Epps Mary Jane, Arnold A Elizabeth
a Department of Ecology and Evolutionary Biology , The University of Arizona , Tucson , Arizona 85721.
b School of Plant Sciences and Department of Ecology and Evolutionary Biology , The University of Arizona , Tucson , Arizona 85721.
Mycologia. 2018 Mar-Apr;110(2):269-285. doi: 10.1080/00275514.2018.1430439. Epub 2018 Mar 26.
Beetles (Coleoptera) are often among the most abundant and diverse insects that feed on sporocarps of macrofungi, but little is known regarding their relative specialism or generalism in most communities. We surveyed >9000 sporocarps in montane hardwood forest in the Appalachian Mountains (USA) to characterize associations of mycophagous beetles and macrofungi. We used traditional metrics and network analyses to quantify relationships between sporocarp traits (mass, age, persistence, and toughness) and assemblages of adult beetles, drawing from >50 000 beetles collected over two survey years. Strict-sense specificity was rare in these associations: most beetle species were found on multiple fungal genera, and most fungi hosted multiple beetle species. Sporocarp age and fresh mass were positively associated with beetle diversity in fungi with ephemeral sporocarps (here including 12 genera of Agaricales and Russulales), but sporocarp persistence was not. In Polyporales, beetle diversity was greater in softer sporocarps than in tough or woody sporocarps. The increase of beetle diversity in aging sporocarps could not be attributed to increases in sporocarp mass or sampling point in the growing season, suggesting that age-related changes in chemistry or structure may support increasingly diverse beetle communities. Interaction networks differed as a function of sporocarp age, revealing that community-wide measures of generalism (i.e., network connectance) and evenness (i.e., variance in normalized degree) change as sporocarps mature and senesce. Beetles observed on Agaricales and Russulales with more persistent sporocarps had narrower interaction breadth (i.e., were more host-specific) than those on less persistent sporocarps, and beetles on Polyporales with tougher sporocarps had narrower interaction breadth than those on soft sporocarps. In addition to providing a large-scale evaluation of sporocarp use by adult beetles in this temperate biodiversity hot spot, this study shows that characteristics of food organisms are associated with specialism and generalism in interactions relevant to fungal and forest ecology.
甲虫（鞘翅目）通常是取食大型真菌子实体的数量最多、种类最为多样的昆虫之一，但在大多数群落中，人们对它们相对的专一性或泛食性却知之甚少。我们对美国阿巴拉契亚山脉山地硬木林中的9000多个子实体进行了调查，以描述食菌甲虫与大型真菌之间的关联。我们运用传统指标和网络分析方法，从两个调查年份收集的50000多只甲虫中，量化子实体特征（质量、年龄、持久性和韧性）与成年甲虫群落之间的关系。在这些关联中，严格意义上的专一性很少见：大多数甲虫物种能在多个真菌属上被发现，且大多数真菌有多种甲虫物种取食。在子实体短暂的真菌（这里包括伞菌目和红菇目的12个属）中，子实体年龄和鲜质量与甲虫多样性呈正相关，但子实体持久性并非如此。在多孔菌目中，较软的子实体上的甲虫多样性高于坚韧或木质的子实体。衰老子实体中甲虫多样性的增加不能归因于子实体质量的增加或生长季节采样点的变化，这表明与年龄相关的化学或结构变化可能支持越来越多样的甲虫群落。相互作用网络因子实体年龄而异，这表明随着子实体成熟和衰老，群落范围内的泛食性（即网络连通性）和均匀度（即标准化度的方差）测量值会发生变化。在子实体更持久的伞菌目和红菇目上观察到的甲虫，其相互作用广度比在子实体持久性较差的真菌上的甲虫更窄（即更具寄主专一性），而在子实体更坚韧的多孔菌目上的甲虫，其相互作用广度比在软子实体上的甲虫更窄。除了对这个温带生物多样性热点地区成年甲虫对子实体的利用进行大规模评估外，本研究还表明，食物生物的特征与真菌和森林生态相关相互作用中的专一性和泛食性有关。
