The costs and benefits of maternal egg care in the earwig Forficula pubescens

Abstract

Maternal egg care is generally considered to be ubiquitous among the 1,700 species of freeliving Dermaptera. However, the forms, costs, and benefits of egg care have only been studied in a handful of species. In this study, we examined for the first time egg care in the earwig Forficula pubescens. Under standard laboratory conditions, we set up 94 families containing mothers with either no eggs, a reduced, normal or increased clutch size, or eggs without mother. We first demonstrate that F. pubescens mothers indeed express multiple forms of egg care including egg grooming, egg guarding, and active defences against predators, some of which vary with clutch size. However, maternal presence had contrasting effects on the eggs' fate. On one hand, it reduced the survival of eggs during their first 30 days of development, which suggests that mothers eat part of their clutch during egg development and, contrary to other Dermapterans, that abandoned eggs can resist fungal development. On the other hand, maternal presence was necessary to allow the remaining eggs to hatch on day 53, indicating that mothers enhance late embryonic development and/or facilitate the hatching process. Finally, our results did not shed light on the costs of egg care for mothers in terms of premature death, reduced expression of self-grooming, or increased weight loss. Overall, our study emphasizes that investigating the costs and benefits of egg care in poorly known species can provide novel insights into our understanding of the evolution of maternal care within and across animal taxa.

Maternal Care Behavior and Its Consequences in Competition

“…This finding underscores that parental behavior strategies are significantly context-dependent. However, the plasticity of egg-guarding behavior under various circumstances remains unexplored despite numerous studies examining the benefits and costs of egg-guarding behavior for offspring and parents in many animals [4,13,[18][19][20][21]. Hence, it would be important to investigate flexible egg-guarding behavior in animals to fully understand the net effects of egg-guarding and its related ecological consequences.…”