Control of arthropod infestation

A dry powder formulation comprising:

• i) spores of an entomopathogenic fungus that has activity against an arthropod selected from Oryzaephilus surinamensis, Sitophilus granarius and Cryptolestes ferrugineus, wherein the spores are present in an amount of 2 to 5% w/w of the formulation, and in an amount of at least 1×1010 CFU/gram dry weight;
• ii) mineral-based particles of an industrial mineral selected from kaolin, talc, and a mixture of kaolin and talc, in an amount of 80 to 88% w/w of the formulation and having a volume mean diameter of ≥5 μm;
• and
• iii) electret particles, different from said mineral-based particles, in an amount of 10 to 15% w/w of the formulation.

A method of producing a dry powder formulation comprising:

• i) spores of an entomopathogenic fungus comprising Beauveria bassiana that has activity against arthropods that infest dry commodity storage areas, wherein the spores are present in an amount of 2 to 5% w/w of the formulation;
• ii) mineral-based particles of an industrial mineral in an amount of 80 to 88% w/w of the formulation and having a volume mean diameter of ≥5 μm;
• and
• iii) electret particles, different from said mineral-based particles, in an amount of 10 to 15% w/w of the formulation, comprising the steps of
• i) micronising dry electret particles;
• ii) admixing dry spores of the entomopathogenic fungus comprising Beauveria bassiana with said electret particles, wherein the spores are present in an amount of 2 to 5% w/w of the formulation and the electret particles are present in an amount of 10 to 15% w/w of the formulation;
• and
• iii) admixing dry industrial mineral earth particles, having a volume mean diameter of ≥5 μm in an amount of 80 to 88% w/w of the formulation, with the product of step ii).