The optimized formulation of Metarhizium anisopliae and its field biocontrol effect of diamondback moth ( Plutella xylostella) on crucifer vegetable

• Main Authors: Li Hsiao Ping, 李曉萍
• Other Authors: Liu Shan Da
• Format: Others
• Language: zh-TW
• Published: 2016
• Online Access: http://ndltd.ncl.edu.tw/handle/95845672199650493277

碩士 === 美和科技大學 === 生技科技系健康產業碩士班 === 104 === The previous researches indicated entomopathogenic fungi could be applied to control agricultural pests successfully and can be developed as microbial pesticide for commercial alternative of conventional chemical pesticides. Therefore, exploring high virulent formulation product for field biocontrol application is essential. A high virulent isolate of green muscardine fungus, Metarhizium anisopliae, MA-126 was used in this study. rDNA ITS-5.8S-ITS2 of MA-126 in length of 554bp was analyzed as molecular structure identification. In order to establish a mechanism for pathogenicity assurance of MA-126, using cabbage leaf disc method feeding with 2nd instars larva of diamondback moth (Plutella xylostella) on cabbage leaf as bio-indicator, standard curves of LC50 and LT50 were developed. The conidial concentration of LC50 was 1.82 × 106 conidia/ml and time of LT50 was 3.4 days. Solid fermentation of MA-126 on rice grain media were incubated for condia mass production and collected conidia powder with floating dry instrument (Retsch, TG200, Germany) for further formulation ingredients. The dry conidia powder added diluents, protectants and carriers amendment for powder and oil formulation. For micro-encapsuation purpose, the low temperature spray dryer (YK 100-1, JUDEN, Taiwan) and efficient vibration technique encapsulator (B-395 Pro, BUCHI, Switzerland) were applied to make dry-form and wet-form micro-encapsulation. These four formulation products were stored at 4oC and 28oC, the conidial germination rate of F powder formulation were 94.9% and 79.1% stored at 4oC and 28 oC for 120 days respectively. The conidial germination rate of mineral oil formulation were 86.7% and 75.5% stored at 4oC and 28 oC for 120 days respectively. Selection of the higher germination rate formulations, F powder and mineral oil formulations together with dry-form and wet-form micro-encapsulation products stored at room temperature, the conidial germination rate were 92-90% and 2nd instars larvae of diamondback moth mortality were 72.5-69% showed best capacity in dry-form and wet-form micro-encapsulation products. F formulation powder was next to above two micro-encapsulation products. Using speedy storage simulation to facilitate products shelf-life study, wet-form micro-encapsulation product was showed having 75% conidial germination rate at 35 oC, 12 weeks storage treatment, and 62% conidial germination rate at 45 oC, 6 weeks storage treatment. Wet-form micro-encapsulation product had best performance in speedy storage simulation test and F formulation powder was next to wet-form micro-encapsulation product. Also mortality of 2nd instar larvae of diamondback moth in wet-form micro-encapsulation product was the best and F formulation powder second accordingly. Analyzing by cabbage leaf disc method, the mortality of 2nd instars larvae of diamondback moth in culture filtrate of MA-126 14 days liquid fermentation diluted 10 and 100 times reached 100%, indicating toxic metabolites such as destruxins presented in MA-126 liquid fermentation. A EUP (Experimental Use Permit) field test was set up for biocontrol of diamondback moth on cabbage with MA-126 F formulation powder. After three times application, the control rate of pest in MA-126 F formulation powder 400 times dilution treatment was 91.71%, significantly different with BT (Bacillus thuringiensis) control treatment (P<0.05), proving that MA-126 formulation product is highly potential to commercialize. Another epidemic pest, lichee stink bug (Tessaratoma papillosa), very severely damaged on lichen, logan, Taiwan golden-rain tree and other ornamental trees lately, was tested for potential host range of MA-126 formulation product. The mortality rate of T. papillosa was 78.34% in MA-126 F formulation powder diluted 100 times treatment. The results showed the development and application of green muscardine fungus as microbial insecticide as new agricultural resource for biocontrol is very promising.