中国亚洲玉米螟发育历期的地理变异

Geographic variation in developmental duration of the Asian corn borer,Ostrinia furnacalis (Guenée)( Lepidoptera: Crambidae) in China

广布种昆虫可调节其生活史以适应栖息地的条件变化,如可以通过调节自身的生长发育和繁殖期,使其发生与栖息地的物候(如食料、气温和降雨等)同步,这对昆虫在栖息地的繁衍具有十分重要的意义。亚洲玉米螟Ostrinia furnacalis为玉米主要害虫,在中国从南到北都有分布,栖息地气候也不同,不同地理种群生活史发生了分化,如化性、临界光周期、滞育后羽化时间、体重和体型、繁殖力和抗寒力等均不同。然而该虫发育历期的地理变异尚未见系统报道。为此,详细比较了来自5个亚洲玉米螟不同地理种群即广西阳朔(YS)、江西南昌(NC)、山东泰安(TA)、河北廊坊(LF)和黑龙江哈尔滨(HEB)在20—31℃下卵、幼虫、蛹发育历期及其与栖息地纬度的关系。结果表明:不同温度下的不同地理种群的卵期不存在显著差异,在20、22和25℃下,卵期从南到北稍有延长,卵期与其栖息地纬度呈正相关;但在28℃下,不同地理种群的卵期基本相等,与纬度相关性不显著。在31℃下,不同地理种群的幼虫期不存在显著差异,而在其他温度下,不同地理种群的幼虫期存在显著差异;在22、25和28℃下,幼虫期与其栖息地纬度呈正相关,而在20和31℃下,幼虫期与其栖息地纬度呈负相关,在20、22和25℃下,最北的哈尔滨种群的幼虫期变幅不大,而其他4个种群的幼虫期随着温度的升高明显缩短。各地理种群20℃下的雌蛹、28℃下的雄蛹和31℃下的雌雄蛹期差异均不显著,其他雌或雄蛹期差异显著;各温度下的雌雄蛹期与其栖息地纬度存在正相关关系。这些研究结果揭示了广布种昆虫可以调节其自身发育历期以适应栖息地环境条件。

Insect species with broad geographic distributions can phenologically adjust their life cycles to adapt to different habitats, for example by altering their growth, development, and reproduction periods to better match their emergence times with local conditions, such as food availability, optimum temperature, rainfall, etc. ）. These adjustments are very important for such widespread species to be able to reproduce in different habitats. The Asian corn borer, Ostrinia furnacalis （Guenee） （Lepidoptera： Crambidae） is a major pest insect of Zea mays L., that poses a serious economic threat to corn production in China. Its distribution ranges from north to south in China, through Southeast Asia, and into Australia, and the pest has recently been found in isolated regions of the United States. Because of its wide distribution, the Asian corn borer encounters great variation in climatic conditions across its range and exhibits considerable diversity in its life-history parameters among geographic populations. Populations differ distinctly in voltinism, critical photoperiod, post-diapause emergence time, body size, fecundity, and cold hardiness. However, little is known about whether the developmental duration of O. furnacalis populations varies with geographic origin. In the present study, we systematically investigated the developmental duration of the egg, larval, and pupal phases at five different temperatures （ 20, 22, 25, 28 and 31 ℃ ） using insects collected from five different populations of the Asian corn borer. Each population inhabited a different latitude ： Yangshuo, Guangxi （YS, 24.8°N, 110.5°E）; Nanchang, Jiangxi （NC, 28.8°N, 115.9°E）; Taian, Shandong （TA, 36.2°N, 117. 1°E） ; Langfang, Hebei （LF, 39.5°N, 116.7°E） and Haerbin, Heilongjiang （HEB, 44.9°N, 127.2°E）. Although at any given temperature the duration of the egg phase did not differ significantly among populations, the length of this phase increased slightly from south to north at 20, 22, and 25℃ and had a highly significant positive correlation with the latitudinal origin of the populations at these three temperatures. However, the egg phase lasted about the same amount of time in all populations at 28℃, with no significant correlation to latitudinal origin. The duration of the larval phase was not significantly different among the five populations at 31℃, but it differed significantly at 20, 22, 25, and 28℃. The larval- phase duration had a significant positive correlation with the latitudinal origin of the populations at 22, 25, and 28℃. However, these two parameters were negatively correlated at 20 and 31 ℃. The duration of the larval phase varied little with temperature in the HEB population, but it decreased significantly as temperature increased in the YS, NC, TA, and LF populations. The developmental durations of female pupae at 20℃, male pupae at 28℃, and all pupae at 31℃ did not differ significantly among populations, but all other pupal categories had significantly~ different durations among the five populations. The pupal-phase duration had a positive relationship with the latitudinal origin of the population at any given temperature. These results indicate that a single widespread species of insect may adapt to varying environmental conditions across its geographic range by altering the developmental duration of its life-history stages in different ways in each population.