Cuticular hydrocarbon chemistry, an important factor shaping the current distribution pattern of the imported fire ants in the USA
Cuticular hydrocarbon chemistry, an important factor shaping the current distribution pattern of the imported fire ants in the USA
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表皮碳氢化合物化学是影响美国进口火蚁当前分布模式的重要因素
DOI：
10.1016/j.jinsphys.2018.08.006
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发表时间：
2018
影响因子：
2.2
通讯作者：
Chen Li
中科院分区：
文献类型：
--
作者：
Xu Meng;Lu ZeKuan;Lu Yong Yue;Balusu Rammohan R;Ajayi Olufemi S;Fadamiro Henry Y;Appel Arthur G;Chen Li
两个姊妹种Solenopsis richteriandS. invicta，都是在世纪早期从南美洲引入美国南部的。今天，S.里希特分布在高纬度和寒冷地区，而invicta占据低纬度地区。在这两个物种的分布区之间，存在着大面积的可育杂种（S。richteri×S. invicta）种群。本研究旨在描述驱动这种分布模式的力量和潜在机制。表皮碳氢化合物（CHCs）的新鲜死亡工人的S。invicta、hybrids和S.用己烷除去Richter。对完整的和提取CHCs的工人进行恒定速率的升温，从10 ° C至60 °C，以获得相对水分损失和水分损失转变温度（Tc-ant）。质量损失和Tc-antwere都显着增加CHCs去除。然后，我们研究了三个物种的CHC组成。S. richteriare的特征在于显著量的短链（C23-C27）饱和和不饱和烃。相反，S.主要是长链（C27-C29）饱和烃;完全不含不饱和烯烃。杂交火蚁表现出两个亲本物种的中间特征。我们分别用差示扫描量热法（DSC）和人工膜系统测定了不同蚁群CHC共混物（Tc-CHC）的熔点（Tm）和失水转变温度。由于其复杂的化学性质，不同蚁群的每个CHC样品有3-5 μ m。CHCs的最高Tms（Tm-maxs）来自S. invicta和杂交种显著高于S. richteri。Tc-CHC与Tm-max的相关性极显著。这些结果表明，具有较高的Tc和Tm-max的物种在相对较高的温度下保留更多的水，因此能够占据温暖的环境。我们的结论是，CHC化学起着塑造当前的分布模式ofS的作用。richteri，S. invictaand their其hybrid混合in the United美国.
Two sibling species,Solenopsis richteriandS. invicta, were both introduced into the southern USA from South America in the early 20th century. Today,S. richterioccupies higher latitudes and colder areas, whileS. invictaoccupies lower latitudes. Between the distributions of the two species, there is a large area of viable hybrid (S. richteri×S. invicta) populations. This study aimed to characterize the forces driving this distribution pattern and the underlying mechanisms. Cuticular hydrocarbons (CHCs) of freshly killed workers ofS. invicta, hybrids, andS. richteriwere removed using hexane. Both intact and CHCs-extracted workers were subjected to a constant rate of increasing temperature from 10 to 60 °C to obtain relative water loss and the water loss transition temperature (Tc-ant). Mass loss and Tc-antwere both significantly increased with CHCs removal. We then examined the CHC composition of three species. CHC profiles ofS. richteriare characterized by significant amounts of short-chain (C23–C27) saturated and unsaturated hydrocarbons. In contrast, profiles ofS. invictaconsist primarily of long-chain (C27–C29) saturated hydrocarbons; unsaturated alkenes are completely lacking. Hybrid fire ants show intermediate profiles of the two parent species. We measured the melting point (Tm) and water-loss transition temperature of CHC blends (Tc-CHC) of different ant species colonies using differential scanning calorimetry (DSC) and an artificial membrane system, respectively. There were 3–5 Tms of each CHCs sample of different ant colonies due to their complex chemistry. The highest Tms (Tm-maxs) of CHCs samples fromS. invictaand the hybrid were significantly higher than that fromS. richteri. The correlation between Tc-CHCand Tm-maxobtained from the same CHCs sample was highly significant. These results reveal that species having higher Tcand Tm-maxretain more water under relatively higher temperature, and consequently are able to occupy warmer environments. We conclude that CHC chemistry plays a role in shaping current distribution patterns ofS. richteri,S. invictaand their hybrid in the United States.