Effects on detoxification enzymes of Helicoverpa armigera (Lepidoptera: Noctuidae) infected by Beauveria bassiana spores and detection of its infection by PCR

This research aimed to investigate virulence of Beauveria bassiana 36 and its pathogenicity on the infected larvae of Helicoverpa armigera. The virulence was measured by LD50 values and pathogenicity was monitored from detoxification enzymatic changes and pathogenic detection using polymerase chain reaction (PCR). LD50 of B. bassiana against H. armigera larvae was highly effective at a very low dose of 7.2 x 10(8) spores/ml. Phenoloxidase (PO), glutathione S-transferase (GST), esterase (EST), and glucose oxidase (GOX) activities were found from the hemolymph of the infected H. armigera larvae. PO and GST activities from the infected larval sample increased from 53.72 +/- 1.10 to 79.03 +/- 1.22 U/mg protein and from 3.81 +/- 0.17 to 5.77 +/- 0.09 U/mg protein, respectively, from 0-48 h and then decreased from 61.75 +/- 1.12 to 37.46 +/- 1.06 U/mg protein and from 4.45 +/- 0.09 to 2.61 +/- 0.12 U/mg protein from 72-120 h, respectively. EST and GOX activities from the infected larval sample increased from 10.24 +/- 0.44 to 21.84 +/- 0.64 U/mg protein and from 3.38 +/- 0.30 to 10.76 +/- 0.34 U/mg protein, respectively, from 0-72 h, but decreased slightly from 21.72 +/- 0.76 to 16.00 +/- 0.89 U/mg protein and from 4.33 +/- 0.55 to 4.02 +/- 0.41 U/mg protein from 96120 h, respectively. The presence of B. bassiana in the infected larvae was detected at post-inoculation using PCR with the specific primers (P1-P3). B. bassiana was successfully and rapidly detected and identified within 72-120 h with molecular techniques.