Conidia (spores), are the active ingredients in some bioinsecticides. They are generally produced in solid fermentation using large volumes of substrate, from which they then need to be recovered. This is labour-intensive, costly, and difficult to scale up. Conidia are also usually very sensitive to environmental and storage conditions.
Recently, researchers described resistant structures that are easy to produce, harvest, store and apply to the soil.
Called microsclerotia, they are small, compact structures of hardened fungal cells. Under the right conditions, they can persist in the environment and then regenerate to form infective conidia. They have been described for biocontrol agents such as Trichoderma harzianum, and Metarhizium spp.
For the first time, AgResearch scientists have been able to form microsclerotia with two important bioinsecticial fungal species: Beauveria pseudobassiana and Beauveria brongniartii.
The scientists then studied the stability of microsclerotia produced by the New Zealand strain of B. pseudobassiana, which is being investigated as a potential biocontrol product for African black beetle and other soil-dwelling scarab pests.