Gielen Robin, Ude Kadri, Kaasik Ants, Põldmaa Kadri, Teder Tiit, Tammaru Toomas
Institute of Ecology and Earth Sciences University of Tartu Tartu Estonia.
Department of Ecology, Faculty of Environmental Sciences Czech University of Life Sciences Prague Prague Czech Republic.
Ecol Evol. 2024 Dec 5;14(12):e70666. doi: 10.1002/ece3.70666. eCollection 2024 Dec.
Natural enemies play a key role in population dynamics of insects and exert significant selective pressures on various traits of these animals. Although there is a wealth of empirical and theoretical research on predators and parasitoids, the ecological role of pathogens (other than viruses) remains less understood. Entomopathogenic fungi (EPF), encompassing over 1000 known species from 11 phyla, have primarily been studied in the context of biocontrol in agroecosystems, while their role in natural ecosystems is poorly known. In this paper, we synthesize case studies reporting the prevalence of EPF infections in field populations of insects. We examine differences in this variable among major host taxa and those of the pathogens. From 79 case studies that met our selection criteria, we retrieved data on 122 species of fungi infecting 104 insect species. The meta-analytic median prevalence of fungal infections was 8.2%; even if likely inflated by publication bias, this suggests that EPF-induced mortality levels are lower than those attributable to predators and parasitoids. We found no substantial differences in fungal prevalence among major insect taxa and only a moderate difference among fungal orders, with Neozygitales showing the highest prevalence and Eurotiales the lowest. Our analysis revealed no significant differences in overall EPF prevalence between tropical and temperate studies, although different fungal taxa showed different geographical patterns. In temperate areas, there is some evidence of increasing infection prevalence toward the end of the growing season. Although quantitative data on the effect of EPF on insect populations are still scarce, evidence is consistent with the emerging generalization that insect populations commonly harbor species-rich assemblages of pathogenic fungi, but infections rarely reach epidemic levels. Further studies on multi-species assemblages of EPF associated with natural insect populations are needed to better understand the ecological role of fungal infections.
天敌在昆虫种群动态中起着关键作用，并对这些动物的各种性状施加重大的选择压力。尽管对捕食者和寄生蜂有大量的实证和理论研究，但病原体（病毒除外）的生态作用仍鲜为人知。昆虫病原真菌（EPF）包括来自11个门的1000多种已知物种，主要是在农业生态系统生物防治的背景下进行研究的，而它们在自然生态系统中的作用却知之甚少。在本文中，我们综合了一些案例研究，这些研究报告了昆虫野外种群中EPF感染的流行情况。我们研究了主要宿主类群以及病原体之间在这一变量上的差异。从符合我们选择标准的79个案例研究中，我们获取了关于122种感染104种昆虫的真菌的数据。真菌感染的元分析中位数患病率为8.2%；即使可能因发表偏倚而被夸大，这也表明EPF导致的死亡率低于捕食者和寄生蜂造成的死亡率。我们发现主要昆虫类群之间的真菌患病率没有实质性差异，真菌目之间只有适度差异，新接霉目患病率最高，散囊菌目最低。我们的分析表明，热带和温带研究之间的总体EPF患病率没有显著差异，尽管不同的真菌类群呈现出不同的地理模式。在温带地区，有一些证据表明在生长季节末期感染患病率有所增加。尽管关于EPF对昆虫种群影响的定量数据仍然稀少，但证据与新出现的普遍观点一致，即昆虫种群通常携带着物种丰富的致病真菌群落，但感染很少达到流行水平。需要对与自然昆虫种群相关的EPF多物种组合进行进一步研究，以更好地了解真菌感染的生态作用。
