Circadian rhythms, which respond to the day/night cycle on the earth, arise from the endogenous timekeeping system within organisms, called the biological clock. For accurate circadian rhythms, endogenous oscillations are synchronized to light and temperature. In social insects, both abiotic and biotic factors (i.e., social interactions) play a significant role in active/rest rhythm regulation. However, it is challenging to monitor individual active-rest rhythms in a colony because of the large group size and small body size. Therefore, it is unclear how social interactions coordinate each individual's active/rest rhythms. This study developed an image-based tracking system using 2D barcodes for Diacamma sp. (a monomorphic ant) and measured the locomotor activities of all colony members under laboratory colony conditions. We also investigated the effect of broods on active/rest rhythms by removing all broods under colony conditions. Active/rest rhythms appeared only in solitary ants, not under colony conditions. In addition, arrhythmic active-rest rhythms were retained after brood removal. Therefore, a mixture of social interactions, not abiotic factors, induces the loss of active/rest rhythms. These results contribute to the knowledge of the diversity pattern of circadian rhythms in social insects.

中文翻译：

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个体蚂蚁在自然巢穴条件下不表现出活跃/休息节奏

昼夜节律响应地球上的昼/夜周期，是由生物体内的内源计时系统（称为生物钟）产生的。为了获得精确的昼夜节律，内源性振荡要与光和温度同步。在社交昆虫中，非生物和生物因素（即社交互动）在主动/休息节奏调节中都起着重要作用。然而，由于群体规模大而体型小，监测菌落中个体的主动-休息节律具有挑战性。因此，尚不清楚社交互动如何协调每个人的活动/休息节奏。这项研究开发了一种基于图像的跟踪系统，该系统使用了用于Diacamma的2D条形码sp。（单形蚂蚁），并在实验室菌落条件下测量了所有菌落成员的运动能力。我们还通过去除菌落条件下的所有育雏来研究育雏对活动/休息节律的影响。主动/休息节律仅在孤独的蚂蚁中出现，而不在群体条件下出现。此外，去除亲子后，心律失常的活动节律得以保留。因此，社交互动而非非生物因素的混合会导致主动/休息节奏的丧失。这些结果有助于了解社交昆虫中昼夜节律的多样性模式。