Adamo Shelley A, Kovalko Ilya, Turnbull Kurtis F, Easy Russell H, Miles Carol I
Department of Psychology and Neuroscience, Dalhousie University, Halifax, NS, Canada B3H 4R2
Department of Psychology and Neuroscience, Dalhousie University, Halifax, NS, Canada B3H 4R2.
J Exp Biol. 2016 Dec 1;219(Pt 23):3750-3758. doi: 10.1242/jeb.145300. Epub 2016 Sep 15.
Some parasites alter the behaviour of their hosts. The larvae of the parasitic wasp Cotesia congregata develop within the body of the caterpillar Manduca sexta During the initial phase of wasp development, the host's behaviour remains unchanged. However, once the wasps begin to scrape their way out of the caterpillar, the caterpillar host stops feeding and moving spontaneously. We found that the caterpillar also temporarily lost sensation around the exit hole created by each emerging wasp. However, the caterpillars regained responsiveness to nociception in those areas within 1 day. The temporary reduction in skin sensitivity is probably important for wasp survival because it prevents the caterpillar from attacking the emerging wasp larvae with a defensive strike. We also found that expression of plasmatocyte spreading peptide (PSP) and spätzle genes increased in the fat body of the host during wasp emergence. This result supports the hypothesis that the exiting wasps induce a cytokine storm in their host. Injections of PSP suppressed feeding, suggesting that an augmented immune response may play a role in the suppression of host feeding. Injection of wasp larvae culture media into non-parasitized caterpillars reduced feeding, suggesting that substances secreted by the wasp larvae may help alter host behaviour.
一些寄生虫会改变宿主的行为。寄生黄蜂聚瘤姬蜂的幼虫在烟草天蛾毛虫体内发育。在黄蜂发育的初始阶段，宿主的行为保持不变。然而，一旦黄蜂开始从毛虫体内钻出，毛虫宿主就会停止自主进食和移动。我们发现，毛虫在每只黄蜂钻出所形成的出口孔周围也会暂时失去感觉。不过，毛虫在1天内会在这些区域恢复对伤害性刺激的反应能力。皮肤敏感性的暂时降低可能对黄蜂的生存很重要，因为这能防止毛虫用防御性攻击来攻击正在钻出的黄蜂幼虫。我们还发现，在黄蜂钻出时，宿主脂肪体中血细胞伸展肽（PSP）和斯佩兹尔基因的表达增加。这一结果支持了这样的假说，即钻出的黄蜂会在其宿主中引发细胞因子风暴。注射PSP会抑制进食，这表明增强的免疫反应可能在抑制宿主进食中起作用。将黄蜂幼虫培养基注射到未被寄生的毛虫体内会减少进食，这表明黄蜂幼虫分泌的物质可能有助于改变宿主行为。
