The Possible Olfactory Function Of The Foreleg Tarsus Setae And Identification Of Niemann-Pick Type C2 Genes In Neoseiulus Barkeri

During the 21 st century,biocontrol enemy has become one of the important agents for the sustainable development of agriculture.Neoseiulus barkeri is one of the important predators for controling the pest(mites)sucks juice such as spider mites and thrips.The odor perception system is crucial for survival and reproduction in insects and mites.Insects or mites find food,appropriate mating partners,and oviposition sites by detecting chemical signals in the environment.On the one hand,the olfactory system of insect is primarily composed of the various types of antennal sensilla.On the other,receptors on the foreleg tarsi and pedipalp of mites are of primary importance in relation to orientation responses to chemical stimuli.Hydrophobic and liposoluble odorant molecules in the environment can induce olfactory responses with insect chemoreceptors,and odorant binding proteins(OBPs)in the lymph are solubilized the odorant by binding to carrier proteins and transporting to odorant receptors.It has well-documented that many predators use herbivore-induced plant volatiles when searching for their prey,but another new kind of Niemann-Pick type2(NPC2)protein is participated in chemical communication of other arthropods which showing as the first biological element to filter and screen the external volatiles.However,there are few studies that research on chemoreceptor and the influence of chemical receptors on the orientation responses to chemical stimuli and NPC2 gene in N.barkeri.This thesis reported the N.barkeri olfactory recepting mechanism in a view of morphological characteristics?behavior and molecular biology of olfactory organs.The main research contents of this experiment are as follows:1.The sensilla of pedipalp of N.barkeri had distinct sockets,setae were shorter with taper tips,they might to be involved in mechanical perception;the one of the setae types of the distal of the tarsus was stout peg-shaped structures without sockets and terminate in blunt points to be though as olfactory sensilla.2.Full HIPVs released by T.urticae-infested cowpea leaves and six single synthetic volatile components: Methyl jasmonate,(Z)-3-Hexenol acetate,Linalool,?-caryophyllene,Methyl salicylate and Ocimene,were all significantly attracted the mites.The attractiveness of individual compounds was lower compared to the full HIPVs blend,but was not significantly difference;males of N.barkeri are more attracted by typical spider mite-induced compounds than females' attraction.A high dose of Ocimene(200 ?g and 20 ?g)would likely lead to the strong attraction,but the Ocimene concentration over a range of 2 ?g – 0.002 ?g that does not induce attraction of the predators and may have been under the mites,detection level.3.If the front legs were cut,the respective female mite did not show preference to three single compounds any more.In the control females,the fourth legs were cut for rule out the mechanical damage,the responses levels of three single compounds obtained by these cut legs treatments were similar to those made by the N.barkeri females without cut legs.The front legs probably contributed to N.barkeri's preference for the HIPVs.4.We reported the full ORFs of three NPC2 genes,Nbar NPC2-1,Nbar NPC2-2 and Nbar NPC2-3,with coding 146,153 and 174 amino acids respectively.The 3 NPC2 protein all belonged to MD-2 family,results of phylogenetic tree indicated that belonged to NPC2 gene family,but different branches.Moreover,Nbar NPC2-1 and Nbar NPC2-2 with NPC2 of Camponotus Japonicus,Microplitis mediator,Helicoverpa armigera all belonged to the same clade.Stage specific transcriptive levels were determined by Real-time quantitative PCR(q PCR)analysis and revealed that the Nbar NPC2-1 and-2 were expressed significantly higher in the male stages than in egg stages;We speculated that NPC2-1 and-2 might be involved in the copulation behavior of male mites.Furthermore,Nbar NPC2-1 was higher transcriptive level in the female adult stages than Nbar NPC2-2;it may play a very important role in the odor recognition process of N.barkeri.In conclusion,this thesis enriched the theoretical information of the olfactory mechanism of N.barkeri,and provided new target site of odor carrier protein for optimum utilization of N.barkeri.