横坑切梢小蠹幼虫触角与口器化学感器的超微结构

Ultrastructure of chemical sensilla on the antennae and mouthparts of the larvae of Tomicus minor (Coleoptera: Curculionidae: Scolytinae)

【目的】了解横坑切梢小蠹幼虫触角和口器上化学感器的类型、数量和分布。【方法】应用扫描电子显微镜观察了横坑切梢小蠹末龄幼虫头部形态及触角和口器上的化学感器。【结果】横坑切梢小蠹幼虫触角仅有1节,着生有2类6种感器,分别为锥形感器1~2和末梢锥形感器1~4;下颚须和下唇须均为2节,共发现有3类5种感器,包括锥形感器3、指形感器、末梢锥形感器2、4和5。锥形感器1~3表面具多孔,为典型的嗅觉器官;末梢锥形感器顶端具孔,应为味觉感器;指形感器为下颚须特有,每侧仅有1个,光滑、无孔表面可能意味其具有声音感知功能。【结论】横坑切梢小蠹末龄幼虫头部化学感器数量少,分布模式简单,且集中分布在触角、下颚须和下唇须的端部,研究将为深入理解横坑切梢小蠹幼虫取食及其相关行为提供科学依据。

【Aim】To investigate the type,number,and distribution of chemical sensilla on the antennae and mouthparts of the larvae of Tomicus minor(Coleoptera:Curculionidae:Scolytinae).【Method】Chemical sensilla on the larval head of the last instar T.minor was examined using scanning electron microscopy.【Result】The larval antennae of T.minor have only one segment that bears six types of sensilla,including sensilla basiconica 1-2 and sensilla twig basiconica 1-4.Both the maxillary and labial palps consist of two segments with five sensory organ types.These were identified as sensilla basiconica 3,sensilla digiformia,and sensilla twig basiconica 2,4,and 5.Sensilla basiconica 1-3 with multiple surface pores may play a typical role in odor sensing of chemicals in the larval gallery.Sensilla twig basiconica with tip pores should be interpreted as having a gustatory function.Sensilla digitiformia with a smooth and nonporous surface were presumed to be sensible to sound production in Scolytinae because only one sensilla digiformia was found on the lateral view of the maxillary palp.【Conclusion】Chemical sensilla on the larval head of the last instar of T.minor exhibited a low abundance,a simple distribution pattern,and an unchanged concentration on the tips of the antennae,maxillary,and labial palp.The findings of this study are expected to provide further scientific data for a deeper understanding of the feeding and related behaviors of the larvae of T.minor under bark.