Costs and benefits of maternal care in the maritime earwig (Anisolabis maritima)

Parental care can be a costly life history trait, therefore it has only evolved when the\ud benefits of care outweigh the costs. We investigated the life-history trade-offs in the\ud earwig Anisolabis maritima in which females establish solitary subterranean nests\ud colonies. Females remain with their eggs for three weeks, past the time of hatching, and\ud provide maternal care in the form of egg cleaning and egg defense. During this egg\ud guarding period adjacent females consistently attempt to invade the nest and, when\ud successful, will cannibalize some fraction of a host female???s clutch. We conducted\ud removal experiments in order to quantify the costs and benefits of maternal care in a\ud solitary context in the lab and a colonial context in the field. . Our results show that\ud maternal care is essential for the survival of eggs, independent of coloniality, due to the\ud sanitation services that a mother provides. However in the field, maternal care also acts to significantly reduce nest invasion and predation. Providing care, however, is costly to the mother in terms of delayed future reproduction. By following clutch development\ud throughout nesting, we found that mothers consistently engage in filial cannibalism. The\ud purpose of this facultative cannibalism may be to mitigate this cost by cannibalizing a\ud portion of their own clutch to offset the energetic demands of care and/or to speed the\ud time to hatching. Together these results show the multiple benefits of maternal care in\ud earwigs, with the magnitude of these benefits varying across different social contexts