| Burying beetles, Nicrophorus orbicollis are unusual among insects in that they provide biparental care. They preserve carrion destined for their young by covering the flesh with oral and anal secretions having antimicrobial immune molecules. Immune defense mounted by individuals for the benefit of others is called social immune system and expected to be as costlier as other forms of immunity. Here we used the burying beetle, Nicrophorus orbicollis, a species that obligatory breed on carcasses of small vertebrates to investigate the role of nutrient rich carcasses and social immunity as antimicrobial strategies. We manipulated competition between beetles and microbes by providing beetles with fresh carcass, dipped carcasses, carcasses burdened with heat killed bacteria, and stale ones that had reached advanced putrefaction. We examined the effects of carcasses quality on life time reproductive output and costs of mounting a social immune response in the burying beetle.;Our experiments suggest that higher levels of microbial competition on the carcass have strong detrimental effects on beetle reproductive success and larval growth.;We conclude that microbe rich breeding environment has selected for an atypical pattern of immune defense with a significant up regulation of social and personal immunity and this eventually reduces lifetime reproductive success. We suggest that the costliness of the immune response is a source of tradeoff between immunity and other life-history traits, such as reproduction and parental care. |
