With my research at the Biosystematics group I focus on (lepidopteran) herbivores and coevolutionary relationships with other organisms that are seen as major driving forces to their enormous success and diversity, namely interactions with their angiosperm hosts, beneficial microorganisms, and parasitoid wasps. My expertise is to understand species interactions during an often-neglected reproductive phase, the insect egg stage. My research can be divided into four main objectives: 1) What is the genetic and molecular basis of these traits (both direct egg-killing by necrosis/neoplasm and indirect egg-killing by attraction of parasitoid wasps) (Microevolution) (NWO/TTW Vidi)? 2) What is the evolutionary origin of egg-killing in the economically important Brassicales plant order and do pierid butterflies counteract egg-killing (Macroevolution) (NWO Aspasia)? 3) What is the role of symbionts and/or their genes/ products in plant responses to eggs and counteradaptations by herbivores? 4) Do egg parasitoid wasps severely constrain the evolution of the use of (anti-) sex pheromones in Lepidoptera? To test these objectives, I use state-of-the-art techniques in comparative genomics and transcriptomics/ metabolomics and combine them with phylogenetic analysis and greenhouse/ field studies. With my research, I want to contribute to solutions to prevent further insect declines by understanding the evolution of species interactions that drive insect biodiversity. I aim to find approaches for agriculture that are integrated into a combination of pest management strategies, by focusing on biological control and crop resistances and diversity. These alternatives for pesticides are part of a sustainable agriculture aimed by the EU and circular agrofood system aimed by the Dutch government. This will eventually help to preserve and even increase insect diversity (see overview).
I am the principle investigator a large national project on the use of natural variation in resistance traits (see NWO/TTW Vidi project: Pest-killing plants). Caterpillars of lepidopteran insect pests cause serious problems in agriculture and forestry, and finding alternatives to chemical pesticides is important to reduce their threats to agricultural production. I received an NWO Aspasia grant meant to encourage the promotion of female Vidi grant candidates to an associate professorship. With the money of this grant I am studying 'The evolutionary history of an insect pest-killing plant trait in the cabbage family'. This project is closely linked to the Vidi grant in which we want to 'Unravel the mechanism of a pest egg-killing trait in a cabbage crop' and that started in September 2016. Together with my Vidi/Aspasia team we will combine evolutionary and molecular biology, (meta)genomics, transcriptional analysis, chemical analysis of plant and insect metabolites, and experimental ecological studies to gain novel insights on how plants make use of this highly effective 'first line of defence' - killing of insect eggs. The Vidi project is further supported by several crop breeding and seed companies. Caterpillars can suffer from defences primed by environmental cues. Egg deposition is a reliable cue for plants to enhance their defences against future attack as studied in the large German CRC 973 project on 'Priming and Memory of Organismic Responses to Stress' in which I am a collaborator and PhD co-supervisor. Furthermore, I was involved in a large European project studying 'Fundamental and applied aspects on biological control by the use of natural enemies' in which I still co-supervise a PhD student together with Bart Pannebakker from the Laboratory of Genetics.