Department of Entomology, Cornell University, Ithaca, NY 14853-0901, USA.
Phytopathology. 2012 Mar;102(3):283-9. doi: 10.1094/PHYTO-09-11-0262.
A series of laboratory experiments were conducted to investigate the capacity of Bradysia impatiens (Johannsen) larvae to ingest propagules from two strains each of Pythium aphanidermatum (Edson) Fitzp. and P. ultimum Trow and transmit the pathogens to healthy geranium seedlings on a filter-paper substrate in petri dishes. The capacity of fungus gnat larvae to transmit P. aphanidermatum to seedlings rooted in a commercial peat-based potting mix and germination of Pythium oospores and hyphal swellings before and after passage through the guts of larval fungus gnats were also examined. Assays revealed that Pythium spp. transmission by larval fungus gnats varied greatly with the assay substrate and also with the number and nature of ingested propagules. Transmission was highest (65%) in the petri dish assays testing larvae fed P. aphanidermatum K-13, a strain that produced abundant oospores. Transmission of strain K-13 was much lower (<6%) in plug cells with potting mix. Larvae were less efficient at vectoring P. ultimum strain PSN-1, which produced few oospores, and no transmission was observed with two non-oospore-producing strains: P. aphanidermatum Pa58 and P. ultimum P4. Passage of P. aphanidermatum K-13 through larval guts significantly increased oospore germination. However, decreased germination of hyphal swellings was observed following larval gut passage for strains of P. ultimum. These results expand previous studies suggesting that larval fungus gnats may vector Pythium spp.
进行了一系列实验室实验，以研究美洲实蝇幼虫摄取两种各菌株的腐霉和终极腐霉的繁殖体的能力，并在培养皿中的滤纸基质上将病原体传播到健康的天竺葵幼苗上。还研究了真菌蚋幼虫将腐霉传播到定植在商业泥炭基盆栽混合物中的幼苗的能力，以及在幼虫肠道中通过后腐霉卵孢子和菌丝膨体的萌发。分析表明，幼虫真菌蚋对腐霉的传播因分析基质而异，也因摄入的繁殖体的数量和性质而异。在测试幼虫摄取腐霉 K-13 的培养皿分析中，传播率最高（65%），K-13 菌株产生大量卵孢子。在带有盆栽混合物的插件细胞中，K-13 菌株的传播率要低得多（<6%）。幼虫在传播终极腐霉 PSN-1 时效率较低，该菌株产生的卵孢子较少，而两个不产卵孢子的菌株：腐霉 Pa58 和终极腐霉 P4 则没有观察到传播。腐霉 K-13 通过幼虫肠道的传递显著增加了卵孢子的萌发。然而，在幼虫肠道通过后，观察到终极腐霉菌株的菌丝膨体萌发减少。这些结果扩展了先前的研究，表明幼虫真菌蚋可能传播腐霉属。
