Abstract
While the role of parasites in shaping population and community dynamics has been increasingly appreciated, researchers have largely ignored the ecology of parasitic plants. Parasitic plants obtain water, sugar, nitrogen compounds, and a variety of secondary metabolites from their host plants. In a greenhouse study, I examined the direct interactions of a parasitic plant, Castilleja wightii (Scrophulariaceae), with three plant hosts and the indirect effects of this parasitism on the performance of a parasite—feeding herbivore. The three host species, Lupinus arboreus, Artemisia pycnocephala, and Eriophyllum staechadifolium, directly and differentially affected C. wightii flower production, although parasite biomass was not affected by host species. Surprisingly, parasite performance was weakest when attacking a leguminous host, although parasite total nitrogen was highest when growing on a legume. Parasites also exerted a strong direct effect on host performance: host dry mass was negatively correlated with parasite mass for all three host species tested. However, this effect differed among hosts: for E. staechadifolium, proportionately larger parasite mass was correlated with smaller overall biomass of the host and parasite combined, while for the other two hosts, overall host—parasite mass was not correlated with parasite mass, indicating that E. staechadifolium was more affected by parasite attack than were the other host species. Finally, host plant chemistry had strong indirect effects on the performance of an aphid, Nearctaphis kachena, that feeds on C. wightii. Aphids feeding on C. wightii that were parasitizing L. arboreus (alkaloid—producing, high nitrogen), A. pycnocephala (alkaloid—free, intermediate nitrogen), and E. staechadifolium (terpenoid—producing, low nitrogen) experienced 68.2, 65.3, and 49.5% survival, respectively. Further, aphids feeding on parasites using L. arboreus and A. pycnocephala produced 2.43 and 1.77 times more offspring on average than those feeding on parasites using E. staechadifolium. My results indicate that interactions between plant parasites and different host species can have strong direct effects on both host and parasite performance, as well as marked effects on the tritrophic interactions among plant hosts, parasitic plants, and their herbivores.
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Claims 12
Claim · model-written summary
Three host species differentially affected Castilleja flower production.
- Taxon
- C. wightii
Castilleja wightiie0 - Interactor
- Lupinus arboreus
.jpg?width=60)
Lupinus arboreuse0host - Outcome
- C. wightii flower productione0
Not reportedDirection
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
.jpg?width=500)
Verbatim
e0“The three host species, Lupinus arboreus, Artemisia pycnocephala, and Eriophyllum staechadifolium, directly and differentially affected C. wightii flower production”
t0“Parasitic Plant‐Host Interactions”
Claim · model-written summary
Parasite biomass did not differ by host species.
- Taxon
- Castilleja wightiiCastilleja wightiie1
- Interactor
- host speciese0host
- Outcome
- parasite biomasse0
- Direction
- not affectede0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“parasite biomass was not affected by host species”
e1“a parasitic plant, Castilleja wightii (Scrophulariaceae), with three plant hosts”
Claim · model-written summary
Parasite performance was weakest on a leguminous host.
- Taxon
- Castilleja wightiiCastilleja wightiie1
- Interactor
- leguminous hoste0host
- Outcome
- parasite performancee0
- Direction
- weakeste0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“parasite performance was weakest when attacking a leguminous host”
e1“a parasitic plant, Castilleja wightii (Scrophulariaceae)”
Claim · model-written summary
Parasite total nitrogen was highest on a legume.
- Taxon
- Castilleja wightiiCastilleja wightiie1
- Interactor
- legumee0host
- Outcome
- parasite total nitrogene0
- Direction
- higheste0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“parasite total nitrogen was highest when growing on a legume”
e1“a parasitic plant, Castilleja wightii (Scrophulariaceae)”
Claim · model-written summary
Host dry mass was negatively correlated with parasite mass across all three host species.
- Taxon
- Castilleja wightiiCastilleja wightiie1
- Interactor
- host speciese0host
- Outcome
- host dry masse0
- Direction
- negatively correlatede0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“host dry mass was negatively correlated with parasite mass for all three host species tested”
e1“a parasitic plant, Castilleja wightii (Scrophulariaceae)”
Claim · model-written summary
Larger parasite mass correlated with smaller combined biomass for E. staechadifolium.
- Taxon
- Castilleja wightiiCastilleja wightiie1
- Interactor
- E. staechadifolium
Eriophyllum staechadifoliume0host - Outcome
- overall biomass of the host and parasite combinede0
- Direction
- smallere0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“for E. staechadifolium, proportionately larger parasite mass was correlated with smaller overall biomass of the host and parasite combined”
e1“a parasitic plant, Castilleja wightii (Scrophulariaceae)”
Claim · model-written summary
Combined host parasite mass was not correlated with parasite mass for the other two hosts.
- Taxon
- Castilleja wightiiCastilleja wightiie1
- Interactor
- other two hostse0host
- Outcome
- overall host—parasite masse0
- Direction
- not correlatede0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“for the other two hosts, overall host—parasite mass was not correlated with parasite mass”
e1“a parasitic plant, Castilleja wightii (Scrophulariaceae)”
Claim · model-written summary
Aphid survival was 68.2% on parasites using L. arboreus.
- Taxon
- C. wightiiCastilleja wightiie0
- Interactor
- AphidsAphidomorphae0herbivore
- Second interactor
- L. arboreusLupinus arboreuse0host
- Outcome
- Aphids feeding on C. wightiie0
- Value
- 68.2e0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Aphids feeding on C. wightii that were parasitizing L. arboreus (alkaloid—producing, high nitrogen), A. pycnocephala (alkaloid—free, intermediate nitrogen), and E. staechadifolium (terpenoid—producing, low nitrogen) experienced 68.2, 65.3, and 49.5% survival, respectively”
Claim · model-written summary
Aphid survival was 65.3% on parasites using A. pycnocephala.
- Taxon
- C. wightiiCastilleja wightiie0
- Interactor
- AphidsAphidomorphae0herbivore
- Second interactor
- A. pycnocephala
Artemisia pycnocephalae0host - Outcome
- Aphids feeding on C. wightiie0
- Value
- 65.3e0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Aphids feeding on C. wightii that were parasitizing L. arboreus (alkaloid—producing, high nitrogen), A. pycnocephala (alkaloid—free, intermediate nitrogen), and E. staechadifolium (terpenoid—producing, low nitrogen) experienced 68.2, 65.3, and 49.5% survival, respectively”
Claim · model-written summary
Aphid survival was 49.5% on parasites using E. staechadifolium.
- Taxon
- C. wightiiCastilleja wightiie0
- Interactor
- AphidsAphidomorphae0herbivore
- Second interactor
- E. staechadifoliumEriophyllum staechadifoliume0host
- Outcome
- Aphids feeding on C. wightiie0
- Value
- 49.5%e0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Aphids feeding on C. wightii that were parasitizing L. arboreus (alkaloid—producing, high nitrogen), A. pycnocephala (alkaloid—free, intermediate nitrogen), and E. staechadifolium (terpenoid—producing, low nitrogen) experienced 68.2, 65.3, and 49.5% survival, respectively”
Claim · model-written summary
Aphids on parasites using L. arboreus produced 2.43 times more offspring than those using E. staechadifolium.
- Taxon
- Castilleja wightiiCastilleja wightiie1
- Interactor
- aphidsAphidomorphae0herbivore
- Second interactor
- L. arboreusLupinus arboreuse0host
- Outcome
- aphids feeding on parasitese0
- Direction
- more offspringe0
- Value
- 2.43e0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“aphids feeding on parasites using L. arboreus and A. pycnocephala produced 2.43 and 1.77 times more offspring on average than those feeding on parasites using E. staechadifolium”
e1“a parasitic plant, Castilleja wightii (Scrophulariaceae)”
Claim · model-written summary
Aphids on parasites using A. pycnocephala produced 1.77 times more offspring than those using E. staechadifolium.
- Taxon
- Castilleja wightiiCastilleja wightiie1
- Interactor
- aphidsAphidomorphae0herbivore
- Second interactor
- A. pycnocephalaArtemisia pycnocephalae0host
- Outcome
- aphids feeding on parasitese0
- Direction
- more offspringe0
- Value
- 1.77e0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“aphids feeding on parasites using L. arboreus and A. pycnocephala produced 2.43 and 1.77 times more offspring on average than those feeding on parasites using E. staechadifolium”
e1“a parasitic plant, Castilleja wightii (Scrophulariaceae)”