昆虫翅型分化的表型可塑性机制

Mechanisms of phenotypic plasticity for wing morph differentiation in insects

翅多型现象在昆虫中广泛存在,是昆虫在飞行扩散和繁殖能力之间权衡的一种策略,对种群的环境适应性进化具有重要的意义。目前在植食性昆虫中研究较多,有关寄生蜂的翅型分化鲜见报道。综述了昆虫翅型分化的表型可塑性机制。遗传因素和环境因素均对昆虫翅的发育产生影响,基因型对翅型的决定具有显著作用,外界环境条件,包括温度、光周期、食物质量、自身密度、外源激素等因素对昆虫翅的发育也产生重要的调节作用,从而产生翅的非遗传多型性现象。此外,天敌的寄生或捕食作用可能会诱导某些昆虫的翅型产生隔代表型变化。对昆虫产生翅多型现象的生态学意义及其在生物进化过程中的作用进行了讨论,并探讨了寄生性昆虫翅型分化机制在生物防治上的可能应用途径。功能基因组学和表观遗传学的进一步发展可望为彻底揭示昆虫翅型分化机制提供新的机遇和技术手段。

Phenotypic plasticity is a phenomenon in which the same genotype produces entirely different phenotypes in response to changes in the environment, and grants an organism the ability to adapt to environmental variations. Wing polymorphism is commonly observed in insects, including Homoptera, Hemiptera, Coleoptera, Hymenoptera, Orthoptera, Diptera, Lepidoptera, Isoptera, Psocoptera, and Dermaptera, as a strategy to tolerate trade-offs between flight capability and fecundity. As a result, it may confer an important adaptive value to the evolution of populations because these winged individuals can migrate long distances and find suitable habitats for development and reproduction of their offspring more easily. At the present time, there is limited knowledge of the mechanisms of wing polymorphism in varying populations. Both genes and the environment are usually considered to affect the developmental outcomes of insect wing morphs. It is easy to understand the contributions of genes to morphology as a consequence of the research of evolution and developmental biology. However, very little is known about the influential mechanism of environmental factors on the development of phenotypes. In fact, it is not yet clear that how the evolutionary shifts of character variation is realized between environmental and genetic control. So far, studies on wing polymorphism are mostly reported on phytophagous insects, very few are known in parasitoids, natural enemies of insect pests. Here we summarized the mechanisms of phenotypic plasticity for wing morph differentiation in insects. Both genetic and environmental factors can act on the wing development of insects. The genotypes have significant effects on the determination of insect wing morphs. External environmental conditions such as temperature, photoperiod, food quality, population density, exogenous hormones, etc., also play important roles in regulating the insect wing development, which produce wing polyphenism. In addition, the parasitism or predation of natural enemies may induce alternative variations across transgenerational wing morphs in some insects. The ecological significance of insect wing polymorphism and its functions during their evolutionary process are discussed. Polyphenism is one of the main reasons why insects have become so successful on the earth, and grants them the capability to effectively utilize the same genome in order to best adapt to predictable changes in the environment, such as degradation of survival conditions after overcrowding, by developing into different phenotypes. Wing polyphenism in insects is a clear example of adaptive phenotypic plasticity, which provides a very good model to study alternative phenotypes from both genetic and environmental perspectives. This may also be advantageous to evaluate how environmental and genetic factors jointly control the same developmental events. Further study recommendations were also discussed in this review, as well as the potential utilization of wing morph differentiation mechanisms of parasitic wasps in biological control, e.g., through artificially culturing the winged individuals of parasitoids for field release to improve the dispersal ability of natural enemies. Some critical aspects still need to be investigated further on the mechanisms of phenotypic plasticity for wing morph differentiation in insects. Further development in functional genomics and epigenetics may provide novel opportunities and technological support for revealing the mechanisms of polyphenism in insects completely.