RT Journal Article
SR Electronic
T1 Parasitoid community responds indiscriminately to fluctuating spruce budworm and other caterpillars on balsam fir
JF bioRxiv
FD Cold Spring Harbor Laboratory
SP 615799
DO 10.1101/615799
A1 Christopher J. Greyson-Gaito
A1 Kevin S. McCann
A1 Jochen Fründ
A1 Christopher J. Lucarotti
A1 M. Alex Smith
A1 Eldon S. Eveleigh
YR 2020
UL http://biorxiv.org/content/early/2020/04/15/615799.abstract
AB The world is astoundingly variable, and individuals to whole communities must respond to variability to survive. One example of nature’s variability is the massive fluctuations in spruce budworm (Choristoneura fumiferana Clemens, Lepidoptera: Tortricidae) populations that occur over 35 years. We examined how the parasitoid community altered its parasitism of budworm and other caterpillar species in response to these fluctuations. Budworm and other caterpillar species were sampled from balsam fir in three plots for 14 years in Atlantic Canada, and then reared to identify any emerging parasitoids. We found that the parasitoid community showed a simple linear, indiscriminate response (i.e., no preference, where densities purely dictated parasitism rates) to changes in budworm densities relative to other caterpillar species on balsam fir. We also observed strong changes in topology and distributions of interaction strengths between the parasitoids, budworm and other caterpillar species as budworm densities fluctuated. Our study contributes to the suggestion that hardwood trees are a critical part of the budworm-parasitoid food web, where parasitoids attack other caterpillar species on hardwood trees when budworm populations are low. Taken together, our study shows that a parasitoid community collectively alters species interactions in response to variable budworm densities, fundamentally shifting food web pathways.Competing Interest StatementThe authors have declared no competing interest.