Study On The Sensillum Of Agasicles Hygrophila By Scanning Electron Microscopy

The sensillum play an important role in locating and identifying the host plant in the field.The surface sensillum of the Agasicles hygrophila are located mainly in head appendage,thoracic tarsus,abdominal external reproductive section and so on.These sensillum of specilist insect is crucial important in host location,feeding and oviposition behavior.In order to further understand the locating mechanism of beetles'electrical physiological reaction and the host plant in future research,ultrastructure of sensillum Agasicles hygrophila are study by scanning electron microscopy in present thesis.The main study results as follows:1 The scanning electron microscope observation of the head appendageThe result suggested that the morphology of the cephalic appendage are similar between male and female by scanning electron microscope,which is moniliform in shape and 11 segments in number of antennae.In addition,both labial palpus and maxillary palp show cone in shape,however,the number of the former is three segments and the latter is four.There are 11 types of sensilla are distributed in head appendage,such as:sensillum chaeticum,sensilla coeloconica,sensilla basiconica,sensillum trichodeum,styloconic sensillum,Bohm bristle sensilla,sensilla digit-like,sensilla dome,sensilla aperture and sensilla campaniform.Interestingly,which are many subtypes.A new type of sensilla in labipalpus and maxillary palp were present in present paper,which named petals sensilla.The sensilly intensive of sensillum in head appendages as follow:antennae>maxillary palp>labial palpus.There are many types of sensilla are occurring from the flagellum in the antennae.Furthermore,both sensilla of the labipalpus and maxillary palp are all showing a trend that more number and less type,which was mainly present in the distal.From the ultramicro-morphological aspects,the sexual dimorphism of A.hygrophila between male and female is mainly manifested in the cephalosome appendage of the receptor subtype distribution,type and size of sensor.2 The scanning electron microscope observation of the tarsiWe found the ultrastructure observation of A.hygrophila three thoracic legs of tarsi and it is a beetl with hidden 5 insect by scanning electron microscope.There are different types of dense adhesive setae on the ventral surface of the leg of the first,second and third tarsomere.The morphological differences in male and female worms 1st tarsomere setae in the ventral central region,are identified based on the shape of the setal tip,spatulate setae in males and hook-like in females.The types of sensilla on three legs,including sensillum chaeticum,sensilla basiconica and sensillum trichodeum.The number and length in hind legs tarsus is more than other legs.The divergence of the number and size is present in male and female,while distribution sites and types is almost no differences.The male and female sexual dimorphism of adult tarsus are expressed in the shape of the pad and the size of the sensilla.3 The scanning electron microscope observation of the external genital segmentThere are sensilla basiconica,chaeticum sensilla and trichoid sensilla are distribution on external genital segment of A.hygrophila.The density,type and size of sensilla in different parts of male and female shown obvious different.4 The scanning electron microscope observation of the 2nd larvaeThe sensilla number of larvae less,but more types,mainly distributed in the head and ventral surface of pereiopoda and abdomen,such as sensilla chaetica,sensilla petal shaped,sensilla basiconca,sensilla terminal,sensilla trichodea,sensilla coeloclnica,sensilla placoclea,sensilla styloconica,bohm bristles.There were differences in the length,the width of the base,the base(loose,tight,raised or sunken)of the male and female sensilla.The was and the difference was greatest in male and female was the length of the chaeticum sensilla I on the antennal,and the difference between them were 90.49 ± 0.80 ?m and 80.11 ± 0.35?m respectively.And there were many epidermal pore on the surface of sensilly parts A.hygrophila,especially in the tip position of the maxillary palp biggest,771.74 ±27.06nm.There are few number of sensilla of larvae are distribute on the head?ventral surface of pereiopoda and abdomen,which are sensilla chaetica,sensilla petal shaped,sensilla basiconca,sensilla terminal,sensilla trichodea,sensilla coeloclnica,Sensilla digit-like,sensilla styloconica and bohm bristles.The differences are present in the number,distribution sites,length,the width of the base,the base(loose,tight,raised or sunken)of the male and female sensilla.The divergence also occurring in different parts of epidermis,especially in the tip position of the labipalpus and maxillary palp.The present thesis identified the ultra-structure of A.hygrophila of cephalosome appendage,externalia,tarsus and the cuticula of larva by scanning electron microscope.The ultra-structure,types,distribution and numbers of sensilla were described and analysis in different locations.Moreover,the functions of each sensilla were inferred in A.hygrophila,suggested the head and tarsus are the mainly distribution position for olfactory receptor.It is important that study on the olfactory receptors of A.hygrophila effected on the host localization and identification.