การควบคุมเพลี้ยอ่อนผัก Lipaphis erysimi (Kalt.) (Hemiptera: Aphididae) ในการปลูกพืชระบบไฮโดรโปนิกส์ด้วยเชื้อราโรคแมลง Metarhizium guizhouense PSUM04 และ Beauveria bassiana PSUB0

Abstract

The Mustard aphid, Lipaphis erysimi, has significant economic affects on cruciferous crops. The control of this insect pest has been accomplished via several methods. Use of entomopathogenic fungi is an alternative method of control that is environmentally safe and highly efficient. Pathogenicity and virulence of Metarhizium guizhouense PSUM04 and Beauveria bassiana PSUB01 were tested on L. erysimi. At 9 the spore concentration at 1×10 spore/ml, M. guizhouense PSUM04 showed the most virulence on L. erysimi with 100 percent mortality, and a highly significant difference on B. bassiana PSUB01 and control (P<0.01), with 89.0 and 4.0 percent mortality, respectively. The percentage of mortality of L. erysimi infected with both entomopathogenic fungi at 1×10, 1x10, 1x10 and 1x10 spore/ml increased concurrently with incubation time. The spore concentrations at 1×10R and 1×10° spore/ ml had a lower average survival time than the spore concentrations at 1×10°, 1×10 spore/ml and control, respectively. The infected L. erysimi with M. guizhouense PSUM04 and B. bassiana PSUB01 transmitted the fungal spore to the normal L. erysimi population. The transmitted ratio of both entomopathogenic fungi at 5: 5 showed the highest percentage of mortality with 73.0 ± 18.0 and 50.0 ± 4.7 percent, and had an average survival time of 8.43 ± 0.5 and 9.29 ± 0.6 days, respectively. The colonization of M. guizhouense PSUM04 and B. bassiana PSUB01 in Chinese kale were investigated. Both entomopathogenic fungi were colonized and detected in root, stem and leaf at 7, 14, 21 and 28 days after application of the fungi. M. guizhouense PSUM04 showed a more positive effect on plant growth than B. bassiana PSUB01 and the control. The Chinese kale treated with M. guizhouense PSUM04 and L. erysimi in a hydroponic crop system test showed a highly significant difference (P<0.01) of shoot length than the control, which had fungal applications of spray, pour and spray, and pour. The Chinese kale treated with M. guizhouense PSUM04 showed longer root length than the control at 28 days after application of the fungus. Chinese kale treated with a spray and pour application, and a pour application of M. guizhouense PSUM04, showed highly significant differences of fresh and dry weights from the control (without fungus) (P<0.01). In addition, the Chinese kale treated with M. guizhouense PSUM04 with a spray and pour application, and a pour application, had low L. erysimi infestation on Chinese kale at 28, 35 and 42 days after fungal application, and significantly different from the control (without fungus) (P<0.01). Conclusion, M. guizhouense PSUM04 was efficient at controlling L. erysimi in a hydroponic crop system.