Castrating the drowning host: the sophisticated manipulation by the horsehair worm

更新日: 2018/10/09

開催日時 2018(平成30)年10月17日(水) 12:30–13:20
開催場所 総合研究実験1号棟5階 HW525
発表者 Ming-Chung Chiu (神戸大学大学院理学研究科・客員研究員)
関連ミッション ミッション1 環境診断・循環機能制御


Horsehair worm (phylum Nematomorpha) is an aquatic parasite commonly found in terrestrial host insects. Infection of the parasite changes host’s responses to water, resulting in abnormal behavior in which the host jumps into an aquatic environment where the adult parasite reproduces. The drowning infected host represents the energy resource that flow from the terrestrial to the aquatic environment, and significantly impacts the behavior of the stream trout. Such alternation on the host behavior is known as host manipulation, which extends the parasitic effects from the host individual to ecosystems. In this seminar the mechanism behind such host manipulation will be discussed. In the relation to parasite’s reproduction, alterations in host behavior occur successively when the horsehair worm matures. Recent studies have found that the parasitic effects on host development can occur in the early stage of infection. The infected hosts, for example, develop abnormal secondary sex characters and courtship, which can lead to reduced reproduction or even castration. The host reproductive reduction allows more resource available for parasite development. Notably, it might also prevent the host defense against the following behavioral manipulation since a castrated insect no more contributes to the existence of its own population.

Seminar-0236Fig. 1 Horsehair worm development in the mantid host with host phenotypic alternations

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