Koprivnikar Janet, Penalva Laura
Department of Chemistry and Biology, Ryerson University, Toronto, Ontario, Canada.
Department of Biology, Brandon University, Brandon, Manitoba, Canada.
PLoS One. 2015 Jan 30;10(1):e0116569. doi: 10.1371/journal.pone.0116569. eCollection 2015.
Predators have documented post-encounter (density-mediated) effects on prey but their pre-encounter impacts, including behavioural alterations, can be substantial as well. While it is increasingly evident that this "ecology of fear" is important to understand for natural enemy-victim relationships, fear responses of hosts to the threat of infection by a parasite are relatively unknown. We examined larval amphibian (Lithobates pipiens) foraging choices by experimentally manipulating the presence of cues relating to predator (larval odonate) or parasite (the trematode Ribeiroia ondatrae) threats. Tadpoles avoided foraging where predator or parasite cues were present; however, they did not treat these as equal hazards. When both threats were simultaneously present, tadpoles strongly preferred to forage under the threat of parasitism compared to predation, likely driven by their relative lethality in our study. Our results indicate that altered spatial use is an important anti-parasite behaviour, and demonstrate that parasite avoidance can affect foraging in a manner similar to predators, warranting greater study of the pre-encounter effects of this enemy type.
捕食者对猎物的遭遇后（密度介导）影响已有记载，但它们的遭遇前影响，包括行为改变，也可能相当大。虽然越来越明显的是，这种“恐惧生态学”对于理解天敌与受害者的关系很重要，但宿主对寄生虫感染威胁的恐惧反应相对未知。我们通过实验操纵与捕食者（幼虫豆娘）或寄生虫（吸虫里氏并殖吸虫）威胁相关的线索，研究了两栖类幼虫（北美豹蛙）的觅食选择。蝌蚪会避开存在捕食者或寄生虫线索的地方觅食；然而，它们并不将这些视为同等危险。当两种威胁同时存在时，与捕食威胁相比，蝌蚪强烈倾向于在寄生威胁下觅食，这可能是由我们研究中它们的相对致命性驱动的。我们的结果表明，空间利用的改变是一种重要的抗寄生虫行为，并证明避免寄生虫可以以类似于捕食者的方式影响觅食，这值得对这种天敌类型的遭遇前影响进行更多研究。
