Cross-fostering reveals that acoustic communication during parental care alleviates prenatal disadvantages in beetle offspring

Abstract

Acoustic communication plays an important role in social interactions for many animals. It is used in a broad range of behaviours, such as parental care. Acoustic communication is also involved in the brood care of Nicrophorus vespilloides (HERBST 1783), which, together with the other burying beetles, are one of the rare exceptions among insects in that they practice biparental brood care. Previous studies showed that a lack of acoustic communication in burying beetles negatively affects the weight and survival rate of their offspring (Conrad et al. 2024). However, it remained unclear whether these results were mainly based on prenatal or postnatal effects of silencing. Therefore, in this study we wanted to find out whether negative effects on N. vespilloides larvae, which are due to a lack of prenatal acoustic communication between the parents, can be compensated by the postnatal brood care of stridulating foster parents. For this purpose, we applied parafilm on the pars stridens of some beetle pairs so that they could no longer stridulate. In a 2x2 cross-fostering experiment, larvae originating from silenced or stridulating parents were reared by either silenced or stridulating foster parents. The larvae of silenced parents showed a lower hatching weight than the larvae of control parents. At dispersal, larvae with stridulating original and foster parents were significantly heavier than those reared by silenced foster parents, from either origin. At dispersal, larvae with stridulating original and foster parents were significantly heavier than those reared by silenced foster parents, from either origin. Thus, the stridulating foster parents were apparently able to partially compensate the initial weight deficits of the larvae from silenced original parents. There were no effects of silencing on offspring survival. Our experiment demonstrates that post-hatching acoustic communication during brood care of N. vespilloides is of greater importance for larval growth than pre-hatching acoustic communication. Still, the inability to stridulate compromises the quality of both prenatal and postnatal care. It is conceivable that the acoustic communication of the parents provides orientation for the larvae when feeding, or that the adults coordinate their tasks and negotiate their parental investment. Our findings contribute further to our understanding of the function of parental communication during brood care.