Christen J M, Campbell J F, Lewis E E, Shapiro-Ilan D I, Ramaswamy S B
Department of Entomology, Kansas State University, Manhattan, KS 66506, USA.
Parasitology. 2007 Jun;134(Pt 6):889-98. doi: 10.1017/S0031182006002101. Epub 2007 Jan 4.
Potential hosts for infective juveniles of entomopathogenic nematodes can vary considerably in quality based on the characteristics of the host species/stage, physiological status (e.g. stress, feeding on toxins), and infection status (heterospecific or conspecific infection). In this study, we investigated responses of the entomopathogenic nematode Steinernema riobrave to hosts (Galleria mellonella or Tenebrio molitor) that were previously parasitized with conspecifics or injected with the nematode-symbiotic bacterium, Xenorhabdus sp., to determine if there is a preference for previously parasitized/injected hosts and when this preference might occur. In no-choice bioassays, the number of juveniles infecting both host species decreased with increasing time post-infection. However, infective juveniles continued to infect previously parasitized hosts up to 72 h. Significant preference was exhibited by S. riobrave for 24 h post-infection G. mellonella larvae over uninfected, and by 24 h post-injection G. mellonella larvae over 48 h post-injection larvae. No significant preference was exhibited by S. riobrave for T. molitor hosts previously parasitized with conspecifics or those injected with bacteria in any treatment combination. Such preference for, or continued infection of parasitized insects, has the potential to impact nematode efficacy.
基于宿主物种/阶段的特征、生理状态（如应激、摄食毒素）以及感染状态（异种或同种感染），昆虫病原线虫感染性幼虫的潜在宿主在质量上可能有很大差异。在本研究中，我们调查了昆虫病原线虫里奥勇敢斯氏线虫对先前被同种线虫寄生或注射了线虫共生细菌嗜线虫致病杆菌的宿主（大蜡螟或黄粉虫）的反应，以确定是否对线虫对先前被寄生/注射的宿主存在偏好以及这种偏好可能在何时出现。在无选择生物测定中，感染两种宿主物种的幼虫数量随着感染后时间的增加而减少。然而，感染性幼虫在长达72小时内继续感染先前被寄生的宿主。里奥勇敢斯氏线虫在感染后24小时对大蜡螟幼虫的偏好显著高于未感染的幼虫，在注射后24小时对大蜡螟幼虫的偏好显著高于注射后48小时的幼虫。在任何处理组合中，里奥勇敢斯氏线虫对先前被同种线虫寄生或注射了细菌的黄粉虫宿主均未表现出显著偏好。这种对被寄生昆虫的偏好或持续感染，有可能影响线虫的效力。
