With my research, I seek to understand how temperature and carbon dioxide might affect host-pathogen interactions in cultures of mass-reared insects. This will help to adjust the environmental conditions in an optimal way to mitigate risks related to diseases in production systems.
As part of my project, I conducted a literature search on how environmental stressors affect the response of mass-reared insects to pathogens. These responses include behavioral and physiological responses (e.g. immune responses). It is especially interesting to understand which environmental conditions decrease susceptibility of insects to pathogens. This knowledge then can be used to modify environments in production systems in the favour of the insects’ health.
The start of my experimental work involved setting up a rearing culture of T. molitor in the laboratory and culturing the pathogens; I am working with the fungus Metarhizium brunneum and the bacterium Bacillus thuringiensis. Afterwards, I set up bioassays in which the larvae of T. molitor were exposed to the pathogens individually to understand which doses of the pathogens lead to which responses in the insects. Once I had this information, I started to expose the larvae to different temperature stresses together with M. brunneum. Now I am analysing the results of these experiments.
In the next step, I am exposing the larvae of T. molitor to elevated carbon dioxide levels and the two pathogens simultaneously to understand the effect on mortality, development and feeding of the larvae. It is important to do these co-exposure experiments because the two pathogens and carbon dioxide might interact with each other. This makes it impossible to predict the outcome of a co-exposure by just combining data of individually exposed larvae. To analyse the data, I am using a mixture toxicity model, which is usually used to analyse data of organisms exposed to more than one chemical in ecotoxicology. I hope to be able to confirm that this model is also suitable in insect pathology studies.