Mating and nesting behaviour of Eurysternus (Coleoptera: Scarabaeinae)

Mating and nesting behavior of Eurysternus caribaeus Magnus and Balachowskyi show features which distinguish them from other scarabaeines and which collectively define a distinct group of nesting behavior designated Pattern VI by Halffter (1977). These distinguishing features are: a) the “nuptial feast”, a massive formation of dung balls by the female initiating nesting; b) partial consumption and abandonment of these balls by the parent(s); c) lack of ball-rolling; d) multiple nests, comprising several brood balls; e) nest care by the female; f) in some species, formation of a pair bond while nesting is in progress; g) destruction of some or all brood balls after a period of nest care (such nests are termed experimental nests); h) repetition of experimental nesting with intermittent periods of feeding until a final, or definitive nest is constructed and cared for until the emergence of progeny. Balls are made only by the female and only during nesting behavior; they are not made for feeding, although some may be consumed. Histological study of the ovary of E. caribaeus suggests that attack and abandonment of an experimental nest is linked to continuation of oocyte development during the period of nest care. Disparity between ovarial function and nest care (which represents a fault in the normal K-strategy of scarabaeines) is evidently what provokes the attack and abandonment of a nest after several days of intensive care. Nesting behavior of E. foedus and an unidentified Mexican species are not like that of the species studied. Rather, their behavior is like that of certain Onitini, and is assignable to Group I behavior (sensu Halffter and Matthews, 1966).