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Chemical cues and signals, especially in insects, play a pivotal role in mediating interactions between individuals. Past studies have largely focused on adult semiochemicals and have neglected those of juvenile stages. Especially in the context of parental care, the larval odor might have a profound impact on parenting behavior, guiding parents in how much resources they should allocate to the different developmental stages. However, whether ontogenetic changes occur in subsocial species and whether larval-emitted scents influence parent–offspring interactions is largely unknown. Using 3 different sampling techniques, we analyzed the cuticular and VOC profile of the 3 larval instars of the burying beetle Nicrophorus vespilloides , which is known for its elaborate parental care. We found distinct differences in the cuticular and VOC profiles across the 3 larval stages. Second-instar larvae, which receive more frequent feedings from parents than the other larval stages, released greater amounts of acetophenone, methyl geranate, and octanoic acid isopropyl ester than the first and third instar. Additionally, using a newly developed bioassay with automated video tracking, we found that adding the odor of second-instar larvae to first-instar larvae increased the number of maternal feeding trips. Our results suggest that the odor produced by larvae plays an important role in mediating parent–offspring interactions. Given these findings, burying beetles might emerge as a promising candidate for identifying a potential begging pheromone. [ABSTRACT FROM AUTHOR]

Communication is fundamental in the animal kingdom, essential to interactions such as mating, defense, and parental care. Vibrational communication has often been overlooked in the past, but in recent decades, it has become clear that insects use substrate vibrations as a communication signal. In burying beetles of the genus Nicrophorus, which are known for their biparental brood care, both parents stridulate. Spending a considerable period of their lives underground, it is very likely the beetles utilize vibrations as part of their communication system. As playback experiments are challenging with this species, this study looked at the physical propagation of the signal of Nicrophorus vespilloides Herbst (Coleoptera: Siliphidae) through three soil types, as well as behavior, to see whether vibrational communication is possible. The aims were to determine: (1) whether the soils used in the laboratory compare to soil from the field, (2) whether the distance of propagation is enough for the range the beetles cover during brood care, (3) whether the two sexes show a difference in stridulation likelihood, (4) whether propagation of defensive signals differs from brood care signals, and (5) whether we can determine a behavior during stridulations that shows a clear and useable reaction to the signal. We manipulated beetles to induce stridulation and then used laser Doppler vibrometers to record the signals using three substrates and various distances, alongside behavioral observations. We showed that the three substrates tested, peat, coconut coir, and forest soil, displayed differences in terms of vibrational propagation, and that burying beetle stridulation signals can be transmitted up to about 25 cm in the soil. We also showed that the location where the animals stridulate exerts a significant influence on the total duration and number of stridulations. Overall, vibrational communication is in principle conceivable in this species, as the signals are transmitted far enough in the natural substrate to allow complex communication, opening possibilities for vibrational communication during this biparental brood care. [ABSTRACT FROM AUTHOR]

Investigating fundamental processes in biology requires the ability to ground broad questions in species‐specific natural history. This is particularly true in the study of behavior because an organism's experience of the environment will influence the expression of behavior and the opportunity for selection. Here, we provide a review of the natural history and behavior of burying beetles of the genus Nicrophorus to provide the groundwork for comparative work that showcases their remarkable behavioral and ecological diversity. Burying beetles have long fascinated scientists because of their well‐developed parenting behavior, exhibiting extended post‐hatching care of offspring that varies extensively within and across taxa. Despite the burgeoning success of burying beetles as a model system for the study of behavioral evolution, there has not been a review of their behavior, ecology, and evolution in over 25 years. To address this gap, we leverage a developing community of researchers who have contributed to a detailed knowledge of burying beetles to highlight the utility of Nicrophorus for investigating the causes and consequences of social and behavioral evolution. [ABSTRACT FROM AUTHOR]

Parental care strategies do not only vary greatly across species, but also within species there can be substantial between‐ and within‐individual variation in parental care behavior. To better understand the evolution of care strategies, it is crucial to determine how and when parents modify their behavior in response to internal as well as environmental factors. Here, we investigated the effect of brood size, resource size and an individual's quality on care strategies of uniparental males and examined the downstream consequences on offspring performance in the burying beetle Nicrophorus vespilloides. Burying beetles breed on small vertebrate cadavers and, on average, males invest much less in care than females. Nevertheless, we found that uniparentally caring males were responsive to their social and non‐social environment and adjusted the amount as well as the type of care to the size of the brood, the size of the cadaver and their own body size. Additionally, we show that the care strategies affected offspring performance. Specifically, males that cared longer had larger and more surviving larvae. Our results add to our understanding of plastic parenting strategies by showing that even the sex that provides less care can evolve a very flexible care behavior. [ABSTRACT FROM AUTHOR]

To link to full-text access for this article, visit this link: http://dx.doi.org/10.1016/j.anbehav.2010.06.018 Byline: Sandra Steiger (a)(b), Josef K. Muller (b) Abstract: Burying beetles exhibit elaborate biparental care, in which a male and a female bury a carcass upon which they rear their brood and defend it against conspecific competitors. If an intruder succeeds in taking over the carcass, it kills the entire brood and rears its own young on the remaining resource. However, the resident male and female are able to discriminate between an intruder and their breeding partner, and assist their mate in driving off intruders of either sex. Efficient brood guarding requires effective recognition and discrimination mechanisms. Theory predicts that the setting of the optimal acceptance threshold should be affected by the rates of interaction with desirable and undesirable individuals, and shift towards a less permissive threshold when the probability of encountering intruders increases. Here we provide a critical test of acceptance-threshold theory by investigating discrimination rules during reproduction in the burying beetle Nicrophorus vespilloides. The beetles typically discriminate between their breeding partners and conspecific intruders based on a class-specific discrimination rule: they generally accept beetles that are also caring for larvae (whether their own partner or not), but are aggressive towards all nonbreeding beetles. However, we demonstrate that this recognition system is flexible at the level of individual experience and changes with context. After the introduction of an intruder, rejection rate increased, which was manifested as a shift from class-specific to individual-specific discrimination: males suddenly began discriminating between their own breeding partner and novel breeding females, and were more aggressive towards the latter. We show that the plasticity in the recognition system is not caused by template updating, but instead by a flexible acceptance threshold. Our experiments suggest that breeding males learn the individual features of their own breeding partner, but set their acceptance threshold depending on the risk of encountering an intruder. Author Affiliation: (a) Behavior, Ecology, Evolution & Systematics Section, School of Biological Sciences, Illinois State University, U.S.A. (b) Faculty of Biology, Department of Evolutionary Biology and Ecology, University of Freiburg, Germany Article History: Received 25 March 2010; Revised 20 April 2010; Accepted 19 May 2010 Article Note: (miscellaneous) MS. number: A10-00208

To link to full-text access for this article, visit this link: http://dx.doi.org/10.1016/j.anbehav.2009.09.019 Byline: Wolf Haberer (a), Sandra Steiger (a)(b), Josef K. Muller (a) Abstract: In recent years, studies have shown that animals can communicate their physiological state or condition by means of chemical signals. However, as the chemicals involved in the condition-dependent signals have rarely been identified, evolutionary mechanisms that ensure their reliability are not well understood. We identified a volatile chemical signal that may serve as a reliable indicator of hormonal state in burying beetles, and is involved in their partner recognition system. Burying beetles reproducing on carcasses are able to distinguish between their breeding partners and infanticidal conspecifics. This discrimination depends on breeding status, which is positively linked to juvenile hormone III (JH III) titre. Breeding Nicrophorus vespilloides beetles, in contrast to nonbreeding ones, emitted considerable amounts of (E)-methylgeranate. The amount of emitted (E)-methylgeranate was positively correlated with juvenile hormone titres known from other burying beetle studies. Moreover, our behavioural experiments showed that dummies treated with methylgeranate induced tolerant behaviour, whereas control dummies were treated aggressively. The fact that (E)-methylgeranate and JH III share a conspicuous structural similarity and the same biosynthetic pathway may explain how the reliability of the signal for JH titre is ensured. We discuss the implications of our results in the light of theoretical work on the evolution of chemical communication, particularly on the origin of chemical signals. Author Affiliation: (a) Faculty of Biology, Department of Evolutionary Biology and Ecology, University of Freiburg, Germany (b) Behavior, Ecology, Evolution and Systematics Section, School of Biological Sciences, Illinois State University, USA Article History: Received 25 June 2009; Revised 4 August 2009; Accepted 9 September 2009 Article Note: (miscellaneous) MS. number: 09-00428