Locust Research Laboratory, National Institute of Agro-biological Sciences at Ohwashi (NIASO), Ohwashi 1-2, Tsukuba, Ibaraki 305-8634, Japan; National Agriculture and Food Research Organization, Institute of Agrobiological Sciences, Ohwashi 1-2, Tsukuba, Ibaraki 305-8634, Japan.
Department of Life Science and Medical Bioscience, School of Advanced Science and Engineering, Waseda University, Wakamatsu-Cho 2-2, Shinjuku-Ku, Tokyo 162-8480, Japan.
J Insect Physiol. 2018 May-Jun;107:125-135. doi: 10.1016/j.jinsphys.2018.03.010. Epub 2018 Mar 27.
The eggs of the migratory locust, Locust migratoria, hatch in synchrony from their pod. In this study, we examined the mechanism controlling hatching synchrony. Two eggs obtained from the same pod hatched in synchrony when kept in contact with one another, whereas those separated by a few millimeters hatched less synchronously. When a screen separated the eggs, the hatching was even more sporadic, indicating that hatching synchrony might be controlled by a two-step mechanism. We hypothesize that in the first step the embryos shortly before hatching control the time to enter a standby stage using some signal from neighboring eggs. The eggs in the standby stage hatch promptly when an additional stimulus is received from neighboring eggs. Before this stage, eggs cannot respond to that stimulus by hatching but may spontaneously hatch later. Introduction of a newly hatched nymph to single eggs 1 or 2 days before hatching advanced hatching of these eggs, but hatching occurred only sporadically. Eggs kept in contact with other eggs that had been killed by freezing shortly before hatching hatched as if they had been kept singly in separate containers, providing no evidence for involvement of chemical stimuli in controlling hatching synchrony. By contrast, eggs separated by several millimeters hatched as synchronously as those kept in contact with one another when they were connected by a piece of wire. Furthermore, vibrational stimulation derived from music greatly advanced hatching of separately kept eggs; however, hatching synchrony was not achieved unless the music started shortly before hatching. These results are consistent with the two-step hypothesis and indicated that locust embryos used vibrational stimuli from neighboring eggs for synchronous hatching.
蝗虫的卵在豆荚中同步孵化。在这项研究中，我们研究了控制孵化同步的机制。从同一个豆荚中取出的两个卵相互接触时会同步孵化，而相隔几毫米的卵则孵化得不太同步。当用筛子隔开卵时，孵化更加零散，这表明孵化同步可能受到两步机制的控制。我们假设，在第一步中，即将孵化的胚胎使用来自邻近卵的某种信号来控制进入待机阶段的时间。当从邻近卵接收到额外的刺激时，处于待机阶段的卵会迅速孵化。在此阶段之前，卵不能通过孵化来响应该刺激，但可能会稍后自发孵化。将一只新孵化的若虫引入提前 1 或 2 天孵化的单个卵中，会提前孵化这些卵，但孵化仅零星发生。将卵与其他在即将孵化前通过冷冻杀死的卵保持接触，孵化就像将它们单独保存在单独的容器中一样，这表明在控制孵化同步中没有涉及化学刺激。相比之下，当相距几毫米的卵通过金属丝连接时，它们的孵化就像相互接触的卵一样同步。此外，来自音乐的振动刺激极大地促进了单独保存的卵的孵化；然而，除非音乐在孵化前不久开始，否则无法实现孵化同步。这些结果与两步假说一致，表明蝗虫胚胎使用来自邻近卵的振动刺激来实现同步孵化。
