Silphidae Research Articles

Parental care and competition with microbes in carrion beetles: a study of ecological adaptation

The investigation of the function of a complex adaptation can benefit from multiple approaches. We used comparative study and physical simulation to re-examine the hypothesis that parental adaptations enable carrion beetles (Silphidae) to better compete with carrion microbes. The comparative study used two closely related species, Nicrophorus orbicollis and Ptomascopus morio, which differ markedly in their level of care. Reproductive performance was measured using carcasses aged on field soil for 0, 3, 6 or 9 days. As expected, N. orbicollis converted more carrion biomass to offspring biomass than did P. morio (27.8% versus 16.6% on fresh carcasses) and both species produced smaller broods on aged carcasses. There was a negative interaction, however, between the level of care and carcass age on reproductive performance; the parental care advantage exhibited by N. orbicollis was less on older carcasses than on fresh carcasses, and was negligible on the oldest (6- and 9-day) carcasses. Ptomascopus morio also demonstrated superior ability to regulate the size of offspring when using carcasses of various ages. In a second experiment, we simulated antimicrobial activity of Nicrophorus anal exudates. A 6-day pretreatment with an antibacterial, an antifungal, or a combination treatment did not result in larger broods relative to those on untreated 6-day carcasses. The results call into question the hypothesis that preparation of the carcass by Nicrophorus evolved primarily as an adaptation for preventing microbial deterioration of carrion. We suggest that selection to compete with microbes may be relaxed in carrion beetles that provide elaborate parental care. A small vertebrate carcass is a potential model system for applying the comparative method to ecological function.

Effects of Bait Presence and Type of Preservative Fluid on Ground and Carrion Beetle Samples Collected by Pitfall Trapping.

Pitfall trapping is a sampling technique frequently used by entomologists around the world. However, there exist sampling biases linked to particular trapping designs, which require investigation. In this study, we compared the effects of the type of preservative fluid (propylene glycol or formaldehyde) and the presence of fish bait in pitfall traps on the number of specimens (individuals) collected, the species richness, and the species composition of carabid (Coleoptera: Carabidae) and silphid (Coleoptera: Silphidae) beetle assemblages. Traps containing propylene glycol collected a substantially higher number of individuals of both taxa and a higher number of silphid species compared with traps containing formaldehyde. The use of fish bait in the traps increased the number of individuals collected and the number of species collected for silphid beetles but had no effect on the collection parameters for carabids. The species composition of the carabid assemblages was minimally affected by the presence of fish bait or the type of preservative fluid, whereas the fish bait had a substantial effect on the species composition of silphids. The silphid species that feed directly on vertebrate carcasses were almost completely absent in the nonbaited traps. The results suggest that pitfall traps baited with fish and containing propylene glycol as a preservative fluid are optimal for the simultaneous sampling of carabid and silphid beetles, which both provide important ecosystem services (e.g., predation of pests and decomposition of vertebrate carcasses) and are therefore interesting for ecological research.

Classification of forensically-relevant larvae according to instar in a closely related species of carrion beetles (Coleoptera: Silphidae: Silphinae).

Carrion beetle larvae of Necrodes littoralis (Linnaeus, 1758), Oiceoptoma thoracicum (Linnaeus, 1758), Thanatophilus sinuatus (Fabricius, 1775), and Thanatophilus rugosus (Linnaeus, 1758) (Silphidae: Silphinae) were studied to test the concept that a classifier of the subfamily level may be successfully used to classify larvae according to instar. Classifiers were created and validated using a linear discriminant analysis (LDA). LDA generates classification functions which are used to calculate classification values for tested specimens. The largest value indicates the larval instar to which the specimen should be assigned. Distance between dorsal stemmata and width of the pronotum were used as classification features. The classifier correctly classified larvae of N. littoralis and O. thoracicum, whereas in the case of T. sinuatus and T. rugosus a few misclassifications were recorded. For this reason, a separate genus level classifier was created for larvae of Thanatophilus. We conclude that larval instar classifiers of the subfamily or genus level have very high classification accuracy and therefore they may be safely used to classify carrion beetle larvae according to instar in forensic practice.

Life history traits predict insect species responses to large herbivore overabundance: a multitaxonomic approach

There is increasing concern over the ecological impact of markedly increasing numbers of large herbivores (hereafter large herbivore overabundance) on forest ecosystems. To predict the ecological consequences of large herbivore overabundance, it is first necessary to understand how biological communities respond to large herbivore overabundance. Here, we examined the relationships between the life history traits of five insect taxonomic groups (moths, dung beetles, longicorn beetles, carabid beetles, and carrion beetles) and their responses to deer overabundance in Hokkaido, northern Japan. Insects were collected from three study sites: enclosure (20 deer/km2), control (10 deer/km2), and exclosure (0 deer/km2). The different taxonomic and functional insect species differed in their response to deer overabundance. The abundance (number of individuals) of longicorn beetles, dung beetles, and arbor-feeding moths was higher in the enclosure site than in the control site, whereas that of carabid beetles, carrion beetles, and herb- or shrub-feeding moths was higher in the control site than in the enclosure site. These results suggest that the type of food and the level of dependence on the understory are key traits determining insect sensitivity to deer overabundance. In addition, large or flightless species responded negatively to deer overabundance. Overall, this study demonstrated a significant change in insect communities following experimental deer overabundance, suggesting that large herbivore overabundance leads to the homogenization of biological communities. Unfortunately, because insects have diverse functions in forest ecosystems, such marked changes in both abundance and composition of insect communities will decrease ecosystem functions and resilience.

Carrion beetles succession in three different habitats in Riyadh, Saudi Arabia.

A main objective of the study is the establishment of a forensic entomological database for Riyadh, Saudi Arabia. Decomposition processes and beetle succession were analysed on rabbit carcasses in three different habitats (agricultural, desert and urban) in the period from May to July 2014. Due to the effects of the high temperature at the study sites, carrion reached the dry stage within 12 days in the agricultural habitat, and 6 days in the desert and urban habitats. A total of 125 beetles belonging to eight species and five families were collected during the decaying process, with their abundances increasing from the fresh to decay stages. The prevailing species belonged to the families of Dermestidae and Histeridae. It was not possible to confirm any definitive relationship between the occurrence of a single species and a particular stage of decomposition. The beetle communities were also not distinctively different between desert and urban habitats, but a distinct community was evident in the agriculture habitat. In addition, there were distinct beetle communities between the decay stage and the other stages. The dry stage recorded the lowest number of beetles. This study indicated that, the habitat type had an effect on the decay process and the abundance rate of the beetles.

Interesting records of two small carrion beetles (Coleoptera: Leiodidae: Cholevinae) from Hungary

Cholevinus pallidus rufus (Kraatz, 1870), found in a red fox den entrance is reported for the first time from Hungary. Choleva (Choleva) lederiana pilisensis Růžicka et Vavra, 2003, an endemic subspecies from Hungary, is reported from additional localities in Pilis Mts and Buda Hills. With 5 figures.

林齢の異なる小面積林分からなる森林における腐肉食性甲虫（腐肉食性シデムシとコガネムシ上科糞虫）群集の反応

簡易な方法で捕獲した腐肉食性甲虫 (シデムシ科とコガネムシ上科食糞群) 群集の森林環境に対する指標性を評価するため, 2012年に熊本市内の林齢が異なる小面積林分からなる森林内の15林分で魚肉を誘引餌としたピットフォールトラップを1個設置した。その結果, 13種7,667個体の腐肉食性甲虫が捕獲された。種数,総捕獲数, シンプソンの多様度指数と6種の捕獲数は, 林齢と有意な正の関係を示した。また, 林分を林齢に伴う3グループ (新植地, 若齢林と壮齢林) に分け, 指標種分析を行ったところ,有意な指標種が若齢林に1種, 壮齢林に7種みられた。非計量多次元尺度構成法 (NMS) による各林分群集の座標付けにおいても, 若齢林の1座標を除くと, 林齢に伴う3グループは分かれた。以上の結果から,今回の方法で得られた腐肉食性甲虫群集は, 小面積林分がモザイク状に存在する森林において, 環境に対して優れた指標性を示し, 林齢に伴う森林環境の変化に反応していると考えられた。

Highlights--Does Methylation Make the Parent? A First Dive into the Genetics of Social Beetles.

Highlights--Does Methylation Make the Parent? A First Dive into the Genetics of Social Beetles.

Is the type of soil an important factor determining the local abundance of carrion beetles (Coleoptera: Silphidae)?

Carrion beetles (Coleoptera: Silphidae) provide a valuable ecosystem service by promoting nutrient cycling and controlling pests like noxious flies (Diptera: Calliphoridae and Sarcophagidae). Our main goal was to examine the relationship between the occur - rence of carrion beetles and soil type. We used pitfall traps to collect 43,856 specimens of 15 species of carrion beetles in the Czech Republic during 2009. We found that the abundance of seven of the carrion beetles - Nicrophorus antennatus (Reitter), N. germanicus (Linnaeus), N. humator (Gleditsch), N. interruptus (Stephens), N. sepultor (Charpentier), Silpha obscura obscura (Herbst) and T. sinuatus (Fabricius) - was significantly higher either in areas with chernozem or fluvisol soils. These findings support our hypothesis that soil type could be an important factor determining the occurrence of necrophagous European carrion beetles. Our findings could be helpful when selecting important nature conservation sites (particularly inasmuch as N. antennatus, N. germanicus and N. sepultor are listed as endangered species on the Czech Red List of Invertebrates) as in this respect localities where there are chernozem soils are potentially valuable.

Coleópteros necrócolos (Scarabaeidae: Scarabaeinae, Silphidae y Trogidae) del Bosque Los Colomos, Guadalajara, Jalisco, México

A survey of the necrocolous beetle assemblage was done in the Bosque Los Colomos, a Protected Natural Area from Guadalajara County, Jalisco, Mexico. The study area contains elements of pine, casuarina and eucalyptus. This area is dedicated to public activities, mainly devoted to sports. Based in the anthropic activity as a qualitative criterion of environmental perturbation, carrion beetle assemblage was evaluated. Fieldwork was done from July 2011 to July 2012 using carrion traps baited with squid. A total of 362 specimens belonging to 8 species of the families Trogidae, Silphidae and Scarabaeidae (Scarabaeinae) were collected. Trox spinulosus dentibius Robinson, 1940, and Oxelytrum discicolle (Brullé, 1840) were the most abundant species. Lower abundance and specific richness in this area is explained as an effect of the landscape changes due to an increase of anthropic activities. Seasonal abundance is closely related to temperature and precipitation values: highest abundance was from June to November in eucalyptus sites. Trox spinulosus dentibius was the dominant species. We do not have detailed information to explain this high abundance, although it could be due to the change in the assemblage structure in these environments.

Identification and synthesis of the male produced volatiles of the carrion beetle, Oxelytrum erythrurum (Coleoptera: Silphidae)

Necrophagous beetles belonging to the family Silphidae are recognized as potentially useful in forensic investigations (to estimate post mortem interval). Gas chromatography analyses of extracts of aerations of adult Oxelytrum erythrurum revealed the presence of two male-specific compounds. These compounds were identified as (Z)-1,10-nonadecadiene (major) and 1-nonadecene (minor) using microderivatizations of the natural male extract, such as hydrogenation, partial reduction and methylthiolation, mass spectrum comparisons, and co-injections with authentic standards. Both compounds might be components of a pheromone responsible for sexual communication in this species.

Beetles (Coleoptera) of the Rogów Region - Part III - Carrion Beetles (Silphidae)

In the present, the third part of the series titled “Beetles (Coleoptera) of the Rogów region” presents a family of carrion beetles (Silphidae), as one of the better-known families of beetles occurring in the Rogów area. The faunistic data of presented species enriched by bionomical information.

Beetles (Coleoptera) of the Rogów Region - Part III - Carrion Beetles (Silphidae)

In the present, the third part of the series titled “Beetles (Coleoptera) of the Rogów region” presents a family of carrion beetles (Silphidae), as one of the better-known families of beetles occurring in the Rogów area. The faunistic data of presented species enriched by bionomical information.

Effects of Deer Grazing on Vegetation and Ground-Dwelling Insects in a Larch Forest in Okutama, Western Tokyo

Sika deer (Cervus nippon) have experienced a rapid increase in the Japanese archipelago. Although the effects of deer grazing have been widely studied, the indirect effects have received little attention. Using an eight-year-old deer exclosure in western Tokyo (Japan), we studied the direct effects on plants and the indirect effects on insects and microenvironments. Plant biomass was 14 times higher inside the exclosure than outside. Shrubs (e.g.,Aralia elataandHydrangea paniculata) and trees (e.g.,Symplocos sawafutagiandClethra barbinervis) were more abundant inside, whereas only unpalatable trees in poor condition grew outside (e.g.,Pterostyrax hispidaandCynanchum caudatum). In the summer months, the maximum temperature was 8–10°C higher outside the exclosure and humidity was lower. Soil movement was 80 times more pronounced outside than inside. These results suggest that the abiotic environment became less stable for ground-dwelling insects. Carabid beetles were less abundant outside than inside, suggesting that deer grazing reduced plants and subsequently lowered habitat quality for these beetles. In contrast, carrion beetles, dung beetles, and camel crickets were more abundant outside. The increase in these insects is attributed to the availability of deer feces and carcasses and is a direct effect of deer presence.

Beetle succession and diversity between clothed sun-exposed and shaded pig carrion in a tropical dry forest landscape in Southern Mexico

Over a 31-day period, the decomposition process, beetle diversity and succession on clothed pig (Sus scrofa L.) carcasses were studied in open (agricultural land) and shaded habitat (secondary forest) in Southern Mexico. The decomposition process was categorised into five stages: fresh, bloated, active decay, advanced decay and remains. Except for the bloated stage, the elapsed time for each decomposition stage was similar between open and shaded habitats, all carcasses reached an advanced decay stage in seven days, and the fifth stage (remains) was not recorded in any carcass during the time of this study. A total of 6344 beetles, belonging to 130 species and 21 families, were collected during the entire decomposition process, and abundances increased from fresh to advanced decay stages. Staphylinidae, Scarabaeidae and Histeridae were taxonomically and numerically dominant, accounting for 61% of the species richness and 87% of the total abundance. Similar numbers of species (87 and 88 species for open and shaded habitats, respectively), levels of diversity and proportions (open 49%; shaded 48%) of exclusive species were recorded at each habitat. There were significantly distinct beetle communities between habitats and for each stage of decomposition. An indicator species analysis (“IndVal”) identified six species associated to open habitats, 10 species to shaded habitats and eight species to advanced decay stages. In addition, 23 beetle species are cited for the first time in the forensic literature. These results showed that open and shaded habitats both provide suitable habitat conditions for the carrion beetle diversity with significant differences in community structure and identity of the species associated to each habitat. This research provides the first empirical evidence of beetle ecological succession and diversity on carrion in Mexican agro-pastoral landscapes.

A review of the small carrion beetles and the round fungus beetles of the West Indies (Coleoptera: Leiodidae), with descriptions of two new genera and 61 new species.

A review of the small carrion beetles and the round fungus beetles of the West Indies (Coleoptera: Leiodidae), with descriptions of two new genera and 61 new species.

Egg survival is reduced by grave-soil microbes in the carrion beetle, Nicrophorus vespilloides.

BackgroundNicrophorus vespilloides eggs are deposited into the soil in close proximity to the decomposing vertebrate carcasses that these insects use as an obligate resource to rear their offspring. Eggs in this environment potentially face significant risks from the bacteria that proliferate in the grave-soil environment following nutrient influx from the decomposing carcass. Our aims in this paper are twofold: first, to examine the fitness effects of grave-soil bacteria to eggs, and second, to quantify egg immunocompetence as a defence against these bacteria.ResultsOur results provide strong evidence that grave-soil microbes significantly reduce the survival of Nicrophorus eggs. Females provided with microbe rich carcasses to rear broods laid fewer eggs that were less likely to hatch than females given uncontaminated carcasses. Furthermore, we show that egg hatch success is significantly reduced by bacterial exposure. Using a split-brood design, which controlled for intrinsic differences in eggs produced by different females, we found that eggs washed free of surface-associated bacteria show increased survival compared to unwashed eggs. By contrast, eggs exposed to the entomopathogen Serratia marcescens show decreased survival compared to unexposed eggs. We next tested the immune competence of eggs under challenge from bacterial infection, and found that eggs lacked endogenous production of antimicrobial peptides, despite well-developed responses in larvae. Finally, we found that despite lacking immunity, N. vespilloides eggs produce an extraembryonic serosa, indicating that the serosa has lost its immune inducing capacity in this species.ConclusionsThe dependency on ephemeral resources might strongly select for fast developing animals. Our results suggest that Nicrophorus carrion beetles, and other species developing on ephemeral resources, face a fundamental trade-off between egg immunity and development time.Electronic supplementary materialThe online version of this article (doi:10.1186/s12862-014-0208-x) contains supplementary material, which is available to authorized users.

Early origin of parental care in Mesozoic carrion beetles.

The reconstruction and timing of the early stages of social evolution, such as parental care, in the fossil record is a challenge, as these behaviors often do not leave concrete traces. One of the intensely investigated examples of modern parental care are the modern burying beetles (Silphidae: Nicrophorus), a lineage that includes notable endangered species. Here we report diverse transitional silphids from the Mesozoic of China and Myanmar that provide insights into the origins of parental care. Jurassic silphids from Daohugou, sharing many defining characters of Nicrophorinae, primitively lack stridulatory files significant for parental care communications; although morphologically similar, Early Cretaceous nicrophorines from the Jehol biota possess such files, indicating that a system of parental care had evolved by this early date. More importantly, burying beetles of the genus Nicrophorus have their earliest first record in mid-Cretaceous Burmese amber, and document early evolution of elaborate biparental care and defense of small vertebrate carcasses for their larvae. Parental care in the Early Cretaceous may have originated from competition between silphids and their predators. The rise of the Cretaceous Nicrophorinae implies a biology similar to modern counterparts that typically feed on carcasses of small birds and mammals.

Differences in surface-dwelling beetles of grasslands invaded and non-invaded by goldenrods (Solidago canadensis, S. gigantea) with special reference to Carabidae

We evaluated surface-dwelling Coleoptera with special reference to ground beetles (Coleoptera: Carabidae) using pitfall traps across fourteen stands of grasslands invaded and non-invaded by invasive goldenrods (Solidago canadensis L. and S. gigantea Ait.) over a 3 year period. We analysed differences in assemblages of invaded and non-invaded grasslands and tested responses of surface-dwelling beetles and carabids to invasion of goldenrods. We identified 29 Coleoptera families and 91 Carabidae species. Solidago invaded grasslands showed significantly higher activity-abundance of rove and carrion beetles and supported greater diversity and significantly higher evenness of surface-dwelling Coleoptera and the number of sampled families and individuals was higher too. We found lower taxonomic richness and significantly lower activity-abundance of carabids across goldenrods stands. Several less common Carabidae species and significantly higher representation of stenotopic brachypterous habitat specialists were also observed within invaded stands. We confirmed that differences in plant cover connected with invasion of goldenrods, soil moisture and abandonment of invaded habitats are the driving mechanisms of changes in surface-dwelling Coleoptera and ground beetles assemblages composition across Solidago invaded grasslands. Overall, changes of grassland biotopes connected with invasion of goldenrods significantly alter Coleoptera families and Carabidae assemblages, but not necessarily reduce diversity.

Do Males Bite Females' Antennae to Coerce Copulation or to Continue Mate Guarding in Oiceoptoma subrufum (Coleoptera: Silphinae)?

In several species, males frequently immobilize females during copulation. In some species, female immobilization enables males to copulate with unwilling females, while in others, female immobilization prolongs postcopulatory guarding. Male carrion beetles often bite and pull hard on one of the female's antennae during copulatory mounting. Previous descriptive studies have hypothesized that antenna biting is important for postcopulatory guarding in Silphinae. Here, we observed the mating behavior of Oiceoptoma subrufum, to understand the roles of antenna-biting in the initiation and termination of copulation. We compared the success and duration of intromission and pre- and postcopulatory mounting duration between males that did and did not bite female antennae during copulatory mounting. The success and duration of intromission and precopulatory mounting duration were unaffected by antenna biting. However, antenna-biting males mounted females for longer after intromission compared to non-biting males. These results indicate that antenna biting contributes to postcopulatory guarding behavior, not coercive copulation, in O. subrufum.