Dakhel Wahid H, Latchininsky Alexandre V, Jaronski Stefan T
Department of Ecosystem Science and Management, University of Wyoming, Laramie, WY 82071, USA.
Department of Agriculture, USDA, Agriculture Research Service (ARS), Sidney, MT 59270, USA.
Insects. 2019 Mar 30;10(4):94. doi: 10.3390/insects10040094.
Grasshopper outbreaks cause significant damage to crops and grasslands in US. Chemical control is widely used to suppress these pests but it reduces environmental quality. Biological control of insect pests is an alternative way to reduce the use of chemical insecticides. In this context, two entomopathogenic fungi, brunneum strain F52 and were evaluated as control agents for the pest migratory grasshopper under laboratory and greenhouse conditions. Third-instar grasshoppers, reared in the laboratory, were exposed up to fourteen days to wheat bran treated with different concentrations of each of the fungi alone or the two pathogens combined. In the greenhouse, nymphs were placed individually in cages where they were able to increase their body temperatures by basking in the sun in an attempt to inhibit the fungal infection, and treated with each pathogen alone or in combination. Mortality was recorded daily and presence of fungal outgrowth in cadavers was confirmed by recording fungal mycosis for two weeks' post-treatment (PT). For combination treatment, the nature of the pathogen interaction (synergistic, additive, or antagonistic effects) was also determined. In laboratory conditions, all treatments except P. locustae alone resulted in grasshopper mortality. The application of the pathogen combinations caused 75% and 77%, mortality for lower and higher concentrations, respectively than each of the pathogens alone. We infer a synergistic effect occurred between the two agents. In greenhouse conditions, the highest mortalities were recorded in combination fungal treatments with a dose (60% mortality) and with a combination of the two pathogens in which was applied at high rate (50%) two weeks after application. This latter combination also exhibited a synergistic effect. Exposure to the treatment did not lead to mortality until day 14 PT. We infer that these pathogens are promising for developing a biopesticide formulation for rangeland pest grasshopper management.
蝗虫爆发对美国的农作物和草原造成了严重破坏。化学防治被广泛用于抑制这些害虫，但它会降低环境质量。害虫的生物防治是减少化学杀虫剂使用的一种替代方法。在此背景下，在实验室和温室条件下，对两种昆虫病原真菌——球孢白僵菌菌株F52和[此处原文缺失一种真菌名称]进行了评估，以作为害虫迁徙蝗虫的防治剂。在实验室饲养的三龄蝗虫，暴露于分别用不同浓度的每种真菌单独处理或两种病原体组合处理的麦麸中长达14天。在温室中，若虫被单独放置在笼子里，它们能够通过晒太阳来提高体温，以试图抑制真菌感染，并分别用每种病原体单独处理或组合处理。每天记录死亡率，并在处理后两周（PT）通过记录真菌霉菌病来确认尸体上真菌生长的存在。对于联合处理，还确定了病原体相互作用的性质（协同、相加或拮抗作用）。在实验室条件下，除了单独使用蝗虫微孢子虫外，所有处理都导致了蝗虫死亡。病原体组合的应用分别导致低浓度和高浓度处理的死亡率为75%和77%，高于单独使用每种病原体的死亡率。我们推断这两种药剂之间发生了协同作用。在温室条件下，联合真菌处理的死亡率最高，一种剂量（60%死亡率）以及在施用两周后以高比率（50%）施用两种病原体的组合处理。后一种组合也表现出协同作用。直到处理后第14天，暴露于[此处原文缺失一种处理名称]处理才导致死亡。我们推断这些病原体有望用于开发一种用于牧场害虫蝗虫管理的生物农药制剂。
