Agricultural and Forest Entomology (2010) 12, 81-87

Annette Heisswolf, Miia Käär, Tero Klemola and Kai Ruohomäki (2010)
Local outbreaks of Operophtera brumata and Operophtera fagata cannot be explained by low vulnerability to pupal predation
Agricultural and Forest Entomology 12 (1), 81-87
Abstract: 1 - One of the unresolved questions in studies on population dynamics of forest Lepidoptera is why some populations at times reach outbreak densities, whereas others never do. Resolving this question is especially challenging if populations of the same species in different areas or of closely-related species in the same area are considered.
2 - The present study focused on three closely-related geometrid moth species, autumnal Epirrita autumnata, winter Operophtera brumata and northern winter moths Operophtera fagata, in southern Finland. There, winter and northern winter moth populations can reach outbreak densities, whereas autumnal moth densities stay relatively low.
3 - We tested the hypothesis that a lower vulnerability to pupal predation may explain the observed differences in population dynamics. The results obtained do not support this hypothesis because pupal predation probabilities were not significantly different between the two genera within or without the Operophtera outbreak area or in years with or without a current Operophtera outbreak.
4 - Overall, pupal predation was even higher in winter and northern winter moths than in autumnal moths. Differences in larval predation and parasitism, as well as in the reproductive capacities of the species, might be other candidates.
(The abstract is excluded from the Creative Commons licence and has been copied with permission by the publisher.)
Link to article at publishers website
Database assignments for author(s): Annette Heisswolf, Tero Klemola

Research topic(s) for pests/diseases/weeds:
population dynamics/ epidemiology
biocontrol - natural enemies
Research topic(s) for beneficials or antagonists:
surveys/distribution/isolation

---

Pest and/or beneficial records:

Beneficial	Pest/Disease/Weed	Crop/Product	Country	Quarant.
	Operophtera brumata		Finland
	Epirrita autumnata		Finland
	Operophtera fagata		Finland