Functional Characterization Of The Long Trichoid Sensilla In The Antennae Of Female Helicoverpa Armigera

During the long time of evolution,insects have evolved an extremely specific and sensitive olfactory system,which makes it possible that insects can precisely locate host,mating partners,and oviposition and subsequently accomplish avoidance of predation.Therefore,it is crucial for regulate insects behaviors to decode insect chemosensory mechanism.It has been confirmed that different PRs expressed in sensilla trichodea of male antennae,which is 80 percent of the total sensillas,complete the reception of pheromone in Helicoverpa armigera.There are no difference in morphology and numbours of sensilla trichodea between female and male antennae in H.armigera.But there are few reports about the function of sensila trichodea in female antennae.In order to clarify the molecular coding mechanism of volatiles in the peripheral olfactory system,we conducted the functional analysis of long sensilla trichodea in H.armigera female moths using electrophysiology technology,bioinformatics and behavioristics methods,which would provide theoretical basis for the further analysis of molecular and neural mechanisms of chemical communication among insects.The main results are as following:1.Sensilla trichodea of H.armigera female moths was divided into 3 types based on their response to 18 test odors through single sensillum recordings.? type,more than 35.73%,was tuned to 7 odrants and Methyl salicylate excited the strongest and most sensitive response.? type,having 27.19%,was inhibited by 6 odors and Salicylaldehyde had the most activity.And three neurons were housed in ? and? sensilia.? type,housing two neurons,about 6.07%,could response to 3 odorants.What's more,the last remaining 133 sensillas(totally 445 sensillas)did not response to all test odors.2.17 ORs were chose for further functional analysis in long trichoid sensilla in the antenna of female H.armigera based on the result of RT-PCR and ORs phylogenetic analysis among H.armigera,H.assulta,S.exigua and M.separata.3.We cloned 17 ORs in H.armigera and functional analysis was performed in vivo with the heterologous Xenopus oocytes expression system.Ten HarmORs had no response to any of the test 18 odorants.HarmOR60 could response to 6 odors and HarmOR27 had3 ligands.HarmOR29,OR40,OR42 and OR43 renponsed to 2 odors and HarmOR31 only tuned to 1 odorant.What' more,one odor could be recognized by more than 1 odorant receptors.These results indicated that the process of odor recognition in insects was a complex and systematic project.According to the result of single sensillum recording,HarmOR27 and OR43 were predicted to be expressed in ? type of sensilla trichodea in female moth and HarmOR29 and OR60were predicted to be expressed in ? type.And it was difficult to infer the ORs housed ? type.4.Methyl salicylate had no effect to H.armigera female moths on the two-way choice assay.H.armigera had a mating peak from 3 hours later entering scotophase to 2 hours before scotophase ending.We further found that Methyl salicylate could stimulate the copulation activity of H.armigera female moths and increased copulation rate and made the mating penk forward.But it had no effect on duration time of copulation and egg amount.