a1 Cardiff School of Biosciences, Biomedical Sciences Building, Cardiff University, Museum Avenue, Cardiff, CF10 3AX, UK
a2 Plant and Invertebrate Ecology, Rothamsted Research, West Common, Harpenden, Hertfordshire, AL5 2JQ, UK
The molecular detection of predation is a fast growing field, allowing highly specific and sensitive detection of prey DNA within the gut contents or faeces of a predator. Like all molecular methods, this technique is prone to potential sources of error that can result in both false positive and false negative results. Here, we test the hypothesis that the use of suction samplers to collect predators from the field for later molecular analysis of predation will lead to high numbers of false positive results. We show that, contrary to previous published work, the use of suction samplers resulted in previously starved predators testing positive for aphid and collembolan DNA, either as a results of ectopic contamination or active predation in the collecting cup/bag. The contradictory evidence for false positive results, across different sampling protocols, sampling devices and different predator-prey systems, highlights the need for experimentation prior to mass field collections of predators to find techniques that minimise the risk of false positives.
(Accepted September 08 2011)
(Online publication November 01 2011)
p1 Current address: College of Life and Environmental Sciences, Geoffrey Pope Building, University of Exeter Stocker Road, Exeter, EX4 4QD, UK
p2 Current address: Centre for Ecology & Hydrology, Maclean Building, Benson Lane, Crowmarsh Gifford, Wallingford, OX10 8BB, UK
p3 Current address: UMR BGA - INRA Centre de Dijon, 17 rue Sully, BP 86510, 21065 Dijon Cedex, France