Necrophorus [sic] vespilloides v. AltumiWesthoff, 1881
Necrophorus [sic] vespilloides v. sylvaticusReitter, 1895
Necrophorus [sic] vespilloides v. sylvivagusReitter, 1897
Necrophorus [sic] vespilloides v. fractusPortevin, 1914
Necrophorus [sic] vespilloides v. borealisPortevin, 1914
Necrophorus [sic] vespilloides v. subfaciatusPortevin, 1914
Necrophorus [sic] vespilloides v. subinterruptusPic, 1917
Necrophorus [sic] vespilloides v. borealisPortevin, 1924 (Preocc.)
Nicrophorus vespilloides is a burying beetle described by Johann Friedrich Wilhelm Herbst in 1783. The beetles vary widely in size and can present with a range of anywhere from 12 mm to 20 mm in size.[1] They have two conspicuous orange-yellow bands on the elytra. The color of the antennae are an important distinguishing feature, being totally black.[2] The color of their orange and black markings is multifunctional, as they are conspicuous to avian predators. In general, they present a unique ecological niche, which is their evolution of aposematism, or the strategy they use to warn predators through their conspicuous signals.[3] The wing cases of these beetles possess a squarish shape and are notably shorter in length than their abdomens, indicating a distinct physical characteristic of the species.[1]
Overall, there are reported differences in coloration and chemical defenses among the sexes. This is hypothesized to stem from conflicting selection pressures for the different sexes. They also produce anal fluid or exudate from their abdomen when they feel threatened. These anal fluids further contribute to the antimicrobial defense of these beetles.
Geography
These insect species boast a wide distribution that spans an extensive range of geographic areas, including the far northern regions of Scandinavia within Europe, to Siberia, and reaching into various parts of Asia, notably China and Japan. Additionally, their geographic range stretches into North America, covering northern parts of the United States and including much of southern Canada.
This broad distribution underscores the beetles' exceptional adaptability and resilience, enabling them to flourish in a diverse array of environmental contexts. They are particularly prevalent in both the Palaearctic and Nearctic biogeographic realms, which is indicative of their ability to adapt and survive under a wide spectrum of environmental conditions. Within the expansive Palaeearctic region, these beetles occupy a wide ecological niche, making their home in environments ranging from the low-lying plains to the higher elevations of alpine regions. They can be found in various habitats that notably encompass dense woodlands, open heathlands, landscaped parklands, and even residential gardens, showcasing their remarkable versatility.
In contrast, within the Nearctic region, their habitat preferences appear to be more selective. Here, they are primarily found in specific types of environments, such as sphagnum bogs, marshy areas, and the fringes of upland regions. This suggests a more specialized adaptive nature to particular environmental conditions prevalent in these parts of North America. This extensive and varied geographical distribution, along with their diverse habitat preferences, highlight the beetles' wide-ranging adaptability and the ecological resilience they exhibit across different regions of the world.[1]
Description
The beetles of N. vespilloides have highly variable body size that ranges from 12–20 mm.[1] They have two conspicuous orange-yellow bands on the elytra. The color of their antennae are completely black.[2] Their orange and black markings serve as a warning sign to avian predators that defends them from attack. Their distinct wing cases are squarish in shape and are shorter than their abdomens.[1]
Activity
The adult beetles are known to follow specific seasonal patterns of activity, which are intricately linked to the cyclical changes in their natural habitats and the current climate that they live in. Typically, these insects emerge from dormancy and become notably active during the spring months, with their activity beginning around spring in early April and May. This period marks the beginning of their most active phase, which continues through the months of spring and summer, extending into the late autumn. Within this active phase, there are particularly significant peaks in activity observed in May, a time when environmental conditions are most favorable for their survival and for engaging in reproductive behaviors. Following this peak, there is a notable resurgence in activity during the late summer months, suggesting a bi-modal pattern of activity. This pattern is not arbitrary but rather is a strategic adaptation to the environmental conditions that are most conducive to their survival and the successful reproduction and nurturing of their offspring.[1]
Bi-parental care
An aspect of the behavioral ecology of these beetles is their commitment to biparental care, where both male and female parents are deeply involved in the care and nurturing of their offspring. This biparental care strategy is characterized by a thoughtful and balanced investment of resources not only towards activities directly related to reproduction, such as egg-laying and the guarding of larvae but also towards maintaining a robust immune function. This dual focus highlights a highly evolved and sophisticated approach to ensuring the survival and well-being of their offspring while, at the same time, preserving the health and vitality of the adult beetles. This approach to parental care is particularly noteworthy as it indicates a level of complex social behavior and cooperation between male and female beetles, contributing significantly to their success as a species. By investing in both their immediate reproductive success and their longer-term health and survival, these beetles demonstrate an adaptive strategy that allows them to thrive across a diverse range of environmental landscapes, underlining the complexity and sophistication of their life strategies in facing the challenges of their ecosystems.[4]
Burying behavior
Nicrophorus vespilloides shares its reproductive behavior with a sister species Nicrophorus nepalensis. Both species locate vertebrate carcasses and bury them underground to use them as a food source for their offspring. While their respective habitats and ecological niches certainly change the exact mechanism of burying tendencies, both species engage in the general framework of this form of bi-parental care.
Sister beetle
What had been considered Nicrophorus vespilloides in mid and eastern Canada and northeastern USA was determined by Sikes et al. in 2016[5] to be a separate, overlooked sister species of Nicrophorus vespilloides that had been named by Kirby in 1837. This sister species, Nicrophorus hebes Kirby,[5] is restricted to Sphagnum bogs and marshes,.[6][7]Nicrophorus vespilloides occurs throughout the northern Palearctic, Alaska and northwestern Canada where it is found in open forest habitats. The restriction of its sister species N. hebes to bogs in North America has been attributed to competition with its closely related congener, N. defodiens which in this area is found in forest habitats. N. hebes reproduces exclusively in bogs in North America and is never found in adjacent (<100m or 330ft) forested habitat in the Mer Bleue bog area near Ottawa, Ontario, Canada.[8]
Mites
Beetles Nicrophorus vespilloides and Oiceoptoma thoracicum perusing an unidentified small carcass.
There are also a number of phoretic (hitch-hiking) mites that are associated with N. vespilloides. These include Pelzneria nr. crenulata, Macrocheles merderius, and Uroobovella nr. novasimilis and the largest mite Poecilochirus carabi.[9]P. carabi is not attached by any physical means (such as a secreted anal stalk in the case of M. merderius) to N. vespilloides. When the males or females of N. vespilloides have finished breeding on a carcass the deutonymphs of P. carabi roam freely about the body of the beetles as they search for new carcasses to reproduce. It had been proposed that P. carabi deutonymphs, on arrival at a new carcass dismounted from the beetles and consumed fly eggs and larvae which would have competed for the beetle larvae for food.[10] This relationship which benefited the beetles has been described as mutualistic.[11][12] However, it has been shown that adults of P. carabi consume the eggs of N. vespilloides and that this has direct and negative effects on the reproduction of this beetle species.[13] This is one of the most well studied of the burying beetles with over 1,000 citations found via Google Scholar.[5]N. vespilloides is also used as a model organism in the study of social immunity.
Reproduction and parental care
The reproductive success of burying beetles is intricately linked to their unique ecological niche, specifically their reliance on securing a small vertebrate carcass for breeding purposes. The discovery of such a carcass is a pivotal moment in the beetles' reproductive cycle, triggering a significant increase in juvenile hormone (JH) levels. It's noteworthy that in other species, elevated JH levels have been associated with the suppression of the immune system, hinting at a possible trade-off in burying beetles where there might be a down regulation of the immune response during the critical period of breeding.[4] This adaptation underscores the beetles' prioritization of reproduction, even at the potential cost of reduced immune defenses.
Upon locating a suitable carcass, the beetle parents engage in a collaborative effort to bury it beneath the soil. This is a meticulous preparation process where any fur or feathers are carefully removed, and the carcass is shaped into a compact ball. This ball is then coated with a concoction of antimicrobials and secretions, a deliberate action taken by the beetles to slow down the decomposition process. It is in the vicinity of this carefully prepared carcass, now nestled within the soil, that the beetles choose to lay their eggs. A few days after the eggs are laid, the larvae hatch and instinctively navigate their way to the carcass, which serves as both their food source and nursery. The adult beetles then take on the role of providers, offering their young pre-digested food and protecting them from potential predators and competitors. This nurturing phase is critical, and should one parent abandon the effort or reduce their participation, the remaining partner compensates by ramping up their caregiving efforts through the efforts of practicing bipartialism. Instances of both parents deserting their offspring are exceptionally rare in this species, underscoring the high degree of parental investment typical of burying beetles. Moreover, the dynamic of parental decision-making in this context is fascinating, suggesting a complex interplay of negotiation and cooperation between the male and female. This is not a scenario where decisions are made unilaterally; rather, it involves continuous interaction and mutual adjustment between the parents, pointing to a sophisticated level of social coordination and communication. The decision-making process is likely a result of a negotiation involving repeated interactions between the male and female, rather than a single decision made by each parent independently.[14]
The link between parental care and the health and growth of the offspring is profound and well-documented. Research indicates that the quality of food provisioning by the parents, particularly in terms of the carcass's freshness, plays a significant role in determining offspring health and development. For instance, one study highlighted that offspring tended to fare better in terms of growth and health when their parents were breeding on higher quality, less decomposed carcasses. This contrasted with scenarios where the parents were utilizing lower quality, more decomposed food sources, thereby underscoring the critical role of parental effort and resource quality in the developmental success of the burying beetles' young.[15] This intricate balance between resource acquisition, parental care, and offspring development highlights the complexity of the burying beetles' reproductive and social behavior, offering valuable insights into the evolutionary pressures and adaptations that shape their life history strategies.
Immunity
In the world of burying beetles, the balance between the imperatives of reproduction and the maintenance of immune function unfolds as a complex natural behavior for these beetles further showcasing the remarkable capabilities of both male and females for their practice of biparental care. This intricate dynamic involves a meticulous calibration where the energy and resources dedicated to reproduction must be judiciously balanced against those reserved for immune defense mechanisms.
Central to the beetle's immune arsenal is the enzyme Phenoloxidase (PO), a critical player in the cellular immune response and vital for the cuticle's hardening process. During the reproductive phase, there's a noticeable increase in PO activity, suggesting a potential impact on parental investment strategies by directly influencing reproductive success metrics. This link is pivotal because the quality and extent of parental care are directly correlated with the growth and survival rates of the offspring, making the number and mass of offspring reliable barometers of parental effort. The life cycle of burying beetles offers a vivid illustration of this equilibrium, with juvenile hormone levels experiencing a surge as larvae emerge—a phase coinciding with a noted decrease in PO levels. However, research indicates that PO levels can be upregulated in response to injury, even as larvae partake in feeding on the carcass. This aspect is particularly pertinent in scenarios involving encapsulation challenges, where a pronounced increase in PO activity would be imperative. Such an adaptive immune response to physical injury underscores the beetles' ability to navigate the potential drawbacks of immunosuppression, effectively masking any trade-offs between immune functionality and reproductive endeavors.
This nuanced dynamic underscores a sophisticated strategy employed by the beetles, deftly allocating resources to ensure the sustenance and protection of their progeny while concurrently safeguarding their survival against the myriad environmental challenges they face. This complex interplay between reproductive strategies and immune function not only highlights the evolutionary adaptiveness of burying beetles but also offers a fascinating glimpse into the resource management strategies critical for their survival and reproductive success.[3]
Genes
In the context of burying beetles, which predominantly feed on the carrion of vertebrates, an intriguing aspect of their biology is their genetic composition, particularly in relation to their digestive capabilities. These beetles possess a very limited set of genes related to the breakdown of lignocellulose, a primary component of plant cell walls. Specifically, their genome includes just a single gene from the glycoside hydrolase family 9 (GH9) and a few from the glycoside hydrolase family 1 (GH1). This genetic makeup is somewhat unexpected, given that their diet does not typically include lignocellulosic materials, which are abundant in plant matter.
Despite the absence of a lignocellulose-rich diet, there exists a complex and highly integrated interaction between the metabolic processes of the beetles and their gut microbiome. This synergistic relationship plays a crucial role in the beetles' ability to digest their food efficiently. Moreover, the gut microbiome assists in the detoxification processes, which is vital for the beetles' ability to consume carrion, a food source that might otherwise be toxic or harmful due to decomposition and the presence of potentially pathogenic microorganisms. Furthermore, the collaboration between the beetles and their gut microbiota extends to the protection of their food source. The microbial community within the beetles' gut contributes to warding off spoilage and inhibiting the growth of competing microorganisms. This ensures that the carrion remains a viable food source for the beetles and their offspring for a longer period. This interaction highlights the importance of the gut microbiome in supplementing the beetles' digestive capabilities, allowing them to extract necessary nutrients from their specialized diet and protect their niche from competitors. This complex interplay between the beetles' metabolic functions and their gut microbiome underscores the adaptive strategies these organisms employ to thrive in their ecological niche, despite the seemingly limited genetic toolkit for digesting their primary food source.[16]
Future research
This is one of the most well-studied of the burying beetles with over 1,000 citations found via Google Scholar. N. vespilloides is also used as a model organism in the study of social immunity. In future research, this beetle will continue to be a model used to understand the many complex social behaviors that exist such as parental care, mating conflict, sibling-sibling conflict, and the genetic architecture of these behaviors.[17]
Silphidae is a family of beetles that are known commonly as large carrion beetles, carrion beetles or burying beetles. There are two subfamilies: Silphinae and Nicrophorinae. Members of Nicrophorinae are sometimes known as burying beetles or sexton beetles. The number of species is relatively small, at around two hundred. They are more diverse in the temperate region although a few tropical endemics are known. Both subfamilies feed on decaying organic matter such as dead animals. The subfamilies differ in which uses parental care and which types of carcasses they prefer. Silphidae are considered to be of importance to forensic entomologists because when they are found on a decaying body they are used to help estimate a post-mortem interval.
Burying beetles or sexton beetles, genus Nicrophorus, are the best-known members of the family Silphidae. Most of these beetles are black with red markings on the elytra (forewings). Burying beetles are true to their name—they bury the carcasses of small vertebrates such as birds and rodents as a food source for their larvae; this makes them carnivorous. They are unusual among insects in that both the male and female parents take care of the brood.
Nicrophorus americanus, also known as the American burying beetle or giant carrion beetle, is a critically endangered species of beetle endemic to North America. It belongs to the order Coleoptera and the family Silphidae. The carrion beetle in North America is carnivorous, feeds on carrion and requires carrion to breed. It is also a member of one of the few genera of beetle to exhibit parental care. The decline of the American burying beetle has been attributed to habitat loss, alteration, and degradation, and they now occur in less than 10% of their historic range.
Life history theory (LHT) is an analytical framework designed to study the diversity of life history strategies used by different organisms throughout the world, as well as the causes and results of the variation in their life cycles. It is a theory of biological evolution that seeks to explain aspects of organisms' anatomy and behavior by reference to the way that their life histories—including their reproductive development and behaviors, post-reproductive behaviors, and lifespan —have been shaped by natural selection. A life history strategy is the "age- and stage-specific patterns" and timing of events that make up an organism's life, such as birth, weaning, maturation, death, etc. These events, notably juvenile development, age of sexual maturity, first reproduction, number of offspring and level of parental investment, senescence and death, depend on the physical and ecological environment of the organism.
Parental care is a behavioural and evolutionary strategy adopted by some animals, involving a parental investment being made to the evolutionary fitness of offspring. Patterns of parental care are widespread and highly diverse across the animal kingdom. There is great variation in different animal groups in terms of how parents care for offspring, and the amount of resources invested by parents. For example, there may be considerable variation in the amount of care invested by each sex, where females may invest more in some species, males invest more in others, or investment may be shared equally. Numerous hypotheses have been proposed to describe this variation and patterns in parental care that exist between the sexes, as well as among species.
Lethocerus deyrollei is a species of giant water bug that traditionally is included in the genus Lethocerus, although recent authorities place it in the monotypic Kirkaldyia. They are large, predatory and nocturnal insects. They are one of the best known giant water bugs and are found in India, Japan, Korea, east China, east Indochina, and the Amur region of Russia. They are very common in much of their range, but have declined drastically in some regions and are considered threatened in Japan and Korea. They live in still waters with vegetation, hatching in the summer months and then overwintering half a year later as adults. They primarily feed on small fish, amphibians and aquatic insects, but have also been recorded taking water snakes and young turtles.
Nicrophorus tomentosus is a species of burying beetle that was described by Friedrich Weber in 1801. The beetle belongs to the family Silphidae which are carrion beetles. The beetles have sensitive antennae that contain olfactory organs. Thus, the beetle can locate dead animals (carcass), and then as the name suggests, can bury them. However, unlike other burying beetles, N. tomentosus does not completely bury these brood carcasses. They instead dig a shallow hole under the carcass and cover it with leaf litter. Recognition of these beetles can be distinguished by its black color with orange markings on the wing covers (elytra).
Nicrophorus nepalensis, commonly known as burying beetle, is widespread across tropical and subtropical countries in Asia. It belongs to the order Coleoptera and the family Silphidae, and is part of the nepalensis species-group, which is the second largest species group within the genus Nicrophorus. N. nepalensis differs from some other beetles in that it exhibits biparental care. Its role as a decomposer is crucial in the energy cycle and energy transformation in the ecosystem.
Nicrophorus pustulatus, also known as the pustulated carrion beetle or blistered burying beetle, is a species of burying beetle that was described by Johann Karl Wilhelm Illiger in 1807. This species is native to North America. N. pustulatus exhibits unique habitat utilization and breeding behaviour relative to other members of the genus. This species may be the only described example of a true parasitoid targeting a vertebrate host.
Nicrophorus vespillo is a burying beetle described by Carl Linnaeus in his landmark 1758 10th edition of Systema Naturae. It has a paleartic distribution and is commonly found across Europe and Asia, extending from Western Europe to Mongolia.
Nicrophorus interruptus is a species of burying beetle or sexton beetle belonging to the family Silphidae subfamily Nicrophorinae.
Nicrophorus quadripunctatus is a species of burying beetle that predominates in East Asia. First described by German entomologist Ernst Kraatz in 1877, this beetle has since been the subject of much scientific inquiry—particularly concerning its parental care. Like other burying beetles, N. quadripunctatus inhabit small, vertebrate animal carcasses. This environment provides the beetles with the requisite nutrients for themselves and their offspring. To limit resource theft and predation, the carcass is buried underground. For additional protection, a single, dominant male-female pair guards the carcass cooperatively.
Nicrophorus orbicollis is a nearctic burying beetle first described by Thomas Say in 1825. It is a member of the genus Nicrophorus or sexton beetles, comprising the most common beetles in the family Silphidae. This species is a decomposer feeding on carcasses of small dead animals. N. orbicollis can be used for scientific research both medically and forensically.
The American carrion beetle is a North American beetle of the family Silphidae. It lays its eggs in, and its larvae consume, raw flesh and fungi. The larvae and adults also consume fly larvae and the larvae of other carrion beetles that compete for the same food sources as their larvae. They prefer to live in marshy and woody habitats. Necrophila americana emerge from their larval state in the early summer. The P. ashtoni cuckoo bumble bee displays close mimicry with the American carrion beetle. They are important in forensic studies because of their tendency to thrive on large carcasses.
Poecilochirus is a Holarctic genus of mites in the family Parasitidae. They are relatively large and often found on rotting corpses, where they are transported by beetles. Deuteronymphs are characterized by two orange dorsal shields and in many species a transverse band on the sternal shield. The juvenile development consists of a larval stage, protonymph, and deuteronymph, but no tritonymph. Females are smaller than males. Males guard female deuteronymphs shortly before these mate, and pairs mate venter-to-venter.
Semelparity and iteroparity are two contrasting reproductive strategies available to living organisms. A species is considered semelparous if it is characterized by a single reproductive episode before death, and iteroparous if it is characterized by multiple reproductive cycles over the course of its lifetime. Iteroparity can be further divided into continuous iteroparity and seasonal iteroparity Some botanists use the parallel terms monocarpy and polycarpy.
Filial cannibalism occurs when an adult individual of a species consumes all or part of the young of its own species or immediate offspring. Filial cannibalism occurs in many species ranging from mammals to insects, and is especially prevalent in various types of fish species with males that engage in egg guardianship. The exact evolutionary purpose of the practice in those species is unclear and debated among zoologists, though there is consensus that it may have, or may have had at some point in species' evolutionary history, certain evolutionary and ecological implications.
Parental care refers to the level of investment provided by the mother and the father to ensure development and survival of their offspring. In most birds, parents invest profoundly in their offspring as a mutual effort, making a majority of them socially monogamous for the duration of the breeding season. This happens regardless of whether there is a paternal uncertainty.
Social immunity is any antiparasite defence mounted for the benefit of individuals other than the actor. For parasites, the frequent contact, high population density and low genetic variability makes social groups of organisms a promising target for infection: this has driven the evolution of collective and cooperative anti-parasite mechanisms that both prevent the establishment of and reduce the damage of diseases among group members. Social immune mechanisms range from the prophylactic, such as burying beetles smearing their carcasses with antimicrobials or termites fumigating their nests with naphthalene, to the active defenses seen in the imprisoning of parasitic beetles by honeybees or by the miniature 'hitchhiking' leafcutter ants which travel on larger worker's leaves to fight off parasitoid flies. Whilst many specific social immune mechanisms had been studied in relative isolation, it was not until Sylvia Cremer et al.'s 2007 paper "Social Immunity" that the topic was seriously considered. Empirical and theoretical work in social immunity continues to reveal not only new mechanisms of protection but also implications for understanding of the evolution of group living and polyandry.
Rebecca M. Kilner FRES is a British evolutionary biologist, and a professor of evolutionary biology at the University of Cambridge.
↑ Robert S. Anderson (1982). "Resource partitioning in the carrion beetle (Coleoptera: Silphidae) fauna of southern Ontario: ecological and evolutionary considerations". Canadian Journal of Zoology. 60 (6): 1314–1325. doi:10.1139/z82-178.
↑ Clifford W. Beninger & Stewart B. Peck (1992). "Temporal and spatial patterns of resource use among Nicrophorus in a Sphagnum bog and adjacent forest near Ottawa, Canada". The Canadian Entomologist. 124 (1): 79–86. doi:10.4039/Ent12479-1. S2CID87153740.
↑ Clifford W. Beninger (1989). A study of the ecology and reproductive biology of the carrion beetle assemblage in the Mer Bleue Bog area with specific reference to the habitat associations of Nicrophorus vespilloides Herbst and N. defodiens Mannerheim (Coleoptera: Silphidae) (M.Sc. thesis). Ottawa, Ontario, Canada: Carleton University.
↑ Clifford W. Beninger (1993). "Egg predation by Poecilochirus carabi (Mesostigmata: Parasitidae) and its effect on reproduction of Nicrophorus vespilloides (Coleoptera:Silphidae)". Environmental Entomology. 22 (4): 766–769. doi:10.1093/ee/22.4.766.
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