Affiliation:
1. Natural Resources Canada, Canadian Forest Service-Atlantic Forestry Centre, P.O. Box 4000, Fredericton, NB, E3B 5P7
2. Population Ecology Group, Faculty of Forestry and Environmental Management, University of New Brunswick, Fredericton, NB, E3B 5A3
Abstract
Abstract
A 5-yr field study was carried out to assess intratree variations in the distribution, abundance, and mortality of immature spruce budworm (Choristoneura fumiferana Clemens) (Lepidoptera: Tortricidae) from the peak to collapse of an outbreak. In most years, the highest density of overwintering second-instar (L2) larvae (per square meter of foliage) was located in the lower crown, whereas all subsequent stages (third- to sixth-instar larvae, pupae, and eggs) were at relatively higher densities in the upper crown. In contrast, overall abundance (per branch) throughout the season tended to be highest in the mid-upper to mid-lower crown. Mortality associated with 16 different parasitoid species varied significantly among years but varied among crown levels for only a few species. In particular, Apanteles fumiferanae (Viereck), Glypta fumiferanae (Viereck), Smidtiafumiferanae (Tothill), and Trichogramma minutum (Riley) all caused higher mortality in the upper crown of trees. Although infection associated with Nosema fumiferanae (Thomson) and mortality associated with fungal and viral pathogens often varied among crown levels, there was no clear or consistent trend from year to year. In general, trends in spruce budworm density and mortality within the crown were similar throughout all years of our study, despite significant variations in herbivore density, foliage availability, and parasitoid and pathogen impact. Our study indicates that intratree patterns of spruce budworm distribution and mortality are likely to remain consistent during an outbreak and further emphasizes the importance of intratree heterogeneity in shaping interactions within plant-herbivore-parasitoid communities.
Publisher
Oxford University Press (OUP)
Reference44 articles.
1. Abbott, K C
2012. The dynamical effects of interactions between inducible plant resistance and food limitation during insect outbreaks, pp. 30 – 46. InPBarbosa, D KLetourneau, and A AAgrawal (eds.), Insect Outbreaks Revisited.Blackwell Publishing Ltd., West Sussex, United Kingdom.
2. Rapid estimation of heat accumulation from maximum and minimum temperatures.;Baskerville;Ecology,1969
3. Net effect of spruce budworm defoliation on mortality and growth of balsam fir.;Batzer;J. For.,1973
4. Effect of Nosemafumiferanae (Microsporidia) on fecundity, fertility, and progeny performance of Choristoneura fumiferana (Lepidoptera: Tortricidae).;Bauer;Environ. Entomol.,1989
5. Spruce budworm parasite investigation in the lower St. Laurence and Gaspé regions of Quebec.;Blais;Can. Entomol.,1960
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