3 By Helen Wong 王思齊 the light source, they inverse, or flip upside down, and crash onto the ground. While below the light source, the insects fly upward and then stall, or slow down. Most importantly, in all three scenarios, the insects tilted their backs toward the light source. Combining all lines of evidence, the most plausible explanation is that the insects are trying to align their backs to the light source under the influence of DLR. Nonetheless, these are just qualitative observations — can we possibly quantify this “dorsal tilting toward light” behavior? An intuitive approach is to track the insects’ flight paths and measure their body orientation as they fly. Back in the lab, the researchers conducted similar flight experiments, this time attaching position markers to several species of interest: Common Darter and Migrant Hawker dragonflies, as well as Yellow Underwing Moths and Lorquin’s Atlas Moth. They then projected the velocity vectors of the insects onto the ground and compared them to the instantaneous direction of light. Results showed that the insects mostly moved at right angles to the direction of the light source (Figure 2) – a piece of strong evidence that the insects are not attracted to the light, but are instead caught in loops around it as they aligned their backs to it due to DLR. The team demonstrated, through simulated flight experiments, that DLR alone is sufficient to produce the observed behavior in both field and lab settings. The significance of this study goes beyond merely answering a longstanding question; it also carries important implications for our use of artificial light. As human civilization progresses, we increasingly rely on artificial lighting at night for convenience, often not realizing that these lights could confuse insects. While many artificial light sources, like streetlamps, are essential, we can still make changes to help. By simply getting rid of unnecessary upward-facing lights that disorient insects and cause them to crash onto the ground (recall the inversion behavior!), we can seek a more harmonious coexistence with nature. 蛾 撲火」新解 1. Insect movements were captured using infrared illumination, as infrared light is assumed to be invisible to insects in this study [1]. This ensures their behavior remains unaffected during the flight experiments. In fact, none of the insects crashed into or interacted with the infrared lights set for videography purposes, which indirectly rejected the hypothesis that the heat of the light intervenes the flight of insects. 2. Videos in our daily life are filmed at 24, 25 or 30 frames per second (fps), while slow-motion videos are captured at 50 or 60 fps. In this study, they shot at an incredibly high frame rate of 500 fps. Figure 2 When insects tilt their backs toward the light source under DLR, their flight direction (solid arrow) will form a right angle to the direction of the light source (dashed arrow). 圖二 當昆蟲在背部光反應的影響下將背部朝向光源時，它們的飛 行方向（實線箭頭）會與光源方向（虛線箭頭）形成直角。 如果你在夜間的荒野點起燭光，你很可能會看見飛蛾 （和其他夜行昆蟲）出於本能反應撲向火焰。這種現象非 常普遍，以至於古人創作了一個成語來形容它：飛蛾撲火。 數世紀以來，科學家一直希望找出火焰吸引昆蟲的原 因 [1]。有人認為昆蟲誤將火焰當作樹葉間隙的線索，或是 當成月亮等可用作導航的天體；又有人提出昆蟲是被火焰 的熱力所吸引，又或是被火焰的強光致盲以致飛行路徑不 穩。 為了回答這個長久以來的問題，倫敦帝國學院的研究 人員記錄並分析了昆蟲在人工光源下的高解析度飛行軌 跡。令人意想不到的是，研究結果指向一個全新的解釋：背 部光反應（Dorsal Light Response / DLR）[1–3]，一種
RkJQdWJsaXNoZXIy NDk5Njg=