高温对莲草直胸跳甲两个地理种群体重和体型的影响

Effects of high temperature on weight and body size of two geographical populations of Agasicles hygrophila Selman & Vogt( Coleoptera :Chrysomelidae)

体型大小与昆虫在温度胁迫下的适应性有关。本文旨在研究入侵杂草空心莲子草Alternanthera philoxeroides生防天敌莲草直胸跳甲Agasicles hygrophila Selman&Vogt不同地理种群对高温的形态响应机制。以恒温25℃作为对照,分别测定莲草直胸跳甲长沙种群和海南种群在模拟夏季特定12∶00-16∶00时段30℃、33℃、36℃高温条件下的幼虫体重、初羽化成虫体重、后足胫节长、鞘翅长、前胸背板宽等指标。结果表明,莲草直胸跳甲两地理种群幼虫体重均随温度升高而增加。两种群雌虫及长沙种群雄虫的体重、后足胫节长、鞘翅长、前胸背板宽度随温度上升显著下降;海南种群雄虫的后足胫节长、鞘翅长、前胸背板宽在各温度处理间无显著差异。在33℃、36℃高温条件下,长沙种群的幼虫体重、雌虫体重及雌虫的后足胫节长、鞘翅长、前胸背板宽显著高于海南种群,而长沙种群雄虫的后足胫节长、鞘翅长、前胸背板宽显著低于海南种群。试验表明,不同地理种群的莲草直胸跳甲形态大小对高温的响应存在差异。本研究结果为探究莲草直胸跳甲种间进化以及人工培育耐热种群的实践提供了一定的参考依据。

Body size was closely related to fitness of insects under thermal stress. We explored the morphological mechanisms responding to high temperature in different geographical populations of Agasicles hygrophila Selman Vogt, which was a promising biological control agent for invasive Alternanthera philoxeroides. Using constant temperature 25℃ as control,we measured the larva weight,adult weight,tibia length,elytra length,pronotum width of Changsha population and Hainan population under the simulative high-temperature period（ 12 ∶ 00- 16 ∶ 00） of summer at 30℃ 、33℃ 、36℃respectively. Larva weight of two populations of A. hygrophila increased with increasing temperature.Adult weight,tibia length,elytra length,pronotum width of females in both populations and male of Changsha population decreased with temperature significantly,though there was no remarkable difference among thermal treatments in male body size of Hainan population. Adult weight,tibia length,elytra length,pronotum width of female and larva weight in Changsha population were bigger than Hainanpopulation at 33℃ or 36℃,while tibia length,elytra length and pronotum width of male in Changsha population were smaller than Hainan population. Thermal plasticity of different geographical populations differed in Morphological variation. The results will be helpful to better understanding the interspecific evolution and the artificial cultivation of heat- tolerant population.