Majumdar Ayanava, Boetel Mark A, Jaronski Stefan T
Department of Entomology, North Dakota State University, Fargo, ND 58105, USA.
J Invertebr Pathol. 2008 Jan;97(1):1-8. doi: 10.1016/j.jip.2007.05.003. Epub 2007 May 18.
The fungus Fusarium solani (Mart.) Sacc. was discovered as a native entomopathogen of the sugarbeet root maggot, Tetanops myopaeformis (Röder), in the Red River Valley of North Dakota during the 2004 sugarbeet production season. This is the first report of a native pathogen affecting the pupal stage of T. myopaeformis. Forty-four percent of larvae collected from a field site near St. Thomas (Pembina Co.) in northeastern North Dakota during May and June of 2004 were infected with the entomopathogen. The mean LC(50) of F. solani, assessed by multiple-dose bioassays with laboratory-reared pupae, was 1.8x10(6)conidia/ml. After isolation and confirmation of pathogenicity, a pure isolate of the fungus was deposited in the ARS Entomopathogenic Fungal Collection (ARSEF, Ithaca, NY) as ARSEF 7382. Symptoms of F. solani infection included rapid pupal tissue atrophy and failure of adults to emerge. Transverse dissections of infected pupae revealed dense hyphal growth inside puparia, thus suggesting fungal penetration and pathogenicity. Mycelia emerged from pupae after host tissues were depleted. Exposure of older pupae to lethal concentrations caused rapid mortality of developing adults inside puparia. A second, more extensive field survey was conducted during the 2005 cropping season, and F. solani infection was observed in root maggots at most locations, although at lower levels (1-10%) of prevalence than in 2004. Aberrant timing or amounts of rainfall received could have caused asynchrony between pathogen and host during the second year of the experiment.
2004年甜菜生产季期间，在北达科他州红河河谷发现茄病镰刀菌（Fusarium solani (Mart.) Sacc.）是甜菜根蛆（Tetanops myopaeformis (Röder)）的一种本地昆虫病原体。这是关于影响甜菜根蛆蛹期的本地病原体的首次报道。2004年5月和6月，从北达科他州东北部圣托马斯（彭比纳县）附近一块农田采集的幼虫中，44%感染了这种昆虫病原体。通过对实验室饲养的蛹进行多剂量生物测定评估，茄病镰刀菌的平均半数致死浓度（LC(50)）为1.8×10(6)分生孢子/毫升。在分离并确认致病性后，该真菌的一个纯分离株被保藏在美国农业部农业研究局昆虫病原真菌保藏中心（ARSEF，纽约州伊萨卡），编号为ARSEF 7382。茄病镰刀菌感染的症状包括蛹组织迅速萎缩以及成虫无法羽化。对受感染蛹的横向解剖显示，蛹壳内有密集的菌丝生长，这表明真菌具有穿透性和致病性。宿主组织耗尽后，菌丝从蛹中长出。将老龄蛹暴露于致死浓度会导致蛹壳内发育中的成虫迅速死亡。在2005年种植季进行了第二次更广泛的田间调查，在大多数地点的根蛆中都观察到了茄病镰刀菌感染，尽管感染率（1 - 10%）低于2004年。实验第二年降雨时间或降雨量异常可能导致病原体与宿主不同步。
