Federal Research Centre for Cultivated Plants, Institute for Biological Control, Julius Kühn Institute, Heinrichstraße 243, 64287, Darmstadt, Germany.
Technische Universität Darmstadt, Schnittspahnstraße 10, 64287, Darmstadt, Germany.
Sci Rep. 2021 May 12;11(1):10151. doi: 10.1038/s41598-021-89583-9.
Microsporidian infections of insects are important natural constraints of population growth, often reducing lifespan, fecundity and fertility of the infected host. The recently discovered Tubulinosema suzukii infects Drosophila suzukii (spotted wing drosophila, SWD), an invasive pest of many fruit crops in North America and Europe. In laboratory tests, fitness effects on larval and adult stages were explored. High level infection after larval treatment caused up to 70% pupal mortality, a decreased lifespan and a 70% reduced oviposition of emerging adults in biparental infection clusters. A shift to higher proportion of female offspring compared to controls suggested a potential parthenogenetic effect after microsporidian infection. A clear sex-linkage of effects was noted; females were specifically impaired, as concluded from fecundity tests with only infected female parents. Additive effects were noted when both parental sexes were infected, whereas least effects were found with only infected male parents, though survival of males was most negatively affected if they were fed with T. suzukii spores in the adult stage. Although most negative effects on fitness parameters were revealed after larval treatment, infection of offspring was never higher than 4%, suggesting limited vertical transmission. For that reason, a self-reliant spread in natural SWD populations would probably only occur by spore release from cadavers or frass.
昆虫微孢子虫感染是种群增长的重要自然限制因素，通常会降低感染宿主的寿命、繁殖力和生育能力。最近发现的 Tubulinosema suzukii 感染果蝇 Drosophila suzukii（斑翅果蝇，SWD），这是北美和欧洲许多水果作物的入侵害虫。在实验室测试中，探讨了对幼虫和成虫阶段的适合度影响。幼虫处理后高水平感染导致多达 70%的蛹死亡、寿命缩短和 70%的产卵量减少。与对照组相比，新生成虫中出现更多的雌性后代，这表明微孢子虫感染后可能存在孤雌生殖效应。感染后明显存在性别连锁效应；从仅感染雌性亲代的繁殖力测试中得出结论，雌性受到了特别的损害。当双亲都被感染时，会出现加性效应，而只有雄性亲代被感染时，效果最小，尽管如果雄性在成虫阶段摄入 T. suzukii 孢子，其存活率会受到最严重的影响。尽管幼虫处理后揭示了对大多数适合度参数的负面影响，但后代的感染率从未超过 4%，表明垂直传播有限。因此，在自然 SWD 种群中，孢子从尸体或粪便中释放可能是自主传播的唯一途径。
