Attractiveness of Cattle Dung to Coprophilous Beetles (Coleoptera: Scarabaeoidea and Sphaeridiinae) and Their Segregation During the Initial Stages of the Heterotrophic Succession on a Pasture in Southeast Michigan

Abstract

Only a few mostly older studies analyzed the heterotrophic succession of dung beetles in the Midwestern United States. Such studies are needed to track the impacts of the climate crisis on heterotrophic succession and the associated decomposition processes that are central to soil fertility and carbon sequestration. The current study closes this knowledge gap and provides an easy and efficient method to estimate the relative attractiveness of individual dung pads during heterotrophic succession. The dung beetle community of Carpenter Farm in Adrian, Southeast Michigan was sampled for an entire year, including the winter months, using 15 pitfall traps baited with fresh cow manure. Samples were collected after 48 h and again after 72 h exposure time from the bucket content while leaving the bait unhampered. Eighty-four percent of all beetles were caught in the early sample, but only 6 species were missing in the later sample. A cluster analysis based on Pianka’s niche overlap identified a statistically higher mean overlap than expected by chance in a null model (model RA3) and divided the species community clearly into three clusters separating most relocators from most dwellers. Despite using a different method, my results confirmed the successional position of most previously described species and added data for several species with poor or unknown successional state. The successional segregation between dwellers and relocators discovered by the cluster analysis was paralleled by a significantly larger body size of relocators across taxonomic groups as compared to dwellers.

Phenological Patterns and Seasonal Segregation of Coprophilous Beetles (Coleoptera: Scarabaeoidea and Hydrophilidae) on a Cattle Farm in SE-Michigan, United States Throughout the Year

“…(2) Succession (exposure time) from the pooled 15 pitfall traps collected after 2 days exposure and a pooled late sample collected after 3 days. Analyses of these data were published in Wassmer (2020).…”

“…Since 2013, the cattle are moved to a larger more productive pasture in mid to late spring and are replaced by a small herd of goats, a pony, and a donkey; cattle return to the farm in late autumn. More details about the study site can be found in Wassmer (2020).…”

“…Due to harsh winter conditions with a deep snow cover, I only collected one sample per month for January and February. For more details on the sampling protocol, beetle identification, and biomass computation, please refer to Wassmer (2020).…”

“…As the man-made climate crisis causes milder winters in temperate, boreal and polar climates, the second objective of this study was to provide a phenology of the coprophilous beetle community throughout the year including the winter months. Menéndez and Gutiérrez (1999), Sladecek et al (2013), and Wassmer (2020) showed that the "relocator" guild has a distinctively different successional timing compared to the "dweller" guild. The third objective of the study was to compare the degree of seasonal segregation in these functional groups and relate those patterns to their successional separation reported in the sister study of this research (Wassmer, 2020) to outline a 2-dimensional temporal niche space for these guilds.…”

“…Menéndez and Gutiérrez (1999), Sladecek et al (2013), and Wassmer (2020) showed that the "relocator" guild has a distinctively different successional timing compared to the "dweller" guild. The third objective of the study was to compare the degree of seasonal segregation in these functional groups and relate those patterns to their successional separation reported in the sister study of this research (Wassmer, 2020) to outline a 2-dimensional temporal niche space for these guilds. The use of phenological patterns (phenophases) of guilds instead of individual species has been shown by Browning et al (2018) to improve the efficiency of ecosystem monitoring and predictive modeling to inform land management outcomes.…”