The Mechnism Of Pheromone Detection In Cotton Bollworm And Asian Corn Boller

Sex pheromones are critical for the courtship and mating behavior of insects.In Lepidoptera,males could dectect the pheromones released by conspecific females and orient towards them to finish the mating.Owing to its characteristic of highly species-specific and environmental friendly,pheromone-based technique has been widely used in the monitoring and controlling of Lepidoptera pest.Sex pheromone is detected by the olfactory sensilla distributed in lepidopteran's antennae.Pheromone sensing neurons are located inside those sensilla and pheromone receptors(PRs)are expressed on the dentrite of those neurons.PRs are activated by its correspondent pheromone components to transform the chemical signal into electrical signal which eventually transmitted to the brain for processing.The perception of sex pheromone is regulated by the physiological state of the insects and olfactory proteins,neurotransmitters and neuropeptides are involved in this process.We take Asian corn borer Ostrinia furnacalis and cotton bollworm Helicoverpa armigera as case studies to focus on the study of dectection of pheromone and physiological state-related placiticity of its perception in Lepidopterans.Our results will not only promote our understanding in the mechanism of pheromone dection in insects,but also provide the fundatmental knowledges for developing novel pest management technique.(1)The regulation of male mating behavior by age was investigated in Helicoverpa armigera.Behavior test indicated that males almost did not mate in the first scotophase(2.5%),but it copulates frequently in the third scotophase(76.4%).Single sensillum recording indicated that the sensitivity of Z11-16:Ald in A type sensilla was higher in the first scotophase than the third scotophase,while the sensitivity of of Z9-16:OAc was lower in the first scotophase than the third scotophase.The dynamics of spontaneous activity and the reponse to Z11-16:Ald in A type sensilla were different between the fisrt and the third scotophase.The frequency of the spike was increased in the third scotophase but its amplitude was decreased.Spikes amplitudes strongly decreased after the corresponding neuron in A type sensilla was activated in the third scotophase.Dose response indicated that EC50 in the first scotophase(8.5?g)was lower than the third scotophase(53.4?g).(2)We identified 67 odorant receptors and 39 odorant binding proteins in the antennae.Acording to the results of DEG analysis and qPCR,HarmOR47,HarmPBP2 and HarmOBP6 were upregulated as age increased,while HarmOR43 and HarmOR50 were downregulated.We identified 57 neuropeptides in the brain.We did not find Glycoprotein hormone compare to the published neuropeptides pool of Lepidoptera insects.Duplication were found in genes ecoding Adipokinetic hormone 1.HarmAKH1a and HarmAKH1b have the same mature peptide,probably their function could be complementary.Alternatvie splicing could be found in CCHamide1,NPF1,Orconin and Ion transported peptide.Acording to the results of DEG analysis and qPCR,HarmAKH1a,HarmAKH1b and HarmILP2 were upregulated as age increased,while HarmBurA,HarmEH and HarmASTCC were downregulated.(3)We deorphanized pheromone receptors in Asian corn borer based available transcriptome and heterologous expression system of Xenopus oocytes.OfurOR4 and OfurOR6 responded to the major sex pheromone Z/E12-14:OAc.OfurOR4 is the main receptor for both Z/E12-14:OAc and OfurOR6 mainly responed to E12-14:OAc.Functional differentiation of gene duplication were found between OfurOR5a and OfurOR5b.OfurOR5b showed a broad response to most of the pheromone components in O.furnacalis,whereas OfurOR5a was found without ligands.OfurOR7 showed a specific response to Z9-14:OAc and OfurOR8 mainly responded to Z11-14:OAc and E11-14:OAc,OfurOR3 did not respond to any pheromone components.