The ectoparasitic fungus Hesperomyces virescens was studied on its invasive host, the harlequin ladybird Harmonia axyridis, in the Czech Republic. A primary aim was to examine the relationship between fungal infection and elytral coloration of the ladybird. Furthermore, the role of host sex and mating status of females were analyzed. Beetles (n = 1,102) were sampled during autumn migration, and then sexed, weighed, and screened for infection. Females were dissected for detection of sperm in their spermathecae. Ladybirds were sorted according to color form and absorbance spectrophotometry was used to quantify carotenoid contents in their elytra. In individuals of the nonmelanic succinea form, the degree of melanization was measured using digital photographs and putative age groups were estimated based on background color of elytra. Sexual differences in infection patterns indicated transmission during copulation: males were infected mostly on elytra and venter, and females had infection almost exclusively on elytra. Mated females had higher infection rate than virgins. There was no influence of genetic color form on the fungal infection. Putative age groups (visual sorting to yellow, orange, and red) correlated with fungal infection. Infected individuals had elevated elytral carotenoid levels in comparison to uninfected individuals, which could be explained by host age. Infection-free succinea beetles were extensively melanized because they emerged later in the season at lower temperatures which induced melanization. Overall, we highlight that H. axyridis is a multivoltine species whose age, if not taken into account in ecophysiological studies, might present a considerable confounding factor.

中文翻译：

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丑角瓢虫的五十度灰和性传播真菌。


在捷克共和国，人们对外寄生真菌 Hesperomyces virescens 的入侵宿主——丑角瓢虫 Harmonia axyridis 进行了研究。主要目的是检查真菌感染与瓢虫的鞘翅颜色之间的关系。此外，还分析了宿主性别和雌性交配状态的作用。在秋季迁徙期间对甲虫（n = 1,102）进行取样，然后进行性别鉴定、称重和感染筛查。解剖雌性以检测其受精囊中的精子。根据颜色形态对瓢虫进行分类，并使用吸光度分光光度法定量其鞘翅中的类胡萝卜素含量。在非黑色素琥珀形式的个体中，使用数码照片测量黑色化程度，并根据鞘翅的背景颜色估计推定的年龄组。感染模式的性别差异表明在交配过程中传播：雄性主要在鞘翅和腹部感染，而雌性几乎仅在鞘翅上感染。已交配的雌性比处女的感染率更高。遗传颜色形式对真菌感染没有影响。假定的年龄组（视觉分类为黄色、橙色和红色）与真菌感染相关。与未感染个体相比，感染个体的鞘质类胡萝卜素水平升高，这可以通过宿主年龄来解释。无感染的琥珀甲虫被广泛黑色化，因为它们在季节晚些时候出现，在较低的温度下诱导黑色化。总体而言，我们强调异色异丝虫是一种多化物种，如果在生态生理学研究中不考虑其年龄，可能会成为一个相当大的混杂因素。