Study On Modification Of Beauveria Bassiana Oil Formulation

The processing level of formulation of fungal insecticides as well as quality directly determines its application on the control of agricultural pests.Green Muscle^?,the most successful commercial product of oil formulation of fungal insecticides produced from Metarhizium flavoviride has being widely used to control desert locust in some arid area in the world.However,no other oil formulation product of fungal insecticides was reported and registered except an oil formulation of Beauveria bassiana named 951 was developed by our staffs in the middle of 1990s in China.But the short storage period of the product with a conidia viability of 40%in 240 days storage at room temperature baffled its widely use.An optimized measuring method of conidia germination in oil formulation as well as technique processing of fermentation and additive agents of oil formulation was studied in the present thesis in order to change the poor present situation on oil formulation study.A novel method combined emulsifying agents and culture liquid was developed to accurately and rapidly measure the conidia germination in oil formulation.The study on emulsifying agents showed:1)Tween80 and NPE-Y at relatively high concentrations posed detrimental effect on conidia germination while AEO-X at all tested concentrations severely prohibited the germination;2)NPE-Y at the concentrations of 0.01%and 0.05% didn't show any adverse influence on germination with percentages of 88.65%and 85.88 %,respectively,and without significant difference to the CK with a percentage of 89.78%. So,NPE-Y at the concentration of 0.01%was the optimal emulsifying agent for germination measuring.The optimal culturing time was 36 hours,which resulted in a germination percentage of 90.37%,almost the same value of CK,90.75%.High-quality conidia powder is the foundation of oil formulation process.The improvement of fermentation technique process got high quality conidia powder with some quality indices of water content,conidia amount,and conidia viability of 9.7±1.7%, 1.30×10¹¹conidia /g and 97.5±2.1%,respectively.The output ratio of conidia powder to solid medium was 15.4mg/g and 2.4×10⁹/g in terms of weight and amount,respectively. Water content of the conidia powder could decrease to 8%,6%and 4%after 2 hours,6 hours and 12 hours vacuum drying,respectively,under a negative 0.1 atmospheric pressure at room temperature.Sieving of solvent oil showed oil A was the best one for the conidia long term storage. The germination percentage of conidia still reached at 81.74%in a system of 30%conidia mixed into the oil A in terms of weight to volume after 2 months storage at room temperature.The result is much better than that in soybean oil,white oil,and olefin oil with significant difference,only 2.51%bellow the CK.Two kinds of nano material showed good anti-UV function compared with the other two anti-UV agents Fe₂O₃ and Ascorbic acid.Nano B,one of the tested nano materials got the best result against UV and with a significant difference to the other tested nano material,nano ZnO.Conidia viability remained at 67.57%and 68.19%,respectively,after 4.5 hours irradiation under UV light(18 watts,40 cm height)with the concentrations of 0.5%and 1%of nano B added into the oil formulation.The germination percentage was much higher than that of CK,5.94%,and also significant higher than that of the other anti-UV agents.The sieving of antioxidants revealed antioxidant B was the optimal one that showed significant difference to the others antioxidants after 60 days storage in room temperature. The germination percentages of 82.64%,82.68%and 82.34%showed no difference among three mixture concentrations of 0.3%,0.9%and 2.7%of the antioxidant B.The antioxidant B can be used for oil formulation with an optimal concentration of 0.3%In order to enhance stability of conidia suspension,3 stabilization agents of suspension were tested and compared.Stabilization agent A showed no detrimental effect on conidia germination at a concentration of 0.3%while the other agents did.Long term storage of oil formulation in two room temperatures showed germination dynamic was closely related to the temperature dynamic.The germination percentage in fermentation room was 63.71±0.22%,5.54 hundred points higher than that in formulation room after one year's storage because the average annual temperature in formulation room was 2-3℃higher than that in fermentation room,and peaked at 37℃.The new developed oil formulation of B.bassiana showed good ability of storage in room temperature,much better than the former product,951.In order to increase the killing speed of the oil formulation,compatibility oil formulation of B.bassiana with several chemical insecticides were studied.The result showed different chemical insecticides posed different influence on conidia.In 30% additive dosage groups,fenvalerate and imidacloprid killed almost all conidia within 1 week.In 3%additive groups,viability of conidia in fenvalerate and imidacloprid mixture groups changed from 31.99%in 1 day to less than 10%in 1 month storage,and from 50% in 1 week to 26.84%in 1 month storage,respectively,while in 0.3%additive group of imidacloprid,the conidia viability still kept at 68.06%in 56 days storage,which showed the potential of the chemical insecticide as a enhancer of oil formulation of B.bassiana.