Burying beetles: intraspecific interactions and reproductive success in the field

Abstract. 1. The discovery and utilization of small carcasses by burying beetles (Silphidae, Nicrophorus ) was studied by placing dead mice at random points on large grids at two Iocations in Michigan, U.S.A.
2. The majority of mice are found within 24 h by more beetles than ultimately will utilize the carcass. If a carcass is likely to be usurped by a larger species of beetle or by a vertebrate, then intraspecific competition may be postponed until the carcass is concealed and buried.
3. Both males and females practice parental care. Maturing broods are tended by no adults, a single female, a single male, or a male—female pair. No differences in brood success were observed among these categories.
4. The female lays a larger clutch than ultimately will survive. Brood size is regulated after the egg stage, such that offspring number varies, but individual offspring size does not.
5. A large amount of unexplained variation exists in brood size, in both the laboratory and the field. This variation is probably caused by the environment, and not the reproductive physiology of the beetles. Competition with microbes is a likely candidate.
6. Differences exist not only between Nicrophorus species, but also between localities for a single species, suggesting adaptation to local environments.     

Stereotyped Burying Behavior in Sicarius

SYNOPSIS. The burying behavior in two South American forms ofthe haplogyne spider genus Sicarius is cinematographically analyzedand found to be qualitatively stereotypic with 16 successive,distinct steps comprising the whole behavior. This ethologicalcharacter is therefore of potentially great systematic value. The quantitative (time) relationships of the components of thebehavior are more variable and probably controlled by certainfeedback mechanisms. Several possible functional explanations are suggested, a defensivefunction appearing most probable.     

不同小蠹类与天牛类引诱剂联用对蛀干甲虫的林间诱捕效果

松墨天牛Monochamus alternatus Hope是传播松材线虫病的主要媒介,引诱剂是抑制松墨天牛种群数量的无公害调控有效方式之一。本研究通过在中国浙江富阳的林间试验测定了6种小蠹类引诱剂与1种天牛引诱剂不同组合联用对松墨天牛成虫以及其他蛀干害虫的诱捕效果。结果表明： 横坑切梢小蠹Tomicus minor引诱剂3-carene-10-ol、云杉八齿小蠹Ips typographus引诱剂2-methyl-3-buten-2-ol、欧洲榆小蠹Scolytus multistriatus引诱剂4-methyl-3-heptanol和纵坑切梢小蠹T. piniperda引诱剂verbenol分别与松墨天牛引诱剂联用后,对松墨天牛的引诱效果无显著性差异(P<0.05)。西部松大小蠹Dendroctonus brevicomis 引诱剂exo-brevicomin或黄杉大小蠹D. pseudotsugae引诱剂1-methylcyclohex-2-en-l-ol与松墨天牛引诱剂联用后对松墨天牛的诱捕效果有减弱的趋势。另外,与单独使用中国天牛引诱剂相比,小蠹类引诱剂与其联用后在诱捕其他蛀干害虫的种类和个体数量上均有所减少。     

Habitat Fragmentation and Burying Beetle Abundance and Success

Four species of burying beetle (Nicrophorus marginatus F., N. tomentosus Weber, N. orbicollis Say and N. defodiens Mannerheim) are attracted to small, fresh mouse carcasses in northern Michigan. The number of burying beetles and their success (burial of a carcass) were greater in woodlands than in edge or field habitats. Species diversity was least in open fields as assessed by two different indices of diversity. Nicrophorus marginatus was the only species captured in large fields (<25ha). This species was never trapped in small fields (>5ha) suggesting that a minimum habitat size might be necessary to maintain local populations. In contrast to previous studies which employed pitfall traps baited with a large quantity of carrion, N. tomentosus was caught exclusively in woodlands at single mouse carcasses. In Connecticut woodlands, burying beetle success, assayed as the proportion of carcasses buried and held for 7 days, was significantly greater in larger as compared to smaller woodlands. The limited success of burying beetles in smaller woodlands was due, in part, to a higher rate of scavenging by vertebrates.     

人文世界里的锹甲

锹甲作为一类观赏昆虫在人文世界里受到长久的关注,文章对人文世界里的锹甲进行回顾：综述不同国家和地区中锹甲的多种称谓;从历史文化角度追溯锹甲学名的由来、锹甲与天牛科学名的关系、欧洲宗教中的锹甲、民间故事与风俗中的锹甲;从艺术欣赏角度介绍锹甲与绘画、锹甲与邮票、锹甲与装饰;着眼与现实生活,对锹甲的综合现状进行评述,并总结锹甲作为物种正面临的问题,呼吁人们在欣赏锹甲的同时,更要关注锹甲的物种多样性保护。     

Burying beetle Nicrophorus investigator reproduction on Pacific salmon carcasses

Abstract.  1. In many undisturbed watersheds along the Pacific Rim, anadromous salmon ( Oncorhynchus spp.) provide a predictable source of carrion to the riparian zone, largely due to horizontal transfer of salmon carcasses by bears ( Ursus spp.) and other vertebrates.
2. Burying beetles are important members of the north-temperate carrion fauna, and may utilise salmon carcasses and remnants for breeding. In this study, isotopic and observational data are reported that demonstrate previously unrecognised Nicrophorus investigator (Zetterstedt) reproduction on large salmon carcasses from five watersheds in coastal British Columbia.
3. Stable isotope signatures (δ¹⁵N and δ¹³C) of adult beetles collected in autumn indicate a diet of salmon origin in all but one individual from all watersheds, suggesting that this beetle–salmon association is widespread. Comparison of autumn isotope signatures to individuals collected randomly in summer suggests that isotope signatures represent the larval carrion source from the previous autumn rather than immediate adult diet.
4. In a survey of N. investigator use of salmon carcasses from two watersheds, 35 broods were observed on chum and pink salmon carcasses, including 16 natural brood complexes containing over 100 larvae, and five ranging from 250 to 750 larvae.
5. Overall, north-coastal populations of N. investigator breed on the rich and reliable salmon resource and may exhibit a system of communal breeding on these carcasses. This is most relevant when the dramatic reduction in salmon spawning biomass over the last century is considered.     

The Costs of Confronting Infanticidal Intruders in a Burying Beetle

Infanticide by unrelated adults is a complex behavior in burying beetles (Nicrophorus spp.) serving multiple functions (resource competition, access to mates, cannibalism). The costs of confronting an infanticidal intruder are likely to vary with context. To assess these costs for a single female parent (Nicrophorus pustulatus), we systematically manipulated the sex of a conspecific intruder and the timing of the intrusion. Male intruders were a greater takeover threat than female intruders, and infanticidal takeovers were more common earlier in the breeding cycle. Even though a male intruder posed a greater threat to the brood, a female intruder was a greater threat to the reproductive success of the resident female. Female intruders that took over a carcass excluded the resident female from the resource. When a male intruder took over a carcass, the resident female was able to recover much of her loss by producing a replacement brood. Even when females successfully defended their broods, they suffered decreased reproductive output relative to control females that never had to confront an intruder (expt 1), but the mechanisms underlying this cost were unclear. To test the hypothesis that defeated female intruders attempt to parasitize late‐stage broods, female intruders whose eggs could be identified by a fat‐soluble dye were introduced to resident females caring for larvae (expt 2). Fifteen of 20 intruders oviposited eggs and the number of eggs were related to intrusion pressure. Because resident females rarely produced eggs while caring for larvae, it is uncertain whether the behavior of the defeated female should be characterized as brood parasitism, a failed takeover attempt, or an attempt to use the remains of the depleted resource. This study provides the most complete picture of the changing costs of confronting an infanticidal threat throughout the vulnerable period of offspring development.     

Developmental constraints in cave beetles

In insects, whilst variations in life cycles are common, the basic patterns typical for particular groups remain generally conserved. One of the more extreme modifications is found in some subterranean beetles of the tribe Leptodirini, in which the number of larval instars is reduced from the ancestral three to two and ultimately one, which is not active and does not feed. We analysed all available data on the duration and size of the different developmental stages and compared them in a phylogenetic context. The total duration of development was found to be strongly conserved, irrespective of geographical location, habitat type, number of instars and feeding behaviour of the larvae, with a single alteration of the developmental pattern in a clade of cave species in southeast France. We also found a strong correlation of the size of the first instar larva with adult size, again regardless of geographical location, ecology and type of life cycle. Both results suggest the presence of deeply conserved constraints in the timing and energy requirements of larval development. Past focus on more apparent changes, such as the number of larval instars, may mask more deeply conserved ontogenetic patterns in developmental timing.     

植食性金龟子信息化学物质的研究

金龟子信息化学物质包括性信息素、聚集信息素和植物源引诱剂。目前已鉴定出的性信息素大多集中于丽金龟科和鳃金龟科,犀金龟科只鉴定出了几种聚集信息素,有关植物源引诱剂方面的研究则集中于丽金龟科和花金龟科。本文总结了金龟子信息化学物质的化学结构特点,并评述了金龟子化学通讯中独特的手性性信息素相互拮抗作用及性信息素生物合成的研究。     

Pathogens of bark beetles (Curculionidae: Scolytinae) and other beetles in Bulgaria

The presence and diversity of beetle pathogens associated with different tree species in Bulgaria was investigated. In total, 818 specimens belonging to 22 beetle species were examined. Pathogens occurred in 9 host species. The infections were found in the gut (virus, nematodes, protozoans, microsporidia) and haemolymph (nematodes) of the infected insects. The following pathogen species: ItEPV, Beauveria bassiana, B. brongniartii, Isaria farinosa, Gregarina typographi, Gregarina spp., Chytridiopsis typographi, Chytridiopsis sp., and nematodes were revealed. Insects with mycoses were mummified and filled up with fungal structures, formed pseudosclerotium. Most pathogens were established in bark beetles (Scolytinae). For the first time, the fungus B. bassiana was reported in Tomicus piniperda, Orthotomicus longicollis, O. erosus, X. spinole, Taphrorychus villifrons and Phylobius sp. in Bulgaria. We also present the first records of gregarines in O. longicollis, Acanthocinus aedilis, Rhagium inquisitor, Pyrochroa coccinea, and of the microsporidium Chytridiopsis sp. in O. longicollis.     

Population dynamics of gyrinid beetles

Summary Survival chances have been estimated for populations of the waterbeetle Gyrinus marinus Gyll. from capture-recapture sequences in 1974–1978. The average weekly survival chance is estimated as 0.9247 in spring, decreasing to 0.7701 in autumn; males survive longer than females. Survival shows little variation in time or space (variation coefficient V<0.1). Survival chance did not significantly decrease with age. Freshly emerged tenerals apparently have a lower survival chance than older beetles. The survival chance during hibernation (October–April) is about 0.33, with a greater variation between years (V=0.7) than between populations (V=0.4).Communication N⁰ 301 of the Biological Station, Wijster     

Niche relations among dung-inhabiting beetles

Summary The whole dung-inhabiting (adult) beetle community living in southern Finland was studied with reference to the seasonal (6 summer months), macrohabitat (open field, half-open pine forest and closed spruce forest) and successional (30 days) gradients. The material comprised 50 coprophagous and 129 carnivorous species, represented by 26,650 and 35,850 individuals, respectively. The most important characteristics of each species are given in an Appendix.In the coprophages the species-abundance relations fitted the lognormal distribution well, but in the carnivores the distribution was strikingly less even. A great number of other differences (see below) apparent between the two trophic groups were explained as the result of a difference in the degree of specialization, apart from the difference in their trophic position: coprophages are microhabitat (dung) and food specialists, while carnivores are microhabitat generalists (and therefore their critical niche space was not completely covered in this study).In the coprophages, two important species guilds were observed: the first occurred at the very geginning of the succession (mean position 2.5 days), and consisted mainly of true dung specialists; the second guild contained species with wider utilization along the successional dimension (mean position 6.5 days), and species of more generalist nature (saprophages). The utilization of carnivores along the successional gradient was more continuous, probably because of their more diversified food resources. The total niche width among the coprophages increased from early successional species to species occurring mainly later on, but was more constant in carnivores. The environmental dimensions proved to be totally independent of each other among the carnivores, while the coprophages showed a clear supplementary relationship along them. Among the carnivores, a spherical niche shape dominated, but among the coprophages elongated and disk-liked shapes were also well represented, especially in specialist species. In both groups, a significant positive correlation existed between niche width and dominance, but not between niche width and abundance. It is suggested that the patchy distribution and transient occurrence of suitable microhabitats contributes to the coexistence of many ecologically similar species.