In organic greenhouses, aphids are controlled with the use of natural enemies such as parasitoid wasps. Unfortunately, the success of biological control is not always guaranteed. Multiple facultative endosymbiont species have shown the ability to provide resistance to aphids against parasitoids. These endosymbionts are present in moderate frequencies in natural aphid populations. However, these infection frequencies may rise or even fixate in aphid populations under parasitoid pressure. The presence of these endosymbionts in greenhouses, and the effects of these symbionts on the success of biological control in greenhouses has never been studied.
This project aims to gain insight into the population dynamics of protective aphid endosymbionts in greenhouses. Our goal is to determine if these symbionts affect the success of biological control. Furthermore, we aim to understand the mechanism underlying symbiont-based resistance. Ultimately, this project aims to provide important insights how to improve biological control of greenhouse aphids.
Aphids are sampled in Dutch greenhouses throughout the crop growth season. With the use of diagnostic PCRs and deep-sequencing of the 16s rRNA gene, the presence of different endosymbionts is analyzed. Infected aphid lines are raised in the lab. To study the effects of different endosymbionts on aphid resistance and fitness, infections are cured with antibiotics and novel infections are created using microinjections. To understand the mechanisms behind endosymbiont-based resistance, gene expression, cellular mechanisms and functional genomic complementary analyses are performed. Tailor-made strategies for biocontrol will be designed and tested in greenhouse-scale population manipulation experiments.
We are open to applications for thesis projects! We have different thesis topics available, including projects with fieldwork, Molecular Techniques and Ecological Tests.
- Thesis projects
- Are you interested? Contact Mariska.Beekman@wur.nl