Nishide Yudai, Tanaka Seiji, Saeki Shinjiro
Locust Research Laboratory, National Institute of Agro-biological Sciences at Ohwashi, Tsukuba, Japan.
Locust Research Laboratory, National Institute of Agro-biological Sciences at Ohwashi, Tsukuba, Japan; Graduate School of Agricultural Science, Kobe University, Japan.
J Insect Physiol. 2015 May;76:24-9. doi: 10.1016/j.jinsphys.2015.03.010. Epub 2015 Mar 18.
The present study showed that the eggs of the desert locust, Schistocerca gregaria, and the migratory locust, Locusta migratoria, responded to photoperiod by hatching when placed on sand in the laboratory. S. gregaria mainly hatched during the dark phase and L. migratoria during the light phase. The importance of light as a hatching cue depended on the magnitude of the temperature change during the thermoperiod; photoperiod played a more important role in the control of hatching time in both species when the magnitude of the temperature change was small. In addition, the eggs of the two species that were covered with sand did not respond to photoperiod and hatched during both the light and dark phases, indicating that light did not penetrate through the sand. Because locust eggs are normally laid as egg pods and a foam plug is deposited between the egg mass and the ground surface, we tested a possibility that naturally deposited eggs perceived light through the foam plug. The eggs that were deposited and left undisturbed in the sand hatched during the light and dark phases at similar frequencies. These results suggest that the eggs of both locust species responded to light and controlled their hatching timing accordingly but would not use light as a hatching cue in the field. The evolutionary significance of the ability of eggs to respond to light in these locusts was discussed.
本研究表明，沙漠蝗（Schistocerca gregaria）和飞蝗（Locusta migratoria）的卵在实验室置于沙子上时会对光周期作出反应而孵化。沙漠蝗主要在黑暗阶段孵化，飞蝗则在光照阶段孵化。光作为孵化线索的重要性取决于热周期中温度变化的幅度；当温度变化幅度较小时，光周期在控制这两个物种的孵化时间方面发挥着更重要的作用。此外，被沙子覆盖的这两个物种的卵对光周期没有反应，在光照和黑暗阶段都会孵化，这表明光无法穿透沙子。由于蝗虫卵通常以卵块形式产下，且在卵块与地面之间会有一个泡沫塞，我们测试了自然产下的卵通过泡沫塞感知光的可能性。放置在沙子中未受干扰的卵在光照和黑暗阶段以相似的频率孵化。这些结果表明，这两种蝗虫的卵都会对光作出反应并相应地控制其孵化时间，但在野外不会将光用作孵化线索。文中还讨论了这些蝗虫卵对光作出反应的能力的进化意义。
