Huang Yunshang, Ao Yan, Jiang Mingxing
Institute of Insect Sciences, Zhejiang University, China.
J Econ Entomol. 2017 Dec 5;110(6):2381-2387. doi: 10.1093/jee/tox274.
Reproductive plasticity is a key determinant of species invasiveness. However, there are a limited number of studies addressing this issue in exotic insects. The rice water weevil Lissorhoptrus oryzophilus Kuschel (Coleoptera: Curculionidae), which is native to North America, is one of the most invasive insect pests in east Asia. In this study, we investigated the reproductive status of first-generation females (progeny of overwintered weevils) from five geographic regions in southern and northern China in the field, and reproductive status and ovipositional features of females provided with suitable host plants in the laboratory after collection. Under field conditions, a proportion of females oviposited, while the rest remained in diapause from all three southern regions investigated, but reproductive development did not take place in females from the two northern regions, where the weevil produces only one generation per year. However, when fed host plants in the laboratory, females from all regions laid eggs. They typically had a very short ovipositional period (3-6 d on average on rice at a temperature of 27°C), laid a low number of eggs, and did not die soon after oviposition; this was different from common reproductive females. We concluded that first-generation L. oryzophilus females, which largely enter diapause after emergence, are highly plastic in their reproductive performance and are ready to reproduce under favorable conditions. Our results indicate the significance of their reproductive plasticity for geographic spread and population development.
生殖可塑性是物种入侵性的关键决定因素。然而，针对外来昆虫这一问题的研究数量有限。稻水象甲Lissorhoptrus oryzophilus Kuschel（鞘翅目：象甲科）原产于北美洲，是东亚地区最具入侵性的害虫之一。在本研究中，我们调查了中国南方和北方五个地理区域的第一代雌性（越冬象甲的后代）在田间的生殖状况，以及采集后在实验室中提供适宜寄主植物时雌性的生殖状况和产卵特征。在田间条件下，来自所有三个被调查南方区域的一部分雌性产卵，而其余的则处于滞育状态，但来自北方两个区域的雌性未发生生殖发育，在北方该象甲每年仅产生一代。然而，当在实验室中给雌性提供寄主植物时，来自所有区域的雌性都产卵。它们通常产卵期非常短（在27°C温度下在水稻上平均为3 - 6天），产卵数量少，并且产卵后不会很快死亡；这与普通生殖雌性不同。我们得出结论，第一代稻水象甲雌性在羽化后大多进入滞育状态，其生殖表现具有高度可塑性，在有利条件下随时准备繁殖。我们的结果表明了它们的生殖可塑性对地理扩散和种群发展的重要性。
