Pheronym, Inc., Davis, CA, 95618, USA.
GRACE Market Place, Gainesville, FL, 32609, USA.
Sci Rep. 2020 Mar 31;10(1):5738. doi: 10.1038/s41598-020-62817-y.
Ascaroside pheromones stimulate dispersal, a key nematode behavior to find a new food source. Ascarosides produced by entomopathogenic nematodes (EPNs) drive infective juvenile (IJ) emergence from consumed cadavers and dispersal in soil. Without ascarosides from host cadavers, Steinernema feltiae (EPN) reduce dispersal substantially. To determine whether other Steinernema spp. exhibit the same behavior, we compared S. feltiae and S. carpocapsae IJs without host cadaver pheromones. Unlike S. feltiae, S. carpocapsae IJs continued to disperse. However, S. carpocapsae IJs exhibited a temperature-dependent quiescent period. The IJ quiescent period increased at ≤20 °C but did not appear at ≥25 °C. Consistent with this, S. carpocapsae IJ quiescence increased from 30 min to 24 h at ≤20 °C over 60 days. The quiescent period was overcome by dispersal pheromone extracts of their own, other Steinernema spp. and Heterorhabditis spp. Furthermore, S. carpocapsae IJ ambush foraging associated behaviors (tail standing, waving, and jumping) were unaffected by the absence or presence of host cadaver pheromones. For S. feltiae, IJ dispersal declined at all temperatures tested. Understanding the interaction between foraging strategies and pheromone signals will help uncover molecular mechanisms of host seeking, pathogenicity and practical applications to improve the EPN's efficacy as biocontrol agents.
阿索菌素信息素刺激扩散，这是线虫寻找新食物源的关键行为。昆虫病原线虫（EPN）产生的阿索菌素促使感染性幼虫（IJ）从被消耗的尸体中出现并在土壤中扩散。如果没有来自宿主尸体的阿索菌素，斯氏线虫（EPN）会大大减少扩散。为了确定其他斯氏线虫是否表现出相同的行为，我们比较了没有宿主尸体信息素的斯氏线虫和斯氏滑刃线虫 IJ。与斯氏线虫不同，斯氏滑刃线虫 IJ 继续扩散。然而，斯氏滑刃线虫 IJ 表现出温度依赖性的静止期。在≤20°C时，IJ 静止期增加，但在≥25°C时不会出现。与此一致，斯氏滑刃线虫 IJ 静止期在≤20°C 时从 30 分钟增加到 60 天内的 24 小时。通过自身、其他斯氏线虫和异小杆线虫的扩散信息素提取物可以克服静止期。此外，斯氏滑刃线虫 IJ 的伏击觅食相关行为（尾直立、摆动和跳跃）不受宿主尸体信息素的存在或不存在的影响。对于斯氏线虫，在测试的所有温度下 IJ 的扩散都下降了。了解觅食策略和信息素信号之间的相互作用将有助于揭示宿主寻找、致病性和实际应用的分子机制，以提高 EPN 作为生物防治剂的功效。
