Brockmann A, Brückner D
Institut für Verhaltensphysiologie und Soziobiologie, Theodor-Boveri-Institut für Biowissenschaften, Universität Würzburg, 97074 Würzburg, Germany.
Naturwissenschaften. 2001 Feb;88(2):78-81. doi: 10.1007/s001140000199.
Male insects that are attracted by sex pheromones to find their female mates over long distances have specialized olfactory subsystems. Morphologically, these subsystems are characterized by a large number of receptor neurons sensitive to components of the female's pheromones and hypertrophied glomerular subunits ('macroglomeruli' or 'macroglomerular complexes') in the antennal lobes, in which the axons of the receptor neurons converge. The olfactory subsystems are adapted for an increased sensitivity to perceive minute amounts of pheromones. In Apis mellifera, drones have 18,600 olfactory poreplate sensilla per antenna, each equipped with receptor neurons sensitive to the queen's sex pheromone, and four voluminous macroglomeruli (MG1-MG4) in the antennal lobes. In contrast, we show that drones of the phylogenetically distant species, Apis florea, have only 1,200 poreplate sensilla per antenna and only two macroglomeruli in their antennal lobes. These macroglomeruli are homologous in anatomical position to the two most prominent macroglomeruli in A. mellifera, the MG1 and MG2, but they are much smaller in size. The morphological and anatomical differences described here suggest major modifications in the sex-pheromone processing subsystem of both species: (1) less pheromone sensitivity in A. florea and (2) a more complex sex-pheromone processing and thus a more complex sex-pheromone communication in A. mellifera. Research in honey bee sex-pheromone communication dates back to the 1960s, when Gary (1962) demonstrated that in Apis mellifera the queen's mandibular gland secretion and especially its main component, 9-ODA (9-keto-2(E)-decenoic acid), is highly attractive to drones on their nuptial flight. Later, cross-species attraction experiments showed that other honey bee species, Apis florea, A. cerana, and A. dorsata probably also use the queen's mandibular gland secretion as a mating attractant (Butler et al. 1967; Sanasi et al. 1971). Besides its function in mating behavior, the queen's mandibular gland secretion is the main pheromone regulating queen-worker interactions (Free 1987). In this context, several studies have demonstrated the behavioral significance of single components (Slessor et al. 1988) and differences in the composition of the secretion between Apis species (Plettner et al. 1996, 1997; Keeling et al. 2000). Regarding the interspecific differences in the queen's signal, the question arises whether this variation is reflected in the olfactory system of drones and workers of the various species.
被性信息素吸引以远距离寻找雌性交配对象的雄性昆虫具有专门的嗅觉子系统。从形态学上讲，这些子系统的特征是有大量对雌性信息素成分敏感的受体神经元，以及触角叶中肥大的肾小球亚单位（“大肾小球”或“大肾小球复合体”），受体神经元的轴突在其中汇聚。嗅觉子系统经过适应性调整，以提高对微量信息素的感知灵敏度。在西方蜜蜂中，雄蜂每根触角有18,600个嗅觉孔板感受器，每个感受器都配备有对蜂王性信息素敏感的受体神经元，并且在触角叶中有四个体积较大的大肾小球（MG1 - MG4）。相比之下，我们发现，在系统发育上距离较远的小蜜蜂物种中，雄蜂每根触角只有1,200个孔板感受器，并且在触角叶中只有两个大肾小球。这些大肾小球在解剖位置上与西方蜜蜂中两个最突出的大肾小球MG1和MG2同源，但它们的尺寸要小得多。这里描述的形态学和解剖学差异表明这两个物种的性信息素处理子系统存在重大变化：（1）小蜜蜂对信息素的敏感性较低；（2）西方蜜蜂的性信息素处理更复杂，因此性信息素交流也更复杂。蜜蜂性信息素交流的研究可以追溯到20世纪60年代，当时加里（1962年）证明，在西方蜜蜂中，蜂王颚腺分泌物，尤其是其主要成分9 - ODA（9 - 酮基 - 2（E） - 癸烯酸），在雄蜂婚飞时对它们具有高度吸引力。后来，跨物种吸引实验表明，其他蜜蜂物种，如小蜜蜂、中华蜜蜂和印度蜜蜂，可能也将蜂王颚腺分泌物用作交配引诱剂（巴特勒等人，1967年；萨纳西等人，1971年）。除了在交配行为中的作用外，蜂王颚腺分泌物是调节蜂王与工蜂相互作用的主要信息素（弗里，1987年）。在这种背景下，多项研究证明了单一成分的行为意义（斯莱索尔等人，1988年）以及不同蜜蜂物种之间分泌物组成的差异（普莱特纳等人，1996年、1997年；基林等人，2000年）。关于蜂王信号的种间差异，问题在于这种变化是否在不同物种的雄蜂和工蜂的嗅觉系统中有所体现。
