Maeno Koutaro, Tanaka Seiji
Locust Research Laboratory, National Institute of Agrobiological Sciences at Ohwashi (NIASO), Tsukuba, Ibaraki, Japan.
J Insect Physiol. 2009 Nov;55(11):1013-20. doi: 10.1016/j.jinsphys.2009.07.005. Epub 2009 Jul 30.
To understand the underlying trans-generational phase accumulation, a classical morphometric characteristic, the F/C ratio (F, hind femur length; C, maximum head width), of adult desert locusts (Schistocerca gregaria) was monitored over eight consecutive generations. Adult F/C ratios, which are larger in solitarious locusts than in gregarious ones, were negatively correlated to the darkness of body color at hatching. Two successive generations were required for a complete shift from the gregarious (crowd-reared) to the solitarious (isolated-reared) phase and vice versa in the laboratory. That is (1) female adults needed to be exposed to crowded (or isolated) conditions so that their hatchlings would become large (or small) and dark (or green) in color, and (2) the hatchlings then needed to be exposed to crowded (or isolated) conditions for their entire nymphal stage. Solitarious locusts exhibited extra molting that influenced the F/C ratio in the adult stage, but did not exert significant influences on the trans-generational changes in this trait because the incidence was low. The incidence of extra molting was negatively correlated with nymphal survival rates. The morphometric trans-generational changes may be explained without assuming any accumulating internal factor.
为了解潜在的跨代阶段积累情况，对成年沙漠蝗虫（沙漠飞蝗）的一个经典形态特征——F/C比（F，后股节长度；C，最大头宽）进行了连续八代的监测。独居蝗虫的成年F/C比大于群居蝗虫，且与孵化时体色的深浅呈负相关。在实验室中，从群居（群体饲养）阶段完全转变为独居（单独饲养）阶段，反之亦然，需要连续两代。也就是说，（1）雌性成虫需要暴露在拥挤（或单独）的条件下，以便它们的幼体在颜色上变得大（或小）且深（或绿），并且（2）幼体随后需要在其整个若虫阶段都暴露在拥挤（或单独）的条件下。独居蝗虫表现出额外蜕皮，这影响了成虫阶段的F/C比，但由于发生率较低，对该性状的跨代变化没有产生显著影响。额外蜕皮的发生率与若虫存活率呈负相关。形态学上的跨代变化无需假定任何累积的内在因素即可得到解释。
