Study On Sensilla Of Antennas And Mouthparts In Nitidulidae Based On Different Food Habits

Insect of Nitidulidae(Coleoptera: Polyphaga: Cucujoidea)is polyphagous and agricultural pest that can damage crops and stored-products.It can also feed on fungi and flowers,and corrupt plants and animal tissues.Some species of Nitidulidae can also spread pathogenic microorganisms that result in economic losses.Moreover,some species play a role as pollinators raising crop yield.Study of the relationship between the sensilla on antenna and mouthpart in Nitidulidae and food habits is helpful to understand the role of sensilla in different feeding behaviors.In this study,to define the sensilla types,quantities and distribution on the antenna and mouthpart in Nitidulidae based on different food habits,we observed the sensilla of the antenna and mouthpart of nine species belonging to three kinds of food habits,such as herbivore,saprophage and fungivore,by scanning electron microscopy.The antenna in insect of Nitidulidae is clavate and comprised scape,pedicel,and nine-segmented flagellomeres.Nine sepecies of Nitidulidae in three food habits had six types antennal sensilla,including B?hm bristles,sensilla chaetica,sensilla basiconica,sensilla trichodea,sensilla styloconica and sensilla cavity.The quantity of sensilla in nine species was greater on the lateral side than on the medialis of the scape.The types and quantities of sensilla were least on the pedicel and 1～6 flagellomeres,whereas the 7～9 flagellomeres possessed the most.B?hm bristles were gravity receptor and distributed in clumps between the head with the scape and the scape with the pedicel;sensilla chaetica were mechanical and chemical sensilla with five subtypes;sensilla basiconica distributed on the last three segment of antenna,and were considered to be olfactory sensilla;sensilla trichodea were the most abundant and had tactile and olfactory function;sensilla styloconica occured in the last segment of antenna,and sensilla cavity located on the scape or the last segment of antenna,and the function of these sensillum were both temperature and humidity receptor.The chewing mouthpart in insect of Nitidulidae is composed of the labrum,mandible,maxillae,labium and hypopharynx.The motuthpart of nine species of Nitidulidae in three food habits had seven types of sensilla including B?hm bristles,sensilla chaetica,sensilla basiconica,sensilla trichodea,sensilla coeloconica,sensilla placodea and sensilla campaniformia.The sensilla of the mouthparts mostly presented on the maxillae and labium.Sensilla chaetica located on the mandible,maxillae and labium and was mechanical receptor.Sensilla basiconica had seven subtypes,and were olfactory receptor,including sensilla basiconica 1,2,3 and 4 distributed in maxillae;sensilla basiconica 3,4 and 5 distributed in labium;sensilla basiconica 6 and 7 occurred in the epipharynx.Sensilla trichodea presented on the mandible and had tactile function;sensilla campaniformia distributed on the epipharynx and was mechanical sensilla;B?hm bristles and sensilla coeloconica are mechanical sensilla and temperature and humidity receptor,respectively,and they all presented on the maxillae and labium;sensilla placodea located in the maxillae and was olfactory receptor.The study of types,quantities and distribution of sensilla in Nitidulidae of three food habits shown that the types and quantities of sensilla on the antenna and mouthpart were the most in fungivore,followed by saprophage,and the last was herbivore;the distribution site of the same sensilla was relatively stable.The study on the same food habit in different subfamily shown that species in different subfamily,even had the same food habit,had great difference in types and quantities of sensilla.The study on the different food habits in the same subfamily shown that the fungivore insect had more types and quantities of sensilla on the antenna and mouthpart than saprophage insect,while the latter more than herbivore insect.Comparing between different and same feeding objects in same subfamily and food habit shown that the smaller the difference between feeding object,the less difference of types and quantities of sensilla on the antenna and mouthpart.