Oral toxicity of Photorhabdus culture media on gene expression of the adult sweetpotato whitefly, Bemisia tabaci

Abstract The oral toxicity of culture media of the symbiotic bacteria, Photorhabdus temperata , mutually associated with entomopathogenic nematode Heterorhabditis megidis and Photorhabdus luminescens ssp. laumondii (TT01) mutually associated with Heterorhabditis bacteriophora , were investigated in the adults of Bemisia tabaci . The oral ingestion of sucrose diet solutions (20%) containing bacteria-free supernatant of the culture media from symbiotic bacteria gradually increased mortalities and was completely lethal at 60 h after the treatments, whereas the mortalities of the controls, sucrose solutions with or without media that uncultured with bacteria, were less than 17% up to 84 h of incubation. The effects of oral ingestion of symbiont culture media were demonstrated on the expression rates of several genes of B. tabaci using quantitative real-time RT-PCR analysis. Genes associated with immunity ( knottin ) and nervous system ( acetylcholine receptor , acetylcholine esterase and sodium channel ) were up-regulated while genes involved in metabolism ( cytochrome p 450 and carboxylesterase ) were down-regulated, but genes involved in development ( ecdysone receptor ), reproduction ( vitellogenin ) and stress ( hsp 70, hsp 90 and shsp ) did not change transcription rates. Our results provide information for the understanding of the mechanism of symbiont pathogenic factors for the manipulation of host physiology at the transcription level.