Abstract：
BACKGROUND: Fall armyworm (Spodoptera frugiperda) is a highly destructive maize pest that significantly threatens agricultural productivity. Existing control methods, such as chemical insecticides and entomopathogens, lack effectiveness, necessitating alternative approaches.
METHODS: Gut-associated bacteria were isolated from the gut samples of fall armyworm and screened based on their chitinase and protease-producing ability before characterization through 16S rRNA gene sequence analysis. The efficient chitinase-producing Bacillus licheniformis FGE4 and Enterobacter cloacae FGE18 were chosen to test the biocontrol efficacy. As their respective cell suspensions and extracted crude chitinase enzyme, these two isolates were applied topically on the larvae, supplemented with their feed, and analyzed for their quantitative food use efficiency and survivability.
RESULTS: Twenty-one high chitinase and protease-producing bacterial isolates were chosen. Five genera were identified by 16S rRNA gene sequencing: Enterobacter, Enterococcus, Bacillus, Pantoea, and Kocuria. In the biocontrol efficacy test, the consumption index and relative growth rate were lowered in larvae treated with Enterobacter cloacae FGE18 by topical application and feed supplementation. Similarly, topical treatment of Bacillus licheniformis FGE4 to larvae decreased consumption index, relative growth rate, conversion efficiency of ingested food, and digested food values.
CONCLUSIONS: The presence of gut bacteria with high chitinase activity negatively affects insect health. Utilizing gut-derived bacterial isolates with specific insecticidal traits offers a promising avenue to control fall armyworms. This research suggests a potential strategy for future pest management.
METHODS: Gut-associated bacteria were isolated from the gut samples of fall armyworm and screened based on their chitinase and protease-producing ability before characterization through 16S rRNA gene sequence analysis. The efficient chitinase-producing Bacillus licheniformis FGE4 and Enterobacter cloacae FGE18 were chosen to test the biocontrol efficacy. As their respective cell suspensions and extracted crude chitinase enzyme, these two isolates were applied topically on the larvae, supplemented with their feed, and analyzed for their quantitative food use efficiency and survivability.
RESULTS: Twenty-one high chitinase and protease-producing bacterial isolates were chosen. Five genera were identified by 16S rRNA gene sequencing: Enterobacter, Enterococcus, Bacillus, Pantoea, and Kocuria. In the biocontrol efficacy test, the consumption index and relative growth rate were lowered in larvae treated with Enterobacter cloacae FGE18 by topical application and feed supplementation. Similarly, topical treatment of Bacillus licheniformis FGE4 to larvae decreased consumption index, relative growth rate, conversion efficiency of ingested food, and digested food values.
CONCLUSIONS: The presence of gut bacteria with high chitinase activity negatively affects insect health. Utilizing gut-derived bacterial isolates with specific insecticidal traits offers a promising avenue to control fall armyworms. This research suggests a potential strategy for future pest management.
摘要：
背景：秋季粘虫（Spodopterafrugiperda）是一种高度破坏性的玉米害虫，显着威胁农业生产力。现有的控制方法，如化学杀虫剂和昆虫病原体，缺乏有效性,需要替代方法。
方法：从秋季粘虫的肠道样品中分离肠道相关细菌，并根据其几丁质酶和蛋白酶的产生能力进行筛选，然后通过16SrRNA基因序列分析进行鉴定。选择有效的产几丁质酶的地衣芽孢杆菌FGE4和阴沟肠杆菌FGE18来测试生物防治功效。作为各自的细胞悬液和提取的粗酶，这两个分离株局部施用于幼虫，补充他们的饲料，并分析了它们的定量食物利用效率和生存能力。
结果：选择了21个高产几丁质酶和蛋白酶的细菌分离株。通过16SrRNA基因测序鉴定了五个属：肠杆菌，肠球菌,芽孢杆菌,泛菌,还有Kocuria.在生物防治功效测试中，通过局部应用和饲料补充，阴沟肠杆菌FGE18处理的幼虫的消耗指数和相对生长速率降低。同样，局部治疗地衣芽孢杆菌FGE4对幼虫的消耗指数降低，相对增长率，摄入食物的转化效率，和消化的食物价值。
结论：具有高几丁质酶活性的肠道细菌的存在对昆虫健康产生负面影响。利用具有特定杀虫特性的肠道来源的细菌分离株为控制秋季粘虫提供了有希望的途径。这项研究为未来的害虫管理提供了潜在的策略。
方法：从秋季粘虫的肠道样品中分离肠道相关细菌，并根据其几丁质酶和蛋白酶的产生能力进行筛选，然后通过16SrRNA基因序列分析进行鉴定。选择有效的产几丁质酶的地衣芽孢杆菌FGE4和阴沟肠杆菌FGE18来测试生物防治功效。作为各自的细胞悬液和提取的粗酶，这两个分离株局部施用于幼虫，补充他们的饲料，并分析了它们的定量食物利用效率和生存能力。
结果：选择了21个高产几丁质酶和蛋白酶的细菌分离株。通过16SrRNA基因测序鉴定了五个属：肠杆菌，肠球菌,芽孢杆菌,泛菌,还有Kocuria.在生物防治功效测试中，通过局部应用和饲料补充，阴沟肠杆菌FGE18处理的幼虫的消耗指数和相对生长速率降低。同样，局部治疗地衣芽孢杆菌FGE4对幼虫的消耗指数降低，相对增长率，摄入食物的转化效率，和消化的食物价值。
结论：具有高几丁质酶活性的肠道细菌的存在对昆虫健康产生负面影响。利用具有特定杀虫特性的肠道来源的细菌分离株为控制秋季粘虫提供了有希望的途径。这项研究为未来的害虫管理提供了潜在的策略。
