Question: Hi Ellie, I was reading through your profile and was intrigued in your insect killing fungi, I was wanting to ask, this fungi, does it not have any effects on the plant itself in any way? Are there perhaps, any effects on the plant? And does this fungi not have any effect if used on plants that us people may consume?

Eleanor Spence answered on 20 Mar 2020:

Hi! Great question! There is no impact in terms of infection of the plant. Several species of fungi do infect plants and cause huge amounts of damage (especially in greenhouses because it is warm and moist) such as botrytis and powdery mildew.

But, the insect killing fungi that are applied for insect control will only penetrate the insect cuticle because of a chemical response that occurs on the surface of the insect. So the fungus needs the presence of certain proteins on the insect in order to start the infection process. As a response, the insect has also evolved fungi defense mechanisms, such as antimicrobial secretions on its cuticle and melanin deposits (the same pigment that is in our hair, skin and eyes), behavioural changes and an immune response.

There is a chance that if the fungi was applied at a very high concentration, the cloudy solution could block the sun reaching the leaves and reduce photosynthesis. This would result in reduced plant growth and less yield of the crop for the grower. But to get concentrations this high, millions of spores would need to be mixed in very little water. Much like a chemical pesticide, fungi have recommended application concentrations that must be followed so this would not occur.

We are able to consume the fungus without any harm in the low doses that is occurs on the plant. In many cases, the insect pest is actually on the plant leaf which would be sprayed with the fungi and the fruit/veg that we eat is not the target for the fungal application so very little will be on the food.

I loved this question! Thanks so much (sorry I got carried away with the answer haha!)