Efficacy of commercial strains of Bacillus thuringiensis in controlling Tuta absoluta: laboratory tests

Several commercially available strains of the entomopathogenic bacteria Bacillusthuringiensis (Bt) were tested to evaluate their efficacy in controlling Tuta absoluta, in terms of larvalmortality, of reduction in larval feeding activity and subsequent damage. Tests were conducted onT. absoluta young larvae under laboratory and extended laboratory conditions, both after ingestion andtopical application. The mortality rate, the number of infested leaflets and the amount of infestedsurface per each leaflet were recorded. The formulation containing the strain kurstaki SA12 resultedthe most effective in controlling T. absoluta in terms of induced mortality as well as damagereduction, both in the topical and ingestion toxicity trial. Similar trend, although without significantdifferences, was recorded in the extended laboratory trial.