Sensilla On Antenna, Maxillary And Labial Palps Of Seven Lamiinae Longhorned Beetle Species At Different Life Stages

Numbers of sever wood boring pests belong to the subfamily of Lamiinae. Larvae of this subfamily usually damage the xylem and phloem, adults chose new shoots of the host plant to supplement nutrition. We aimed at investigating the variation trends of the typology, morphology and distribution of sensilla on the antennal, maxillary and labial palps sensilla among larval, pupal and adult stages of seven species belonging to the subfamily Lamiinae:Anoplophora glabripennis (Motschulsky), Anoplophora chinensis (Forster), Monochamus alternatus Hope, Monochamus guerryi Pic, Apriona rugicollis Chevrolat, Apriona swainsoni Hope, Batocera lineolata Chevrolat. We used scanning electron microscopy to determine the typology, morphology, and distribution of the sensilla. The main results are listed as below:1. Larva:The types of the larval sensilla were similar among the above seven species. No sensillum was observed on the first segment of the antenna; however, three types of sensilla:sensilla twig basiconica (7 subtypes) and sensilla basiconica (3 subtypes) and peg with deep socket located on the terminal portion of the second and third segments. Three different types of sensilla were observed on the larval maxillary and labial palps:sensilla digitiformia, sensilla chaetica, and sensilla twig basiconica (4 subtypes). The types, quantities and distributions of sensilla on antenna were almost the same among the A. glabripennis, A. chinensis, M. alternatus, M. guerryi and B. lineolata, their antenna had three segments, but it was significantly different to the antenna of A. rugicollis and A. swainsoni whose antenna had two segments. However, the types and quantities of sensilla on antenna had significant differences between A. rugicollis and A. swainsoni. The typologies and quantities of sensilla on the antennae, maxillary and labial palps remained the same in different larval instars, but the basal width and length of all sensilla types increased throughout the whole development cycle. There was no significant difference between the typologies and quantities of sensilla on antenna and labial palps between different biotypes, while there was significant difference in quantity on maxillary palp.2. Pupa:No sensillum was observed on the pupal antenna. The pupal maxillary and labial palps had two types of sensilla:sensilla chaetica and sensilla twig basiconica (6 subtypes). The subtypes of sensilla twig basiconica were different among the five species in the pupal stages.3. Adult:Five different types of sensilla were observed on the adult antenna:sensilla trichodea, sensilla chaetica (5 subtypes), sensilla basiconica (8 subtypes), sensilla campaniformia and sensilla coeloconica. Subtypes of sensilla chaetica and sensilla basiconica were different among the seven species of longhomed beetles. The adult maxillary and labial palps had five types of sensilla:sensilla twig basiconica (5 subtypes), sensilla digitiformia, sensilla chaetica (2 subtypes), sensilla trichodea and sensilla pit basiconica. Subtypes of the sensilla twig basiconica on maxillary and labial palps were different.4. Among different life stages:The adult antennal sensilla had more sensilla types than larva’s. There were more cuticular wall-pore sensilla in the adult antenna than the larvae, and more apical pore sensilla in the larval antenna than the adult. The morphology and typology were similar in all three life stages of the longhorned beetles, but the quantities were increased throughout the development.In this research we have determined the typology, morphology, quantity and distribution of the sensilla on the antenna, maxillary and labial palps of seven longhorned beetle species. We aslo made a comparative analysis of the varition trends throughout the larva, pupa and adult stages. Our results will provide a basis for further studies on the typology, number and distribution of different stages of longhorned beetles in Lamiinae And also provide a theoretical understanding and information for the further research on the effction of the olfactory and gustatory receptor mechanism to the behaviour and electrophysiology experiments of this group of forest pests.