Efficiency of Bacillus thuringiensis var. Kurstaki for controlling Helicoverpa armigera (Hubner) on cotton
1993
Damo, M.C. (Cotton Research and Development Inst., Batac, Ilocos Norte (Philippines))
The study investigated the effects of Bacillus thuringiensis var Kustaki (commercial formulation) on the survival and other effects of Helicoverpa armigera and to determine its field efficacy on cotton at different growth stages. The survivors of Helicoverpa armigera treated with B. thuringiensis had prolonged larval duration as well as longer pupal stage than the untreated larvae. This indicates that mean generation cycle of H. armigera is shortened, thus damage potential of succeeding generation is reduced. Early application of B. thurigiensis effectively reduced H. armigera population in the field. However, it was not effective when alternated with chemical insecticides. Highest number of bolls per plant, seed cotton yield and net returns were derived from plants treated with B. thuringiensis at 41 days after planting in rotation with any of the recommended insecticides
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