Santos Amaral Ludimila, Tunholi-Alves Vinícius Menezes, Castro Lorena Souza, Tunholi Victor Menezes, Gaudêncio Fabrício, Monteiro Caio de Oliveira, Couto-Chambarelli Melissa Carvalho Machado do, Pinheiro Jairo, Freire-Martins Isabella Vilhena
Departamento de Medicina Veterinária, Centro de Ciências Agrárias e Engenharias, Universidade Federal do Espírito Santo (UFES), Alegre, ES, Brazil.
Curso de Pós-Graduação em Ciências, Departamento de Parasitologia Animal (DPA), Instituto de Veterinária, Universidade Federal Rural do Rio de Janeiro (UFRRJ), Rio de Janeiro, Brasil; Universidade Estácio de Sá. Bolsista do Programa Pesquisa e Produtividade da UNESA.
Acta Trop. 2022 Jun;230:106396. doi: 10.1016/j.actatropica.2022.106396. Epub 2022 Mar 10.
Heterorhabditis bacteriophora is an entomopathogenic nematode (EPN) that is mutually associated with Photorhabdus luminescens, utilized globally for biological control of numerous organisms. Freshwater snails of the species Biomphalaria glabrata have been incriminated as the main intermediate hosts of Schistosoma mansoni in Brazil, but virtually nothing is known about the susceptibility of these gastropod to EPNs. Information in this respect is relevant for control of these intermediate hosts, and thus of the helminthiases they transmit. This paper for the first time reports the susceptibility of B. glabrata to infective juveniles of H. bacteriophora (isolate HP88) under laboratory conditions. For that purpose, six groups were formed: three Control groups (not exposed) and three Treated groups, in which the snails were exposed to 300 juveniles infecting the nematode over three weeks. The entire experiment was conducted in triplicate, using a total of 270 snails. Significant physiological alterations in B. glabrata were observed in response to the infection by H. bacteriophora HP88, characterized by decreased levels of hemolymphatic glucose as well as reduced contents of glycogen stored in the host's digestive gland. In parallel, the hemolymphatic activity of lactate dehydrogenase increased in the infected snails, indicating that the infection induces breakdown of carbohydrate homeostasis in B. glabrata. Additionally, all the reproductive parameters analyzed were reduced as a consequence of the infection. The results indicate the occurrence of the phenomenon of parasitic castration in the B. glabrata/H. bacteriophora HP88 interface, probably due to the depletion of galactogen in the parasitized organism. Although the infection did not cause lethality in the population of infected snails, H. bacteriophora HP88 compromised the reproductive performance of B. glabrata, suggesting its applicability in programs for biological control of this planorbid.
嗜菌异小杆线虫是一种昆虫病原线虫，与发光光杆状菌相互关联，在全球范围内用于多种生物的生物防治。光滑双脐螺这种淡水螺被认为是巴西曼氏血吸虫的主要中间宿主，但对于这些腹足纲动物对昆虫病原线虫的易感性几乎一无所知。这方面的信息对于控制这些中间宿主以及它们传播的蠕虫病至关重要。本文首次报道了在实验室条件下光滑双脐螺对嗜菌异小杆线虫（分离株HP88）感染性幼虫的易感性。为此，组建了六组：三个对照组（未接触）和三个处理组，在处理组中，蜗牛在三周内接触300条感染性线虫幼虫。整个实验重复进行三次，共使用270只蜗牛。观察到光滑双脐螺在受到嗜菌异小杆线虫HP88感染后出现了显著的生理变化，其特征是血淋巴葡萄糖水平降低以及宿主消化腺中储存的糖原含量减少。同时，感染蜗牛的血淋巴乳酸脱氢酶活性增加，表明感染导致光滑双脐螺碳水化合物稳态失衡。此外，所有分析的生殖参数因感染而降低。结果表明在光滑双脐螺/嗜菌异小杆线虫HP88界面出现了寄生性阉割现象，这可能是由于被寄生生物中半乳糖原的消耗所致。虽然感染并未导致受感染蜗牛群体死亡，但嗜菌异小杆线虫HP88损害了光滑双脐螺的生殖性能，表明其在该扁卷螺生物防治计划中的适用性。
