Phase polyphenism in locusts: factors inducing gregarization

沙漠蝗在种群密度或拥挤情况下表现出相多态现象。本研究通过对蝗虫子代大小和颜色的控制因素以及若虫体颜色和群居行为的研究，了解期多表型的控制机制。拥挤引起这种蝗虫身体颜色和行为的相位依赖性变化。我们发现单独的视觉刺激可以诱导绿色孤独的若虫发展出黑色图案。我们还发现，短至1天的拥挤可以使绿色孤立的3龄若虫发育成黑色图案。通常会避开其他个体的三龄孤立若虫，需要2天的拥挤才能开始被其他个体吸引。这些发现将为研究蝗虫相多表型的潜在遗传机制提供一个很好的分析体系。

The desert locust exhibits phase polyphenism in response to population density or crowding. In this study we examined the factors controlling progeny size and color as well as nymphal body color and gregarious behavior in this locust to understand the mechanism controlling the phase polyphenism. Crowding induces phase-dependent change in body color and behavior in this locust. We found that visual stimuli alone can induce green solitarious nymphs to develop black patterns. We also found that as short as 1 day of crowding can cause green solitarious 3rd instar nymphs to develop black patterns. Third instar isolated nymphs, which normally avoid other individuals, required 2 days of crowding to start being attracted to other individuals. These findings would provide an excellent assay system to examine the underlying genetic mechanism regulating the phase polyphenism in this locust.