Resquín-Romero G, Garrido-Jurado I, Delso C, Ríos-Moreno A, Quesada-Moraga E
Department of Agricultural and Forestry Sciences, ETSIAM, University of Cordoba, Campus de Rabanales, Building C4 "Celestino Mutis", Cordoba 14071, Spain; Faculty of Agrarian Sciences of the National University of Asunción, Paraguay.
Department of Agricultural and Forestry Sciences, ETSIAM, University of Cordoba, Campus de Rabanales, Building C4 "Celestino Mutis", Cordoba 14071, Spain.
J Invertebr Pathol. 2016 May;136:23-31. doi: 10.1016/j.jip.2016.03.003. Epub 2016 Mar 2.
The current work reports how spray application of entomopathogenic fungi on alfalfa, tomato and melon plants may cause an additional Spodoptera littoralis larvae mortality due to a temporal colonization of the leaves and subsequent ingestion of those leaves by the larvae. Most entomopathogenic fungi (EF) (Ascomycota: Hypocreales) endophytes seem to colonize their host plants in a non-systemic pattern, in which case at least a transient endophytic establishment of the fungus should be expected in treated areas after spray application. In this work, all strains were able to endophytically colonize roots, stems and leaves during the first 96h after inoculation. Whilst the treatment of S. littoralis larvae with a 10(8)ml(-1) conidial suspension resulted in moderate to high mortality rates for the Metarhizium brunneum EAMb 09/01-Su (41.7-50.0%) and Beauveria bassiana EABb 01/33-Su (66.7-76.6%) strains, respectively, an additive effect was detected when these larvae were also fed endophytically colonized alfalfa, tomato, and melon leaves, with mortality rates varying from 25.0% to 46.7% as a function of the host plant and total mortality rates in the combined treatment of 75-80% and 33-60% for B. bassiana and M. brunneum, respectively. Fungal outgrowth was not detected in any of the dead larvae feeding on colonized leaves, whereas traces of destruxin A were detected in 11% of the insects fed tomato discs endophytically colonized by M. brunneum. The combined effects of the fungal spray with the mortality caused by the feeding of insects on transient EF-colonized leaves have to be considered to estimate the real acute impact of field sprays with entomopathogenic fungi on chewing insects.
当前研究报告了在苜蓿、番茄和甜瓜植株上喷施昆虫病原真菌如何因叶片的短暂定殖以及随后幼虫取食这些叶片而导致斜纹夜蛾幼虫额外死亡。大多数昆虫病原真菌（子囊菌门：肉座菌目）内生菌似乎以非系统性模式定殖其寄主植物，在这种情况下，喷施后在处理区域应至少预期真菌有短暂的内生定殖。在本研究中，所有菌株在接种后的前96小时内都能够内生定殖根、茎和叶。用10⁸个/毫升的分生孢子悬浮液处理斜纹夜蛾幼虫时，球孢白僵菌EABb 01/33-Su菌株（66.7%-76.6%）和布氏绿僵菌EAMb 09/01-Su菌株（41.7%-50.0%）分别导致中度到高度死亡率，当这些幼虫也取食内生定殖的苜蓿、番茄和甜瓜叶片时，检测到有累加效应，死亡率因寄主植物而异，在25.0%至46.7%之间，联合处理中球孢白僵菌和布氏绿僵菌的总死亡率分别为75%-80%和33%-60%。在取食定殖叶片的任何死亡幼虫中均未检测到真菌生长，而在取食布氏绿僵菌内生定殖番茄圆盘的11%的昆虫中检测到痕量的白僵菌素A。为了估计田间喷施昆虫病原真菌对咀嚼式昆虫的实际急性影响，必须考虑真菌喷施与昆虫取食短暂定殖于内生真菌的叶片所导致的死亡率的联合效应。
