The toxin-producing bacterium Bacillus thuringiensis (Berliner) (Bt) is the
principal pathogen in use for control of lepidopterous pests and some
others in agriculture. It requires a high pH, found in the gut of Lepidoptera
and some beetle species, for optimal replication. In the stored product fi eld,
commercial formulations provide a control method for almond moth and
Indian meal moth when applied to grain or other durable commodities as
an aqueous suspension or as a dust. These are effective when all the grain
is treated, or when just several inches of the surface layer are treated,
because lepidopterous larvae usually live near the surface of the bulk.
Residual activity against susceptible insects can last for more than a year
but the problem of resistance to Bt, has arisen in some moth populations
(McGaughey and Beeman, 1988 )