Study On Protein Bait Of Bactrocera Dorsalis (Hendel) From Brewers Grain By Mixed Strains

Bactrocera dorsalis （Hendel） is a destructive pest. Chemical pesticides are now the dominant to control B. dorsalis,however, the high cost, environmental pollution and pesticide residues have became serious problems.Protein bait is one of the biocontrol to control B.dorsalis due to attracting both male and female. In this paper, the liquid fermentation to produce protein bait by bacterial strains with brewer’s grains as raw material was studied.The growth cycle and the optimal inoculation time of fermentation medium with bacteria seed liquid of the four bacterial strains of Candida tropicalis, Candida utilis, Trichoderma koningii and Trichoderma viride were got. The bacteria ratio of fermentation medium was solved by simplex-centroid design. The optimum bacterial strains were Trichoderma koningii and Candida tropicalis and the seed liquid were 2.4ml and 2.6ml separately by Programming Solver in Excel.The effects of different nitrogen sources and different amounts of KH₂PO₄, MgSO₄ and CaCl2 on fermentation were studied by single factor experiment and orthogonal experiment based on the optimum ratio, The optimal formula consisted of MgSO₄ 0.23 mg/ml, urea 1.24 mg/ml, ammonium sulfate 2.52 mg/ml, ammonium nitrate 1.65mg/ml, CaCl₂ 0.24 mg/ml and KH2PO₄ 0.71 mg/ml.The influences of temperature, shaker speed, pH and time on fermentation were also studied by single factor experiment and orthogonal experiment. The optimal fermentation conditions were time 48 h, temperature 23℃, pH 4.4 and speed of 210 r/min. The optimum enzymatic hydrolysis process was enzyme 0.04 g, temperature of 54℃, pH 6.3 and time 21 h.The proteins made from brewer’s grains could attract some both males and females of B.dorsalis compared with common attractants on laboratory. To develop protein bait from brewer’s grain will be an effective way to produce protein bait to control B.dorsalis.