10.5061/DRYAD.3R041
Ali, Jared G.
Pennsylvania State University
Agrawal, Anurag A.
Cornell University
Data from: Trade-offs and tritrophic consequences of host shifts in
specialized root herbivores
Dryad
dataset
2017
Asclepias asperula
Asclepias exaltata
Tritrophic interactions
Tetraopes tetraophthalmus
Tetraopes texanus
Asclepias syriaca
Entomopathogenic nematodes
Coevolution
Asclepias viridis
Tetraopes tetraophthalmus
2017-05-31T00:00:00Z
2017-05-31T00:00:00Z
en
https://doi.org/10.1111/1365-2435.12698
43821 bytes
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CC0 1.0 Universal (CC0 1.0) Public Domain Dedication
Trade-offs in an herbivore's ability to feed, avoid predation and
succeed on alternative hosts are thought to be major driving factors in
host specialization. In this study, we compared how two closely related
milkweed beetles (Tetraopes spp.) that have specialized on separate
Asclepias species respond to host switching to alternative milkweed
plants. By additionally examining effects on the beetles’ entomopathogenic
natural enemies, we test whether host plant specialization is driven by
plant–herbivore interactions alone or whether there is a role for the
tritrophic interactions. Tetraopes beetles feed on milkweed roots as
larvae and on milkweed shoots as adults, and they sequester toxic
cardenolides from their host plants. We predicted that growth and
sequestration would be compromised on alternative hosts as a consequence
of specialization. Larvae of each Tetraopes species were reared on their
native host plant, the host plant of the other species and two closely
related Asclepias species that do not typically host Tetraopes. Regardless
of beetle specialization, survival of both beetles was highest on A.
syriaca, which has the second-to-lowest levels of root cardenolides and is
the native host for T. tetraophthalmus. Larval growth was not affected by
host plant for T. texanus, but T. tetraophthalmus grew best on A.
exaltata, a close relative of A. syriaca that does not typically
experience beetle feeding. We found that larval sequestration of
cardenolides largely mirrored host plant values in the roots, with the
exception of T. texanus on A. asperula, which sequestered a low proportion
of the cardenolides from this host. Although all larvae were susceptible
to entomopathogenic nematodes (EPNs), the number of EPNs emerging from
cadavers depended on the beetle–plant combination, with more EPNs produced
when beetles were feeding on native compared to non-native hosts. The
observed consequences for tritrophic interactions did not fit expectations
for specialized herbivores (i.e. EPN predation was highest when beetles
were on their native hosts), suggesting that specialization may be driven
primarily by a plant–herbivore interaction in this system, not by a
tritrophic effect.
ALI_ AGRAWAL 2016_DATALarval weight data, Larval survival data, HPLC
cardenolide determinations from plant and larval tissue, Entomopathogenic
nematode performance data. The excel file contains two sheets listing
experimental data and a short descriptions of abbreviations where
necessary.