Nesting behaviour of Canthon unicolor and C. histrio: a new subsocial nesting variation in dung beetles (Coleoptera: Scarabaeidae: Deltochilini)

ABSTRACT

Ball-roller dung beetles of the subfamily Scarabaeinae exhibit two nesting patterns ranging from simple nests (nesting pattern IV) to highly complex nests with parental care (nesting pattern V). Most species of the genus Canthon build a simple nest formed by a single brood ball that is abandoned after oviposition. We studied the nesting behaviour and brood ball architecture of two dung beetle species from South America. Canthon unicolor (Blanchard, 1846) and C. histrio (Le Peletier de Saint-Fargeau & Audinet-and Serville, 1828) construct a shallow nest containing a single brood ball. This brood ball is unique in that it is covered with a thick shield layer made of soil. The shield layer provides to the final brood ball an amorphous external aspect, never described in roller dung beetles. It is less dense than the brood ball layer, and provides, an additional post-ovipositional care. Our results suggest that the nesting behaviour observed in C. unicolor and C. histrio can be considered a new variation of the nesting pattern IV in dung beetles, in which post-ovipositional care through the outer shield layer could increase survival chance of the offspring by protecting them from potential predators, desiccation and a variety of other environmental hazards.

KEYWORDS:

• Nesting patterns
• shield layer
• parental care
• subsocial behaviour
• Scarabaeinae

Acknowledgements

We thank CONACYT (Consejo Nacional de Ciencia y Tecnología, México) for financial support in the form of postdoctoral fellowships to V. Cortez (No. 184878 and No. 203310) and projects AICO/2020/031 (Generalitat Valenciana) and PID2019-105418RB-I00 (Secretaría de Estado de Investigación, Desarrollo e Innovación – Ministerio de Ciencia e Innovación). We also thank V. Giménez-Gómez for her assistance in the field work. Thanks to Mario Cupello for his critical revision and providing constructive comments on an earlier version of the manuscript.

Disclosure statement

No potential conflict of interest was reported by the author(s).

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Funding

This work was supported by the Consejo Nacional de Ciencia y Tecnología [184878,203310]; Generalitat Valenciana [AICO/2020/031]; Spanish Ministry of Science and Innovation [PID2019-105418RB-I00].