Chemosensory Laboratory, Department of Psychology, Norwegian University of Science and Technology, NTNU, Trondheim, Norway.
Department of Teachers Education, Norwegian University of Science and Technology, NTNU, Trondheim, Norway.
Sci Rep. 2020 Nov 16;10(1):19838. doi: 10.1038/s41598-020-76918-1.
Many insects possess the ability to detect fine fluctuations in the environmental CO concentration. In herbivorous species, plant-emitted CO, in combination with other sensory cues, affect many behaviors including foraging and oviposition. In contrast to the comprehensive knowledge obtained on the insect olfactory pathway in recent years, we still know little about the central CO system. By utilizing intracellular labeling and mass staining, we report the neuroanatomy of projection neurons connected with the CO sensitive antennal-lobe glomerulus, the labial pit organ glomerulus (LPOG), in the noctuid moth, Helicoverpa armigera. We identified 15 individual LPOG projection neurons passing along different tracts. Most of these uniglomerular neurons terminated in the lateral horn, a previously well-described target area of plant-odor projection neurons originating from the numerous ordinary antennal-lobe glomeruli. The other higher-order processing area for odor information, the calyces, on the other hand, was weakly innervated by the LPOG neurons. The overlapping LPOG terminals in the lateral horn, which is considered important for innate behavior in insects, suggests the biological importance of integrating the CO input with plant odor information while the weak innervation of the calyces indicates the insignificance of this ubiquitous cue for learning mechanisms.
许多昆虫具有检测环境 CO 浓度细微波动的能力。在草食性物种中，植物释放的 CO 与其他感官线索结合，影响许多行为，包括觅食和产卵。与近年来昆虫嗅觉通路获得的全面知识相比，我们对中枢 CO 系统仍然知之甚少。通过利用细胞内标记和质量染色，我们报告了与 CO 敏感触角叶神经节、唇窝神经节（LPOG）相连的投射神经元的神经解剖结构，在夜蛾 Helicoverpa armigera 中。我们鉴定了 15 个单独的 LPOG 投射神经元，它们沿着不同的轨迹传递。这些单神经节神经元中的大多数终止于侧角，这是一个以前描述过的植物气味投射神经元的目标区域，这些神经元源自众多普通的触角叶神经节。另一方面，对气味信息的另一个更高阶处理区域——卷须，被 LPOG 神经元弱支配。侧角中重叠的 LPOG 末梢，被认为对昆虫的先天行为很重要，这表明在整合 CO 输入与植物气味信息时，这种末梢具有重要的生物学意义，而卷须的弱支配则表明这个普遍存在的线索对于学习机制并不重要。
