title: Impact of abiotic factors on predator-prey interactions: DNA-based gut content analysis in a microcosm experiment.
abstract: The effects of predators on prey populations can be modified by a number of abiotic factors. Here, we investigated the combined and separate effects of rain and ground-dwelling predators on aphid populations in a microcosm experiment lasting for 21 days, using PCR to analyse the gut content of the predators. Rain significantly dislodged aphids from shoots and ears by 57% and 25%, respectively. The gut content analysis showed that more predators consumed aphids in the rain treatment than without rain, indicating higher availability of aphids to ground-dwelling predators after rain. However, no synergistic effects of rain and ground-dwelling predators on aphid population development could be demonstrated. Rain alone significantly decreased aphid populations by 27%, suggesting that this is a significant mortality factor. Predators alone had no significant effect on aphid numbers, but the gut content analyses showed aphid consumption also in the no-rain treatments, indicating that aphids were available to the predators on the soil surface even without rain. Our results suggest that weather conditions such as rain can modify predator-prey interactions in the field. Employing PCR-based predator gut content analyses proved to be useful as trophic links could be directly verified.
authors.affiliation: Animal Ecology, Darmstadt University of Technology, Darmstadt, Germany. vonberg@bio.tu-darmstadt.de
authors.forename: K von
authors.initials: Kv
authors.lastname: Berg
authors.forename: M
authors.initials: M
authors.lastname: Traugott
authors.forename: W O C
authors.initials: WO
authors.lastname: Symondson
authors.forename: S
authors.initials: S
authors.lastname: Scheu
mesh_terms: D000818:Animals; D001042:Aphids; D001517:Coleoptera; D004247:DNA / Q000737:chemistry; D017753:Ecosystem; D005247:Feeding Behavior; D016133:Polymerase Chain Reaction; D011158:Population Growth; D011891:Rain; D014908:Triticum / Q000469:parasitology
chemical_list: D004247:DNA