.

| Date | Date moth was collected |
| :------- | :----------------------------------------------------------------------------------------- ...