Vannini L, Carapelli A, Frati F, Beani L
Department of Evolutionary Biology, University of Siena, via A. Moro 2, 53100 Siena, Italy.
Parasitology. 2008 May;135(6):705-13. doi: 10.1017/S0031182008004320.
Host discrimination by immature host-seeking endoparasites is a complex and somewhat unexplored topic. In the case of multiple infections, conflicts among conspecifics may occur to monopolize space and resources in the same host. Two or more 1st instar larvae of Xenos vesparum (Strepsiptera, Stylopidae) may enter into a Polistes dominulus (Hymenoptera, Vespidae) larva and develop together until the adult stage of both parasite and host. We carried out a screening of mitochondrial haplotypes in X. vesparum individuals extracted from superparasitized wasps taken in 5 naturally infected nests from different areas of Tuscany (Italy), to assess whether non-sibling parasites may infect the same colony and host. In total, we obtained 12 different haplotypes out of 122 genotyped individuals of both sexes: 17 of 34 superparasitized wasps hosted parasites that originated from females differing in their haplotypes. To date, this is the first described case of superparasitism with non-sibling host-seeking larvae infecting a single individual hymenopteran host. In addition, at least in heavily infected colonies, there is evidence of a male-biased sex-ratio and synchronous development of the parasites, regardless of their haplotypes. Finally, the distribution of haplotypes per nest is consistent with either phoretic infection or larvipositing on nests by means of superparasitized wasps.
未成熟的宿主寻找型内寄生虫对宿主的辨别是一个复杂且尚未充分探索的话题。在多重感染的情况下，同种个体之间可能会发生冲突，以垄断同一宿主内的空间和资源。两只或更多只黄腹蜂虱（捻翅目，捻翅科）的一龄幼虫可能会进入一只意大利黄蜂（膜翅目，胡蜂科）的幼虫体内，并一起发育至寄生虫和宿主的成虫阶段。我们对从意大利托斯卡纳不同地区的5个自然感染巢穴中采集的被超寄生的黄蜂体内提取出的黄腹蜂虱个体的线粒体单倍型进行了筛选，以评估非同胞寄生虫是否会感染同一蜂群和宿主。在总共122个已进行基因分型的雌雄个体中，我们一共获得了12种不同的单倍型：34只被超寄生的黄蜂中有17只体内的寄生虫来自单倍型不同的雌性个体。迄今为止，这是首次描述的非同胞宿主寻找型幼虫感染单个膜翅目宿主的超寄生案例。此外，至少在感染严重的蜂群中，有证据表明存在雄性偏向的性别比例以及寄生虫的同步发育，无论它们的单倍型如何。最后，每个巢穴中单倍型的分布与通过被超寄生的黄蜂进行的携带感染或在巢穴上产幼虫的情况一致。
