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Most insect herbivores specialize on a few host plants; however, there are a minority of highly generalized species capable of feeding on hundreds of hosts. Generalism could emerge as a property of the species as a whole, while individuals would still exhibit greater specialization at more specific organizational levels. Yet, we lack studies with generalist insect herbivores directly testing this prediction. Here, we test if the highly generalized fall webworm (Hyphantria cunea) maintains its broad diet through specialization at the population, maternal genotype, or individual level. We reared two populations and multiple matrilines on either a static or rotating diet of four host plants. We found that both populations survived and pupated on all hosts, suggesting population-level generalization. We found evidence for generalization at the genotype level, as maternal genotypes did not vary in performance rankings across host plants. Finally, we found generalism at the individual level, as individuals reared on a rotating diet had no difference or showed intermediate performance to those reared on static diets. Overall, we found support for the maintenance of generalism across all levels, suggesting that generalist species need not be locally specialized to maintain their extremely broad diet.
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Nonadaptive host‐use specificity in tropical armored scale insects
Abstract Most herbivorous insects are diet specialists in spite of the apparent advantages of being a generalist. This conundrum might be explained by fitness trade‐offs on alternative host plants, yet the evidence of such trade‐offs has been elusive. Another hypothesis is that specialization is nonadaptive, evolving through neutral population‐genetic processes and within the bounds of historical constraints. Here, we report on a striking lack of evidence for the adaptiveness of specificity in tropical canopy communities of armored scale insects. We find evidence of pervasive diet specialization, and find that host use is phylogenetically conservative, but also find that more‐specialized species occur on fewer of their potential hosts than do less‐specialized species, and are no more abundant where they do occur. Of course local communities might not reflect regional diversity patterns. But based on our samples, comprising hundreds of species of hosts and armored scale insects at two widely separated sites, more‐specialized species do not appear to outperform more generalist species.
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- Award ID(s):
- 1744552
- PAR ID:
- 10455295
- Publisher / Repository:
- Wiley Blackwell (John Wiley & Sons)
- Date Published:
- Journal Name:
- Ecology and Evolution
- Volume:
- 10
- Issue:
- 23
- ISSN:
- 2045-7758
- Page Range / eLocation ID:
- p. 12910-12919
- Format(s):
- Medium: X
- Sponsoring Org:
- National Science Foundation
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