Three-Dimensional Atlas Of Brain And Antennal Neurons Projections Of The Diamondback Moth,Plutella Xylostella (L.) Adults

Receptor neurons(RNs)in insect antennae detect external stimuli and extend axons into the brain,where the brain integrates information inputs to produce a specific behavior required for an animal’s survival.A prerequisite for understanding how information is coded in the central nervous system is to know the morphology and spatial relationship of the principal neurons in insect brain.However,relatively little is known about anatomy and function of the central nervous system and brain structure of Plutella xylostella,which is a major worldwide pest of cruciferous vegetables.In the present study,we generated the digital three-dimensional reconstruction of the brain and identified the patterns of antennal neuronal projections through Propidium iodide(PI)labeled,Neurobiotin backfills of the antennal neurons and confocal laser scanning microscopy reconstruction.The results will be helpful to understand the olfactory mechanism of P.xylostella and to explore new ways to control this species.The specific results are as follows:1.The three dimensional reconstruction of brain center of P.xylostella adults.The structure of brain of P.xylostella moth is similar to that of other insects.The brain includes protocerebrum,deutocerebrum and tritocerebrum.In protocerebrum,we clearly identified anterior optic tubercle(AOTu),central complex(CX),mushroom body(MB),Y-track and medial antennal lobe tract(m ALT),These structures have clear boundary.The main composition of deutocerebrum is antennal lobes(AL).The main structure of tritocerebrum is suboesophageal ganglion.The anterior optic tubercle(AOTu)was located just below the anterior surface of the brain and occupies the dorsolateral part of the anterior protocerebrum,which consists of the large upper unit(AOTu-UU),the smaller lower unit(AOTu-LU)and the nodular unit(AOTu-NU).the mushroom bodies(MB),the major higher order processing centers for olfactory information and for learning and memory in many insects,it was composed of the calyx(Ca)and the pedunculus(Pe),which contained α-、β-,and γ-lobe.Furthermore,Y-tract and medial antennal lobe tract(m ALT)were discernible protrusions in our reconstruction,and they located dorsal and ventral of Pe,separately.Between the mushroom bodies lies the central complex,is composed of a group of four neuropiles:the protocerebral bridge(PB),the upper and lower unit of the central body(CBU,CBL),and the paired noduli(No)which ventrally attached to the central body(CB).The deutocerebral antennal lobes(AL)were identified below the MB.2.The projection of antennal nerve to brain center in P.xylostella adults.The antennal neurons afferent from antennae,these tracing neurons reliably labeled afferences to the ipsilateral brain,and they divided into three tracing neurons from the entrance of the antennae.The major tracing neurons project into the ipsilateral AL,projections of olfactory receptor neurons(ORNs)formed glomeruli;The minor tracing neurons project into the antennal mechanosensory and motor center(AMMC)which locate at the dorsal lobe,and some of nerve fibers arborized to the Suboesophageal ganglion(SOG),which indicating the presence of gustatory sensory neurons;The third tracing neurons were three single neurites bypassing the AL,one projects into the protocerebrum along the brain midline from anterior,and reached at Lateral Horn(HL);the other two project into the protocerebrum from the ventral AL,and they passed the m ALT,then the Pe,and finally reached the MB.