title: Irradiation influence on the phenoloxidase pathway and an anti-oxidant defense mechanism in Spodoptera litura (Lepidoptera: Noctuidae) and its implication in radio-genetic 'F 1 sterility' and biorational pest suppression tactics.
abstract: The present study was conducted to appraise the ontogenic radio-sensitivity of a serious tropical pest, Spodoptera litura (Fabr.). The molecular responses pertaining to the phenoloxidase (PO) pathway and an anti-oxidant defense mechanism were evaluated in order to understand its implication in pest control at pre-harvest and post-harvest intervals. Irradiation exhibited an inverse relationship with age with respect to impact on developmental and transcriptional responses. Transcript abundance of PO cascade enzymes, prophenoloxidase (slppo-2), its activating enzyme (slppae-1) and free-radical scavenging enzymes, superoxide dismutase (slsod) and catalase (slcat) was evaluated upon gamma irradiation alone and the dual-stress of radiation plus microbial challenge. The slppo-2, slppae-1, slsod and slcat transcripts were significantly up-regulated in F 1 L6 larvae (6th-instar) resulting from 100 Gy sub-sterilized male adults and unirradiated female moths. The extent of upregulation was relatively higher in comparison with L6 survivors (6th-instar larvae) developed from irradiated neonates (L1) treated with 100 Gy. Upon Photorhabdus challenge, the transcripts were down-regulated in irradiated L1 suggesting increased larval susceptibility to bacterial infections. Radioresistance increased with the age of the insect, and molecular responses (transcript abundance) of insect defense mechanism were less influenced when older age (F 1 progeny) were irradiated. These findings will help to optimize the gamma dose to be employed in inherited sterility technique for (pre-harvest) pest suppression and (post-harvest) phytosanitation and quarantine, and suggest compatible integration of biorational tactics including nuclear technology.
authors.affiliation: International Centre for Genetic Engineering and Biotechnology (ICGEB),New Delhi-110067,India.
authors.forename: B
authors.initials: B
authors.lastname: Sachdev
authors.affiliation: Department of Zoology,University of Delhi,Delhi-110007,India.
authors.forename: Z
authors.initials: Z
authors.lastname: Khan
authors.affiliation: Department of Zoology,University of Delhi,Delhi-110007,India.
authors.forename: M
authors.initials: M
authors.lastname: Zarin
authors.affiliation: International Centre for Genetic Engineering and Biotechnology (ICGEB),New Delhi-110067,India.
authors.forename: P
authors.initials: P
authors.lastname: Malhotra
authors.affiliation: Department of Zoology,University of Delhi,Delhi-110007,India.
authors.forename: R K
authors.initials: RK
authors.lastname: Seth
authors.affiliation: International Centre for Genetic Engineering and Biotechnology (ICGEB),New Delhi-110067,India.
authors.forename: R K
authors.initials: RK
authors.lastname: Bhatnagar
mesh_terms: D000818:Animals; D005260:Female; D016166:Free Radical Scavengers / Q000378:metabolism*; D005720:Gamma Rays; D019476:Insect Proteins / Q000378:metabolism*; D007814:Larva / Q000254:growth & development / Q000378:metabolism / Q000528:radiation effects; D008297:Male; D014442:Monophenol Monooxygenase / Q000378:metabolism*; D010572:Pest Control, Biological; D015398:Signal Transduction; D018411:Spodoptera / Q000254:growth & development / Q000378:metabolism* / Q000528:radiation effects
chemical_list: D016166:Free Radical Scavengers; D019476:Insect Proteins; D014442:Monophenol Monooxygenase
keywords: 
                 F
                 1 sterility; 
                 Spodoptera litura
              ; Gamma radiation; phenoloxidase pathway; scavenging enzymes