Related Experiment Video
Updated: May 24, 2026
Development of Metarhizium anisopliae as a Mycoinsecticide: From Isolation to Field Performance
Published on: July 30, 2017
Milling effect on the control efficacy of spray-dried Bacillus thuringiensis technical powder against diamondback
1Entomology Research Laboratory, University of Vermont, Burlington, VT, USA.
Background:
The relationship between the particle size of spray-dried Bacillus thuringiensis NT0423 technical powder and its insecticidal activity against diamondbackmoth was investigated in laboratory and glasshouse conditions. A variety of sizes of Bt particles were made by homogenisation, followed by pilot-scale milling to optimise further the current Bt formulation process.
Results:
In laboratory conditions, homogenised Bt suspension with smaller particles had higher control efficacy against diamondback moth. However, in glasshouse conditions, the smallest particle treatment did not follow the size-dependent insecticidal activity, rather showing decreased control efficacy. Secondly, air-jet-milled Bt powder (16.9 μm) had higher control efficacy than hammer-milled Bt powder (35.1 μm) in glasshouse conditions. However, double air-jet milling (5.3 μm) had lower control efficacy compared with one-time milling.
Conclusion:
These results suggest that NT0423 technical powder with smaller particles is better in controlling diamondback moths, but excessively small particles (<10 μm) possibly reduce the insecticidal activity.
