The significance of facultative scavenging in generalist predator nutrition: detecting decayed prey in the guts of predators using PCR

Foltan, Pavel, Sheppard, Samuel Keir, Konvicka, Martin and Symondson, William Oliver Christian ORCID: https://orcid.org/0000-0002-3343-4679 2005. The significance of facultative scavenging in generalist predator nutrition: detecting decayed prey in the guts of predators using PCR. Molecular Ecology 14 (13) , pp. 4147-4158. 10.1111/j.1365-294X.2005.02732.x

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Abstract

Gut-content analyses using molecular techniques are an effective approach to quantifying predator–prey interactions. Predation is often assumed but scavenging is an equally likely route by which animal DNA enters the gut of a predator/scavenger. We used PCR (polymerase chain reaction) to detect scavenged material in predator gut homogenates. The rates at which DNA in decaying slugs (Mollusca: Pulmonata) and aphids (Homoptera: Aphididae) became undetectable were estimated. The detectability of DNA from both carrion types in the guts of the generalist predator Pterostichus melanarius (Coleoptera: Carabidae) was then determined. The effects of carrion age and weight, as well as beetle sex, on detection periods, were quantified. Laboratory trials measured prey preference of beetles between live and decaying prey. Further experiments measured, for the first time, feeding by P. melanarius on dead slugs and aphids directly in the field. In both field and laboratory, P. melanarius preferentially fed on dead prey if available, but preference changed as the prey became increasingly decayed. Disappearance rates for slug carrion in wheat fields and grasslands were estimated and P. melanarius was identified as the main scavenger. Comparison of the retention time for dead slugs in the field, with the detection period for decaying slug material in the guts of the predators, showed that PCR-based techniques are not able to distinguish between predated and scavenged food items. This could potentially lead to overestimation of the impact of predation on slugs (and other prey) by carabids. Possible implications of facultative scavenging by invertebrate predators for biocontrol and food-web research are discussed.

Item Type:	Article
Date Type:	Publication
Status:	Published
Schools:	Biosciences
Subjects:	Q Science > Q Science (General)
Uncontrolled Keywords:	Aphid; DNA degradation; gut content; Pterostichus melanarius; scavenging; slug.
Publisher:	Blackwell Publishing
ISSN:	0962-1083
Last Modified:	27 Oct 2022 08:38
URI:	https://orca.cardiff.ac.uk/id/eprint/62933

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