Biological control of Spodoptera frugiperda (J.E. Smith) with native isolates of Bacillus thuringiensis (Berliner)

Abstract

This research aims to provide a methodology in order to evaluate the insecticidal activity of various native isolates of Bacillus thuringiensis used against Spodoptera frugiperda - fall armyworm, and thus contribute with alternatives which can be used to the biological control of this pest. In this research study, the insecticidal activity of ten Bacillus thuringiensis (B.T.) isolates (M3001, M3003, M3004, M3007, M3008, M4001, M2006, M5002, M5004 and M28 005) was tested comparing them to a commercial strain HD1 (subsp. Kurstaki) against S. frugiperda. The HD1 of the strain’s LC50 was initially determined by means of the probit analisys of the strain HD1 with different doses (0.0; 6.8 E-2; 3.4E-2; 6.8E -3; 6.8E-4; 6.8E-5 6.8E-6 mg ai / ml diet) on first instar larvae of S. frugiperda. In addition to qualitative observations, the mortality was measured at 96 and 120 hours. The concentration LC50 was subsequently used with the strain HD1 in each native B. T. isolates to be compared with the commercial strain LC50.The results indicated that the native isolates M3008 and M4001 have higher mortality ranges, whose percentages were 75% and 71.65% respectively in first instar larvae in purified diet, in comparison with the mortality rate of the LC50 of the commercial strain.