Department of Biochemistry and Molecular Biology, Shahjalal University of Science and Technology, Sylhet, Bangladesh.
Department of Biological Science, Macquarie University, NSW, Australia.
PLoS One. 2022 Jul 8;17(7):e0261540. doi: 10.1371/journal.pone.0261540. eCollection 2022.
The prevalence and intensity of parasitism can have different fitness costs between sexes, and across species and developmental stages. This variation could arise because of species specific sexual and developmental differences in body condition, immunity, and resistance. Theory predicts that the prevalence of parasitism will be greater in individuals with poor body condition and the intensity of parasitism will be greater in individuals with larger body size. These predictions have been tested and verified in vertebrates. In insects, however, contradictory evidence has been found in different taxa. Here, we tested these predictions on two species of Agriocnemis (Agriocnemis femina and Agriocnemis pygmaea) damselflies, which are parasitized by Arrenurus water mite ectoparasites. We measured body weight, total body length, abdomen area and thorax area of non-parasitized damselflies and found body condition varied between males and females, between immature females and mature females and between A. femina and A. pygmaea. Then, we calculated the parasite prevalence, i.e., the absence or presence of parasites and intensity, i.e., the number of parasites per infected damselfly in eleven natural populations of both species. In line to our predictions, we observed greater prevalence in immature females than mature females but found no difference in parasite prevalence between males and females. Furthermore, we found that parasite intensity was higher in females than males and in immature females than mature females. Our result also showed that the frequency and intensity of parasitism varied between the two studied species, being higher in A. pygmaea than A. femina. Our study provides evidence that parasitism impacts sexes, developmental stages and species differentially and suggests that variation may occur due to sex, developmental stage, and species-specific resistance and tolerance mechanism.
寄生虫的流行程度和强度在不同性别之间以及不同物种和发育阶段可能存在不同的适应成本。这种变化可能是由于物种特异性的身体状况、免疫力和抵抗力在性别和发育上的差异造成的。理论预测,身体状况较差的个体寄生虫流行程度较高,而体型较大的个体寄生虫强度较高。这些预测在脊椎动物中已经得到了检验和验证。然而,在昆虫中,不同分类群却发现了相互矛盾的证据。在这里,我们在两种 Agriocnemis (Agriocnemis femina 和 Agriocnemis pygmaea)豆娘上测试了这些预测,这些豆娘被 Arrenurus 水螨外寄生虫寄生。我们测量了未被寄生的豆娘的体重、全长、腹部面积和胸部面积,发现身体状况在雄性和雌性之间、未成熟雌性和成熟雌性之间以及 A. femina 和 A. pygmaea 之间存在差异。然后,我们计算了寄生虫的流行率,即寄生虫的有无,以及强度,即每只感染的豆娘寄生的寄生虫数量,在这两个物种的 11 个自然种群中进行了测量。与我们的预测一致,我们观察到未成熟的雌性寄生虫流行率高于成熟的雌性,但在雄性和雌性之间没有发现寄生虫流行率的差异。此外,我们发现寄生虫强度在雌性中高于雄性,在未成熟的雌性中高于成熟的雌性。我们的研究结果还表明,两种研究物种的寄生虫感染频率和强度不同,A. pygmaea 高于 A. femina。我们的研究提供了证据表明,寄生虫对性别、发育阶段和物种有不同的影响,并表明这种差异可能是由于性别、发育阶段和物种特异性的抵抗力和耐受性机制造成的。