Substrate moisture effect on reproduction of the Coleoptera Onthophagus squalidus, Onthophagus consentaneus (Scarabaeidae), Saprinus cupreus (Histeridae), and Liparochrus sp. (Hybosoridae), in New South Wales, Australia

Abstract

This study examined the reproductive strategies and resilience of dung beetle species Onthophagus squalidus and O. consentaneus (Scarabaeidae) and two coprophagous beetle species, Saprinus cupreus (Histeridae), Liparochrus sp. (Hybosoridae). The objective was to ascertain whether the lack of substrate moisture could be the reason for the absence of dung beetles during the 2018/19 drought. The investigation focused on whether the distinctive breeding behaviours of S. cupreus and Liparochrus sp. enabled them to thrive under those conditions. Beetles were collected using dog dung baited pitfall traps, after collection, the beetles were identified, sexed, grouped in male + female pairs, and reared on coco peat substrate with 4, 8, 12, and 16% of substrate moisture levels. Results indicated that O. squalidus and O. consentaneus adult beetle emergence was greater in low substrate moisture levels at 4% and 8%; Liparochrus sp. had better adult beetle emergence in treatments with higher substrate moisture (12% and 16%). While S. cupreus adult beetle emergence was unaffected by substrate moisture. This study identified the two coprophagous that both had unique reproductive strategies that may contribute to them being effective during drought conditions. Liparochrus sp. needed high substrate moisture to achieve adult beetle emergence, but as they likely can actively seek moist environments containing rotting wood, they have an adaptive advantage over tunnelling dung beetles that bury dung where it is deposited. Both dung beetle species had high adult beetle emergence at low substrate moisture indicating that substrate moisture was likely not the cause of dung beetles being absent during drought conditions.