Ecological Entomology (2016) 41, 413-420

Meggy Hervieux, Dorothy Y. Maguire, Rob C. Johns, Éric Bauce, Chris M. Buddle and Dan T. Quiring (2016)
Hanging in the treetops: an in situ experiment in ancient hemlock assessing outbreak defoliator performance among crown levels
Ecological Entomology 41 (4), 413-420
Abstract: 1. Past studies have shown that both egg lay and larval feeding of a generalist defoliator, pale-winged gray (Iridopsis ephyraria Walker) (Lepidoptera: Geometridae), are concentrated in the mid-lower crown of eastern hemlock [Tsuga canadensis (L.) Carr.].
2. Using tree-climbing techniques, we carried out in situ bioassays in large hemlock trees (~25 m) to determine whether the observed foraging preferences are adaptive and how they reflect associated intra-tree variations in microhabitat quality associated with temperature and foliage nutritional quality.
3. In 1 of 2 years, larval survival was significantly higher in the shaded lower versus sunlit upper crown; however, in both years, groups that fed in the sunlit upper crown branches had larger male and female moths and more female-biased sex ratios.
4. Differences in pale-winged gray performance among crown levels were somewhat supported by trends in foliage nutritional chemistry but not well-correlated with variation in temperature.
5. The present study is one of only a few to carry out bioassays on large mature trees and results reinforce the idea that foraging patterns of herbivores are likely to reflect trade-offs among several factors that vary between sunlit and shaded branches within forest canopies.
(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): Rob C. Johns, Eric Bauce, Christopher M. Buddle

Research topic(s) for pests/diseases/weeds:
environment - cropping system/rotation
general biology - morphology - evolution

---

Pest and/or beneficial records:

Beneficial	Pest/Disease/Weed	Crop/Product	Country	Quarant.
	Iridopsis ephyraria	Hemlock (Tsuga)