Dr. A.M. (Charissa) de Bekker

Dr. A.M. (Charissa) de Bekker

Universitair docent
Molecular Microbiology
Universitair hoofddocent
Molecular Microbiology
030 253 2999
a.m.debekker@uu.nl

Unraveling the biology of zombie fungi to discover novel natural products applicable in medicine and sustainable pest control practices

My research centers around the manipulated behaviour exhibited by ants that are infected with fungal species of the genus Ophiocordyceps; the so-called "zombie ants". I use this fungus-insect interaction as a model system to study the fungal natural products involved in host manipulation and their effects on insect physiology and behavioral pathways. The overarching aim of this work is to elucidate how parasites can affect the behaviour of their hosts, how behaviour is regulated and dysregulated at the molecular level, and what fungal proteins and secondary metabolites are involved. In this endeavor, I am using an integrative approach that combines multi-omics techniques, molecular microbiology techniques, infection biology, chronobiology, and animal behaviour. Ultimately, this work will result in a better understanding of animal mycoses, which could improve treatment of fungal infections in humans. Moreover, the discovery of novel natural products involved in these fungus-animal interactions could have impactful medicinal applications and lead to more sustainable and evolutionarily robust pest control practices.

 

Zombie ant, infected by the fungus that is growing out of the back of its head after it caused the ant to bite down on a piece of spanish moss

 

Parasite manipulation of animal behaviour

For millions of years, the ongoing battles between parasites and their hosts have been taking place, in which each party is trying to get the upper hand. Such prolonged parasite-host co-evolution can result in complex phenotypes. Parasite adaptive manipulation of host behaviour is a widespread example. Here, parasites use intricate strategies to manipulate their hosts’ behaviours such that they benefit parasite transmission. For many manipulative parasite-host interactions, their captivating natural history has been rather well-described. However, it remains a largely unanswered question how exactly manipulating parasites are able to hijack their hosts. The research done in my lab aims to bridge this knowledge gap by providing a deeper mechanistic understanding of parasite manipulation of host behaviour. We ask how host behaviour changes, which proteins and secondary metabolites parasites produce that can work as neuromodulators, and how these products can affect host physiology and behavioural pathways such that they result in altered behavioural phenotypes.

 

 

Model System: Behaviour manipulating fungi (BMF) and their ant hosts

Parasites that modify host behaviour to increase their own reproductive success are often referred to as “zombie-makers”. The so-called “zombie ants” are a widespread, evident example. When infected by fungi that hijack behavioural outputs, these ants start to wander, followed by climbing, and latching themselves to vegetation (via biting) to ease the wind dispersal of infectious spores. Inducing hosts to ascend and bite are common themes among zombie-makers, which suggests that similar mechanisms for how parasites alter the behavioural phenotype of their host might be used. Understanding this (naturally) corrupted chain of events towards the expression of an altered behavioural phenotype in the lab-amenable zombie ant system offers the chance to better understand how behavioural phenotypes evolve and are expressed. As such, my lab mainly uses fungal insect parasites of the genus Ophiocordyceps to learn how certain microbes are able to control animal behaviour. More specifically, we currently focus on Ophiocordyceps camponoti-floridani, a fungal species from Florida, which infects and manipulates the Florida Carpenter ant (Camponotus floridanus).

 

Research Approach

I like to approach my research from both the parasite and the host perspective, to ask questions that range from the gene and molecule level to the level of whole-organism phenotypes, to organismic functioning within an ecosystem. As such, my research program has so far relied on an integrative approach in which we combine:

  • Infection studies
  • Behavioural analyses
  • Genomics, transcriptomics and metabolomics tools
  • Functional genetics and molecular microbiology techniques
  • Field surveys and collections