生物多样性对传染性疾病的稀释效应及其在鱼类寄生虫病控制中的应用

Extensive argument was concentrated on the dilution effects of biodiversity on infectious diseases, which originated from zooprophylaxis of human infectious diseases. However, few experiments can provide evidences for the hypothesis because of lack of suitable pathogen-host system. In the present study, by using artificial infectious system Dactylogyrusvastator and Lernaeacyprinacea, relationship between biodiversity and infectious diseases will be investigated. To understand dilution effects of diversity of incompetent hosts on transmission of parasitic diseases, effects of host species richness on abundance of Dactylogyrusvastator with high host specificity in the goldfish Carassiusauratus will be studied. To make clear effects of diversity of competent hosts on infection of parasite, the relationship between host species richness and infection level of Lernaeacyprinacea in Cyprinid carpio will be investigated. Effects of parasite diversity on transmission of parasitic diseases will also be clarified. Furthermore, differences in abundance of parasite with different host specificity between in single and multiple host species will be compared under field experiment condition. Results of the experiments will make us understand the dilution or amplification effects of biodiversity on infectious diseases. And application of the dilution or amplification effects in aquaculture will also be contribute to control of fish infectious diseases.

根据人类传染性疾病的动物预防理论提出的生物多样性稀释效应假说，引起广泛关注和争论，由于缺乏合适的病原研究系统，对该假说缺乏充分的实验验证。本项目利用两种具有代表性的鱼类寄生虫人工感染系统，即坏鳃指环虫和鲤锚头鳋人工感染系统，来研究生物多样性与传染性疾病传播的关系。通过研究宿主种类增加后，强宿主特异性的坏鳃指环虫感染的变化，弄清低敏感性宿主多样性对寄生虫病传播的影响；研究宿主种类增加后，弱宿主特异性的鲤锚头鳋感染的变化，阐明高敏感性宿主多样性对寄生虫病传播的影响；研究寄生虫种类增加后，另一种寄生虫感染的变化，阐明寄生虫多样性对寄生虫传播的影响；在野外池塘中，比较混养模式中鱼类寄生虫的感染与单养模式中的差异，弄清鱼类混养对不同宿主特异性寄生虫传播的影响。该项目的完成将阐明生物多样性对传染性疾病的稀释效应或放大效应的机理，该理论在水产养殖中的应用有助于鱼类传染性疾病的控制。

根据人类传染性疾病的动物预防理论提出的生物多样性稀释效应假说，引起广泛关注和争论，由于缺乏合适的病原研究系统，对该假说缺乏充分的实验验证。本项目利用两种具有代表性的鱼类寄生虫人工感染系统，即坏鳃指环虫和鲤锚头鳋人工感染系统，来研究生物多样性与传染性疾病传播的关系。.本研究建立了小林三代虫的人工感染系统，研究了宿主种群大小对三代虫传播的影响，发现在较高的宿主密度下，三代虫传播是频率制约的传播方式；利用小林三代虫人工感染系统，研究了宿主密度对三代虫传播的影响，发现三代虫的传播与宿主密度正相关，即密度制约的传播方式；不同敏感性宿主对三代虫传播的稀释作用，只有那些具有低敏感宿主才具有稀释效应，而那些不能感染的鱼类则不能起到稀释作用，甚至由于对空间资源的竞争，反而会促进寄生虫的传播；研究了鲤锚头鳋的生活史和感染条件，研究了鲤锚头鳋感染不同宿主后形态变化情况。