Intergenerational Transmission of Extremism [NCTV project] - ongoing 2022-2023

This project is funded by the National Coordinator Counterterrorism and Security (NCTV) and builds on our Van Ouder op Kind [From Parent to Child] project. In the current project (starting March 2021), Layla van Wieringen, Daan Weggemans, and Marieke Liem empirically examine the intergenerational transmission of extremist ideologies within the family context. Findings are based on in-depth interviews with family members and case-file data from partner organizations

Van Ouder op Kind [WODC project] - published 2021

Research project Van Ouder op Kind [From Parent to Child], funded by the Scientific Research and Documentation Center (WODC) from 2020-2021 (final report published in June 2021). In this report, Layla van Wieringen, Katharina Krüsselmann, Daan Weggemans, and Marieke Liem shed light on the intergenerational transmission of extremist ideologies within the family context. Findings are based on a systematic literature review and interviews with practitioners and academics

Rotten Trees, Bad Apples? On the Intergenerational Transmission of Extremist Ideologies

This is the OSF page for our research on the intergenerational transmission of extremist ideologies, conducted by Layla van Wieringen, Daan Weggemans and Marieke Liem at the Institute of Security and Global Affairs (Leiden University). On this page, you will find information on the projects being developed within the group, and links to relevant documents. For further information about our research group, please visit https://www.universiteitleiden.nl/en/research/research-projects/governance-and-global-affairs/intergenerational-transmissio

Herbivores avoid host plants previously exposed to their omnivorous predator Macrolophus pygmaeus

Herbivorous arthropods use various cues to choose suitable host plants. We investigated whether three species of herbivores use cues associated with their omnivorous predator Macrolophus pygmaeus to select host plants. Earlier, we found that this omnivore induces plant defences which decreased the performance of two of the herbivores, i.e. the spider mite Tetranychus urticae and the western flower thrips Frankliniella occidentalis, whereas the green peach aphid Myzus persicae was not affected. Hence, the spider mite and thrips were expected to avoid plants that were previously exposed to M. pygmaeus because of their lower quality, and the aphid was not expected to avoid exposed plants because they were of equal quality as unexposed plants. However, the cues left behind by M. pygmaeus may also be indicative of predation risk, in which case all three herbivores were expected to avoid exposed plants. Spider mites and western flower thrips preferred clean plants over plants that had previously been exposed to M. pygmaeus, but no longer harboured this omnivore. Aphids showed no preference, in agreement with their performance, but not in agreement with reducing predation risk. We furthermore showed that the preference of spider mites and thrips for clean plants increased through time. Higher proportions of aphids left plants previously exposed to M. pygmaeus than clean plants through time. Hence, omnivorous predators can decrease herbivore densities on plants not only by killing them but also by indirectly affecting herbivore host plant selection.</p