Department of Conservation Ecology and Entomology, Faculty of AgriSciences, Private Bag X1;
Department of Conservation Ecology and Entomology, Faculty of AgriSciences, Private Bag X1.
J Vis Exp. 2022 Mar 31(181). doi: 10.3791/63246.
Entomopathogenic fungi of the Metarhizium anisopliae species complex have gained importance as the biological control agents of agricultural insect pests. The increase in pest resistance to chemical insecticides, the growing concerns regarding the negative effects of insecticides on human health, and the environmental pollution from pesticides have led to a global drive to find novel sustainable strategies for crop protection and pest control. Previously, attempts to mass culture such entomopathogenic fungi (EPF) species as Beauveria bassiana have been conducted. However, only limited attempts have been conducted to mass culture Metarhizium robertsii and M. pinghaense for use against insect pests. This study aimed to mass-produce a sufficient number of resilient infective propagules of South African isolates of M. robertsii and M. pinghaense for commercial application. Three agricultural grain products, flaked oats, flaked barley, and rice, were used as the EPF solid fermentation substrates. Two inoculation methods, conidial suspensions and the liquid fungal culture of blastospores were used to inoculate the solid substrates. Inoculation using conidial suspensions was observed to be relatively less effective, as increased levels of contamination were observed on the solid substrates relative to when using the blastospore inoculation method. Flaked oats were found not to be a suitable growth substrate for both M. robertsii and M. pinghaense, as no dry conidia were harvested from the substrate. Flaked barley was found to favor the production of M. robertsii conidia over that of M. pinghaense, and an average of 1.83 g ± 1.47 g of dry M. robertsii conidia and zero grams of M. pinghaense conidia was harvested from the substrate. Rice grains were found to favor the conidial mass production of both M. pinghaense and M. robertsii isolates, with an average of 8.2 g ± 4.38 g and 6 g ± 2 g harvested from the substrate, respectively.
绿僵菌属的虫生真菌作为农业害虫的生物防治剂的重要性日益增加。害虫对化学杀虫剂的抗性增加，人们对杀虫剂对人类健康的负面影响的担忧日益增加，以及杀虫剂对环境的污染，导致了全球寻找新型可持续的作物保护和害虫控制策略的努力。以前，人们曾尝试大规模培养球孢白僵菌等虫生真菌。然而，只有有限的尝试用于大规模培养金龟子绿僵菌和淡紫拟青霉以防治害虫。本研究旨在大量生产足够数量的南非金龟子绿僵菌和淡紫拟青霉的抗性感染繁殖体，用于商业应用。三种农业谷物产品，即燕麦片、大麦片和大米，被用作 EPF 固体发酵基质。使用两种接种方法，即分生孢子悬浮液和液体真菌芽生孢子接种法来接种固体基质。观察到使用分生孢子悬浮液接种相对不太有效，因为与使用芽生孢子接种方法相比，固体基质上观察到的污染水平增加。燕麦片不适合金龟子绿僵菌和淡紫拟青霉的生长，因为从基质中没有收获到干燥的分生孢子。大麦片有利于金龟子绿僵菌分生孢子的产生，而不利于淡紫拟青霉分生孢子的产生，从基质中收获到的平均 1.83 g ± 1.47 g 的金龟子绿僵菌分生孢子和零克的淡紫拟青霉分生孢子。稻谷粒有利于淡紫拟青霉和金龟子绿僵菌分离株的分生孢子大量生产，分别从基质中收获到平均 8.2 g ± 4.38 g 和 6 g ± 2 g 的分生孢子。
