Programa de Pós-Graduação em Microbiologia Agrícola e do Ambiente, Universidade Federal do Rio Grande do Sul, Porto Alegre, Rio Grande do Sul, Brazil.
Parasitol Res. 2013 Aug;112(8):2891-6. doi: 10.1007/s00436-013-3460-x. Epub 2013 Jun 1.
Dengue fever is an important vector-borne disease, mainly transmitted by Aedes aegypti. To date, there are no vaccines or effective drugs available against this arboviral disease. As mosquito control is practically the only method available to control dengue fever, alternative and cost-effective pest control strategies need to be explored. The gram-negative enteric bacteria Xenorhabdus and Photorhabdus are symbiotically associated with nematode parasites, which themselves are highly pathogenic for insect larvae. Here, we evaluate the oral toxicity of these entomopathogenic bacteria in A. aegypti larvae. The susceptibility of larvae (third late or fourth early instars) was assessed by exposing them to suspensions containing Photorhabdus luminescens or Xenorhabdus nematophila, respectively. Two diet treatments were tested with larvae fed on pet food and unfed larvae. After 24 h, larvae began to die when exposed to the bacteria. Exposure to P. luminescens killed 73% of the fed and 83% of the unfed larvae, respectively. In comparison, X. nematophila was less pathogenic, killing 52% of the larvae in the fed and 42% in the unfed treatment. Remarkably, cannibalism was observed in all bioassays after exposing larvae to either of the bacterial species. To our knowledge, this is the first report demonstrating the efficiency of these entomopathogenic bacteria for oral A. aegypti killing. Our results provide a promising basis for using these bacteria as bioinsecticides for mosquito control in the future.
登革热是一种重要的虫媒传染病，主要由埃及伊蚊传播。迄今为止，针对这种虫媒病毒病尚无疫苗或有效药物。由于蚊虫控制实际上是控制登革热的唯一方法，因此需要探索替代的、具有成本效益的害虫控制策略。革兰氏阴性肠道细菌 Xenorhabdus 和 Photorhabdus 与线虫寄生虫共生，而这些寄生虫本身对昆虫幼虫具有高度致病性。在这里，我们评估了这些昆虫病原细菌对埃及伊蚊幼虫的口服毒性。通过将幼虫暴露于分别含有 Photorhabdus luminescens 或 Xenorhabdus nematophila 的悬浮液中，评估幼虫（第三晚期或第四早期）的易感性。用宠物食品喂养幼虫和未喂养幼虫进行了两种饮食处理测试。24 小时后，当幼虫暴露于细菌时，它们开始死亡。暴露于 P. luminescens 分别杀死了 73%的喂食幼虫和 83%的未喂食幼虫。相比之下，X. nematophila 的致病性较低，在喂食和未喂食处理中分别杀死了 52%的幼虫。值得注意的是，在暴露于任何一种细菌的所有生物测定中都观察到了同类相食现象。据我们所知，这是首次报道证明这些昆虫病原细菌对口服埃及伊蚊具有杀伤效率。我们的结果为将来将这些细菌用作控制蚊虫的生物杀虫剂提供了有希望的基础。
