Saxena Nitesh, Natesan Dinesh, Sane Sanjay P
National Centre for Biological Sciences (NCBS), Tata Institute of Fundamental Research, GKVK campus, Bellary Road, Bangalore 560065, India.
Department of Computational Science and Technology, School of Computer Science and Communication, KTH Royal Institute of Technology, Stockholm 10044, Sweden.
J Exp Biol. 2018 Jan 19;221(Pt 2):jeb172023. doi: 10.1242/jeb.172023.
Flying insects routinely forage in complex and cluttered sensory environments. Their search for a food or a pheromone source typically begins with a whiff of odor, which triggers a flight response, eventually bringing the insect near the odor source. However, pinpointing the precise location of an odor source requires use of both visual and olfactory modalities, aided by odor plumes. Here, we investigated odor-tracking behavior in fruit flies () presented with low- or high-contrast visual landmarks, either paired with or separate from an attractive odor cue. These experiments were conducted either in a gentle air stream which generated laminar odor plumes or in still air in which odor dissipates uniformly in all directions. Trajectories of flies revealed several novel features of their odor-tracking behavior in addition to those previously documented. First, in both moving and still air, odor-seeking flies rely on the co-occurrence of visual landmarks with olfactory cues to guide them to odorant objects. Second, flies abruptly decelerate upon encountering an odor plume, thereafter steering towards the nearest visual objects that had no inherent salience in the absence of odor. Thus, interception of an attractive odor increases their salience to nearby high-contrast visual landmarks. Third, flies adopt distinct odor-tracking strategies during flight in moving versus still air. Whereas they weave in and out of plumes towards an odor source in airflow, their approach is more incremental in still air. Both strategies are robust and flexible, and enable flies to reliably find odor sources under diverse visual and airflow environments.
飞行昆虫经常在复杂且混乱的感官环境中觅食。它们寻找食物或信息素源通常始于闻到一股气味，这会触发飞行反应，最终将昆虫带到气味源附近。然而，要精确确定气味源的位置，需要利用视觉和嗅觉两种方式，并借助气味羽流。在这里，我们研究了果蝇在呈现低对比度或高对比度视觉地标时的气味追踪行为，这些地标与诱人的气味线索配对或分开。这些实验要么在产生层流气味羽流的微风中进行，要么在气味向各个方向均匀消散的静止空气中进行。果蝇的轨迹揭示了其气味追踪行为的几个新特征，除了之前记录的那些。首先，在流动空气和静止空气中，寻找气味的果蝇都依赖视觉地标与嗅觉线索的共同出现来引导它们找到有气味的物体。其次，果蝇在遇到气味羽流时会突然减速，此后转向在没有气味时没有固有显著性的最近视觉物体。因此，截获诱人的气味会增加这些视觉物体对附近高对比度视觉地标的显著性。第三，果蝇在流动空气和静止空气中飞行时采用不同的气味追踪策略。在气流中，它们会穿梭于羽流中朝着气味源前进，而在静止空气中它们的接近方式则更具渐进性。这两种策略都稳健且灵活，使果蝇能够在不同的视觉和气流环境下可靠地找到气味源。
