飞蝗变型及体色多型的内分泌控制机理

Endocrine Mechanisms Controlling Phase Polymorphism and Body-color Polymorphism in Locusta migratoria

飞蝗具变型现象 ,散居型和群居型在形态特征、生理机能、行为及体色等方面存在明显差异。保幼激素已被证实能诱导飞蝗散居型绿色的出现。近年 ,从飞蝗心侧体成功地分离了一种神经肽———黑化诱导激素([His7] corazonin) ,并用白化型进行检测 ,证实了其对体色黑化作用的活性。不同时间对飞蝗若虫注射不同剂量的 [His7] corazonin ,能诱导出现除绿色以外的散居型体色 ,如浅褐色、褐色、赤褐色、黑色等 ;也能诱导出现群居型的体色 ,即黑色配以橘黄色的底色。而且 ,对散居型若虫注射 [His7] corazonin能诱导其形态向群居型转换。这些研究证实 [His7] corazonin对飞蝗的变型有着重要的控制作用 ,但又不是唯一的。

The migratory locust,Locusta migratoria,occurs in two extreme phases,solitarious and gregarious,with intermediate forms in between.Solitarious and gregarious individuals look so different in morphological,physiological,behavioral traits,and body-color that they had been regarded as two different species until Uvarov (1921) formulated the phase polymorphism theory.In this locust,the juvenile hormone is responsible for the induction of green color in solitary hoppers.In recent studies,a dark-color inducing neuropeptide,[His 7]-corazonin,was isolated and identified from the corpora cardiaca (CC) of locusts through a convenient bioassay using an albino mutant of L.migratoria.Albinism in this mutant is controlled by a single recessive Mendelian unit and it is caused by an absence of [His 7]-corazonin from the brain and the CC.Injection of [His 7]-corazonin into nymphs caused them to develop various non-green colors,such as fawn,brown,reddish-brown,black (solitarious body-color) and black patterns with an orange background color (gregarious body-color).Injection of [His 7]-corazonin into isolated-reared nymphs caused a shift in morphometrics towards values typical for gregarious insects.Those studies provide strong evidences for an important role of [His 7]-corazonin in the control of phase polymorphism in L.migratoria.