Social and personal immunity of parents and larvae in the burying beetle, Nicrophorus orbicollis

Adam John Riley, Purdue University

Abstract

The burying beetle Nicrophorus orbicollis, through biparental care, raise their young on small vertebrate carrion which exposes them to microbial parasites and competitors. These interactions have led to elaborate strategies to combat microorganisms. Through the application of anal and oral secretions adults are able to preserve a carcass from which larvae feed, constituting a social immune response. Evidence suggests that larvae also contribute to this social immunity through their own secretions. Social immunity was tested through exposing larvae to an isolated food source with an experimentally elevated microbial signal, dead Micrococcus luteus. Larvae maintained higher lysozyme-like activity (LLA) in their oral secretions in response to the microbial signal. However, if personal immunity was compromised LLA was not maintained. Larvae and parents were tested for response to increased competition of feeding on fresh or aged carcasses with greater levels of decay. Larvae were not shown to alter LLA of their oral secretions but female parents did have a negative relationship of LLA in their oral secretions and in relation to brood size. Larvae had a negative relationship of phenoloxidase activity in their oral secretions in relation to brood size. This suggests influence of individual larval investment to social immunity affecting both parents and sibling investment. These findings show that oral secretions in N. orbicollis larvae, like adults, has adaptive antimicrobial activity which acts as a social immune response for defending a carrion food source and is sacrificed for personal immunity.

Degree

M.S.

Advisors

Creighton, Purdue University.

Subject Area

Ecology|Entomology|Immunology

COinS