Limits...
Consumptive and nonconsumptive effect ratios depend on interaction between plant quality and hunting behavior of omnivorous predators

View Article: PubMed Central - PubMed

ABSTRACT

Predators not only consume prey but exert nonconsumptive effects in form of scaring, consequently disturbing feeding or reproduction. However, how alternative food sources and hunting mode interactively affect consumptive and nonconsumptive effects with implications for prey fitness have not been addressed, impending functional understanding of such tritrophic interactions. With a herbivorous beetle, two omnivorous predatory bugs (plant sap as alternative food, contrasting hunting modes), and four willow genotypes (contrasting suitability for beetle/omnivore), we investigated direct and indirect effects of plant quality on the beetles key reproductive traits (oviposition rate, clutch size). Using combinations of either or both omnivores on different plant genotypes, we calculated the contribution of consumptive (eggs predated) and nonconsumptive (fewer eggs laid) effect on beetle fitness, including a prey density‐independent measure (c:nc ratio). We found that larger clutches increase egg survival in presence of the omnivore not immediately consuming all eggs. However, rather than lowering mean, the beetles generally responded with a frequency shift toward smaller clutches. However, female beetles decreased mean and changed clutch size frequency with decreasing plant quality, therefore reducing intraspecific exploitative competition among larvae. More importantly, variation in host plant quality (to omnivore) led to nonconsumptive effects between one‐third and twice as strong as the consumptive effects. Increased egg consumption on plants less suitable to the omnivore may therefore be accompanied by less searching and disturbing the beetle, representing a “cost” to the indirect plant defense in the form of a lower nonconsumptive effect. Many predators are omnivores and altering c:nc ratios (with egg retention as the most direct link to prey fitness) via plant quality and hunting behavior should be fundamental to advance ecological theory and applications. Furthermore, exploring modulation of fitness traits by bottom‐up and top‐down effects will help to explain how and why species aggregate.

No MeSH data available.


Related in: MedlinePlus

Contributions of consumptive and nonconsumptive effects on survival of herbivore eggs depending on omnivore treatment (AN = Anthocoris nemorum, OM = Orthotylus marginalis) and plant genotype (S. dasyclados: Gudrun, Loden; S. viminalis: 78021, 78183). The consumptive effect is expressed as the proportion of predated eggs of the total number of laid eggs on a plant and the nonconsumptive effect as the proportion of eggs not laid in the presence of omnivores compared to their absence (numbers within bars, respectively). The numbers above the bars express the consumptive: nonconsumptive ratio (for each genotype–treatment combination)
© Copyright Policy - creativeCommonsBy
Related In: Results  -  Collection

License
getmorefigures.php?uid=PMC5383501&req=5

ece32828-fig-0005: Contributions of consumptive and nonconsumptive effects on survival of herbivore eggs depending on omnivore treatment (AN = Anthocoris nemorum, OM = Orthotylus marginalis) and plant genotype (S. dasyclados: Gudrun, Loden; S. viminalis: 78021, 78183). The consumptive effect is expressed as the proportion of predated eggs of the total number of laid eggs on a plant and the nonconsumptive effect as the proportion of eggs not laid in the presence of omnivores compared to their absence (numbers within bars, respectively). The numbers above the bars express the consumptive: nonconsumptive ratio (for each genotype–treatment combination)

Mentions: Visualizing the consumptive and nonconsumptive effects for all omnivore treatments revealed that the plant genotype affected not only the consumptive effect (egg survival), but also the nonconsumptive effect (eggs not laid due to omnivore presence) (Figure 5). The nonconsumptive effect ranged from 0.10 (= 10% fewer eggs laid in the presence of omnivores) to 0.62 and was generally larger on Loden than on genotype 78183. The c:nc ratio ranged from 0.33, indicating a nonconsumptive effect approximately three times greater than the consumptive effect, over exactly the same contributions (ratio of 1), to a consumptive effect about twice that of the nonconsumptive effect (1.92).


Consumptive and nonconsumptive effect ratios depend on interaction between plant quality and hunting behavior of omnivorous predators
Contributions of consumptive and nonconsumptive effects on survival of herbivore eggs depending on omnivore treatment (AN = Anthocoris nemorum, OM = Orthotylus marginalis) and plant genotype (S. dasyclados: Gudrun, Loden; S. viminalis: 78021, 78183). The consumptive effect is expressed as the proportion of predated eggs of the total number of laid eggs on a plant and the nonconsumptive effect as the proportion of eggs not laid in the presence of omnivores compared to their absence (numbers within bars, respectively). The numbers above the bars express the consumptive: nonconsumptive ratio (for each genotype–treatment combination)
© Copyright Policy - creativeCommonsBy
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC5383501&req=5

ece32828-fig-0005: Contributions of consumptive and nonconsumptive effects on survival of herbivore eggs depending on omnivore treatment (AN = Anthocoris nemorum, OM = Orthotylus marginalis) and plant genotype (S. dasyclados: Gudrun, Loden; S. viminalis: 78021, 78183). The consumptive effect is expressed as the proportion of predated eggs of the total number of laid eggs on a plant and the nonconsumptive effect as the proportion of eggs not laid in the presence of omnivores compared to their absence (numbers within bars, respectively). The numbers above the bars express the consumptive: nonconsumptive ratio (for each genotype–treatment combination)
Mentions: Visualizing the consumptive and nonconsumptive effects for all omnivore treatments revealed that the plant genotype affected not only the consumptive effect (egg survival), but also the nonconsumptive effect (eggs not laid due to omnivore presence) (Figure 5). The nonconsumptive effect ranged from 0.10 (= 10% fewer eggs laid in the presence of omnivores) to 0.62 and was generally larger on Loden than on genotype 78183. The c:nc ratio ranged from 0.33, indicating a nonconsumptive effect approximately three times greater than the consumptive effect, over exactly the same contributions (ratio of 1), to a consumptive effect about twice that of the nonconsumptive effect (1.92).

View Article: PubMed Central - PubMed

ABSTRACT

Predators not only consume prey but exert nonconsumptive effects in form of scaring, consequently disturbing feeding or reproduction. However, how alternative food sources and hunting mode interactively affect consumptive and nonconsumptive effects with implications for prey fitness have not been addressed, impending functional understanding of such tritrophic interactions. With a herbivorous beetle, two omnivorous predatory bugs (plant sap as alternative food, contrasting hunting modes), and four willow genotypes (contrasting suitability for beetle/omnivore), we investigated direct and indirect effects of plant quality on the beetles key reproductive traits (oviposition rate, clutch size). Using combinations of either or both omnivores on different plant genotypes, we calculated the contribution of consumptive (eggs predated) and nonconsumptive (fewer eggs laid) effect on beetle fitness, including a prey density‐independent measure (c:nc ratio). We found that larger clutches increase egg survival in presence of the omnivore not immediately consuming all eggs. However, rather than lowering mean, the beetles generally responded with a frequency shift toward smaller clutches. However, female beetles decreased mean and changed clutch size frequency with decreasing plant quality, therefore reducing intraspecific exploitative competition among larvae. More importantly, variation in host plant quality (to omnivore) led to nonconsumptive effects between one‐third and twice as strong as the consumptive effects. Increased egg consumption on plants less suitable to the omnivore may therefore be accompanied by less searching and disturbing the beetle, representing a “cost” to the indirect plant defense in the form of a lower nonconsumptive effect. Many predators are omnivores and altering c:nc ratios (with egg retention as the most direct link to prey fitness) via plant quality and hunting behavior should be fundamental to advance ecological theory and applications. Furthermore, exploring modulation of fitness traits by bottom‐up and top‐down effects will help to explain how and why species aggregate.

No MeSH data available.


Related in: MedlinePlus