Parasitism by multiple strepsipterans accelerates timing of adult parasite emergence
Parasitism by multiple strepsipterans accelerates timing of adult parasite emergence
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多种链翅目昆虫的寄生加速了成虫寄生虫的出现时间
DOI：
10.1002/ecy.3811
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发表时间：
2022
期刊：
影响因子：
4.8
通讯作者：
Itino Takao
中科院分区：
文献类型：
--
作者：
Nakase Yuta;Fukumasu Yuichiro;Toji Tsubasa;Ishimoto Natsumi;Itino Takao
链翅目是一种表现出极端性二态性的寄生昆虫：成年雄性是自由生活的有翅昆虫，一生都在寻找雌性进行受精（Pohl & Beutel，2005），而雌性则处于幼态，完全内寄生在宿主体内（除了基础寄生类群）。雌性通过头胸部的育雏管开口释放自由生活的第一龄幼虫，然后寻找自己的宿主进行寄生（Kathirithamby，2018）。在 Corioxenidae strepsipterans 中，第一龄幼虫寄生于异翅目若虫（Kirkpatrick，1937；Nakase & Kato，2011）。成熟时，链翅目雄性和雌性将其头胸部伸出宿主体外（图 1a、b）。在 Blissoxenos esakii（链翅目：Corioxenidae）中，经常观察到超级寄生（宿主体内有多种寄生虫）（Miyamoto & Kifune，1984；Nakase & Kato，2011），但是 B. esakii 可以伸出其头胸部的空间（“出口”空间）仅限于背侧之间的膜区域寄主 Macropes obnubilus（异翅目：Blissidae）的胸部和腹部（图 1a、b）。由于出口空间有限，最多有两只B. esakii可以伸出头胸部。因此，宿主体内任何额外的 esakii 幼虫都无法挤出并最终死亡（Nakase & Kato，2011）。 M. obnubilus 是一性的；新一代的若虫在八月出现，到了九月，上一代的大部分都死亡了。大约一半的新一代在九月成为成虫，但个体之间的生长情况不同，从九月到次年初夏，种群由若虫和成虫混合组成。 B. esakii 的一龄幼虫寄生于 M. obnubilus 若虫，但只有在 M. obnubilus 成为成虫后，它们才开始在体内生长（Nakase & Kato，2011）。雄性B. esakii通常在五月出现并与雌性成虫交配，雌性成虫在八月释放第一龄幼虫以寄生新一代M. obnubilus。然而，一些 Esakii 成熟较早，在 9 月至 12 月，其中的雌性在那时（11 月至 12 月）释放出一龄幼虫。这些早期出现的 B. esakii 几乎只出现在超寄生宿主中，即携带两种或多种寄生虫的宿主中（图 2）。单寄生宿主（即孤生B. esakii）中的Blissoxenos esakii成虫只发生在6-8月，即第一龄幼虫寄生在宿主后一年（羽化缓慢）。
Strepsiptera is an order of parasitic insects that exhibit extreme sexual dimorphism: Adult males are free-living, winged insects that spend their lives seeking females to fertilize (Pohl & Beutel, 2005), whereas females are neotenic and completely endoparasitic within their hosts (except for basal parasitoid groups). The female releases free-living first instar larvae via a brood canal opening in the cephalothorax, which then seek a host of their own to parasitize (Kathirithamby, 2018). In Corioxenidae strepsipterans, the first instar larvae parasitize heteropteran nymphs (Kirkpatrick, 1937; Nakase & Kato, 2011). At maturity strepsipteran males and females extrude their cephalothoraxes outside the host body (Figure 1a, b). In Blissoxenos esakii (Strepsiptera: Corioxenidae), superparasitism (multiple parasites in a host) is often observed (Miyamoto & Kifune, 1984; Nakase & Kato, 2011), but the space where B. esakii can extrude its cephalothorax (the “exit” space) is limited to the membranous area between the dorsal thorax and abdomen of the host Macropes obnubilus (Heteroptera: Blissidae)(Figure 1a, b). Because the exit space is limited, at most two B. esakii can extrude their cephalothoraxes. Thus, any additional B. esakii larvae inside the host body cannot extrude and eventually die (Nakase & Kato, 2011). M. obnubilus is univoltine; nymphs of the new generation emerge in August, and by September most of the previous generation are dead. About half of the new generation become adults in September, but growth varies among individuals, and from September to early summer of the following year the population consists of a mixture of nymphs and adults. First instar larvae of B. esakii parasitize M. obnubilus nymphs, but they begin to grow inside the body only after M. obnubilus has become an adult (Nakase & Kato, 2011). Adult male B. esakii typically emerge in May and copulate with female adults, which release first instar larvae in August to parasitize the new generation of M. obnubilus. However, some B. esakii reach maturity earlier, in September–December, and the females among them release first instar larvae at that time (November–December). These early-emerging B. esakii occur almost exclusively in superparasitized hosts, ie, those harboring two or more parasites (Figure 2). Blissoxenos esakii adults in singly parasitized hosts (ie, solitary B. esakii) occurred only in June–August, that is, a year after the first instar larva parasitized the host (slow emergence).