Insecticidal impacts of Bacillus flexus S13 biofilm'extracellular matrix' on cowpea weevil, Callosobruchus maculatus

Abstract

Abstract In an attempt to throw light on the chemical composition of the extracellular matrix (ECM) of Bacillus flexes S13; biofilm’ and its potential activity as insect biocontrol agents. This study investigated the insecticidal efficacy of ECM of Bacillus flexus; S13 against adults of Callosobruchus maculatus. The toxicity results revealed LC50 values as 22.6455 g/100 ml and 10.8524 g/100 ml after 24 and 48 h respectively. Also, the Biochemical assays revealed a significant reduction in total protein, total lipids and chitin contents in survival adults treated with LC50 of Bacillus flexus' ECM where's, the total protein was decreased down to the half (15.54 mg/g) in adults treating with ECM compared to untreated-negative control (39.34 mg/g) while the positive control group treated with NaCl showed a mild decrease (23.57 mg/g). Furthermore, the GC/MS analyses of the methanolic solution of Bacillus flexus ECM showed a high content of polyphenols especially; flavonoid compounds while the major compound was (3, 5, 7, 3\, 4\, penta hydroxyl flavone)with percentage of (40.93%).