Elongated hindguts in desert‐living dung beetles (Scarabaeidae: Scarabaeinae) feeding on dry dung pellets or plant litter

Abstract

Most adult dung beetles (Scarabaeidae: Scarabaeinae) feed on fresh, wet dung of larger herbivorous or omnivorous mammals. As indigestible plant fragments are filtered out before ingestion, the food is presumed easily digestible. However, members of the desert-living scarabaeine genus Pachysoma (probably evolved from an ancestor closely related to the wet-dung feeding genus Scarabaeus) select dry dung pellets and/or plant litter. Thus they ingest a much higher proportion of refractory plant material which, interestingly, seems to be digested rather efficiently. This study investigates morphological modifications of the gut for this digestion in adults of eight Pachysoma species, both pellet and litter feeders. To ascertain hypothesized ancestral conditions, four fresh-dung feeding Scarabaeus species were also examined. The latter Presumably, plant fragments in the food are digested, at least partly, in the hindgut. If so, the morphological adaptation is unusual: simple elongation rather than expansion of part of the hindgut, as found in several other plant-or detritus-feeding scarabs.

The Gut Microbiomes of Two Pachysoma MacLeay Desert Dung Beetle Species (Coleoptera: Scarabaeidae: Scarabaeinae) Feeding on Different Diets

“…), the classification adopted in this study. Pachysoma species have specialised anatomical and physiological features for mastication and digestion of fragments from plant detritus and dry dung [ 44 , 45 ].…”

“…Members of Pachysoma exhibit atypical feeding behaviour. While most adult dung beetles feed, by filtration, on minute particulate fragments in wet dung [ 44 , 45 ], adult Pachysoma feed on various and varying dry food sources: plant detritus, dung pellets or both. These substrates are collected on the soil surface and masticated with specially-adapted mouthparts ( Fig 1 ; [ 42 , 43 , 45 , 46 ]).…”

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

“…However, this hypothesis seems somewhat improbable. The gut of adult dung‐feeding beetles is a simple, undifferentiated tube without any fermentation chamber or other structures where symbiotic microbes would be likely to work (Holter & Scholtz, ). Also, most of the cellulose (and the hemicellulose) in dung is probably protected by lignin which must be digested before the cellulose is accessible, something that even the efficient microorganisms in the herbivore's rumen/hindgut did not do.…”

Brood Ball-Mediated Transmission of Microbiome Members in the Dung Beetle, Onthophagus taurus (Coleoptera: Scarabaeidae)

“…As critical decomposers in all temperate and tropical terrestrial ecosystems, dung beetles have evolved to feed on both dry [3,4] and wet dung of mammals in general, and large herbivorous mammals in particular [5], on every continent except Antarctica [6,7]. While many beetles have radiated onto dung as a food source, dung is a nutritionally incomplete diet.…”