Department of Plant Protection, Faculty of Agriculture and Natural Resources, University of Tehran, Karaj, Iran.
Department of Plant Protection, College of Agriculture, University of Bu Ali, Hamadan, Iran.
J Exp Biol. 2021 Jun 1;224(11). doi: 10.1242/jeb.240549. Epub 2021 Jun 4.
Upon encountering a host, a female parasitoid wasp has to decide whether to learn positive or negative cues related to the host. The optimal female decision will depend on the fitness costs and benefits of learned stimuli. Reward quality is positively related to the rate of behavioral acquisition in processes such as associative learning. Wolbachia, an endosymbiotic bacterium, often plays an impressive role in the manipulation of its arthropod host's biology. Here, we studied the responses of two natural Wolbachia infected/uninfected Trichogramma brassicae wasp populations to theoretically high- and low-reward values during a conditioning process and the consequences of their responses in terms of memory duration. According to our results, uninfected wasps showed an attraction response to high-value rewards, but showed aversive learning in response to low-value rewards. The memory span of uninfected wasps after conditioning by low-value rewards was significantly shorter than that for high-value rewards. As our results revealed, responses to high-quality hosts will bring more benefits (bigger size, increased fecundity and enhanced survival) than those to low-quality hosts for uninfected wasps. Infected wasps were attracted to conditioned stimuli with the same memory duration after conditioning by both types of hosts. This was linked to the fact that parasitoids emerging from both types of hosts present the same life-history traits. Therefore, these hosts represent the same quality reward for infected wasps. According to the obtained results, it can be concluded that Wolbachia manipulates the learning ability of its host, resulting in the wasp responding to all reward values similarly.
当遇到宿主时，雌性寄生蜂必须决定是学习与宿主相关的正或负线索。女性的最佳决策将取决于学习刺激的适应成本和收益。奖励质量与行为习得过程（如联想学习）中的行为习得速度呈正相关。沃尔巴克氏体是一种内共生细菌，它经常在操纵其节肢动物宿主的生物学方面发挥令人印象深刻的作用。在这里，我们研究了两种自然感染/未感染的赤眼蜂对理论上高值和低值奖励的反应，以及它们在记忆持续时间方面的反应的后果。根据我们的结果，未感染的黄蜂对高价值奖励表现出吸引反应，但对低价值奖励表现出厌恶学习。经低价值奖励条件作用后，未感染黄蜂的记忆持续时间明显短于高价值奖励。正如我们的结果所揭示的那样，未感染的黄蜂对高质量宿主的反应将带来更多的好处（更大的体型、更高的繁殖力和更高的存活率），而不是对低质量宿主的反应。感染的黄蜂对两种类型的宿主进行条件作用后，对条件刺激的记忆持续时间相同。这与从两种类型的宿主中孵化出的寄生蜂具有相同的生活史特征有关。因此，这些宿主对感染的黄蜂来说代表着相同的高质量奖励。根据获得的结果，可以得出结论，沃尔巴克氏体操纵其宿主的学习能力，导致黄蜂对所有奖励值的反应相似。
