Dr Melissa Tomkins

Postdoctoral Scientist Genes in the Environment

Melissa’sĀ area of interest is in the development and use of modelling techniques to untangle complex biological systems, with a particular focus on the use of agent-based technologies.

Currently, she is working with Professor Saskia Hogenhout and Professor Stan Maree (Cardiff University), along with our international collaborators, on a project to understand how phytoplasma virulence genes influence the dynamics of the pathogen spread.

This involves understanding the system at a number of different levels, ranging from the molecular, within-plant dynamics, up to infection patterns across large areas (1,000s kms) of agriculturally important fields in Wisconsin.

Melissa is employing a range of individual-based modelling techniques and analyses, to demonstrate the importance of spatial patterns at both an ecological and evolutionary scale.

This video shows the output of a simulation from an individual-based model designed to represent the spread of a phytoplasma outbreak.

The leafhoppers are represented as particles, and move about the simulation, using a random walk. They can then spread the infection between the host plants. This simulation predicts patterns of infection that are highly heterogenous in space and time – something that is also observed in historical datasets obtained from carrot fields in Wisconsin.


  • Blue circles = healthy leafhoppers
  • Purple circles = infected leafhoppers
  • Green squares = healthy host plants
  • Yellow – Red = infected host plants and infection density