School of Biological Sciences, The University of Queensland, Brisbane, Australia.
J Biol Rhythms. 2011 Feb;26(1):34-43. doi: 10.1177/0748730410391947.
Larvae of the genus Arachnocampa, known as glowworms, are bioluminescent predatory insects that use light to attract prey. One species, Arachnocampa flava, is known to possess true circadian regulation of bioluminescence: light:dark cycles entrain the rhythm of nocturnal glowing. Given the absence of natural light as a cue in caves, we addressed the question of whether cave populations of Arachnocampa tasmaniensis, a species known to inhabit caves as well as epigean environments, are rhythmic. We found that the major dark-zone cave populations of A. tasmaniensis maintain a high-amplitude 24-hour rhythm of bioluminescence, with the acrophase during external daylight hours. Populations of A. tasmaniensis in caves many kilometers apart show similar, but not exactly the same, timing of the acrophase. Systematic investigation of colonies in the dark zone of a single cave showed that some smaller colonies distant to the main ceiling colony, also in the dark zone, glow in antiphase. Periodic monitoring of a single colony over several years showed that the acrophase shifted from nocturnal to diurnal some time between October 2008 and January 2009. Prey availability was investigated as a possible zeitgeber. The acrophase of prey availability, as measured by light trapping, and the acrophase of bioluminescence do not precisely match, occurring 3 hours apart. Using in-cave artificial light exposure, we show that after LD cycles, cave larvae become entrained to bioluminesce during the foregoing photophase. In contrast, epigean larvae exposed to artificial LD cycles after a period of DD become entrained to bioluminesce during the foregoing scotophase. One explanation is that individuals within colonies in the dark zone synchronize their bioluminescence rhythms through detection and matching of each other 's bioluminescence.
已知蛛形目幼虫（俗称萤火虫）是发光的捕食性昆虫，它们利用光来吸引猎物。有一种物种，即黄萤（Arachnocampa flava），其生物发光具有真正的昼夜节律调节：光暗周期使夜间发光的节律同步。由于洞穴中没有自然光作为提示，我们提出了这样一个问题：是否塔斯马尼亚蛛形目（Arachnocampa tasmaniensis）的洞穴种群具有节律性，这种物种已知栖息在洞穴和地上环境中。我们发现，主要的黑暗区洞穴种群维持着高振幅的 24 小时生物发光节律，顶峰出现在外部白天时段。相隔数公里的洞穴种群表现出相似的，但不完全相同的，顶峰时间。对单个洞穴黑暗区的殖民地进行系统调查显示，一些距离主天花板殖民地较远的较小殖民地也在黑暗区呈反相发光。对单个殖民地进行多年的定期监测显示，顶峰时间从夜间变为白天，发生在 2008 年 10 月至 2009 年 1 月之间的某个时间。我们调查了猎物可获得性作为可能的时间信号。通过灯光诱捕测量的猎物可获得性的顶峰时间与生物发光的顶峰时间并不完全匹配，相差 3 个小时。我们利用洞穴内的人工光照暴露实验表明，在 LD 周期后，洞穴幼虫会在先前的光照阶段被生物发光节律同步。相比之下，在经历一段时间的 DD 后，暴露于人工 LD 周期的地上幼虫会在先前的暗期被生物发光节律同步。一种解释是，黑暗区殖民地中的个体通过检测和匹配彼此的生物发光来同步它们的生物发光节律。
