Abstract
1. The impact of predators on prey has traditionally been attributed to the act of consumption. Prey responses to the presence of the predator (non-consumptive effects), however, can be as important as predation itself. While plant defences are known to influence predator-prey interactions, their relative effects on consumptive vs. non-consumptive effects are not well understood. 2. We evaluated the consequences of plant resistance and predators (Hippodamia convergens) on the mass, number of nymphs, population growth, density and dispersal of aphids (Macrosiphum euphorbiae). We tested for the effects of plant resistance on non-consumptive and consumptive effects of predators on aphid performance and dispersal using a combination of path analysis and experimental manipulation of predation risk. 3. We manipulated plant resistance using genetically modified lines of tomato (Solanum lycopersicum) that vary incrementally in the expression of the jasmonate pathway, which mediates induced resistance to insects and manipulated aphid exposure to lethal and risk predators. Predation risk predators had mandibles impaired to prevent killing. 4. Plant resistance reduced predation rate (consumptive effect) on high resistance plants. As a consequence, predators had no impact on the number of nymphs, aphid density or population growth on high resistance plants, whereas on low resistance plants, predators reduced aphid density by 35% and population growth by 86%. Path analysis and direct manipulation of predation risk showed that predation risk rather than predation rate promoted aphid dispersal and varied with host plant resistance. Aphid dispersal in response to predation risk was greater on low compared to high resistance plants. The predation risk experiment also showed that the number of aphid nymphs increased in the presence of risk predators but did not translate into increased population growth. 5. In conclusion, the consumptive and non-consumptive components of predators affect different aspects of prey demography, acting together to shape prey population dynamics. While predation risk accounts for most of the total effect of the predator on aphid dispersal and number of nymphs, the suppressive effect of predators on aphid population occurred largely through consumption. These effects are strongly influenced by plant resistance levels, suggesting that they are context dependent.
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Claims 7
Claim · model-written summary
Plant resistance reduced predator consumption on high resistance tomato plants.
- Taxon
- tomato
Solanum lycopersicumt0 - Material
- high resistance plantse0
- Interactor
- Hippodamia convergens
.jpg?width=60)
Hippodamia convergense1other - Second interactor
- Macrosiphum euphorbiae
Macrosiphum euphorbiaee1pest - Outcome
- predation ratee0
- Direction
- reducede0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
.jpg?width=500)
Verbatim
e0“Plant resistance reduced predation rate (consumptive effect) on high resistance plants.”
e1“predators (Hippodamia convergens) on the mass, number of nymphs, population growth, density and dispersal of aphids (Macrosiphum euphorbiae)”
t0“tomato (Solanum lycopersicum)”
Claim · model-written summary
Predators had no impact on aphid nymph number, density or population growth on high resistance plants.
- Taxon
- tomatoSolanum lycopersicumt0
- Treatment
- predatorse0
- Interactor
- aphide0pest
- Outcome
- number of nymphs, aphid density or population growthe0
- Direction
- no impacte0
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“predators had no impact on the number of nymphs, aphid density or population growth on high resistance plants”
t0“tomato (Solanum lycopersicum)”
Claim · model-written summary
Predators reduced aphid density by 35% on low resistance plants.
- Taxon
- tomatoSolanum lycopersicumt0
- Material
- low resistance plantse0
- Treatment
- predatorse0
- Interactor
- aphide0pest
- Outcome
- aphid densitye0
- Direction
- reducede0
- Value
- 35%e0
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“on low resistance plants, predators reduced aphid density by 35% and population growth by 86%”
t0“tomato (Solanum lycopersicum)”
Claim · model-written summary
Predators reduced aphid population growth by 86% on low resistance plants.
- Taxon
- tomatoSolanum lycopersicumt0
- Material
- low resistance plantse0
- Treatment
- predatorse0
- Interactor
- aphide0pest
- Outcome
- population growthe0
- Direction
- reducede0
- Value
- 86%e0
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“on low resistance plants, predators reduced aphid density by 35% and population growth by 86%”
t0“tomato (Solanum lycopersicum)”
Claim · model-written summary
Risk predators increased the number of aphid nymphs.
- Taxon
- tomatoSolanum lycopersicumt0
- Treatment
- risk predatorse0
- Interactor
- aphide0pest
- Outcome
- number of aphid nymphse0
- Direction
- increasede0
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“the number of aphid nymphs increased in the presence of risk predators”
t0“tomato (Solanum lycopersicum)”
Claim · model-written summary
The nymph increase under risk predators did not increase aphid population growth.
- Taxon
- tomatoSolanum lycopersicumt0
- Treatment
- risk predatorse0
- Interactor
- aphide0pest
- Outcome
- population growthe0
- Direction
- did not translate into increasede0
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“the number of aphid nymphs increased in the presence of risk predators but did not translate into increased population growth”
t0“tomato (Solanum lycopersicum)”
Claim · model-written summary
Predator suppression of aphid population occurred largely through consumption.
- Taxon
- tomatoSolanum lycopersicumt0
- Interactor
- aphide0pest
- Outcome
- aphid populatione0
- Direction
- suppressivee0
- Qualifier
- through consumptione0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“the suppressive effect of predators on aphid population occurred largely through consumption”
t0“tomato (Solanum lycopersicum)”
The same questions in other papers
biocontrol · pest · Solanum lycopersicum (tomato)Positive and negative results
22 papers in the same direction as this paper · 2 in the opposite direction
- no effect
- no effect
- positive
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See all 25 papers →Claims are grouped by organism, treatment and what was measured or targeted. A paper counts as positive when any of its claims in the group is positive.