Herbivore dung as food for dung beetles: elementary coprology for entomologists

Abstract

Abstract. 1. How do dung beetles and their larvae manage to subsist on herbivore dung consisting of plant remains that are at least partly indigestible, mixed with various metabolic waste products? To clarify what is known and not known about this basic aspect of dung beetle biology, the present review summarises information on dung composition and discusses the feeding of beetles (food: fresh dung) and larvae (food: older dung) in relation to this information.2. There is 70-85% water in typical fresh dung, and undigested lignocellulose or 'fibre' constitutes about 70% of the organic matter which also contains 1.5-3% N. About 75% of this is 'metabolic faecal nitrogen', mostly associated with dead and alive microbial biomass. As all essential amino acids and cholesterol are probably present, additional synthesis by microbial symbionts may not be needed by the beetles.3. Beetles minimise the intake of lignocellulose by filtering fibre particles out of their food which is probably microbial biomass/debris with much smaller particle size. Excess fluid may be squeezed out of this material by the mandibles before ingestion.4. All larvae are bulk feeders and unable to filtrate, but little is known about the composition of their food, i.e. older dung in pats or underground brood masses. Larvae in dung pats may depend on easily digestible dung components, probably microbial biomass, whereas the nutritional ecology of larvae in brood masses is still not understood. Unravelling the composition of their food might answer some of the so far unanswered questions.

Extinctions of interactions: quantifying a dung beetle–mammal network

“…). This could prevent declines in dung beetle populations by buffering dung beetles against the loss of mammal species, although the extent to which changes in dung composition effects reproductive success is still unknown (Holter ). We also assumed that resource use switching in feeding or breeding resources will not have fitness consequences to the dung beetle species.…”

“…The loss of large-bodied mammal species could result in population increases in smaller mammal species and a subsequent compensation in dung availability (Wright 2003, Nichols et al 2009). This could prevent declines in dung beetle populations by buffering dung beetles against the loss of mammal species, although the extent to which changes in dung composition effects reproductive success is still unknown (Holter 2016). We also assumed that resource use switching in feeding or breeding resources will not have fitness consequences to the dung beetle species.…”

Developmental bias in horned dung beetles and its contributions to innovation, adaptation, and resilience

“…Microbes have long been hypothesized to play a critical role in enabling both juvenile and adult Onthophagus to subsist and diversify upon dung, which is primarily composed of complex polysaccharides such as cellulose and relatively low in amino acids (Flachowsky & Hennig, 1990;Frank, Brückner, Hilpert, Heethoff, & Blüthgen, 2017;Halffter & Edmonds, 1982;Holter, 2016;Muller, 1980). Recent work on O. taurus and the closely related genus Euoniticellus now shows that pedestal microbiota are enriched for genes implicated in cellulose degradation and nitrogen fixation (Estes et al, 2013;Shukla, Sanders, Byrne, & Pierce, 2016).…”

Morphology of the third instar larva of Colobopterus quadratus (Coleoptera: Scarabaeidae: Aphodiinae) using scanning electron microscopy

“…Aphodiinae are a large cosmopolitan subfamily of Scarabaeidae in Scarabaeoidea, comprising more than 3,000 species assigned into around 200 recognized genera (Dellacasa, Bordat, & Dellacasa, ). Most of the species in Aphodiinae are small‐sized (1.5–13 mm in lengths) and inconspicuous beetles residing in dung or in the soil (Holter, ; Jameson & Ratcliffe, ; Yoshida & Katakura, ). The adults of Aphodiinae usually dwell in and feed on the dung debris (Cambefort, ), different from subfamily in Geotrupidae or Scarabaeinae, members of which bury or roll away the dung portions (Halffter & Edmonds, ; Scholtz, Davis, & Kryger, ).…”

“…Most of the species in Aphodiinae are small-sized (1.5-13 mm in lengths) and inconspicuous beetles residing in dung or in the soil (Holter, 2016;Jameson & Ratcliffe, 2002;Yoshida & Katakura, 1986).…”