Rantala Markus J, Vainikka Anssi, Kortet Raine
Department of Biology, University of California, Riverside, CA 92521, USA.
Proc Biol Sci. 2003 Nov 7;270(1530):2257-61. doi: 10.1098/rspb.2003.2472.
The immunocompetence handicap hypothesis postulates that secondary sexual traits are honest signals of mate quality because the hormones (e.g. testosterone) needed to develop secondary sexual traits have immunosuppressive effects. The best support for predictions arising from the immunocompetence handicap hypothesis so far comes from studies of insects, although they lack male-specific hormones such as testosterone. In our previous studies, we found that female mealworm beetles prefer pheromones of immunocompetent males. Here, we tested how juvenile hormone (JH) affects male investment in secondary sexual characteristics and immune functions in the mealworm beetle, Tenebrio molitor. We injected male mealworm beetles with JH (type III) and found that injection increased the attractiveness of male pheromones but simultaneously suppressed immune functions (phenoloxidase activity and encapsulation). Our results suggest that JH, which is involved in the control of reproduction and morphogenesis, also plays a central role in the regulation of a trade-off between the immune system and sexual advertisement in insects. Thus, the results reflect a general mechanism by which the immunocompetence handicap hypothesis may work in insects.
免疫能力缺陷假说假定，第二性征是配偶质量的诚实信号，因为发育第二性征所需的激素（如睾酮）具有免疫抑制作用。迄今为止，对免疫能力缺陷假说所产生预测的最佳支持来自对昆虫的研究，尽管昆虫缺乏诸如睾酮等雄性特异性激素。在我们之前的研究中，我们发现雌性黄粉虫更喜欢具有免疫能力的雄性的信息素。在此，我们测试了保幼激素（JH）如何影响黄粉虫（黄粉甲）雄性在第二性征和免疫功能方面的投入。我们给雄性黄粉虫注射了JH（III型），发现注射增加了雄性信息素的吸引力，但同时抑制了免疫功能（酚氧化酶活性和包囊化）。我们的结果表明，参与繁殖和形态发生控制的JH，在昆虫免疫系统与性信号传递之间权衡的调节中也起着核心作用。因此，这些结果反映了免疫能力缺陷假说可能在昆虫中起作用的一种普遍机制。
