OVIPOSITION CHOICES OF EPIRRITA-AUTUMNATA (LEPIDOPTERA, GEOMETRIDAE) IN RELATION TO ITS ERUPTIVE POPULATION-DYNAMICS

We found that oviposition behaviour is indiscriminative in Epirrita au tumnata (Lepidoptera, Geometridae), a species known as a periodical pe st of birch forests in northernmost Europe. Oviposition in E. autumnat a was not suppressed by low host quality injured host leaves, or the p resence of conspecific eggs or sex pheromone. Oviposition was not limi ted to host plants, whereas physical characteristics of the substrate were decisive in oviposition site selection. Therefore, the ovipositio n behaviour of E. autumnata is typical for an outbreak species and cer tainly contributes to the eruptive population dynamics of the species. Young larvae are responsible for finding a host plant but their capac ity for host selection is rather restricted; larval dispersal cannot c ompensate for indiscriminative oviposition. Indiscriminative ovipositi on should not be seen as a phylogenetic constraint in E. autumnata mor e probably, it results from selection in favour of large body size in females which reduces their flying ability.