Morphology And Ultrastructure Of Head Sensilla In Staphylinidae In The Rice Field Of Chongqing

Staphylinidae,a big family in Coleoptera,is widely distributed throughout the world except Antarctica.In the rice field ecosystem,there are plenty of staphylinids.Staphylinid with greater economic significance preys on the majority of main agricultural pests.It is significant to study the external shape,ultrastructure and feature of head sensilla in Staphylinidae which gain us a better understanding morphology of Staphylinidae and evolution of insect sensilla.What's more,it also provides guidance for the use of natural enemy insects in the rice field.In this paper,through optical microscope and electron microscope technology the external morphology of head sensilla of 14 species in Staphylinidae is observed and described,then the types,numbers,distribution and functions of sensilla are deeply explored.The main results are as follows.1 Investigation and description of Staphylinidae in rice field14 species of staphylinids collected were identified and described,belonging to 5subfamilies,11 genera,Steninae: Stenus melanarius,S.lewisius,S.tenuipes,S.macies and S.cicindeloides;Paederinae: Paederus fuscipes,Astenus discopunctatus,Rugileus rufescens and Lithocharis sp.;Oxytelinae: Carpelimus sichuanensis and Platystethus jinyunshanensis sp.nov.;Staphylininae: Philonthus kailiensis,Ph.lewisius and Quedius robustus.Among them,Platystethus jinyunshanensis sp.nov.is a new species(unpublished),and Ph.lewisius is one newly recorded in China.2 Ultramorphology of head sensilla2.1 Ultramorphology of antennal sensillaThe antenna is filiform and consists of 11 segments,including scape,pedicel and flagellum(flagellomere:?~?).7 types and 15 subtypes of sensilla are foundB?hm bristles(BB),sensilla trichodea(ST1,ST2,ST3,ST4),sensilla chaetica(SC1,SC2),sensilla basiconica(SB1,SB2,SB3,SB4,SB5),sensilla styloconic(SS),sensilla coeloconica 1(SCo1)and sensilla campaniform(SCa).The distribution and number of sensilla: ST and SC the most widely distribute,even almost all over the antennae.However BB only distributes in the scape and pedicel,SB and SCa only distribute in the flagellum,and SCo1 and SS only distribute in the flagellomere ?.Sensilla in the scape and pedicel are fewer in number that they are mechanoreceptors.The sensilla gradually increase from base to the end of the flagellum,what's more the type and number of sensilla on the flagellomere ? are the most abundant,involving mechanoreceptors and chemoreceptors.At the different subfamily level,ST1 does not exist in the scape and pedicel of Staphylininae,and the total number of sensilla in Staphylininae is significantly more than the other subfamilies.At the different genera of the same subfamily,subtypes of SB in Astenus of are significantly more than those in the other three genera in Paederinae.The sensilla on the flagellomere ?of Philonthus vary from Quedius because the former possesses SB.At the same genus level,there is no significant difference among species in the Stenus.In the flagellomere ? of Ph.lewisius is lacking ST1,while Ph.kailiensis has several ST1.The type,distribution and number of sensilla are not significantly diverse among species and between female and male.2.2 Ultramorphology of sensilla on the maxillary and labial palpsMaxillary palp is composed of 4 segments(?~?),and the labial palp consists of3 segments(?~?).The sensilla on the maxillary and labial palps are divided into 8types and 16 subtypes: B?hm bristles(BB),sensilla trichodea(ST1),sensilla chaetica(SC1,SC2,SC3),sensilla basiconica(SB1,SB6,SB7),sensilla placodea(SP1,SP2),sensilla cylindra(SCy1,SCy2,SCy3),sensilla coeloconica(SCo2,SCo3)and sensilla furcatea(SF).The distribution and number of sensilla: Only 1-2 BB distribute at the base of the maxillary and labial palps,a large number of ST1 and SC distribute in the segment?~?of maxillary palp and segment ?~? of the labial palp.So BB,ST1 and SC are supposed to mechanoreceptors.SB,SP,SCy,and SCo are located in the last segment of the maxillary and labial palps,and are fewer in number that they are chemical sensilla with olfactory and gustatory functions.At the different subfamily,maxillary and labial palps of Staphylininae have no ST that the types and number of their sensilla have to be most.Compared with several other subfamilies,only the maxillary and labial palps of Steninae have no sensilla,and SB1 distributes in the third segment of the maxillary palp of Steninae.At the different genus of the same subfamily,in the four genera of the Paederinae,SCy only exists in the distal part of the maxillary palp of Paederus.The sensilla on labial palp of Quedius in Staphylininae vary from those of Philonthus because the former possesses SP2.At the same genus level: Although there is no significant difference among species in Stenus,the sensilla on the second segment of the maxillary palps of Ph.kailiensis in Philonthus vary from those of Ph.lewisius in terms of Ph.kailiensis possessing SF.There is no significant difference in the type,distribution and number of sensilla on the maxillary and labial palps among species and between male and female.In summary,head sensilla of 14 species were studied that difference in type,distribution,and number of these sensilla were compared in the level of subfamily,genus and species.There was a large difference that head sensilla is greater different at the level of the subfamily,and the difference is less at the level of the genus.But there is no difference in sensilla between species and gender.Therefore,the difference in type,distribution,and number of head sensilla can be used as the identification criteria for the subfamily and genus of Staphylinidae.There are many types of chemical sensilla on the maxillary and labial palps,which means that the maxillary and labial palps must be important in the feeding process of the staphylinid.