Quantifying beetle-macrofungal associations in a temperate biodiversity hot spot

<p>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.</p

Pollen & wing scale load on stigmas from naturally visited flowers

After observing a visit by a butterfly in the field, stigmas from R. calendulaceum flowers were clipped and attached to a microscope slide in the field. Data show presence/absence (=Y/N) of pollen and butterfly wing scales on stigmas as scored after examining stigmas under the microscope

2011 wings v body data

Data from observations of _Papilio glaucus_ butterflies foraging on _Rhododendron calendulaceum_ flowers in the field. Showing contact between butterfly wings and an anther & stigma versus contact between butterfly's body and an anther & stigma. Observed contact = 1, absence of contact = 0. Note that these data should not be used to draw any conclusions about which visits had BOTH wings and bodies contact anthers and stigmas. Data collected June 2011

Flower visitor observations

Observations of flower visitors on _Rhododendron calendulaceum_ and flower parts contacted; taken June 2014

Butterfly pollen loads

Pollen carried on wings and bodies of butterflies collected in the field near R. calendulaceum plants in June of 2011 and 2014 (data in separate tabs). Individual pollen grains counted for 2011 butterflies and half of 2014 butterflies before switching to categorical ranges for 2014 butterflies (data for both ranges and counts shown here, in separate tabs)

Pollinator exclusion experiment data

Data from experimental exclusion of flower visitors to _Rhododendron calendulaceum_. Treatments applied 6/12/14 - 6/13/14 and fruit set scored 8/4/14-8/7/14. Treatments defined as follows: A = flowers open to all visitors; B = mesh + cage (all visitors excluded); C = cage (only large visitors, e.g. big butterflies, excluded); D = maximum fruit set (unopened flwrs covered with ziplock until open, then pollinated by hand with outcrossed pollen)

Stigma load from single butterfly visits on emasculated flowers

_Rhododendron calendulaceum_ twigs bearing budding inflorescences were cut in the field and kept in water in the lab. Flowers were emasculated upon anthesis, and emasculated inflorescences were attached to the end of a pole and presented to foraging _Papilio glaucus_ butterflies near flowering _R. calendulaceum_ plants in the field. Stigmas of emasculated flowers were removed and attached to a microscope slide in the field following a visit, and scored for the presence/absence (=Y/N) of pollen grains and butterfly wing scales upon inspection under the microscope

Appendix A. A table listing: the herbivore abbreviations used in the article's figs. and tables, the morphospecies code from our database, and the scientific names (when available) of herbivores involved in the study.

A table listing: the herbivore abbreviations used in the article's figs. and tables, the morphospecies code from our database, and the scientific names (when available) of herbivores involved in the study

Appendix B. A figure showing the number of caterpillar species collected on different numbers of Inga hosts.

A figure showing the number of caterpillar species collected on different numbers of Inga hosts